National Library of Energy BETA

Sample records for determination modeling carbon

  1. Experimental determination of lead carbonate solubility at high ionic strengths: A Pitzer model description

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Xiong, Yongliang

    2015-05-06

    In this article, solubility measurements of lead carbonate, PbCO3(cr), cerussite, as a function of total ionic strengths are conducted in the mixtures of NaCl and NaHCO3 up to I = 1.2 mol•kg–1 and in the mixtures of NaHCO3 and Na2CO3 up to I = 5.2 mol•kg–1, at room temperature (22.5 ± 0.5 °C). The solubility constant (log Ksp) for cerussite, PbCO3(cr) = Pb2+ + CO32- was determined as –13.76 ± 0.15 (2σ) with a set of Pitzer parameters describing the specific interactions of PbCO3(aq), Pb(CO3)22-, and Pb(CO3)Cl– with the bulk-supporting electrolytes, based on the Pitzer model. The model developed inmore » this work can reproduce the experimental results including model-independent solubility values from the literature over a wide range of ionic strengths with satisfactory accuracy. The model is expected to find applications in numerous fields, including the accurate description of chemical behavior of lead in geological repositories, the modeling of formation of oxidized Pb–Zn ore deposits, and the environmental remediation of lead contamination.« less

  2. Experimental determination of lead carbonate solubility at high ionic strengths: A Pitzer model description

    SciTech Connect (OSTI)

    Xiong, Yongliang

    2015-05-06

    In this article, solubility measurements of lead carbonate, PbCO3(cr), cerussite, as a function of total ionic strengths are conducted in the mixtures of NaCl and NaHCO3 up to I = 1.2 mol•kg–1 and in the mixtures of NaHCO3 and Na2CO3 up to I = 5.2 mol•kg–1, at room temperature (22.5 ± 0.5 °C). The solubility constant (log Ksp) for cerussite, PbCO3(cr) = Pb2+ + CO32- was determined as –13.76 ± 0.15 (2σ) with a set of Pitzer parameters describing the specific interactions of PbCO3(aq), Pb(CO3)22-, and Pb(CO3)Cl with the bulk-supporting electrolytes, based on the Pitzer model. The model developed in this work can reproduce the experimental results including model-independent solubility values from the literature over a wide range of ionic strengths with satisfactory accuracy. The model is expected to find applications in numerous fields, including the accurate description of chemical behavior of lead in geological repositories, the modeling of formation of oxidized Pb–Zn ore deposits, and the environmental remediation of lead contamination.

  3. Use of molecular modeling to determine the interaction and competition of gases within coal for carbon dioxide sequestration

    SciTech Connect (OSTI)

    Jeffrey D. Evanseck; Jeffry D. Madura; Jonathan P. Mathews

    2006-04-21

    Molecular modeling was employed to both visualize and probe our understanding of carbon dioxide sequestration within a bituminous coal. A large-scale (>20,000 atoms) 3D molecular representation of Pocahontas No. 3 coal was generated. This model was constructed based on a the review data of Stock and Muntean, oxidation and decarboxylation data for aromatic clustersize frequency of Stock and Obeng, and the combination of Laser Desorption Mass Spectrometry data with HRTEM, enabled the inclusion of a molecular weight distribution. The model contains 21,931 atoms, with a molecular mass of 174,873 amu, and an average molecular weight of 714 amu, with 201 structural components. The structure was evaluated based on several characteristics to ensure a reasonable constitution (chemical and physical representation). The helium density of Pocahontas No. 3 coal is 1.34 g/cm{sup 3} (dmmf) and the model was 1.27 g/cm{sup 3}. The structure is microporous, with a pore volume comprising 34% of the volume as expected for a coal of this rank. The representation was used to visualize CO{sub 2}, and CH{sub 4} capacity, and the role of moisture in swelling and CO{sub 2}, and CH{sub 4} capacity reduction. Inclusion of 0.68% moisture by mass (ash-free) enabled the model to swell by 1.2% (volume). Inclusion of CO{sub 2} enabled volumetric swelling of 4%.

  4. Simple ocean carbon cycle models

    SciTech Connect (OSTI)

    Caldeira, K.; Hoffert, M.I.; Siegenthaler, U.

    1994-02-01

    Simple ocean carbon cycle models can be used to calculate the rate at which the oceans are likely to absorb CO{sub 2} from the atmosphere. For problems involving steady-state ocean circulation, well calibrated ocean models produce results that are very similar to results obtained using general circulation models. Hence, simple ocean carbon cycle models may be appropriate for use in studies in which the time or expense of running large scale general circulation models would be prohibitive. Simple ocean models have the advantage of being based on a small number of explicit assumptions. The simplicity of these ocean models facilitates the understanding of model results.

  5. Integrated Climate and Carbon-cycle Model

    Energy Science and Technology Software Center (OSTI)

    2006-03-06

    The INCCA model is a numerical climate and carbon cycle modeling tool for use in studying climate change and carbon cycle science. The model includes atmosphere, ocean, land surface, and sea ice components.

  6. Determination of Total Petroleum Hydrocarbons (TPH) Using Total Carbon Analysis

    SciTech Connect (OSTI)

    Ekechukwu, A.A.

    2002-05-10

    Several methods have been proposed to replace the Freon(TM)-extraction method to determine total petroleum hydrocarbon (TPH) content. For reasons of cost, sensitivity, precision, or simplicity, none of the replacement methods are feasible for analysis of radioactive samples at our facility. We have developed a method to measure total petroleum hydrocarbon content in aqueous sample matrixes using total organic carbon (total carbon) determination. The total carbon content (TC1) of the sample is measured using a total organic carbon analyzer. The sample is then contacted with a small volume of non-pokar solvent to extract the total petroleum hydrocarbons. The total carbon content of the resultant aqueous phase of the extracted sample (TC2) is measured. Total petroleum hydrocarbon content is calculated (TPH = TC1-TC2). The resultant data are consistent with results obtained using Freon(TM) extraction followed by infrared absorbance.

  7. Modeling the Impact of Carbon Dioxide Leakage into an Unconfined...

    Office of Scientific and Technical Information (OSTI)

    the Impact of Carbon Dioxide Leakage into an Unconfined, Oxidizing Carbonate Aquifer Citation Details In-Document Search Title: Modeling the Impact of Carbon Dioxide Leakage ...

  8. A universal model for nanoporous carbon supercapacitors

    SciTech Connect (OSTI)

    Huang, Jingsong; Sumpter, Bobby G; Meunier, Vincent

    2009-01-01

    Supercapacitors based on nanoporous carbon materials, commonly called electric double-layer capacitors (EDLCs), are emerging as a novel type of energy-storage device with the potential to substitute batteries in applications that require high power densities. Nanoporous carbon supercapacitors are generally viewed as a parallel-plate capacitor since supercapacitors store energy by charge separation in an electric double layer formed at the electrode/electrolyte interface. The EDLC model has been used to characterize the energy storage of supercapacitors for decades. We comment in this chapter on the shortcomings of the EDLC model when applied to nanoporous carbon supercapacitors. In response to the latest experimental breakthrough in nanoporous carbon supercapacitors, we have proposed a heuristic model that takes pore curvature into account as a replacement for the EDLC model. When the pore size is in the mesopore regime (2 50 nm), electrolyte counterions enter mesoporous carbons and approach the pore wall to form an electric double-cylinder capacitor (EDCC); in the micropore regime (< 2 nm), solvated/desolvated counterions line up along the pore axis to form an electric wire-in-cylinder capacitor (EWCC). In the macropore regime (> 50 nm), where pores are large enough so that pore curvature is no longer significant, the EDCC model can be reduced to the EDLC model. With the backing of experimental data and quantum density functional theory calculations, we have shown that the EDCC/EWCC model is universal for carbon supercapacitors with diverse carbon materials and electrolytes. The strengths and limitations of this new model are discussed. The new model allows the supercapacitor properties to be correlated with pore size, specific surface area, Debye length, electrolyte concentration, dielectric constant, and solute ion size, and may lend support to the systematic optimization of the properties of carbon supercapacitors through experiments.

  9. Theoretical Model for Nanoporous Carbon Supercapacitors

    SciTech Connect (OSTI)

    Sumpter, Bobby G; Meunier, Vincent; Huang, Jingsong

    2008-01-01

    The unprecedented anomalous increase in capacitance of nanoporous carbon supercapacitors at pore sizes smaller than 1 nm [Science 2006, 313, 1760.] challenges the long-held presumption that pores smaller than the size of solvated electrolyte ions do not contribute to energy storage. We propose a heuristic model to replace the commonly used model for an electric double-layer capacitor (EDLC) on the basis of an electric double-cylinder capacitor (EDCC) for mesopores (2 {50 nm pore size), which becomes an electric wire-in-cylinder capacitor (EWCC) for micropores (< 2 nm pore size). Our analysis of the available experimental data in the micropore regime is confirmed by 1st principles density functional theory calculations and reveals significant curvature effects for carbon capacitance. The EDCC (and/or EWCC) model allows the supercapacitor properties to be correlated with pore size, specific surface area, Debye length, electrolyte concentration and dielectric constant, and solute ion size. The new model not only explains the experimental data, but also offers a practical direction for the optimization of the properties of carbon supercapacitors through experiments.

  10. Low Carbon Development: Planning & Modelling Course | Open Energy...

    Open Energy Info (EERE)

    & Modelling Course Jump to: navigation, search Tool Summary LAUNCH TOOL Name: Low Carbon Development: Planning & Modelling Course AgencyCompany Organization: World Bank...

  11. Silicon Carbide Derived Carbons: Experiments and Modeling

    SciTech Connect (OSTI)

    Kertesz, Miklos

    2011-02-28

    The main results of the computational modeling was: 1. Development of a new genealogical algorithm to generate vacancy clusters in diamond starting from monovacancies combined with energy criteria based on TBDFT energetics. The method revealed that for smaller vacancy clusters the energetically optimal shapes are compact but for larger sizes they tend to show graphitized regions. In fact smaller clusters of the size as small as 12 already show signatures of this ?¢????graphitization?¢????. The modeling gives firm basis for the ?¢????slit-pore?¢???? modeling of porous carbon materials and explains some of their properties. 2. We discovered small vacancy clusters and their physical characteristics that can be used to spectroscopically identify them. 3. We found low barrier pathways for vacancy migration in diamond-like materials by obtaining for the first time optimized reaction pathways.

  12. Ab Initio Thermodynamic Model for Magnesium Carbonates and Hydrates

    SciTech Connect (OSTI)

    Chaka, Anne M.; Felmy, Andrew R.

    2014-03-28

    An ab initio thermodynamic framework for predicting properties of hydrated magnesium carbonate minerals has been developed using density-functional theory linked to macroscopic thermodynamics through the experimental chemical potentials for MgO, water, and CO2. Including semiempirical dispersion via the Grimme method and small corrections to the generalized gradient approximation of Perdew, Burke, and Ernzerhof for the heat of formation yields a model with quantitative agreement for the benchmark minerals brucite, magnesite, nesquehonite, and hydromagnesite. The model shows how small differences in experimental conditions determine whether nesquehonite, hydromagnesite, or magnesite is the result of laboratory synthesis from carbonation of brucite, and what transformations are expected to occur on geological time scales. Because of the reliance on parameter-free first principles methods, the model is reliably extensible to experimental conditions not readily accessible to experiment and to any mineral composition for which the structure is known or can be hypothesized, including structures containing defects, substitutions, or transitional structures during solid state transformations induced by temperature changes or processes such as water, CO2, or O2 diffusion. Demonstrated applications of the ab initio thermodynamic framework include an independent means to evaluate differences in thermodynamic data for lansfordite, predicting the properties of Mg analogs of Ca-based hydrated carbonates monohydrocalcite and ikaite which have not been observed in nature, and an estimation of the thermodynamics of barringtonite from the stoichiometry and a single experimental observation.

  13. Pore Models Track Reactions in Underground Carbon Capture

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Pore Models Track Reactions in Underground Carbon Capture Pore Models Track Reactions in Underground Carbon Capture September 25, 2014 trebotich2 Computed pH on calcite grains at 1 micron resolution. The iridescent grains mimic crushed material geoscientists extract from saline aquifers deep underground to study with microscopes. Researchers want to model what happens to the crystals' geochemistry when the greenhouse gas carbon dioxide is injected underground for sequestration. Image courtesy of

  14. New Computer Model Pinpoints Prime Materials for Carbon Capture

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Computer Model Pinpoints Prime Materials for Carbon Capture New Computer Model Pinpoints Prime Materials for Carbon Capture July 17, 2012 NERSC Contact: Linda Vu, lvu@lbl.gov, +1 510 495 2402 UC Berkeley Contact: Robert Sanders, rsanders@berkeley.edu zeolite350.jpg One of the 50 best zeolite structures for capturing carbon dioxide. Zeolite is a porous solid made of silicon dioxide, or quartz. In the model, the red balls are oxygen, the tan balls are silicon. The blue-green area is where carbon

  15. Carbon Mineralizability Determines Interactive Effects on Mineralization of Pyrogenic Organic Matter and Soil Organic Carbon

    SciTech Connect (OSTI)

    Whitman, Thea L.; Zhu, Zihua; Lehmann, Johannes C.

    2014-10-31

    Soil organic carbon (SOC) is a critical and active pool in the global C cycle, and the addition of pyrogenic organic matter (PyOM) has been shown to change SOC cycling, increasing or decreasing mineralization rates (often referred to as priming). We adjusted the amount of easily mineralizable C in the soil, through 1-day and 6-month pre-incubations, and in PyOM made from maple wood at 350°C, through extraction. We investigated the impact of these adjustments on C mineralization interactions, excluding pH and nutrient effects and minimizing physical effects. We found short-term increases (+20-30%) in SOC mineralization with PyOM additions in the soil pre-incubated for 6 months. Over the longer term, both the 6-month and 1-day pre-incubated soils experienced net ~10% decreases in SOC mineralization with PyOM additions. This was possibly due to stabilization of SOC on PyOM surfaces, suggested by nanoscale secondary ion mass spectrometry. Additionally, the duration of pre-incubation affected priming interactions, indicating that there may be no optimal pre-incubation time for SOC mineralization studies. We show conclusively that relative mineralizability of SOC in relation to PyOM-24 C is an important determinant of the effect of PyOM additions on SOC mineralization.

  16. Modeling the Impact of Carbon Dioxide Leakage into an Unconfined, Oxidizing Carbonate Aquifer

    SciTech Connect (OSTI)

    Bacon, Diana H.; Qafoku, Nikolla; Dai, Zhenxue; Keating, Elizabeth; Brown, Christopher F.

    2016-01-01

    Multiphase, reactive transport modeling was used to identify the mechanisms controlling trace metal release under elevated CO2 conditions from a well-characterized carbonate aquifer. Modeling was conducted for two experimental scenarios: batch experiments to simulate sudden, fast, and short-lived release of CO2 as would occur in the case of well failure during injection, and column experiments to simulate more gradual leaks such as those occurring along undetected faults, fractures, or well linings. Observed and predicted trace metal concentrations are compared to groundwater concentrations from this aquifer to determine the potential for leaking CO2 to adversely impact drinking water quality. Finally, a three-dimensional multiphase flow and reactive-transport simulation of CO2 leakage from an abandoned wellbore into a generalized model of the shallow, unconfined portion of the aquifer is used to determine potential impacts on groundwater quality. As a measure of adverse impacts on groundwater quality, both the EPAs MCL limits and the maximum trace metal concentration observed in the aquifer were used as threshold values.

  17. Determination of carbon distributions in quenched and partitioned microstructures using nanoscale secondary ion mass spectroscopy

    SciTech Connect (OSTI)

    Choi, Kyoo Sil; Zhu, Zihua; Sun, Xin; De Moor, Emmanuel; Taylor, Mark D.; Speer, John; Matlock, David K.

    2015-04-20

    A multi-modal characterization technique, which combines nanoscale secondary ion mass spectroscopy (Nano-SIMS) with a spatial resolution of ~100 nm and electron back scatter diffraction (EBSD) to determine carbon distributions in austenite and martensite in a quenched and partitioned (Q&P) Fe-0.29C-2.95Mn-1.59Si steel is presented. Significant carbon enrichment of austenite was measured with decreased levels of carbon in martensite, supporting the carbon partitioning mechanism. Fresh untempered martensite could be identified, and different degrees of enrichment were observed for blocky and lath austenite.

  18. Getting Forest Carbon Right in Climate Models | U.S. DOE Office...

    Office of Science (SC) Website

    Getting Forest Carbon Right in Climate Models Biological and Environmental Research (BER) ... Getting Forest Carbon Right in Climate Models New method predicts how climates will move ...

  19. Determining Reduced Order Models for Optimal Stochastic Reduced Order Models

    SciTech Connect (OSTI)

    Bonney, Matthew S.; Brake, Matthew R.W.

    2015-08-01

    The use of parameterized reduced order models(PROMs) within the stochastic reduced order model (SROM) framework is a logical progression for both methods. In this report, five different parameterized reduced order models are selected and critiqued against the other models along with truth model for the example of the Brake-Reuss beam. The models are: a Taylor series using finite difference, a proper orthogonal decomposition of the the output, a Craig-Bampton representation of the model, a method that uses Hyper-Dual numbers to determine the sensitivities, and a Meta-Model method that uses the Hyper-Dual results and constructs a polynomial curve to better represent the output data. The methods are compared against a parameter sweep and a distribution propagation where the first four statistical moments are used as a comparison. Each method produces very accurate results with the Craig-Bampton reduction having the least accurate results. The models are also compared based on time requirements for the evaluation of each model where the Meta- Model requires the least amount of time for computation by a significant amount. Each of the five models provided accurate results in a reasonable time frame. The determination of which model to use is dependent on the availability of the high-fidelity model and how many evaluations can be performed. Analysis of the output distribution is examined by using a large Monte-Carlo simulation along with a reduced simulation using Latin Hypercube and the stochastic reduced order model sampling technique. Both techniques produced accurate results. The stochastic reduced order modeling technique produced less error when compared to an exhaustive sampling for the majority of methods.

  20. A Universal Model for Nanoporous Carbon Supercapacitors Applicable to Diverse Pore Regimes, Carbons, and Electrolyte

    SciTech Connect (OSTI)

    Sumpter, Bobby G; Huang, Jingsong; Meunier, Vincent

    2008-01-01

    Supercapacitors, commonly called electric double-layer capacitors (EDLCs), are emerging as a novel type of energy storage device with the potential to substitute batteries in applications requiring high power densities. In response to the latest experimental breakthrough in nanoporous carbon supercapacitors, we propose a heuristic theoretical model that takes pore curvature into account as a replacement for the EDLC model which is based on a traditional parallel-plate capacitor. When the pore size is in the mesopore regime (2-50 nm), counterions enter mesoporous carbons and approach the pore wall to form an electric double-cylinder capacitor (EDCC); in the micropore regime (< 2 nm), solvated/desolvated counterions line up along the pore axis to form an electric wire-in-cylinder capacitor (EWCC). In the macropore regime (> 50 nm) where pores are large enough so that the pore curvature is no longer significant, the EDCC model can be reduced naturally to the EDLC model. We present density functional theory calculations and detailed analyses of available experimental data in various pore regimes, showing the significant effects of pore curvature on the supercapacitor properties of nanoporous carbons. It is shown that the EDCC/EWCC model is universal to carbon supercapacitors with diverse carbon materials including activated carbons, template carbons, and novel carbide-derived carbons, and with diverse electrolytes including organic electrolytes such as tetraethylammonium tetrafluoroborate (TEABF4), tetraethylammonium methyl-sulfonate (TEAMS) in acetonitrile, aqueous H2SO4 and KOH electrolytes, and even ionic liquid electrolyte such as 1-ethyl-3-methylimmidazolium bis(trifluromethane-sulfonyl)imide (EMI-TFSI). The EDCC/EWCC model allows the supercapacitor properties to be correlated with pore size, specific surface area, Debye length, electrolyte concentration and dielectric constant, and solute ion size, and may lend a support for the systematic optimization of the

  1. Substrate and environmental controls on microbial assimilation of soil organic carbon: a framework for Earth System Models

    SciTech Connect (OSTI)

    Xu, Xiaofeng; Schimel, Joshua; Thornton, Peter E; Song, Xia; Yuan, Fengming; Goswami, Santonu

    2014-01-01

    Microbial assimilation of soil organic carbon is one of the fundamental processes of global carbon cycling and it determines the magnitude of microbial biomass in soils. Mechanistic understanding of microbial assimilation of soil organic carbon and its controls is important for to improve Earth system models ability to simulate carbon-climate feedbacks. Although microbial assimilation of soil organic carbon is broadly considered to be an important parameter, it really comprises two separate physiological processes: one-time assimilation efficiency and time-dependent microbial maintenance energy. Representing of these two mechanisms is crucial to more accurately simulate carbon cycling in soils. In this study, a simple modeling framework was developed to evaluate the substrate and environmental controls on microbial assimilation of soil organic carbon using a new term: microbial annual active period (the length of microbes remaining active in one year). Substrate quality has a positive effect on microbial assimilation of soil organic carbon: higher substrate quality (lower C:N ratio) leads to higher ratio of microbial carbon to soil organic carbon and vice versa. Increases in microbial annual active period from zero stimulate microbial assimilation of soil organic carbon; however, when microbial annual active period is longer than an optimal threshold, increasing this period decreases microbial biomass. The simulated ratios of soil microbial biomass to soil organic carbon are reasonably consistent with a recently compiled global dataset at the biome-level. The modeling framework of microbial assimilation of soil organic carbon and its controls developed in this study offers an applicable ways to incorporate microbial contributions to the carbon cycling into Earth system models for simulating carbon-climate feedbacks and to explain global patterns of microbial biomass.

  2. Simulation of carbon gasification kinetics using an edge recession model

    SciTech Connect (OSTI)

    Takashi Kyotani; Leon y Leon, C.A.L.; Radovic, L.R. )

    1993-07-01

    An edge recession modeling method is proposed as a new approach to the prediction of carbon gasification kinetics. Using this method, the variations in reactive surface area (RSA) and specific reactivity (R) with conversion were simulated for several polynuclear aromatic molecules adopted as models of carbon crystallites. The effects of crystallite size and shape, edge site reactivity and vacancies on the changes in RSA and R with conversion were investigated. As a result, RSA and R were found to be essentially independent of crystallite shape, but to depend on crystallite size and the presence of vacancies. Good agreement was obtained between model predictions and experimental data for several kinds of model carbon crystallites. In the case of structurally disordered carbons (such as chars), simultaneous gasification of model crystallites of two different sizes gave better predictions than that of single-size crystallites. The edge recession model is proposed as an alternative, or at least complementary, approach to the more conventional (and, arguably, less physically meaningful) pore structure development models.

  3. Reduced-Order Model for the Geochemical Impacts of Carbon Dioxide...

    Office of Scientific and Technical Information (OSTI)

    Reduced-Order Model for the Geochemical Impacts of Carbon Dioxide, Brine and Trace Metal Leakage into an Unconfined, Oxidizing Carbonate Aquifer, Version 2.1 Citation Details...

  4. Reduced-Order Model for the Geochemical Impacts of Carbon Dioxide...

    Office of Scientific and Technical Information (OSTI)

    Reduced-Order Model for the Geochemical Impacts of Carbon Dioxide, Brine and Trace Metal Leakage into an Unconfined, Oxidizing Carbonate Aquifer, Version 2.1 Bacon, Diana H. carbon...

  5. Computer Modeling of Carbon Metabolism Enables Biofuel Engineering (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2011-09-01

    In an effort to reduce the cost of biofuels, the National Renewable Energy Laboratory (NREL) has merged biochemistry with modern computing and mathematics. The result is a model of carbon metabolism that will help researchers understand and engineer the process of photosynthesis for optimal biofuel production.

  6. Soil carbon sensitivity to temperature and carbon use efficiency compared across microbial-ecosystem models of varying complexity

    SciTech Connect (OSTI)

    Li, Jianwei; Wang, Gangsheng; Allison, Steven D.; Mayes, Melanie; Luo, Yiqi

    2014-01-01

    Global ecosystem models may require microbial components to accurately predict feedbacks between climate warming and soil decomposition, but it is unclear what parameters and levels of complexity are ideal for scaling up to the globe. Here we conducted a model comparison using a conventional model with first-order decay and three microbial models of increasing complexity that simulate short- to long-term soil carbon dynamics. We focused on soil carbon responses to microbial carbon use efficiency (CUE) and temperature. Three scenarios were implemented in all models: constant CUE (held at 0.31), varied CUE ( 0.016 C 1), and 50 % acclimated CUE ( 0.008 C 1). Whereas the conventional model always showed soil carbon losses with increasing temperature, the microbial models each predicted a temperature threshold above which warming led to soil carbon gain. The location of this threshold depended on CUE scenario, with higher temperature thresholds under the acclimated and constant scenarios. This result suggests that the temperature sensitivity of CUE and the structure of the soil carbon model together regulate the long-term soil carbon response to warming. Equilibrium soil carbon stocks predicted by the microbial models were much less sensitive to changing inputs compared to the conventional model. Although many soil carbon dynamics were similar across microbial models, the most complex model showed less pronounced oscillations. Thus, adding model complexity (i.e. including enzyme pools) could improve the mechanistic representation of soil carbon dynamics during the transient phase in certain ecosystems. This study suggests that model structure and CUE parameterization should be carefully evaluated when scaling up microbial models to ecosystems and the globe.

  7. Ocean Carbon Cycle Models from the Carbon Dioxide Information Analysis Center (CDIAC)

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    The following Ocean Carbon Cycle models and modeling results are available from CDIAC: • CSIRO/Matear Data [Model simulation of climate change from 1880 till 2100 (Matear and Hirst 2003, GBC) • Lequere Data, Model Results • McKinley MITgcm offline biogeochemical model - posted May 2004 • McKinley MITgcm offline biogeochemical model - posted December 2004 • NCOM-Pacific-Biogeochemical Modeling Results from Fei Chai • ROMS-Pacific-Biogeochemical Modeling Results from Fei CHai • WHOI/NCAR/Irvine Eco-BGC (Doney, Moore, Lindsay, and Lima) - Posted May 2005 • Max-Planck-Institut f?r Biogeochemie (Lequere, Buitenhuis) Modeling Results • Max-Planck-Institut f?r Biogeochemie (Lequere, Buitenhuis) Modeling Results - Posted March 2005 • Jim Christian model output for (a) Climatologies of T, S, PO4 at 50 m depth intervals; (b) SST, SSS, MLD, pCO2, CO2 flux from 1990-2003, and (c) climatological surface horizontal velocity • Max-Planck-Institut f?r Biogeochemie (Lequere, Buitenhuis) Modeling Results • Deutsch (UW) model output results for Oxygen variability in the North Pacific • Pacific data-model intercomparison from Patrick Wetzel (Max Planck Institute for Meteorology, Germany)

  8. Modeling of Carbon Migration During JET Injection Experiments

    SciTech Connect (OSTI)

    Strachan, J. D.; Likonen, J.; Coad, P.; Rubel, M.; Widdowson, A.; Airila, M.; Andrew, P.; Brezinsek, S.; Corrigan, G.; Esser, H. G.; Jachmich, S.; Kallenbach, A.; Kirschner, A.; Kreter, A.; Matthews, G. F.; Philipps, V.; Pitts, R. A.; Spence, J.; Stamp, M.; Wiesen, S.

    2008-10-15

    JET has performed two dedicated carbon migration experiments on the final run day of separate campaigns (2001 and 2004) using {sup 13}CH{sub 4} methane injected into repeated discharges. The EDGE2D/NIMBUS code modelled the carbon migration in both experiments. This paper describes this modelling and identifies a number of important migration pathways: (1) deposition and erosion near the injection location, (2) migration through the main chamber SOL, (3) migration through the private flux region aided by E x B drifts, and (4) neutral migration originating near the strike points. In H-Mode, type I ELMs are calculated to influence the migration by enhancing erosion during the ELM peak and increasing the long-range migration immediately following the ELM. The erosion/re-deposition cycle along the outer target leads to a multistep migration of {sup 13}C towards the separatrix which is called 'walking'. This walking created carbon neutrals at the outer strike point and led to {sup 13}C deposition in the private flux region. Although several migration pathways have been identified, quantitative analyses are hindered by experimental uncertainty in divertor leakage, and the lack of measurements at locations such as gaps and shadowed regions.

  9. Organic carbon cycling in landfills: Model for a continuum approach

    SciTech Connect (OSTI)

    Bogner, J.; Lagerkvist, A.

    1997-09-01

    Organic carbon cycling in landfills can be addressed through a continuum model where the end-points are conventional anaerobic digestion of organic waste (short-term analogue) and geologic burial of organic material (long-term analogue). Major variables influencing status include moisture state, temperature, organic carbon loading, nutrient status, and isolation from the surrounding environment. Bioreactor landfills which are engineered for rapid decomposition approach (but cannot fully attain) the anaerobic digester end-point and incur higher unit costs because of their high degree of environmental isolation and control. At the other extreme, uncontrolled land disposal of organic waste materials is similar to geologic burial where organic carbon may be aerobically recycled to atmospheric CO{sub 2}, anaerobically converted to CH{sub 4} and CO{sub 2} during early diagenesis, or maintained as intermediate or recalcitrant forms into geologic time (> 1,000 years) for transformations via kerogen pathways. A family of improved landfill models are needed at several scales (molecular to landscape) which realistically address landfill processes and can be validated with field data.

  10. Model independent determination of the {sigma} pole

    SciTech Connect (OSTI)

    Leutwyler, H.

    2008-08-31

    The first part of this report reviews recent developments at the interface between lattice work on QCD with light dynamical quarks, effective field theory and low energy precision experiments. Then I discuss how dispersion theory can be used to analyze the low energy structure of the {pi}{pi} scattering amplitude in a model independent manner. This leads to an exact formula for the mass and width of the lowest few resonances, in terms of observable quantities. As an application, I consider the pole position of the {sigma}, paying particular to error propagation in the numerical analysis. The report is based on work done in collaboration with Irinel Caprini and Gilberto Colangelo.

  11. Validation and Comparison of Carbon Sequestration Project Cost Models with Project Cost Data Obtained from the Southwest Partnership

    SciTech Connect (OSTI)

    Robert Lee; Reid Grigg; Brian McPherson

    2011-04-15

    Obtaining formal quotes and engineering conceptual designs for carbon dioxide (CO{sub 2}) sequestration sites and facilities is costly and time-consuming. Frequently, when looking at potential locations, managers, engineers and scientists are confronted with multiple options, but do not have the expertise or the information required to quickly obtain a general estimate of what the costs will be without employing an engineering firm. Several models for carbon compression, transport and/or injection have been published that are designed to aid in determining the cost of sequestration projects. A number of these models are used in this study, including models by J. Ogden, MIT's Carbon Capture and Sequestration Technologies Program Model, the Environmental Protection Agency and others. This report uses the information and data available from several projects either completed, in progress, or conceptualized by the Southwest Regional Carbon Sequestration Partnership on Carbon Sequestration (SWP) to determine the best approach to estimate a project's cost. The data presented highlights calculated versus actual costs. This data is compared to the results obtained by applying several models for each of the individual projects with actual cost. It also offers methods to systematically apply the models to future projects of a similar scale. Last, the cost risks associated with a project of this scope are discussed, along with ways that have been and could be used to mitigate these risks.

  12. Evaluation of Black Carbon Estimations in Global Aerosol Models

    SciTech Connect (OSTI)

    Koch, D.; Schulz, M.; Kinne, Stefan; McNaughton, C. S.; Spackman, J. R.; Balkanski, Y.; Bauer, S.; Berntsen, T.; Bond, Tami C.; Boucher, Olivier; Chin, M.; Clarke, A. D.; De Luca, N.; Dentener, F.; Diehl, T.; Dubovik, O.; Easter, Richard C.; Fahey, D. W.; Feichter, J.; Fillmore, D.; Freitag, S.; Ghan, Steven J.; Ginoux, P.; Gong, S.; Horowitz, L.; Iversen, T.; Kirkevag, A.; Klimont, Z.; Kondo, Yutaka; Krol, M.; Liu, Xiaohong; Miller, R.; Montanaro, V.; Moteki, N.; Myhre, G.; Penner, J.; Perlwitz, Ja; Pitari, G.; Reddy, S.; Sahu, L.; Sakamoto, H.; Schuster, G.; Schwarz, J. P.; Seland, O.; Stier, P.; Takegawa, Nobuyuki; Takemura, T.; Textor, C.; van Aardenne, John; Zhao, Y.

    2009-11-27

    We evaluate black carbon (BC) model predictions from the AeroCom model intercomparison project by considering the diversity among year 2000 model simulations and comparing model predictions with available measurements. These model-measurement intercomparisons include BC surface and aircraft concentrations, aerosol absorption optical depth (AAOD) from AERONET and OMI retrievals and BC column estimations based on AERONET. In regions other than Asia, most models are biased high compared to surface concentration measurements. However compared with (column) AAOD or BC burden retreivals, the models are generally biased low. The average ratio of model to retrieved AAOD is less than 0.7 in South American and 0.6 in African biomass burning regions; both of these regions lack surface concentration measurements. In Asia the average model to observed ratio is 0.6 for AAOD and 0.5 for BC surface concentrations. Compared with aircraft measurements over the Americas at latitudes between 0 and 50N, the average model is a factor of 10 larger than observed, and most models exceed the measured BC standard deviation in the mid to upper troposphere. At higher latitudes the average model to aircraft BC is 0.6 and underestimate the observed BC loading in the lower and middle troposphere associated with springtime Arctic haze. Low model bias for AAOD but overestimation of surface and upper atmospheric BC concentrations at lower latitudes suggests that most models are underestimating BC absorption and should improve estimates for refractive index, particle size, and optical effects of BC coating. Retrieval uncertainties and/or differences with model diagnostic treatment may also contribute to the model-measurement disparity. Largest AeroCom model diversity occurred in northern Eurasia and the remote Arctic, regions influenced by anthropogenic sources. Changing emissions, aging, removal, or optical properties within a single model generated a smaller change in model predictions than the

  13. Integrated Assessment Modeling of Carbon Sequestration and Land Use Emissions Using Detailed Model Results and Observations

    SciTech Connect (OSTI)

    Dr. Atul Jain

    2005-04-17

    This report outlines the progress on the development and application of Integrated Assessment Modeling of Carbon Sequestrations and Land Use Emissions supported by the DOE Office of Biological and Environmental Research (OBER), U.S. Department of Energy, Grant No. DOE-DE-FG02-01ER63069. The overall objective of this collaborative project between the University of Illinois at Urbana-Champaign (UIUC), Oak Ridge National Laboratory (ORNL), Lawrence Livermore National Laboratory (LLNL), and Pacific Northwest National Laboratory (PNNL) was to unite the latest advances in carbon cycle research with scientifically based models and policy-related integrated assessment tools that incorporate computationally efficient representations of the latest knowledge concerning science and emission trajectories, and their policy implications. As part of this research we accomplished the following tasks that we originally proposed: (1) In coordination with LLNL and ORNL, we enhanced the Integrated Science Assessment Model's (ISAM) parametric representation of the ocean and terrestrial carbon cycles that better represent spatial and seasonal variations, which are important to study the mechanisms that influence carbon sequestration in the ocean and terrestrial ecosystems; (2) Using the MiniCAM modeling capability, we revised the SRES (IPCC Special Report on Emission Scenarios; IPCC, 2000) land use emission scenarios; and (3) On the application front, the enhanced version of ISAM modeling capability is applied to understand how short- and long-term natural carbon fluxes, carbon sequestration, and human emissions contribute to the net global emissions (concentrations) trajectories required to reach various concentration (emission) targets. Under this grant, 21 research publications were produced. In addition, this grant supported a number of graduate and undergraduate students whose fundamental research was to learn a disciplinary field in climate change (e.g., ecological dynamics and

  14. Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 2. Model prediction

    SciTech Connect (OSTI)

    Yu, Z.; Peldszus, S.; Huck, P.M.

    2009-03-01

    The adsorption of two representative pharmaceutically active compounds (PhACs) naproxen and carbamazepine and one endocrine disrupting compound (EDC) nonylphenol was studied in pilot-scale granular activated carbon (GAC) adsorbers using post-sedimentation (PS) water from a full-scale drinking water treatment plant. The GAC adsorbents were coal-based Calgon Filtrasorb 400 and coconut shell-based PICA CTIF TE. Acidic naproxen broke through fastest while nonylphenol was removed best, which was consistent with the degree to which fouling affected compound removals. Model predictions and experimental data were generally in good agreement for all three compounds, which demonstrated the effectiveness and robustness of the pore and surface diffusion model (PSDM) used in combination with the time-variable parameter approach for predicting removals at environmentally relevant concentrations (i.e., ng/L range). Sensitivity analyses suggested that accurate determination of film diffusion coefficients was critical for predicting breakthrough for naproxen and carbamazepine, in particular when high removals are targeted. Model simulations demonstrated that GAC carbon usage rates (CURs) for naproxen were substantially influenced by the empty bed contact time (EBCT) at the investigated conditions. Model-based comparisons between GAC CURs and minimum CURs for powdered activated carbon (PAC) applications suggested that PAC would be most appropriate for achieving 90% removal of naproxen, whereas GAC would be more suitable for nonylphenol. 25 refs., 4 figs., 1 tab.

  15. New analytical reagents for the determination of sulfur dioxide and carbon monoxide

    SciTech Connect (OSTI)

    Trump, E.L.

    1987-01-01

    Four solid reagent methods were developed for the determination of sulfur dioxide in air, and one method was developed to measure carbon monoxide. When applied to filter paper with acetamide as the humectant and 4-phenylcyclohexanone as a bisulfite absorbent, oxohydroxybis(8-hydroxyquinolinyl-) vanadium (V) changes from yellow to black in the presence of sulfur dioxide. The three other methods, also on a filter paper support, utilized the reduction of bromate to bromine which then changed 3-,3'-, 5-,5'-tetramethylbenzidine from yellow to blue, phenothiazine from white to green, and 4-dimethylamino-4'-,4/double prime/-dimethoxytriphenylmethanol from colorless to red-purple. Quantitative measurements were made by reflectance spectroscopy. The method for carbon monoxide involved the use of tetrakis (acetamide-) Pd(II) ditetrafluoroborate, sodium iodate, and leuco crystal violet all together on a filter paper support. Carbon monoxide reduced the Pd(II)-acetamide complex to metallic palladium. The metallic palladium then reduced iodate to hypoiodous acid, HOI, which, in turn, oxidized leuco crystal violet to crystal violet. The crystal violet color was then measured by reflectance.

  16. Integrated Experimental and Modeling Studies of Mineral Carbonation as a Mechanism for Permanent Carbon Sequestration in Mafic/Ultramafic Rocks

    SciTech Connect (OSTI)

    Wang, Zhengrong; Qiu, Lin; Zhang, Shuang; Bolton, Edward; Bercovici, David; Ague, Jay; Karato, Shun-Ichiro; Oristaglio, Michael; Zhu, Wen-Iu; Lisabeth, Harry; Johnson, Kevin

    2014-09-30

    A program of laboratory experiments, modeling and fieldwork was carried out at Yale University, University of Maryland, and University of Hawai‘i, under a DOE Award (DE-FE0004375) to study mineral carbonation as a practical method of geologic carbon sequestration. Mineral carbonation, also called carbon mineralization, is the conversion of (fluid) carbon dioxide into (solid) carbonate minerals in rocks, by way of naturally occurring chemical reactions. Mafic and ultramafic rocks, such as volcanic basalt, are natural candidates for carbonation, because the magnesium and iron silicate minerals in these rocks react with brines of dissolved carbon dioxide to form carbonate minerals. By trapping carbon dioxide (CO2) underground as a constituent of solid rock, carbonation of natural basalt formations would be a secure method of sequestering CO2 captured at power plants in efforts to mitigate climate change. Geochemical laboratory experiments at Yale, carried out in a batch reactor at 200°C and 150 bar (15 MPa), studied carbonation of the olivine mineral forsterite (Mg2SiO4) reacting with CO2 brines in the form of sodium bicarbonate (NaHCO3) solutions. The main carbonation product in these reactions is the carbonate mineral magnesite (MgCO3). A series of 32 runs varied the reaction time, the reactive surface area of olivine grains and powders, the concentration of the reacting fluid, and the starting ratio of fluid to olivine mass. These experiments were the first to study the rate of olivine carbonation under passive conditions approaching equilibrium. The results show that, in a simple batch reaction, olivine carbonation is fastest during the first 24 hours and then slows significantly and even reverses. A natural measure of the extent of carbonation is a quantity called the carbonation fraction, which compares the amount of carbon removed from solution, during a run, to the maximum amount

  17. AN INTEGRATED MODELING FRAMEWORK FOR CARBON MANAGEMENT TECHNOLOGIES

    SciTech Connect (OSTI)

    Anand B. Rao; Edward S. Rubin; Michael B. Berkenpas

    2004-03-01

    CO{sub 2} capture and storage (CCS) is gaining widespread interest as a potential method to control greenhouse gas emissions from fossil fuel sources, especially electric power plants. Commercial applications of CO{sub 2} separation and capture technologies are found in a number of industrial process operations worldwide. Many of these capture technologies also are applicable to fossil fuel power plants, although applications to large-scale power generation remain to be demonstrated. This report describes the development of a generalized modeling framework to assess alternative CO{sub 2} capture and storage options in the context of multi-pollutant control requirements for fossil fuel power plants. The focus of the report is on post-combustion CO{sub 2} capture using amine-based absorption systems at pulverized coal-fired plants, which are the most prevalent technology used for power generation today. The modeling framework builds on the previously developed Integrated Environmental Control Model (IECM). The expanded version with carbon sequestration is designated as IECM-cs. The expanded modeling capability also includes natural gas combined cycle (NGCC) power plants and integrated coal gasification combined cycle (IGCC) systems as well as pulverized coal (PC) plants. This report presents details of the performance and cost models developed for an amine-based CO{sub 2} capture system, representing the baseline of current commercial technology. The key uncertainties and variability in process design, performance and cost parameters which influence the overall cost of carbon mitigation also are characterized. The new performance and cost models for CO{sub 2} capture systems have been integrated into the IECM-cs, along with models to estimate CO{sub 2} transport and storage costs. The CO{sub 2} control system also interacts with other emission control technologies such as flue gas desulfurization (FGD) systems for SO{sub 2} control. The integrated model is applied to

  18. A Hydro-mechanical Model and Analytical Solutions for Geomechanical Modeling of Carbon Dioxide Geological Sequestration

    SciTech Connect (OSTI)

    Xu, Zhijie; Fang, Yilin; Scheibe, Timothy D.; Bonneville, Alain

    2012-05-15

    We present a hydro-mechanical model for geological sequestration of carbon dioxide. The model considers the poroelastic effects by taking into account the coupling between the geomechanical response and the fluid flow in greater detail. The simplified hydro-mechanical model includes the geomechanical part that relies on the linear elasticity, while the fluid flow is based on the Darcys law. Two parts were coupled using the standard linear poroelasticity. Analytical solutions for pressure field were obtained for a typical geological sequestration scenario. The model predicts the temporal and spatial variation of pressure field and effects of permeability and elastic modulus of formation on the fluid pressure distribution.

  19. A Semi-Empirical Two Step Carbon Corrosion Reaction Model in PEM Fuel Cells

    SciTech Connect (OSTI)

    Young, Alan; Colbow, Vesna; Harvey, David; Rogers, Erin; Wessel, Silvia

    2013-01-01

    The cathode CL of a polymer electrolyte membrane fuel cell (PEMFC) was exposed to high potentials, 1.0 to 1.4 V versus a reversible hydrogen electrode (RHE), that are typically encountered during start up/shut down operation. While both platinum dissolution and carbon corrosion occurred, the carbon corrosion effects were isolated and modeled. The presented model separates the carbon corrosion process into two reaction steps; (1) oxidation of the carbon surface to carbon-oxygen groups, and (2) further corrosion of the oxidized surface to carbon dioxide/monoxide. To oxidize and corrode the cathode catalyst carbon support, the CL was subjected to an accelerated stress test cycled the potential from 0.6 VRHE to an upper potential limit (UPL) ranging from 0.9 to 1.4 VRHE at varying dwell times. The reaction rate constants and specific capacitances of carbon and platinum were fitted by evaluating the double layer capacitance (Cdl) trends. Carbon surface oxidation increased the Cdl due to increased specific capacitance for carbon surfaces with carbon-oxygen groups, while the second corrosion reaction decreased the Cdl due to loss of the overall carbon surface area. The first oxidation step differed between carbon types, while both reaction rate constants were found to have a dependency on UPL, temperature, and gas relative humidity.

  20. A Finite Element Model for Simulation of Carbon Dioxide Sequestration

    SciTech Connect (OSTI)

    Bao, Jie; Xu, Zhijie; Fang, Yilin

    2013-11-02

    We present a hydro-mechanical model, followed by stress, deformation, and shear-slip failure analysis for geological sequestration of carbon dioxide (CO2). The model considers the poroelastic effects by taking into account of the two-way coupling between the geomechanical response and the fluid flow process. Analytical solutions for pressure and deformation fields were derived for a typical geological sequestration scenario in our previous work. A finite element approach is introduced here for numerically solving the hydro-mechanical model with arbitrary boundary conditions. The numerical approach was built on an open-source finite element code Elmer, and results were compared to the analytical solutions. The shear-slip failure analysis was presented based on the numerical results, where the potential failure zone is identified. Information is relevant to the prediction of the maximum sustainable injection rate or pressure. The effects of caprock permeability on the fluid pressure, deformation, stress, and the shear-slip failure zone were also quantitatively studied. It was shown that a larger permeability in caprock and base rock leads to a larger uplift but a smaller shear-slip failure zone.

  1. Reactive transport modeling of stable carbon isotope fractionation in a multi-phase multi-component system during carbon sequestration

    SciTech Connect (OSTI)

    Zhang, Shuo [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); DePaolo, Donald J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zheng, Liange [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Mayer, Bernhard [Univ. of Calgary (Canada). Dept. of Geosciences

    2014-12-31

    Carbon stable isotopes can be used in characterization and monitoring of CO2 sequestration sites to track the migration of the CO2 plume and identify leakage sources, and to evaluate the chemical reactions that take place in the CO2-water-rock system. However, there are few tools available to incorporate stable isotope information into flow and transport codes used for CO2 sequestration problems. We present a numerical tool for modeling the transport of stable carbon isotopes in multiphase reactive systems relevant to geologic carbon sequestration. The code is an extension of the reactive transport code TOUGHREACT. The transport module of TOUGHREACT was modified to include separate isotopic species of CO2 gas and dissolved inorganic carbon (CO2, CO32-, HCO3-,). Any process of transport or reaction influencing a given carbon species also influences its isotopic ratio. Isotopic fractionation is thus fully integrated within the dynamic system. The chemical module and database have been expanded to include isotopic exchange and fractionation between the carbon species in both gas and aqueous phases. The performance of the code is verified by modeling ideal systems and comparing with theoretical results. Efforts are also made to fit field data from the Pembina CO2 injection project in Canada. We show that the exchange of carbon isotopes between dissolved and gaseous carbon species combined with fluid flow and transport, produce isotopic effects that are significantly different from simple two-component mixing. These effects are important for understanding the isotopic variations observed in field demonstrations.

  2. Reactive transport modeling of stable carbon isotope fractionation in a multi-phase multi-component system during carbon sequestration

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Shuo; DePaolo, Donald J.; Zheng, Liange; Mayer, Bernhard

    2014-12-31

    Carbon stable isotopes can be used in characterization and monitoring of CO2 sequestration sites to track the migration of the CO2 plume and identify leakage sources, and to evaluate the chemical reactions that take place in the CO2-water-rock system. However, there are few tools available to incorporate stable isotope information into flow and transport codes used for CO2 sequestration problems. We present a numerical tool for modeling the transport of stable carbon isotopes in multiphase reactive systems relevant to geologic carbon sequestration. The code is an extension of the reactive transport code TOUGHREACT. The transport module of TOUGHREACT was modifiedmore » to include separate isotopic species of CO2 gas and dissolved inorganic carbon (CO2, CO32-, HCO3-,…). Any process of transport or reaction influencing a given carbon species also influences its isotopic ratio. Isotopic fractionation is thus fully integrated within the dynamic system. The chemical module and database have been expanded to include isotopic exchange and fractionation between the carbon species in both gas and aqueous phases. The performance of the code is verified by modeling ideal systems and comparing with theoretical results. Efforts are also made to fit field data from the Pembina CO2 injection project in Canada. We show that the exchange of carbon isotopes between dissolved and gaseous carbon species combined with fluid flow and transport, produce isotopic effects that are significantly different from simple two-component mixing. These effects are important for understanding the isotopic variations observed in field demonstrations.« less

  3. Controls on terrestrial carbon feedbacks by productivity vs. turnover in the CMIP5 Earth System Models

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Koven, C. D.; Chambers, J. Q.; Georgiou, K.; Knox, R.; Negron-Juarez, R.; Riley, W. J.; Arora, V. K.; Brovkin, V.; Friedlingstein, P.; Jones, C. D.

    2015-04-16

    To better understand sources of uncertainty in projections of terrestrial carbon cycle feedbacks, we present an approach to separate the controls on modeled carbon changes. We separate carbon changes into 4 categories using a linearized, equilibrium approach: those arising from changed inputs (productivity-driven changes), and outputs (turnover-driven changes), and apply the analysis separately to the live and dead carbon pools. Using Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations for 5 models, we find that changes to the live pools are primarily explained by productivity-driven changes, with only one model showing large compensating changes to live carbon turnover times. Formore » dead carbon pools, the situation is more complex as all models predict a large reduction in turnover times in response to increases in productivity. This responses arises from the common representation of a broad spectrum of decomposition turnover times via a multi-pool approach, in which flux-weighted turnover times are faster than mass-weighted turnover times. This leads to a shift in the distribution of carbon among dead pools in response to changes in inputs, and therefore a transient but long-lived reduction in turnover times in response to increases in productivity. Since this behavior, a reduction in inferred turnover times resulting from an increase in inputs, is superficially similar to priming processes, but occurring without the mechanisms responsible for priming, we call the phenomenon "false priming", and show that it masks much of the intrinsic changes to dead carbon turnover times as a result of changing climate. These patterns hold across the fully-coupled, biogeochemically-coupled, and radiatively-coupled 1% yr−1 increasing CO2 experiments. We disaggregate inter-model uncertainty in the globally-integrated equilibrium carbon responses to initial turnover times, inital productivity, fractional changes in turnover, and fractional changes in

  4. Controls on terrestrial carbon feedbacks by productivity versus turnover in the CMIP5 Earth System Models

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Koven, C. D.; Chambers, J. Q.; Georgiou, K.; Knox, R.; Negron-Juarez, R.; Riley, W. J.; Arora, V. K.; Brovkin, V.; Friedlingstein, P.; Jones, C. D.

    2015-09-07

    To better understand sources of uncertainty in projections of terrestrial carbon cycle feedbacks, we present an approach to separate the controls on modeled carbon changes. We separate carbon changes into four categories using a linearized, equilibrium approach: those arising from changed inputs (productivity-driven changes), and outputs (turnover-driven changes), of both the live and dead carbon pools. Using Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations for five models, we find that changes to the live pools are primarily explained by productivity-driven changes, with only one model showing large compensating changes to live carbon turnover times. For dead carbon pools, themore » situation is more complex as all models predict a large reduction in turnover times in response to increases in productivity. This response arises from the common representation of a broad spectrum of decomposition turnover times via a multi-pool approach, in which flux-weighted turnover times are faster than mass-weighted turnover times. This leads to a shift in the distribution of carbon among dead pools in response to changes in inputs, and therefore a transient but long-lived reduction in turnover times. Since this behavior, a reduction in inferred turnover times resulting from an increase in inputs, is superficially similar to priming processes, but occurring without the mechanisms responsible for priming, we call the phenomenon "false priming", and show that it masks much of the intrinsic changes to dead carbon turnover times as a result of changing climate. These patterns hold across the fully coupled, biogeochemically coupled, and radiatively coupled 1 % yr−1 increasing CO2 experiments. We disaggregate inter-model uncertainty in the globally integrated equilibrium carbon responses to initial turnover times, initial productivity, fractional changes in turnover, and fractional changes in productivity. For both the live and dead carbon pools, inter-model

  5. Ignoring mesophyll diffusion causes carbon cycle models to underestima...

    Office of Scientific and Technical Information (OSTI)

    ... achieved via a parameter conversion function that was ... Biomass carbon residence time will need to be considered as ... about key biochemical processes of photosynthesis (13-14). ...

  6. Pore Models Track Reactions in Underground Carbon Capture

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    extract from saline aquifers deep underground. The goal is to learn what will happen when fluids pass through the material should power plants inject carbon dioxide underground. ...

  7. Multi-century Changes to Global Climate and Carbon Cycle: Results from a Coupled Climate and Carbon Cycle Model

    SciTech Connect (OSTI)

    Bala, G; Caldeira, K; Mirin, A; Wickett, M; Delire, C

    2005-02-17

    In this paper, we use a coupled climate and carbon cycle model to investigate the global climate and carbon cycle changes out to year 2300 that would occur if CO{sub 2} emissions from all the currently estimated fossil fuel resources were released to the atmosphere. By year 2300, the global climate warms by about 8 K and atmospheric CO{sub 2} reaches 1423 ppmv. The warming is higher than anticipated because the sensitivity to radiative forcing increases as the simulation progresses. In our simulation, the rate of emissions peak at over 30 PgC yr{sup -1} early in the 22nd century. Even at year 2300, nearly 50% of cumulative emissions remain in the atmosphere. In our simulations both soils and living biomass are net carbon sinks throughout the simulation. Despite having relatively low climate sensitivity and strong carbon uptake by the land biosphere, our model projections suggest severe long-term consequences for global climate if all the fossil-fuel carbon is ultimately released to the atmosphere.

  8. Modeling the role of terrestrial ecosystems in the global carbon cycle

    SciTech Connect (OSTI)

    Emanuel, W.R.; Post, W.M.; Shugart, H.H. Jr.

    1980-01-01

    A model for the global biogeochemical cycle of carbon which includes a five-compartment submodel for circulation in terrestrial ecosystems of the world is presented. Although this terrestrial submodel divides carbon into compartments with more functional detail than previous models, the variability in carbon dynamics among ecosystem types and in different climatic zones is not adequately treated. A new model construct which specifically treats this variability by modeling the distribution of ecosystem types as a function of climate on a 0.5/sup 0/ latitude by 0.5/sup 0/ longitude scale of resolution is proposed.

  9. Method of determining pH by the alkaline absorption of carbon dioxide

    DOE Patents [OSTI]

    Hobbs, David T.

    1992-01-01

    A method for measuring the concentration of hydroxides in alkaline solutions in a remote location using the tendency of hydroxides to absorb carbon dioxide. The method includes the passing of carbon dioxide over the surface of an alkaline solution in a remote tank before and after measurements of the carbon dioxide solution. A comparison of the measurements yields the absorption fraction from which the hydroxide concentration can be calculated using a correlation of hydroxide or pH to absorption fraction.

  10. Electrical utilities model for determining electrical distribution capacity

    SciTech Connect (OSTI)

    Fritz, R. L.

    1997-09-03

    In its simplest form, this model was to obtain meaningful data on the current state of the Site`s electrical transmission and distribution assets, and turn this vast collection of data into useful information. The resulting product is an Electrical Utilities Model for Determining Electrical Distribution Capacity which provides: current state of the electrical transmission and distribution systems; critical Hanford Site needs based on outyear planning documents; decision factor model. This model will enable Electrical Utilities management to improve forecasting requirements for service levels, budget, schedule, scope, and staffing, and recommend the best path forward to satisfy customer demands at the minimum risk and least cost to the government. A dynamic document, the model will be updated annually to reflect changes in Hanford Site activities.

  11. Structural analysis of three global land models on carbon cycle simulations using a traceability framework

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rafique, R.; Xia, J.; Hararuk, O.; Luo, Y.

    2014-06-27

    Modeled carbon (C) storage capacity is largely determined by the C residence time and net primary productivity (NPP). Extensive research has been done on NPP dynamics but the residence time and their relationships with C storage are much less studied. In this study, we implemented a traceability analysis to understand the modeled C storage and residence time in three land surface models: CSIRO's Atmosphere Biosphere Land Exchange (CABLE) with 9 C pools, Community Land Model (version 3.5) combined with Carnegie-Ames-Stanford Approach (CLM3.5-CASA) with 12 C pools and Community Land Model (version 4) (CLM4) with 26 C pools. The globally averagedmoreC storage and residence time was computed at both individual pool and total ecosystem levels. The spatial distribution of total ecosystem C storage and residence time differ greatly among the three models. The CABLE model showed a closer agreement with measured C storage and residence time in plant and soil pools than CLM3.5-CASA and CLM4. However, CLM3.5-CASA and CLM4 were close to each other in modeled C storage but not with measured data. CABLE stores more C in root whereas CLM3.5-CASA and CLM4 store more C in woody pools, partly due to differential NPP allocation in respective pools. The C residence time in individual C pools is greatly different among models, largely because of different transfer coefficient values among pools. CABLE had higher bulk residence time for soil C pools than the other two models. Overall, the traceability analysis used in this study can help fully characterizes the behavior of complex land models.less

  12. Determination of the permeability of carbon aerogels by gas flow measurements

    SciTech Connect (OSTI)

    Kong, F.M.; Hulsey, S.S.; Alviso, C.T.; Pekala, R.W.

    1992-04-01

    Carbon aerogels are synthesized via the polycondensation of resorcinol and formaldehyde, followed by supercritical drying and pyrolysis at 1050{degree}C in nitrogen. Because of their interconnected porosity, ultrafine cell structure and high surface area, carbon aerogels have many potential applications, such as in supercapacitors, battery electrodes, catalyst supports, and gas filters. The performance of carbon aerogels in the latter two applications depends on the permeability or gas flow conductance in these materials. By measuring the pressure differential across a thin specimen and the nitrogen gas flow rate in the viscous regime, we calculated the permeability of carbon aerogels from equations based upon Darcy's law. Our measurements show that carbon aerogels have apparent permeabilities on the order of 10{sup {minus}12}to 10{sup {minus}10} cm{sup 2} for densities ranging from 0.44 to 0.05 g/cm{sup 3}. Like their mechanical properties, the permeability of carbon aerogels follows a power law relationship with density and average pore size. Such findings help us to estimate the average pore sizes of carbon aerogels once their densities are known. This paper reveals the relationships among permeability, pore size and density in carbon aerogels.

  13. Determination of the permeability of carbon aerogels by gas flow measurements

    SciTech Connect (OSTI)

    Kong, F.M.; Hulsey, S.S.; Alviso, C.T.; Pekala, R.W.

    1992-04-01

    Carbon aerogels are synthesized via the polycondensation of resorcinol and formaldehyde, followed by supercritical drying and pyrolysis at 1050{degree}C in nitrogen. Because of their interconnected porosity, ultrafine cell structure and high surface area, carbon aerogels have many potential applications, such as in supercapacitors, battery electrodes, catalyst supports, and gas filters. The performance of carbon aerogels in the latter two applications depends on the permeability or gas flow conductance in these materials. By measuring the pressure differential across a thin specimen and the nitrogen gas flow rate in the viscous regime, we calculated the permeability of carbon aerogels from equations based upon Darcy`s law. Our measurements show that carbon aerogels have apparent permeabilities on the order of 10{sup {minus}12}to 10{sup {minus}10} cm{sup 2} for densities ranging from 0.44 to 0.05 g/cm{sup 3}. Like their mechanical properties, the permeability of carbon aerogels follows a power law relationship with density and average pore size. Such findings help us to estimate the average pore sizes of carbon aerogels once their densities are known. This paper reveals the relationships among permeability, pore size and density in carbon aerogels.

  14. Ecosystem carbon storage capacity as affected by disturbance regimes: A general theoretical model

    SciTech Connect (OSTI)

    Weng, Ensheng; Luo, Yiqi; Wang, Weile; Wang, Han; Hayes, Daniel J; McGuire, A. David; Hastings, Alan; Schimel, David

    2012-01-01

    Disturbances have been recognized as a key factor shaping terrestrial ecosystem states and dynamics. A general model that quantitatively describes the relationship between carbon storage and disturbance regime is critical for better understanding large scale terrestrial ecosystem carbon dynamics. We developed a model (REGIME) to quantify ecosystem carbon storage capacities (E[x]) under varying disturbance regimes with an analytical solution E[x] = U {center_dot} {tau}{sub E} {center_dot} {lambda}{lambda} + s {tau} 1, where U is ecosystem carbon influx, {tau}{sub E} is ecosystem carbon residence time, and {tau}{sub 1} is the residence time of the carbon pool affected by disturbances (biomass pool in this study). The disturbance regime is characterized by the mean disturbance interval ({lambda}) and the mean disturbance severity (s). It is a Michaelis-Menten-type equation illustrating the saturation of carbon content with mean disturbance interval. This model analytically integrates the deterministic ecosystem carbon processes with stochastic disturbance events to reveal a general pattern of terrestrial carbon dynamics at large scales. The model allows us to get a sense of the sensitivity of ecosystems to future environmental changes just by a few calculations. According to the REGIME model, for example, approximately 1.8 Pg C will be lost in the high-latitude regions of North America (>45{sup o} N) if fire disturbance intensity increases around 5.7 time the current intensity to the end of the twenty-first century, which will require around 12% increases in net primary productivity (NPP) to maintain stable carbon stocks. If the residence time decreased 10% at the same time additional 12.5% increases in NPP are required to keep current C stocks. The REGIME model also lays the foundation for analytically modeling the interactions between deterministic biogeochemical processes and stochastic disturbance events.

  15. A Carbon Flux Super Site. New Insights and Innovative Atmosphere-Terrestrial Carbon Exchange Measurements and Modeling

    SciTech Connect (OSTI)

    Leclerc, Monique Y.

    2014-11-17

    This final report presents the main activities and results of the project “A Carbon Flux Super Site: New Insights and Innovative Atmosphere-Terrestrial Carbon Exchange Measurements and Modeling” from 10/1/2006 to 9/30/2014. It describes the new AmeriFlux tower site (Aiken) at Savanna River Site (SC) and instrumentation, long term eddy-covariance, sodar, microbarograph, soil and other measurements at the site, and intensive field campaigns of tracer experiment at the Carbon Flux Super Site, SC, in 2009 and at ARM-CF site, Lamont, OK, and experiments in Plains, GA. The main results on tracer experiment and modeling, on low-level jet characteristics and their impact on fluxes, on gravity waves and their influence on eddy fluxes, and other results are briefly described in the report.

  16. Global Biogeochemistry Models and Global Carbon Cycle Research at Lawrence Livermore National Laboratory

    SciTech Connect (OSTI)

    Covey, C; Caldeira, K; Guilderson, T; Cameron-Smith, P; Govindasamy, B; Swanston, C; Wickett, M; Mirin, A; Bader, D

    2005-05-27

    The climate modeling community has long envisioned an evolution from physical climate models to ''earth system'' models that include the effects of biology and chemistry, particularly those processes related to the global carbon cycle. The widely reproduced Box 3, Figure 1 from the 2001 IPCC Scientific Assessment schematically describes that evolution. The community generally accepts the premise that understanding and predicting global and regional climate change requires the inclusion of carbon cycle processes in models to fully simulate the feedbacks between the climate system and the carbon cycle. Moreover, models will ultimately be employed to predict atmospheric concentrations of CO{sub 2} and other greenhouse gases as a function of anthropogenic and natural processes, such as industrial emissions, terrestrial carbon fixation, sequestration, land use patterns, etc. Nevertheless, the development of coupled climate-carbon models with demonstrable quantitative skill will require a significant amount of effort and time to understand and validate their behavior at both the process level and as integrated systems. It is important to consider objectively whether the currently proposed strategies to develop and validate earth system models are optimal, or even sufficient, and whether alternative strategies should be pursued. Carbon-climate models are going to be complex, with the carbon cycle strongly interacting with many other components. Off-line process validation will be insufficient. As was found in coupled atmosphere-ocean GCMs, feedbacks between model components can amplify small errors and uncertainties in one process to produce large biases in the simulated climate. The persistent tropical western Pacific Ocean ''double ITCZ'' and upper troposphere ''cold pole'' problems are examples. Finding and fixing similar types of problems in coupled carbon-climate models especially will be difficult, given the lack of observations required for diagnosis and validation

  17. Method of determining pH by the alkaline absorption of carbon dioxide

    DOE Patents [OSTI]

    Hobbs, D.T.

    1992-10-06

    A method is described for measuring the concentration of hydroxides in alkaline solutions in a remote location using the tendency of hydroxides to absorb carbon dioxide. The method includes the passing of carbon dioxide over the surface of an alkaline solution in a remote tank before and after measurements of the carbon dioxide solution. A comparison of the measurements yields the absorption fraction from which the hydroxide concentration can be calculated using a correlation of hydroxide or pH to absorption fraction. 2 figs.

  18. Critique of the carbonate mass loss model for paint damage functions

    SciTech Connect (OSTI)

    Livingston, R.A.

    1987-06-01

    One of the key questions concerning the assessment of acid deposition damage is its effect on painted surfaces. In order to determine this it is necessary to have a paint damage function that expresses the quantity of physical damage associated with a given level of acid deposition. This problem is now a major focus of EPA's current research; however, results are not yet available. Consequently, the NAPAP paint damage function was derived from data collected in several studies that substantially predated the acid rain research program. Although this damage function may appear plausible at first glance, it has been criticized, in part because paint damage constitutes such an important part of the total, but mainly because it is based largely on a conceptual model involving erosion due to dissolution loss of carbonate extenders in the paint formulation.

  19. Constraint-Based Modeling of Carbon Fixation and the Energetics of Electron Transfer in Geobacter metallireducens

    SciTech Connect (OSTI)

    Feist, AM; Nagarajan, H; Rotaru, AE; Tremblay, PL; Zhang, T; Nevin, KP; Lovley, DR; Zengler, K

    2014-04-24

    Geobacter species are of great interest for environmental and biotechnology applications as they can carry out direct electron transfer to insoluble metals or other microorganisms and have the ability to assimilate inorganic carbon. Here, we report on the capability and key enabling metabolic machinery of Geobacter metallireducens GS-15 to carry out CO2 fixation and direct electron transfer to iron. An updated metabolic reconstruction was generated, growth screens on targeted conditions of interest were performed, and constraint-based analysis was utilized to characterize and evaluate critical pathways and reactions in G. metallireducens. The novel capability of G. metallireducens to grow autotrophically with formate and Fe(III) was predicted and subsequently validated in vivo. Additionally, the energetic cost of transferring electrons to an external electron acceptor was determined through analysis of growth experiments carried out using three different electron acceptors (Fe(III), nitrate, and fumarate) by systematically isolating and examining different parts of the electron transport chain. The updated reconstruction will serve as a knowledgebase for understanding and engineering Geobacter and similar species. Author Summary The ability of microorganisms to exchange electrons directly with their environment has large implications for our knowledge of industrial and environmental processes. For decades, it has been known that microbes can use electrodes as electron acceptors in microbial fuel cell settings. Geobacter metallireducens has been one of the model organisms for characterizing microbe-electrode interactions as well as environmental processes such as bioremediation. Here, we significantly expand the knowledge of metabolism and energetics of this model organism by employing constraint-based metabolic modeling. Through this analysis, we build the metabolic pathways necessary for carbon fixation, a desirable property for industrial chemical production. We

  20. Atmospheric 14CO2 Constraints on and Modeling of Net Carbon Fluxes...

    Office of Scientific and Technical Information (OSTI)

    In parallel we utilized the LLNL-IMPACT global atmospheric chemistry transport model and the TransCom inversion algorithm to utilize these data in inversion estimates of carbon ...

  1. Sensitivity of injection costs to input petrophysical parameters in numerical geologic carbon sequestration models

    SciTech Connect (OSTI)

    Cheng, C. L.; Gragg, M. J.; Perfect, E.; White, Mark D.; Lemiszki, P. J.; McKay, L. D.

    2013-08-24

    Numerical simulations are widely used in feasibility studies for geologic carbon sequestration. Accurate estimates of petrophysical parameters are needed as inputs for these simulations. However, relatively few experimental values are available for CO2-brine systems. Hence, a sensitivity analysis was performed using the STOMP numerical code for supercritical CO2 injected into a model confined deep saline aquifer. The intrinsic permeability, porosity, pore compressibility, and capillary pressure-saturation/relative permeability parameters (residual liquid saturation, residual gas saturation, and van Genuchten alpha and m values) were varied independently. Their influence on CO2 injection rates and costs were determined and the parameters were ranked based on normalized coefficients of variation. The simulations resulted in differences of up to tens of millions of dollars over the life of the project (i.e., the time taken to inject 10.8 million metric tons of CO2). The two most influential parameters were the intrinsic permeability and the van Genuchten m value. Two other parameters, the residual gas saturation and the residual liquid saturation, ranked above the porosity. These results highlight the need for accurate estimates of capillary pressure-saturation/relative permeability parameters for geologic carbon sequestration simulations in addition to measurements of porosity and intrinsic permeability.

  2. Short-Term Energy Outlook Model Documentation: Carbon Dioxide (CO2) Emissions Model

    Reports and Publications (EIA)

    2009-01-01

    Description of the procedures for estimating carbon dioxide emissions in the Short-Term Energy Outlook

  3. Advanced modeling to accelerate the scale up of carbon capture technologies

    SciTech Connect (OSTI)

    Miller, David C.; Sun, XIN; Storlie, Curtis B.; Bhattacharyya, Debangsu

    2015-06-01

    In order to help meet the goals of the DOE carbon capture program, the Carbon Capture Simulation Initiative (CCSI) was launched in early 2011 to develop, demonstrate, and deploy advanced computational tools and validated multi-scale models to reduce the time required to develop and scale-up new carbon capture technologies. This article focuses on essential elements related to the development and validation of multi-scale models in order to help minimize risk and maximize learning as new technologies progress from pilot to demonstration scale.

  4. Key factors for determining groundwater impacts due to leakage from geologic carbon sequestration reservoirs

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Carroll, Susan A.; Keating, Elizabeth; Mansoor, Kayyum; Dai, Zhenxue; Sun, Yunwei; Trainor-Guitton, Whitney; Brown, Chris; Bacon, Diana

    2014-09-07

    The National Risk Assessment Partnership (NRAP) is developing a science-based toolset for the analysis of potential impacts to groundwater chemistry from CO2 injection (www.netldoe.gov/nrap). The toolset adopts a stochastic approach in which predictions address uncertainties in shallow groundwater and leakage scenarios. It is derived from detailed physics and chemistry simulation results that are used to train more computationally efficient models, referred to here as reduced-order models (ROMs), for each component system. In particular, these tools can be used to help regulators and operators understand the expected sizes and longevity of plumes in pH, TDS, and dissolved metals that could resultmore » from a leakage of brine and/or CO2 from a storage reservoir into aquifers. This information can inform, for example, decisions on monitoring strategies that are both effective and efficient. We have used this approach to develop predictive reduced-order models for two common types of reservoirs, but the approach could be used to develop a model for a specific aquifer or other common types of aquifers. In this paper we describe potential impacts to groundwater quality due to CO2 and brine leakage, discuss an approach to calculate thresholds under which no impact to groundwater occurs, describe the time scale for impact on groundwater, and discuss the probability of detecting a groundwater plume should leakage occur. To facilitate this, multi-phase flow and reactive transport simulations and emulations were developed for two classes of aquifers, considering uncertainty in leakage source terms and aquifer hydrogeology. We targeted an unconfined fractured carbonate aquifer based on the Edwards aquifer in Texas and a confined alluvium aquifer based on the High Plains Aquifer in Kansas, which share characteristics typical of many drinking water aquifers in the United States. The hypothetical leakage scenarios centered on the notion that wellbores are the most likely

  5. Key factors for determining groundwater impacts due to leakage from geologic carbon sequestration reservoirs

    SciTech Connect (OSTI)

    Carroll, Susan A.; Keating, Elizabeth; Mansoor, Kayyum; Dai, Zhenxue; Sun, Yunwei; Trainor-Guitton, Whitney; Brown, Chris; Bacon, Diana

    2014-09-07

    The National Risk Assessment Partnership (NRAP) is developing a science-based toolset for the analysis of potential impacts to groundwater chemistry from CO2 injection (www.netldoe.gov/nrap). The toolset adopts a stochastic approach in which predictions address uncertainties in shallow groundwater and leakage scenarios. It is derived from detailed physics and chemistry simulation results that are used to train more computationally efficient models, referred to here as reduced-order models (ROMs), for each component system. In particular, these tools can be used to help regulators and operators understand the expected sizes and longevity of plumes in pH, TDS, and dissolved metals that could result from a leakage of brine and/or CO2 from a storage reservoir into aquifers. This information can inform, for example, decisions on monitoring strategies that are both effective and efficient. We have used this approach to develop predictive reduced-order models for two common types of reservoirs, but the approach could be used to develop a model for a specific aquifer or other common types of aquifers. In this paper we describe potential impacts to groundwater quality due to CO2 and brine leakage, discuss an approach to calculate thresholds under which no impact to groundwater occurs, describe the time scale for impact on groundwater, and discuss the probability of detecting a groundwater plume should leakage occur. To facilitate this, multi-phase flow and reactive transport simulations and emulations were developed for two classes of aquifers, considering uncertainty in leakage source terms and aquifer hydrogeology. We targeted an unconfined fractured carbonate aquifer based on the Edwards aquifer in Texas and a confined alluvium aquifer based on the High Plains Aquifer in Kansas, which share characteristics typical of many drinking water aquifers in the United States. The hypothetical leakage scenarios centered on the notion that wellbores

  6. Review and model-based analysis of factors influencing soil carbon sequestration beneath switchgrass (Panicum virgatum)

    SciTech Connect (OSTI)

    Garten Jr, Charles T [ORNL

    2012-01-01

    Abstract. A simple, multi-compartment model was developed to predict soil carbon sequestration beneath switchgrass (Panicum virgatum) plantations in the southeastern United States. Soil carbon sequestration is an important component of sustainable switchgrass production for bioenergy because soil organic matter promotes water retention, nutrient supply, and soil properties that minimize erosion. A literature review was included for the purpose of model parameterization and five model-based experiments were conducted to predict how changes in environment (temperature) or crop management (cultivar, fertilization, and harvest efficiency) might affect soil carbon storage and nitrogen losses. Predictions of soil carbon sequestration were most sensitive to changes in annual biomass production, the ratio of belowground to aboveground biomass production, and temperature. Predictions of ecosystem nitrogen loss were most sensitive to changes in annual biomass production, the soil C/N ratio, and nitrogen remobilization efficiency (i.e., nitrogen cycling within the plant). Model-based experiments indicated that 1) soil carbon sequestration can be highly site specific depending on initial soil carbon stocks, temperature, and the amount of annual nitrogen fertilization, 2) response curves describing switchgrass yield as a function of annual nitrogen fertilization were important to model predictions, 3) plant improvements leading to greater belowground partitioning of biomass could increase soil carbon sequestration, 4) improvements in harvest efficiency have no indicated effects on soil carbon and nitrogen, but improve cumulative biomass yield, and 5) plant improvements that reduce organic matter decomposition rates could also increase soil carbon sequestration, even though the latter may not be consistent with desired improvements in plant tissue chemistry to maximize yields of cellulosic ethanol.

  7. Ocean Carbon Cycle Models from the Carbon Dioxide Information Analysis Center (CDIAC)

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    \tPacific data-model intercomparison from Patrick Wetzel (Max Planck Institute for Meteorology, Germany)

  8. Conceptual design of an integrated technology model for carbon policy assessment.

    SciTech Connect (OSTI)

    Backus, George A.; Dimotakes, Paul E.

    2011-01-01

    This report describes the conceptual design of a technology choice model for understanding strategies to reduce carbon intensity in the electricity sector. The report considers the major modeling issues affecting technology policy assessment and defines an implementable model construct. Further, the report delineates the basis causal structure of such a model and attempts to establish the technical/algorithmic viability of pursuing model development along with the associated analyses.

  9. Rate of reduction of ore-carbon composites: Part II. Modeling of reduction in extended composites

    SciTech Connect (OSTI)

    Fortini, O.M.; Fruehan, R.J.

    2005-12-01

    A new process for ironmaking was proposed using a rotary hearth furnace and an iron bath smelter to produce iron employing wood charcoal as an energy source and reductant. This paper examines reactions in composite pellet samples with sizes close to sizes used in industrial practice (10 to 16 min in diameter). A model was constructed using the combined kinetic mechanism developed in Part I of this series of articles along with equations for the computation of pellet temperature and shrinkage during the reaction. The analysis of reaction rates measured for pellets with wood charcoal showed that heat transfer plays a significant role in their overall rate of reaction at elevated temperatures. The slower rates measured in pellets containing coal char show that the intrinsic kinetics of carbon oxidation is more significant than heat transfer. Model calculations suggest that the rates are highly sensitive to the thermal conductivity of pellets containing wood charcoal and are less sensitive to the external conditions of heat transfer. It was seen that the changes in pellet surface area and diameter due to shrinkage introduce little change on reaction rates. The model developed provides an adequate description of pellets of wood charcoal up to circa 90% of reduction. Experimentally determined rates of reduction of iron oxide by wood charcoal were approximately 5 to 10 times faster than rates measured in pellets with coal char.

  10. Multi-phase CFD modeling of solid sorbent carbon capture system

    SciTech Connect (OSTI)

    Ryan, E. M.; DeCroix, D.; Breault, Ronald W.; Xu, W.; Huckaby, E. David

    2013-01-01

    Computational fluid dynamics (CFD) simulations are used to investigate a low temperature post-combustion carbon capture reactor. The CFD models are based on a small scale solid sorbent carbon capture reactor design from ADA-ES and Southern Company. The reactor is a fluidized bed design based on a silica-supported amine sorbent. CFD models using both Eulerian–Eulerian and Eulerian–Lagrangian multi-phase modeling methods are developed to investigate the hydrodynamics and adsorption of carbon dioxide in the reactor. Models developed in both FLUENT® and BARRACUDA are presented to explore the strengths and weaknesses of state of the art CFD codes for modeling multi-phase carbon capture reactors. The results of the simulations show that the FLUENT® Eulerian–Lagrangian simulations (DDPM) are unstable for the given reactor design; while the BARRACUDA Eulerian–Lagrangian model is able to simulate the system given appropriate simplifying assumptions. FLUENT® Eulerian–Eulerian simulations also provide a stable solution for the carbon capture reactor given the appropriate simplifying assumptions.

  11. Multi-Phase CFD Modeling of Solid Sorbent Carbon Capture System

    SciTech Connect (OSTI)

    Ryan, Emily M.; DeCroix, David; Breault, Ronald W.; Xu, Wei; Huckaby, E. D.; Saha, Kringan; Darteville, Sebastien; Sun, Xin

    2013-07-30

    Computational fluid dynamics (CFD) simulations are used to investigate a low temperature post-combustion carbon capture reactor. The CFD models are based on a small scale solid sorbent carbon capture reactor design from ADA-ES and Southern Company. The reactor is a fluidized bed design based on a silica-supported amine sorbent. CFD models using both Eulerian-Eulerian and Eulerian-Lagrangian multi-phase modeling methods are developed to investigate the hydrodynamics and adsorption of carbon dioxide in the reactor. Models developed in both FLUENT® and BARRACUDA are presented to explore the strengths and weaknesses of state of the art CFD codes for modeling multi-phase carbon capture reactors. The results of the simulations show that the FLUENT® Eulerian-Lagrangian simulations (DDPM) are unstable for the given reactor design; while the BARRACUDA Eulerian-Lagrangian model is able to simulate the system given appropriate simplifying assumptions. FLUENT® Eulerian-Eulerian simulations also provide a stable solution for the carbon capture reactor given the appropriate simplifying assumptions.

  12. Modelled Black Carbon Radiative Forcing and Atmospheric Lifetime...

    Office of Scientific and Technical Information (OSTI)

    Adjusting model results to measurements in remote regions, and at high altitudes, leads to a 25% reduction in the multi-model median direct BC forcing from fossil fuel and biofuel ...

  13. Measurement of carbon capture efficiency and stored carbon leakage

    DOE Patents [OSTI]

    Keeling, Ralph F.; Dubey, Manvendra K.

    2013-01-29

    Data representative of a measured carbon dioxide (CO.sub.2) concentration and of a measured oxygen (O.sub.2) concentration at a measurement location can be used to determine whether the measured carbon dioxide concentration at the measurement location is elevated relative to a baseline carbon dioxide concentration due to escape of carbon dioxide from a source associated with a carbon capture and storage process. Optionally, the data can be used to quantify a carbon dioxide concentration increase at the first location that is attributable to escape of carbon dioxide from the source and to calculate a rate of escape of carbon dioxide from the source by executing a model of gas-phase transport using at least the first carbon dioxide concentration increase. Related systems, methods, and articles of manufacture are also described.

  14. On linking an Earth system model to the equilibrium carbon representation of an economically optimizing land use model

    SciTech Connect (OSTI)

    Bond-Lamberty, Benjamin; Calvin, Katherine V.; Jones, Andrew D.; Mao, Jiafu; Patel, Pralit L.; Shi, Xiaoying; Thomson, Allison M.; Thornton, Peter E.; Zhou, Yuyu

    2014-01-01

    Human activities are significantly altering biogeochemical cycles at the global scale, posing a significant problem for earth system models (ESMs), which may incorporate static land-use change inputs but do not actively simulate policy or economic forces. One option to address this problem is a to couple an ESM with an economically oriented integrated assessment model. Here we have implemented and tested a coupling mechanism between the carbon cycles of an ESM (CLM) and an integrated assessment (GCAM) model, examining the best proxy variables to share between the models, and quantifying our ability to distinguish climate- and land-use-driven flux changes. CLMs net primary production and heterotrophic respiration outputs were found to be the most robust proxy variables by which to manipulate GCAMs assumptions of long-term ecosystem steady state carbon, with short-term forest production strongly correlated with long-term biomass changes in climate-change model runs. By leveraging the fact that carbon-cycle effects of anthropogenic land-use change are short-term and spatially limited relative to widely distributed climate effects, we were able to distinguish these effects successfully in the model coupling, passing only the latter to GCAM. By allowing climate effects from a full earth system model to dynamically modulate the economic and policy decisions of an integrated assessment model, this work provides a foundation for linking these models in a robust and flexible framework capable of examining two-way interactions between human and earth system processes.

  15. Modeling the impact of agricultural land use and management on US carbon budgets

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Drewniak, B. A.; Mishra, U.; Song, J.; Prell, J.; Kotamarthi, V. R.

    2014-09-22

    Cultivation of the terrestrial land surface can create either a source or sink of atmospheric CO2, depending on land management practices. The Community Land Model (CLM) provides a useful tool to explore how land use and management impact the soil carbon pool at regional to global scales. CLM was recently updated to include representation of managed lands growing maize, soybean, and spring wheat. In this study, CLM-Crop is used to investigate the impacts of various management practices, including fertilizer use and differential rates of crop residue removal, on the soil organic carbon (SOC) storage of croplands in the continental Unitedmore » States over approximately a 170 year period. Results indicate that total US SOC stocks have already lost over 8 Pg C (10%) due to land cultivation practices (e.g., fertilizer application, cultivar choice, and residue removal), compared to a land surface composed of native vegetation (i.e., grasslands). After long periods of cultivation, individual plots growing maize and soybean lost up to 65% of the carbon stored, compared to a grassland site. Crop residue management showed the greatest effect on soil carbon storage, with low and medium residue returns resulting in additional losses of 5% and 3.5%, respectively, in US carbon storage, while plots with high residue returns stored 2% more carbon. Nitrogenous fertilizer can alter the amount of soil carbon stocks significantly. Under current levels of crop residue return, not applying fertilizer resulted in a 5% loss of soil carbon. Our simulations indicate that disturbance through cultivation will always result in a loss of soil carbon, and management practices will have a large influence on the magnitude of SOC loss.« less

  16. Modeling the impact of agricultural land use and management on US carbon budgets

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Drewniak, B. A.; Mishra, U.; Song, J.; Prell, J.; Kotamarthi, V. R.

    2015-04-09

    Cultivation of the terrestrial land surface can create either a source or sink of atmospheric CO2, depending on land management practices. The Community Land Model (CLM) provides a useful tool for exploring how land use and management impact the soil carbon pool at regional to global scales. CLM was recently updated to include representation of managed lands growing maize, soybean, and spring wheat. In this study, CLM-Crop is used to investigate the impacts of various management practices, including fertilizer use and differential rates of crop residue removal, on the soil organic carbon (SOC) storage of croplands in the continental Unitedmore » States over approximately a 170-year period. Results indicate that total US SOC stocks have already lost over 8 Pg C (10%) due to land cultivation practices (e.g., fertilizer application, cultivar choice, and residue removal), compared to a land surface composed of native vegetation (i.e., grasslands). After long periods of cultivation, individual subgrids (the equivalent of a field plot) growing maize and soybean lost up to 65% of the carbon stored compared to a grassland site. Crop residue management showed the greatest effect on soil carbon storage, with low and medium residue returns resulting in additional losses of 5 and 3.5%, respectively, in US carbon storage, while plots with high residue returns stored 2% more carbon. Nitrogenous fertilizer can alter the amount of soil carbon stocks significantly. Under current levels of crop residue return, not applying fertilizer resulted in a 5% loss of soil carbon. Our simulations indicate that disturbance through cultivation will always result in a loss of soil carbon, and management practices will have a large influence on the magnitude of SOC loss.« less

  17. Exploring growth kinetics of carbon nanotube arrays by in situ optical diagnostics and modeling

    SciTech Connect (OSTI)

    Puretzky, Alexander A; Geohegan, David B; Pannala, Sreekanth; Rouleau, Christopher

    2014-01-01

    Simple kinetic models of carbon nanotube growth have been able to successfully link together many experimental parameters involved in the growth of carbon nanotubes for practical applications including the prediction of growth rates, terminal lengths, number of walls, activation energies, and their dependences on the growth environment. The implications of recent experiments utilizing in situ monitoring of carbon nanotube growth on our past kinetic model are first reviewed. Then, sub-second pulsed feedstock gas introduction is discussed to explore the nucleation and initial growth of carbon nanotubes in the context of the kinetic model. Moreover, kinetic effects in "pulsed CVD" - using repeated pulsed gas introduction to stop and restart nanotube growth - are explored to understand renucleation, the origin of alignment in nanotube arrays, and incremental growth. Time-resolved reflectivity of the surface is used to remotely understand the kinetics of nucleation and the coordinated growth of arrays. This approach demonstrates that continuous vertically aligned single wall carbon nanotubes can be grown incrementally by pulsed CVD, and that the first exposure of fresh catalyst to feedstock gas is critical to nanotubes site density required for coordinated growth. Aligned nanotube arrays (as short as 60 nm) are shown to nucleate and grow within single, sub-second gas pulses. The multiple-pulse growth experiments (> 100 pulses) show that a high fraction of nanotubes renucleate on subsequent gas pulses.

  18. Determination of Organophosphate Pesticides at a Carbon Nanotube/Organophosphorus Hydrolase Electrochemical Biosensor

    SciTech Connect (OSTI)

    Deo, R P.; Wang, Joseph; Block, I; Mulchandani, Ashok; Joshi, K; Trojanowicz, M; Scholz, F; Chen, Wilfred; Lin, Yuehe

    2005-02-08

    An amperometric biosensor for organophosphorus (OP) pesticides based on a carbon-nanotube (CNT) modified transducer and an organophosphorus hydrolase (OPH) biocatalyst is described. A bilayer approach with the OPH layer atop of the CNT film was used for preparing the CNT/OPH biosensor. The CNT layer leads to a greatly improved anodic detection of the enzymatically-generated p-nitrophenol product, including higher sensitivity and stability. The sensor performance was optimized with respect to the surface modification and operating conditions. Under the optimal conditions the biosensor was used to measure as low as 0.15 {micro}M paraoxon and 0.8 {micro}M methyl parathion with sensitivities of 25 and 6 nA/{micro}M, respectively.

  19. Assessing FPAR Source and Parameter Optimization Scheme in Application of a Diagnostic Carbon Flux Model

    SciTech Connect (OSTI)

    Turner, D P; Ritts, W D; Wharton, S; Thomas, C; Monson, R; Black, T A

    2009-02-26

    The combination of satellite remote sensing and carbon cycle models provides an opportunity for regional to global scale monitoring of terrestrial gross primary production, ecosystem respiration, and net ecosystem production. FPAR (the fraction of photosynthetically active radiation absorbed by the plant canopy) is a critical input to diagnostic models, however little is known about the relative effectiveness of FPAR products from different satellite sensors nor about the sensitivity of flux estimates to different parameterization approaches. In this study, we used multiyear observations of carbon flux at four eddy covariance flux tower sites within the conifer biome to evaluate these factors. FPAR products from the MODIS and SeaWiFS sensors, and the effects of single site vs. cross-site parameter optimization were tested with the CFLUX model. The SeaWiFs FPAR product showed greater dynamic range across sites and resulted in slightly reduced flux estimation errors relative to the MODIS product when using cross-site optimization. With site-specific parameter optimization, the flux model was effective in capturing seasonal and interannual variation in the carbon fluxes at these sites. The cross-site prediction errors were lower when using parameters from a cross-site optimization compared to parameter sets from optimization at single sites. These results support the practice of multisite optimization within a biome for parameterization of diagnostic carbon flux models.

  20. Development of a coupled thermo-hydro-mechanical model in discontinuous media for carbon sequestration

    SciTech Connect (OSTI)

    Fang, Yilin; Nguyen, Ba Nghiep; Carroll, Kenneth C.; Xu, Zhijie; Yabusaki, Steven B.; Scheibe, Timothy D.; Bonneville, Alain

    2013-09-12

    Geomechanical alteration of porous media is generally ignored for most shallow subsurface applications, whereas CO2 injection, migration, and trapping in deep saline aquifers will be controlled by coupled multifluid flow, energy transfer, and geomechanical processes. The accurate assessment of the risks associated with potential leakage of injected CO2 and the design of effective injection systems requires that we represent these coupled processes within numerical simulators. The objectives of this study were to develop a coupled thermal-hydro-mechanical model into a single software, and to examine the coupling of thermal, hydrological, and geomechanical processes for simulation of CO2 injection into the subsurface for carbon sequestration. A numerical model is developed to couple nonisothermal multiphase hydrological and geomechanical processes for prediction of multiple interconnected processes for carbon sequestration in deep saline aquifers. The geomechanics model was based on Rigid Body-Spring Model (RBSM), one of the discrete methods to model discontinuous rock system. Poissons effect that was often ignored by RBSM was considered in the model. The simulation of large-scale and long-term coupled processes in carbon capture and storage projects requires large memory and computational performance. Global Array Toolkit was used to build the model to permit the high performance simulations of the coupled processes. The model was used to simulate a case study with several scenarios to demonstrate the impacts of considering coupled processes and Poissons effect for the prediction of CO2 sequestration.

  1. Models of carbon flow in tropical ecosystems with emphasis on their role in the global carbon cycle. Final report, September 15, 1978-September 14, 1980

    SciTech Connect (OSTI)

    Brown, S.; Lugo, A.E.

    1980-01-01

    The role of tropical forests on the carbon balance of the world is studied with four different approaches: (1) to quantify the area of tropical forests and the changes in forest cover; (2) to calculate the storage and production of organic carbon in tropical forests; (3) the modelling of land use changes in tropical countries using computer simulation models; and (4) the synthesis of information from many sources into conceptual schemes using Life Zone and energy use concepts. Results are not yet conclusive but indicate that tropical forests play a significant role in the global carbon cycle, and they are likely to be small sources of carbon to the atmosphere. The basis for this statement is: (1) the large area of tropical forests do not appear to be changing as fast as suggested earlier; (2) the storage of carbon in the tropics is about one half as previously suggested; (3) the turnover of carbon in the tropics is very fast with large exports to the ocean via rivers; and (4) models of land use change using data from Bolivia show only a small net addition of carbon to the atmosphere.

  2. Modeling predicts which counties could store more carbon in soil by growing

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    bioenergy crops | Argonne National Laboratory Modeling predicts which counties could store more carbon in soil by growing bioenergy crops By Katie Elyce Jones * July 13, 2016 Tweet EmailPrint To help stakeholders in government and business make smart decisions about the best types of land and local climates for planting bioenergy crops, researchers at the U.S. Department of Energy's (DOE's) Argonne National Laboratory are using computational modeling to predict which counties could see

  3. Effective permittivity of single-walled carbon nanotube composites: Two-fluid model

    SciTech Connect (OSTI)

    Moradi, Afshin; Zangeneh, Hamid Reza; Moghadam, Firoozeh Karimi

    2015-12-15

    We develop an effective medium theory to obtain effective permittivity of a composite of two-dimensional (2D) aligned single-walled carbon nanotubes. Electronic excitations on each nanotube surface are modeled by an infinitesimally thin layer of a 2D electron gas represented by two interacting fluids, which takes into account different nature of the σ and π electrons. Calculations of both real and imaginary parts of the effective dielectric function of the system are presented, for different values of the filling factor and radius of carbon nanotubes.

  4. Accelerating the spin-up of the coupled carbon and nitrogen cycle model in CLM4

    SciTech Connect (OSTI)

    Fang, Yilin; Liu, Chongxuan; Leung, Lai-Yung R.

    2015-03-24

    The commonly adopted biogeochemistry spin-up process in an Earth system model (ESM) is to run the model for hundreds to thousands of years subject to periodic atmospheric forcing to reach dynamic steady state of the carbon–nitrogen (CN) models. A variety of approaches have been proposed to reduce the computation time of the spin-up process. Significant improvement in computational efficiency has been made recently. However, a long simulation time is still required to reach the common convergence criteria of the coupled carbon–nitrogen model. A gradient projection method was proposed and used to further reduce the computation time after examining the trend of the dominant carbon pools. The Community Land Model version 4 (CLM4) with a carbon and nitrogen component was used in this study. From point-scale simulations, we found that the method can reduce the computation time by 20–69% compared to one of the fastest approaches in the literature. We also found that the cyclic stability of total carbon for some cases differs from that of the periodic atmospheric forcing, and some cases even showed instability. Close examination showed that one case has a carbon periodicity much longer than that of the atmospheric forcing due to the annual fire disturbance that is longer than half a year. The rest was caused by the instability of water table calculation in the hydrology model of CLM4. The instability issue is resolved after we replaced the hydrology scheme in CLM4 with a flow model for variably saturated porous media.

  5. Accelerating the spin-up of the coupled carbon and nitrogen cycle model in CLM4

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Fang, Yilin; Liu, Chongxuan; Leung, Lai-Yung R.

    2015-03-24

    The commonly adopted biogeochemistry spin-up process in an Earth system model (ESM) is to run the model for hundreds to thousands of years subject to periodic atmospheric forcing to reach dynamic steady state of the carbon–nitrogen (CN) models. A variety of approaches have been proposed to reduce the computation time of the spin-up process. Significant improvement in computational efficiency has been made recently. However, a long simulation time is still required to reach the common convergence criteria of the coupled carbon–nitrogen model. A gradient projection method was proposed and used to further reduce the computation time after examining the trendmore » of the dominant carbon pools. The Community Land Model version 4 (CLM4) with a carbon and nitrogen component was used in this study. From point-scale simulations, we found that the method can reduce the computation time by 20–69% compared to one of the fastest approaches in the literature. We also found that the cyclic stability of total carbon for some cases differs from that of the periodic atmospheric forcing, and some cases even showed instability. Close examination showed that one case has a carbon periodicity much longer than that of the atmospheric forcing due to the annual fire disturbance that is longer than half a year. The rest was caused by the instability of water table calculation in the hydrology model of CLM4. The instability issue is resolved after we replaced the hydrology scheme in CLM4 with a flow model for variably saturated porous media.« less

  6. Total cyanide mass measurement with micro-ion selective electrode for determination of specific activity of carbon-11 cyanide

    SciTech Connect (OSTI)

    Shea, Colleen; Alexoff, David L.; Kim, Dohyun; Hoque, Ruma; Schueller, Michael J.; Fowler, Joanna S.; Qu, Wenchao

    2015-04-25

    In this study, we aim to directly measure the specific activity (SA) of the carbon-11 cyanide ([11C]CN¯) produced by our in-house built automated [11C]HCN production system and to identify the major sources of 12C-cyanide (12CN¯). The [11C]CN¯ is produced from [11C]CO2, which is generated by the 14N(p,α)11C nuclear reaction using a cyclotron. Direct measurement of cyanide concentrations was accomplished using a relatively inexpensive, and easy to use ion selective electrode (ISE) which offered an appropriate range of sensitivity for detecting mass. Multiple components of the [11C]HCN production system were isolated in order to determine their relative contributions to 12CN¯ mass. It was determined that the system gases were responsible for approximately 30% of the mass, and that the molecular sieve/nickel furnace unit contributed approximately 70% of the mass. Beam on target (33 µA for 1 and 10 min) did not contribute significantly to the mass. Additionally, we compared the SA of our [11C]HCN precursor determined using the ISE to the SA of our current [11C]CN¯ derived radiotracers determined by HPLC to assure there was no significant difference between the two methods. These results are the first reported use of an ion selective electrode to determine the SA of no-carrier-added cyanide ion, and clearly show that it is a valuable, inexpensive and readily available tool suitable for this purpose.

  7. Total cyanide mass measurement with micro-ion selective electrode for determination of specific activity of carbon-11 cyanide

    SciTech Connect (OSTI)

    Shea, Colleen; Alexoff, David L.; Kim, Dohyun; Hoque, Ruma; Schueller, Michael J.; Fowler, Joanna S.; Qu, Wenchao

    2015-04-25

    In this study, we aim to directly measure the specific activity (SA) of the carbon-11 cyanide ([11C]CN) produced by our in-house built automated [11C]HCN production system and to identify the major sources of 12C-cyanide (12CN). The [11C]CN is produced from [11C]CO2, which is generated by the 14N(p,?)11C nuclear reaction using a cyclotron. Direct measurement of cyanide concentrations was accomplished using a relatively inexpensive, and easy to use ion selective electrode (ISE) which offered an appropriate range of sensitivity for detecting mass. Multiple components of the [11C]HCN production system were isolated in order to determine their relative contributions to 12CN mass. It was determined that the system gases were responsible for approximately 30% of the mass, and that the molecular sieve/nickel furnace unit contributed approximately 70% of the mass. Beam on target (33 A for 1 and 10 min) did not contribute significantly to the mass. Additionally, we compared the SA of our [11C]HCN precursor determined using the ISE to the SA of our current [11C]CN derived radiotracers determined by HPLC to assure there was no significant difference between the two methods. These results are the first reported use of an ion selective electrode to determine the SA of no-carrier-added cyanide ion, and clearly show that it is a valuable, inexpensive and readily available tool suitable for this purpose.

  8. Total cyanide mass measurement with micro-ion selective electrode for determination of specific activity of carbon-11 cyanide

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Shea, Colleen; Alexoff, David L.; Kim, Dohyun; Hoque, Ruma; Schueller, Michael J.; Fowler, Joanna S.; Qu, Wenchao

    2015-04-25

    In this study, we aim to directly measure the specific activity (SA) of the carbon-11 cyanide ([11C]CN¯) produced by our in-house built automated [11C]HCN production system and to identify the major sources of 12C-cyanide (12CN¯). The [11C]CN¯ is produced from [11C]CO2, which is generated by the 14N(p,α)11C nuclear reaction using a cyclotron. Direct measurement of cyanide concentrations was accomplished using a relatively inexpensive, and easy to use ion selective electrode (ISE) which offered an appropriate range of sensitivity for detecting mass. Multiple components of the [11C]HCN production system were isolated in order to determine their relative contributions to 12CN¯ mass.more » It was determined that the system gases were responsible for approximately 30% of the mass, and that the molecular sieve/nickel furnace unit contributed approximately 70% of the mass. Beam on target (33 µA for 1 and 10 min) did not contribute significantly to the mass. Additionally, we compared the SA of our [11C]HCN precursor determined using the ISE to the SA of our current [11C]CN¯ derived radiotracers determined by HPLC to assure there was no significant difference between the two methods. These results are the first reported use of an ion selective electrode to determine the SA of no-carrier-added cyanide ion, and clearly show that it is a valuable, inexpensive and readily available tool suitable for this purpose.« less

  9. Geophysical monitoring and reactive transport modeling of ureolytically-driven calcium carbonate precipitation

    SciTech Connect (OSTI)

    Wu, Y.; Ajo-Franklin, J.B.; Spycher, N.; Hubbard, S.S.; Zhang, G.; Williams, K.H.; Taylor, J.; Fujita, Y.; Smith, R.

    2011-07-15

    Ureolytically-driven calcium carbonate precipitation is the basis for a promising in-situ remediation method for sequestration of divalent radionuclide and trace metal ions. It has also been proposed for use in geotechnical engineering for soil strengthening applications. Monitoring the occurrence, spatial distribution, and temporal evolution of calcium carbonate precipitation in the subsurface is critical for evaluating the performance of this technology and for developing the predictive models needed for engineering application. In this study, we conducted laboratory column experiments using natural sediment and groundwater to evaluate the utility of geophysical (complex resistivity and seismic) sensing methods, dynamic synchrotron x-ray computed tomography (micro-CT), and reactive transport modeling for tracking ureolytically-driven calcium carbonate precipitation processes under site relevant conditions. Reactive transport modeling with TOUGHREACT successfully simulated the changes of the major chemical components during urea hydrolysis. Even at the relatively low level of urea hydrolysis observed in the experiments, the simulations predicted an enhanced calcium carbonate precipitation rate that was 3-4 times greater than the baseline level. Reactive transport modeling results, geophysical monitoring data and micro-CT imaging correlated well with reaction processes validated by geochemical data. In particular, increases in ionic strength of the pore fluid during urea hydrolysis predicted by geochemical modeling were successfully captured by electrical conductivity measurements and confirmed by geochemical data. The low level of urea hydrolysis and calcium carbonate precipitation suggested by the model and geochemical data was corroborated by minor changes in seismic P-wave velocity measurements and micro-CT imaging; the latter provided direct evidence of sparsely distributed calcium carbonate precipitation. Ion exchange processes promoted through NH{sub 4}{sup

  10. Geophysical Monitoring and Reactive Transport Modeling of Ureolytically-Driven Calcium Carbonate Precipitation

    SciTech Connect (OSTI)

    Yuxin Wu; Jonathan B. Ajo-Franklin; Nicolas Spycher; Susan S. Hubbard; Guoxiang Zhang; Kenneth H. Williams; Joanna Taylor; Yoshiko Fujita; Robert Smith

    2011-09-01

    Ureolytically-driven calcium carbonate precipitation is the basis for a promising in-situ remediation method for sequestration of divalent radionuclide and trace metal ions. It has also been proposed for use in geotechnical engineering for soil strengthening applications. Monitoring the occurrence, spatial distribution, and temporal evolution of calcium carbonate precipitation in the subsurface is critical for evaluating the performance of this technology and for developing the predictive models needed for engineering application. In this study, we conducted laboratory column experiments using natural sediment and groundwater to evaluate the utility of geophysical (complex resistivity and seismic) sensing methods, dynamic synchrotron x-ray computed tomography (micro-CT), and reactive transport modeling for tracking ureolytically-driven calcium carbonate precipitation processes under site relevant conditions. Reactive transport modeling with TOUGHREACT successfully simulated the changes of the major chemical components during urea hydrolysis. Even at the relatively low level of urea hydrolysis observed in the experiments, the simulations predicted an enhanced calcium carbonate precipitation rate that was 3-4 times greater than the baseline level. Reactive transport modeling results, geophysical monitoring data and micro-CT imaging correlated well with reaction processes validated by geochemical data. In particular, increases in ionic strength of the pore fluid during urea hydrolysis predicted by geochemical modeling were successfully captured by electrical conductivity measurements and confirmed by geochemical data. The low level of urea hydrolysis and calcium carbonate precipitation suggested by the model and geochemical data was corroborated by minor changes in seismic P-wave velocity measurements and micro-CT imaging; the latter provided direct evidence of sparsely distributed calcium carbonate precipitation. Ion exchange processes promoted through NH4

  11. Low Cost Carbon Fibre: Applications, Performance and Cost Models - Chapter 17

    SciTech Connect (OSTI)

    Warren, Charles David; Wheatley, Dr. Alan; Das, Sujit

    2014-01-01

    Weight saving in automotive applications has a major bearing on fuel economy. It is generally accepted that, typically, a 10% weight reduction in an automobile will lead to a 6-8% improvement in fuel economy. In this respect, carbon fibre composites are extremely attractive in their ability to provide superlative mechanical performance per unit weight. That is why they are specified for high-end uses such as Formula 1 racing cars and the latest aircraft (e.g. Boeing 787, Airbus A350 and A380), where they comprise over 50% by weight of the structure However, carbon fibres are expensive and this renders their composites similarly expensive. Research has been carried out at Oak Ridge National Laboratories (ORNL), Tennessee, USA for over a decade with the aim of reducing the cost of carbon fibre such that it becomes a cost-effective option for the automotive industry. Aspects of this research relating to the development of low cost carbon fibre have been reported in Chapter 3 of this publication. In this chapter, the practical industrial applications of low-cost carbon fibre are presented, together with considerations of the performance and cost models which underpin the work.

  12. The Carbon-Land Model Intercomparison Project (C-LAMP): A Model-Data Comparison System for Evaluation of Coupled Biosphere-Atmosphere Models

    SciTech Connect (OSTI)

    Hoffman, Forrest M; Randerson, Jim; Thornton, Peter E; Mahowald, Natalie; Bonan, Gordon; Running, Steven; Fung, Inez

    2009-01-01

    The need to capture important climate feebacks in general circulation models (GCMs) has resulted in new efforts to include atmospheric chemistry and land and ocean biogeochemistry into the next generation of production climate models, now often referred to as Earth System Models (ESMs). While many terrestrial and ocean carbon models have been coupled to GCMs, recent work has shown that such models can yield a wide range of results, suggesting that a more rigorous set of offline and partially coupled experiments, along with detailed analyses of processes and comparisons with measurements, are warranted. The Carbon-Land Model Intercomparison Project (C-LAMP) provides a simulation protocol and model performance metrics based upon comparisons against best-available satellite- and ground-based measurements (Hoffman et al., 2007). C-LAMP provides feedback to the modeling community regarding model improvements and to the measurement community by suggesting new observational campaigns. C-LAMP Experiment 1 consists of a set of uncoupled simulations of terrestrial carbon models specifically designed to examine the ability of the models to reproduce surface carbon and energy fluxes at multiple sites and to exhibit the influence of climate variability, prescribed atmospheric carbon dioxide (CO{sub 2}), nitrogen (N) deposition, and land cover change on projections of terrestrial carbon fluxes during the 20th century. Experiment 2 consists of partially coupled simulations of the terrestrial carbon model with an active atmosphere model exchanging energy and moisture fluxes. In all experiments, atmospheric CO{sub 2} follows the prescribed historical trajectory from C{sup 4}MIP. In Experiment 2, the atmosphere model is forced with prescribed sea surface temperatures (SSTs) and corresponding sea ice concentrations from the Hadley Centre; prescribed CO{sub 2} is radiatively active; and land, fossil fuel, and ocean CO{sub 2} fluxes are advected by the model. Both sets of experiments

  13. OAK FOREST CARBON AND WATER SIMULATIONS: MODEL INTERCOMPARISONS AND EVALUATIONS AGAINST INDEPENDENT DATA

    SciTech Connect (OSTI)

    Hanson, Paul J; Amthor, Jeffrey S; Wullschleger, Stan D; Wilson, K.; Grant, Robert F.; Hartley, Anne; Hui, D.; HuntJr., E. Raymond; Johnson, Dale W.; Kimball, John S.; King, Anthony Wayne; Luo, Yiqi; McNulty, Steven G.; Sun, G.; Thornton, Peter; Wang, S.; Williams, M.; Baldocchi, D. D.; Cushman, Robert Michael

    2004-01-01

    Models represent our primary method for integration of small-scale, processlevel phenomena into a comprehensive description of forest-stand or ecosystem function. They also represent a key method for testing hypotheses about the response of forest ecosystems to multiple changing environmental conditions. This paper describes the evaluation of 13 stand-level models varying in their spatial, mechanistic, and temporal complexity for their ability to capture intra- and interannual components of the water and carbon cycle for an upland, oak-dominated forest of eastern Tennessee. Comparisons between model simulations and observations were conducted for hourly, daily, and annual time steps. Data for the comparisons were obtained from a wide range of methods including: eddy covariance, sapflow, chamber-based soil respiration, biometric estimates of stand-level net primary production and growth, and soil water content by time or frequency domain reflectometry. Response surfaces of carbon and water flux as a function of environmental drivers, and a variety of goodness-of-fit statistics (bias, absolute bias, and model efficiency) were used to judge model performance. A single model did not consistently perform the best at all time steps or for all variables considered. Intermodel comparisons showed good agreement for water cycle fluxes, but considerable disagreement among models for predicted carbon fluxes. The mean of all model outputs, however, was nearly always the best fit to the observations. Not surprisingly, models missing key forest components or processes, such as roots or modeled soil water content, were unable to provide accurate predictions of ecosystem responses to short-term drought phenomenon. Nevertheless, an inability to correctly capture short-term physiological processes under drought was not necessarily an indicator of poor annual water and carbon budget simulations. This is possible because droughts in the subject ecosystem were of short duration and

  14. Determination

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Determinants of Household Use of Selected Energy Star Appliances May 2016 Independent Statistics & Analysis www.eia.gov U.S. Department of Energy Washington, DC 20585 U.S. Energy Information Administration | Determinants of Household Use of Selected Energy Star Appliances i This report was prepared by the U.S. Energy Information Administration (EIA), the statistical and analytical agency within the U.S. Department of Energy. By law, EIA's data, analyses, and forecasts are independent of

  15. Thermodynamic Data for Geochemical Modeling of Carbonate Reactions Associated with CO2 Sequestration – Literature Review

    SciTech Connect (OSTI)

    Krupka, Kenneth M.; Cantrell, Kirk J.; McGrail, B. Peter

    2010-09-28

    Permanent storage of anthropogenic CO2 in deep geologic formations is being considered as a means to reduce the concentration of atmospheric CO2 and thus its contribution to global climate change. To ensure safe and effective geologic sequestration, numerous studies have been completed of the extent to which the CO2 migrates within geologic formations and what physical and geochemical changes occur in these formations when CO2 is injected. Sophisticated, computerized reservoir simulations are used as part of field site and laboratory CO2 sequestration studies. These simulations use coupled multiphase flow-reactive chemical transport models and/or standalone (i.e., no coupled fluid transport) geochemical models to calculate gas solubility, aqueous complexation, reduction/oxidation (redox), and/or mineral solubility reactions related to CO2 injection and sequestration. Thermodynamic data are critical inputs to modeling geochemical processes. The adequacy of thermodynamic data for carbonate compounds has been identified as an important data requirement for the successful application of these geochemical reaction models to CO2 sequestration. A review of thermodynamic data for CO2 gas and carbonate aqueous species and minerals present in published data compilations and databases used in geochemical reaction models was therefore completed. Published studies that describe mineralogical analyses from CO2 sequestration field and natural analogue sites and laboratory studies were also reviewed to identify specific carbonate minerals that are important to CO2 sequestration reactions and therefore require thermodynamic data. The results of the literature review indicated that an extensive thermodynamic database exists for CO2 and CH4 gases, carbonate aqueous species, and carbonate minerals. Values of ∆fG298° and/or log Kr,298° are available for essentially all of these compounds. However, log Kr,T° or heat capacity values at temperatures above 298 K exist for less than

  16. The North American Carbon Program Multi-scale synthesis and Terrestrial Model Intercomparison Project Part 1: Overview and experimental design

    SciTech Connect (OSTI)

    Huntzinger, D.N.; Schwalm, C.; Michalak, A.M; Schaefer, K.; King, A.W.; Wei, Y.; Jacobson, A.; Liu, S.; Cook, R.; Post, W.M.; Berthier, G.; Hayes, D.; Huang, M.; Ito, A.; Lei, H.; Lu, C.; Mao, J.; Peng, C.H.; Peng, S.; Poulter, B.; Riccuito, D.; Shi, X.; Tian, H.; Wang, W.; Zeng, N.; Zhao, F.; Zhu, Q.

    2013-01-01

    Terrestrial biosphere models (TBMs) have become an integral tool for extrapolating local observations and understanding of land-atmosphere carbon exchange to larger regions. The North American Carbon Program (NACP) Multi-scale synthesis and Terrestrial Model Intercomparison Project (MsTMIP) is a formal model intercomparison and evaluation effort focused on improving the diagnosis and attribution of carbon exchange at regional and global scales. MsTMIP builds upon current and past synthesis activities, and has a unique framework designed to isolate, interpret, and inform understanding of how model structural differences impact estimates of carbon uptake and release. Here we provide an overview of the MsTMIP effort and describe how the MsTMIP experimental design enables the assessment and quantification of TBM structural uncertainty. Model structure refers to the types of processes considered (e.g. nutrient cycling, disturbance, lateral transport of carbon), and how these processes are represented (e.g. photosynthetic formulation, temperature sensitivity, respiration) in the models. By prescribing a common experimental protocol with standard spin-up procedures and driver data sets, we isolate any biases and variability in TBM estimates of regional and global carbon budgets resulting from differences in the models themselves (i.e. model structure) and model-specific parameter values. An initial intercomparison of model structural differences is represented using hierarchical cluster diagrams (a.k.a. dendrograms), which highlight similarities and differences in how models account for carbon cycle, vegetation, energy, and nitrogen cycle dynamics. We show that, despite the standardized protocol used to derive initial conditions, models show a high degree of variation for GPP, total living biomass, and total soil carbon, underscoring the influence of differences in model structure and parameterization on model estimates.

  17. Exploration model for shallow Silurian (Kankakee) carbonate reservoirs in western Illinois

    SciTech Connect (OSTI)

    Crockett, J.E.; Seyler, B.J.; Whitaker, S.

    1987-09-01

    Reservoirs in shallow (600-650 ft deep) basal Silurian Kankakee carbonates at Buckhorn consolidated, Siloam, and Kellerville oil fields in western Illinois have produced nearly 2 million bbl of oil, but were developed essentially by random drilling. A new exploration model that combines lithologic studies and isopach mapping has been developed at the Illinois State Geological Survey. Isopach mapping of Silurian and Devonian rocks between an organic facies in the Mississippian-Devonian New Albany Shale and the top of the Ordovician Maquoketa Shale reveals thickened sequences that coincide with most of the oil fields. These thickened intervals apparently reflect subtle paleovalleys eroded into the Maquoketa shale during the Ordovician-Silurian hiatus. During the initial Silurian marine transgression, these paleovalleys at the base of the Kankakee were filled with carbonates to form the thickened sequences. Differential erosion at the top of the Kankakee does not satisfactorily explain the locally thickened sequences in the Kankakee. Lithologic studies suggest that subsurface fluid flows concentrated along these paleovalleys contributed to subsequent diagenesis of valleyfill carbonates. Diagenetic alteration of these carbonates resulted in development of basal Kankakee reservoirs within the paleovalleys. This concept of Kankakee reservoirs occurring within paleovalleys at the Ordovician-Silurian unconformity is a new exploration model that can aid in the search for similar traps in western Illinois.

  18. A model-data intercomparison of CO2 exchange across North America: Results from the North American Carbon Program Site Synthesis

    SciTech Connect (OSTI)

    Schwalm, C.R.; Williams, C.A.; Schaefer, K.; Anderson, R.; Arain, M.A.; Baker, I.; Black, T.A.; Chen, G.; Ciais, P.; Davis, K. J.; Desai, A. R.; Dietze, M.; Dragoni, D.; Fischer, M.L.; Flanagan, L.B.; Grant, R.F.; Gu, L.; Hollinger, D.; Izaurralde, R.C.; Kucharik, C.; Lafleur, P.M.; Law, B.E.; Li, L.; Li, Z.; Liu, S.; Lokupitiya, E.; Luo, Y.; Ma, S.; Margolis, H.; Matamala, R.; McCaughey, H.; Monson, R. K.; Oechel, W. C.; Peng, C.; Poulter, B.; Price, D.T.; Riciutto, D.M.; Riley, W.J.; Sahoo, A.K.; Sprintsin, M.; Sun, J.; Tian, H.; Tonitto, C.; Verbeeck, H.; Verma, S.B.

    2011-06-01

    Our current understanding of terrestrial carbon processes is represented in various models used to integrate and scale measurements of CO{sub 2} exchange from remote sensing and other spatiotemporal data. Yet assessments are rarely conducted to determine how well models simulate carbon processes across vegetation types and environmental conditions. Using standardized data from the North American Carbon Program we compare observed and simulated monthly CO{sub 2} exchange from 44 eddy covariance flux towers in North America and 22 terrestrial biosphere models. The analysis period spans {approx}220 site-years, 10 biomes, and includes two large-scale drought events, providing a natural experiment to evaluate model skill as a function of drought and seasonality. We evaluate models' ability to simulate the seasonal cycle of CO{sub 2} exchange using multiple model skill metrics and analyze links between model characteristics, site history, and model skill. Overall model performance was poor; the difference between observations and simulations was {approx}10 times observational uncertainty, with forested ecosystems better predicted than nonforested. Model-data agreement was highest in summer and in temperate evergreen forests. In contrast, model performance declined in spring and fall, especially in ecosystems with large deciduous components, and in dry periods during the growing season. Models used across multiple biomes and sites, the mean model ensemble, and a model using assimilated parameter values showed high consistency with observations. Models with the highest skill across all biomes all used prescribed canopy phenology, calculated NEE as the difference between GPP and ecosystem respiration, and did not use a daily time step.

  19. Use of ARM observations and numerical models to determine radiative...

    Office of Scientific and Technical Information (OSTI)

    We investigated whether the West African anvil clouds connected with squall line MCSs passing over the Niamey ARM site could be simulated in a numerical model by comparing the ...

  20. Modeling carbon nanotube growth on the catalyst-substrate surface subjected to reactive plasma [

    SciTech Connect (OSTI)

    Tewari, Aarti; Sharma, Suresh C.

    2014-06-15

    The paper presents a theoretical model to study the growth of the carbon nanotube (CNT) on the catalyst substrate surface subjected to reactive plasma. The charging rate of the CNT, kinetics of electron, ions and neutral atoms, the growth rate of the CNT because of diffusion and accretion of ions on the catalyst nanoparticle inclusion of the issue of the plasma sheath is undertaken in the present model. Numerical calculations on the effect of ion density and temperature and the substrate bias on the growth of the CNT have been carried out for typical glow discharge plasma parameters. It is found that the height of CNT increases with the ion density of carbon ions and radius of CNT decreases with hydrogen ion density. The substrate bias also affects the growth rate of the CNT. The field emission characteristics from the CNTs can be analyzed from the results obtained.

  1. Chombo-Crunch: Modeling Pore-Scale Reactive Transport in Carbon

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Sequestration | Argonne Leadership Computing Facility Transient pH on calcite grains in capillary tube experiment. 1 billion grid points computed on 48K cores. 1 micron resolution. Transient pH on calcite grains in capillary tube experiment. 1 billion grid points computed on 48K cores. 1 micron resolution. David Trebotich, Lawrence Berkeley National Laboratory Chombo-Crunch: Modeling Pore-Scale Reactive Transport in Carbon Sequestration PI Name: David Trebotich PI Email: treb@lbl.gov

  2. Using Advanced Modeling to Accelerate the Scale-Up of Carbon Capture Technologies

    SciTech Connect (OSTI)

    Miller, David; Sun, Xin; Storlie, Curtis; Bhattacharyya, Debangsu

    2015-06-18

    Carbon capture and storage (CCS) is one of many approaches that are critical for significantly reducing domestic and global CO2 emissions. The U.S. Department of Energy’s Clean Coal Technology Program Plan envisions 2nd generation CO2 capture technologies ready for demonstration-scale testing around 2020 with the goal of enabling commercial deployment by 2025 [1]. Third generation technologies have a similarly aggressive timeline. A major challenge is that the development and scale-up of new technologies in the energy sector historically takes up to 15 years to move from the laboratory to pre-deployment and another 20 to 30 years for widespread industrial scale deployment. In order to help meet the goals of the DOE carbon capture program, the Carbon Capture Simulation Initiative (CCSI) was launched in early 2011 to develop, demonstrate, and deploy advanced computational tools and validated multi-scale models to reduce the time required to develop and scale up new carbon capture technologies. The CCSI Toolset (1) enables promising concepts to be more quickly identified through rapid computational screening of processes and devices, (2) reduces the time to design and troubleshoot new devices and processes by using optimization techniques to focus development on the best overall process conditions and by using detailed device-scale models to better understand and improve the internal behavior of complex equipment, and (3) provides quantitative predictions of device and process performance during scale up based on rigorously validated smaller scale simulations that take into account model and parameter uncertainty[2]. This article focuses on essential elements related to the development and validation of multi-scale models in order to help minimize risk and maximize learning as new technologies progress from pilot to demonstration scale.

  3. Causes and Implications of Persistent Atmospheric Carbon Dioxide Biases in Earth System Models

    SciTech Connect (OSTI)

    Hoffman, Forrest M [ORNL] [ORNL; Randerson, James T. [University of California, Irvine] [University of California, Irvine; Arora, Vivek K. [Canadian Centre for Climate Modelling and Analysis, Meteorological Service of Canada] [Canadian Centre for Climate Modelling and Analysis, Meteorological Service of Canada; Bao, Qing [State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics] [State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics; Cadule, Patricia [Institut Pierre Simon Laplace, Laboratoire des Sciences du Climat et de l'Environment] [Institut Pierre Simon Laplace, Laboratoire des Sciences du Climat et de l'Environment; Ji, Duoying [State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing] [State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing; Jones, Chris D. [Hadley Centre, U.K. Met Office] [Hadley Centre, U.K. Met Office; Kawamiya, Michio [Japan Agency for Marine-Earth Science and Technology (JAMSTEC)] [Japan Agency for Marine-Earth Science and Technology (JAMSTEC); Khatiwala, Samar [Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY] [Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY; Lindsay, Keith [National Center for Atmospheric Research (NCAR)] [National Center for Atmospheric Research (NCAR); Obata, Atsushi [Meteorological Research Institute, Japan] [Meteorological Research Institute, Japan; Shevliakova, Elena [Princeton University] [Princeton University; Six, Katharina D. [Max Planck Institute for Meteorology, Hamburg, Germany] [Max Planck Institute for Meteorology, Hamburg, Germany; Tjiputra, Jerry F. [Uni Climate, Uni Research] [Uni Climate, Uni Research; Volodin, Evgeny M. [Institute of Numerical Mathematics, Russian Academy of Science, Moscow] [Institute of Numerical Mathematics, Russian Academy of Science, Moscow; Wu, Tongwen [China Meteorological Administration (CMA), Beijing] [China Meteorological Administration (CMA), Beijing

    2014-01-01

    The strength of feedbacks between a changing climate and future CO2 concentrations are uncertain and difficult to predict using Earth System Models (ESMs). We analyzed emission-driven simulations--in which atmospheric CO2 levels were computed prognostically--for historical (1850-2005) and future periods (RCP 8.5 for 2006-2100) produced by 15 ESMs for the Fifth Phase of the Coupled Model Intercomparison Project (CMIP5). Comparison of ESM prognostic atmospheric CO2 over the historical period with observations indicated that ESMs, on average, had a small positive bias in predictions of contemporary atmospheric CO2. Weak ocean carbon uptake in many ESMs contributed to this bias, based on comparisons with observations of ocean and atmospheric anthropogenic carbon inventories. We found a significant linear relationship between contemporary atmospheric CO2 biases and future CO2 levels for the multi-model ensemble. We used this relationship to create a contemporary CO2 tuned model (CCTM) estimate of the atmospheric CO2 trajectory for the 21st century. The CCTM yielded CO2 estimates of 600 {plus minus} 14 ppm at 2060 and 947 {plus minus} 35 ppm at 2100, which were 21 ppm and 32 ppm below the multi-model mean during these two time periods. Using this emergent constraint approach, the likely ranges of future atmospheric CO2, CO2-induced radiative forcing, and CO2-induced temperature increases for the RCP 8.5 scenario were considerably narrowed compared to estimates from the full ESM ensemble. Our analysis provided evidence that much of the model-to-model variation in projected CO2 during the 21st century was tied to biases that existed during the observational era, and that model differences in the representation of concentration-carbon feedbacks and other slowly changing carbon cycle processes appear to be the primary driver of this variability. By improving models to more closely match the long-term time series of CO2 from Mauna Loa, our analysis suggests uncertainties in

  4. Divergent predictions of carbon storage between two global land models: attribution of the causes through traceability analysis

    SciTech Connect (OSTI)

    Rafique, Rashid; Xia, Jianyang; Hararuk, Oleksandra; Asrar, Ghassem R.; Wang, Yingping; Luo, Yiqi

    2015-08-27

    Representations of the terrestrial carbon cycle in land models are becoming increasingly complex. It is crucial to develop approaches for critical assessment of the complex model properties in order to understand key factors contributing to models’ performance. In this study, we applied a traceability analysis, which decomposes carbon cycle models into traceable components, to two global land models (CABLE and CLM-CASA’) to diagnose the causes of their differences in simulating ecosystem carbon storage capacity. Driven with similar forcing data, the CLM-CASA’ model predicted ~31% larger carbon storage capacity than the CABLE model. Since ecosystem carbon storage capacity is a product of net primary productivity (NPP) and ecosystem residence time (τE), the predicted difference in the storage capacity between the two models results from differences in either NPP or τE or both. Our analysis showed that CLM-CASA’ simulated 37% higher NPP than CABLE due to higher rates of carboxylation (Vcmax) in CLM-CASA’. On the other hand, τE , which was a function the baseline carbon residence time (τ´E) and environmental effect on carbon residence time, was on average 11 years longer in CABLE than CLM-CASA’. The difference in τE was mainly found to be caused by longer τ´E in CABLE than CLM-CASA’. This difference in τE was mainly caused by longer τ´E of woody biomass (23 vs. 14 years in CLM-CASA’) and higher proportion of NPP allocated to woody biomass (23% vs. 16%). Differences in environmental effects on carbon residence times had smaller influences on differences in ecosystem carbon storage capacities compared to differences in NPP and τ´E. Overall; the traceability analysis is an effective method for identifying sources of variations between the two models.

  5. Model Components of the Certification Framework for Geologic Carbon Sequestration Risk Assessment

    SciTech Connect (OSTI)

    Oldenburg, Curtis M.; Bryant, Steven L.; Nicot, Jean-Philippe; Kumar, Navanit; Zhang, Yingqi; Jordan, Preston; Pan, Lehua; Granvold, Patrick; Chow, Fotini K.

    2009-06-01

    We have developed a framework for assessing the leakage risk of geologic carbon sequestration sites. This framework, known as the Certification Framework (CF), emphasizes wells and faults as the primary potential leakage conduits. Vulnerable resources are grouped into compartments, and impacts due to leakage are quantified by the leakage flux or concentrations that could potentially occur in compartments under various scenarios. The CF utilizes several model components to simulate leakage scenarios. One model component is a catalog of results of reservoir simulations that can be queried to estimate plume travel distances and times, rather than requiring CF users to run new reservoir simulations for each case. Other model components developed for the CF and described here include fault characterization using fault-population statistics; fault connection probability using fuzzy rules; well-flow modeling with a drift-flux model implemented in TOUGH2; and atmospheric dense-gas dispersion using a mesoscale weather prediction code.

  6. Determining Interactions in PSA models: Application to a Space PSA

    SciTech Connect (OSTI)

    C. Smith; E. Borgonovo

    2010-06-01

    This paper addresses use of an importance measure interaction study of a probabilistic risk analysis (PSA) performed for a hypothetical aerospace lunar mission. The PSA methods used in this study follow the general guidance provided in the NASA Probabilistic Risk Assessment Procedures Guide for NASA Managers and Practitioners. For the PSA portion, we used phased-based event tree and fault tree logic structures are used to model a lunar mission, including multiple phases (from launch to return to the Earth surface) and multiple critical systems. Details of the analysis results are not provided in this paper instead specific basic events are denoted by number (e.g., the first event is 1, the second is 2, and so on). However, in the model, we used approximately 150 fault trees and over 800 basic events. Following analysis and truncation of cut sets, we were left with about 400 basic events to evaluate. We used this model to explore interactions between different basic events and systems. These sensitivity studies provide high-level insights into features of the PSA for the hypothetical lunar mission.

  7. Development and application of the EPIC model for carbon cycle, greenhouse-gas mitigation, and biofuel studies

    SciTech Connect (OSTI)

    Izaurralde, Roberto C.; Mcgill, William B.; Williams, J.R.

    2012-06-01

    This chapter provides a comprehensive review of the EPIC model in relation to carbon cycle, greenhouse-gas mitigation, and biofuel applications. From its original capabilities and purpose (i.e., quantify the impacts or erosion on soil productivity), the EPIC model has evolved into a comprehensive terrestrial ecosystem model for simulating with more or less process-level detail many ecosystem processes such as weather, hydrology, plant growth and development, carbon cycle (including erosion), nutrient cycling, greenhouse-gas emissions, and the most complete set of manipulations that can be implemented on a parcel of land (e.g. tillage, harvest, fertilization, irrigation, drainage, liming, burning, pesticide application). The chapter also provides details and examples of the latest efforts in model development such as the coupled carbon-nitrogen model, a microbial denitrification model with feedback to the carbon decomposition model, updates on calculation of ecosystem carbon balances, and carbon emissions from fossil fuels. The chapter has included examples of applications of the EPIC model in soil carbon sequestration, net ecosystem carbon balance, and biofuel studies. Finally, the chapter provides the reader with an update on upcoming improvements in EPIC such as the additions of modules for simulating biochar amendments, sorption of soluble C in subsoil horizons, nitrification including the release of N2O, and the formation and consumption of methane in soils. Completion of these model development activities will render an EPIC model with one of the most complete representation of biogeochemical processes and capable of simulating the dynamic feedback of soils to climate and management in terms not only of transient processes (e.g., soil water content, heterotrophic respiration, N2O emissions) but also of fundamental soil properties (e.g. soil depth, soil organic matter, soil bulk density, water limits).

  8. Soil Carbon Change and Net Energy Associated with Biofuel Production on Marginal Lands: A Regional Modeling Perspective

    SciTech Connect (OSTI)

    Bandaru, Varaprasad; Izaurralde, Roberto C.; Manowitz, David H.; Link, Robert P.; Zhang, Xuesong; Post, W. M.

    2013-12-01

    The use of marginal lands (MLs) for biofuel production has been contemplated as a promising solution for meeting biofuel demands. However, there have been concerns with spatial location of MLs, their inherent biofuel potential, and possible environmental consequences with the cultivation of energy crops. Here, we developed a new quantitative approach that integrates high-resolution land cover and land productivity maps and uses conditional probability density functions for analyzing land use patterns as a function of land productivity to classify the agricultural lands. We subsequently applied this method to determine available productive croplands (P-CLs) and non-crop marginal lands (NC-MLs) in a nine-county Southern Michigan. Furthermore, Spatially Explicit Integrated Modeling Framework (SEIMF) using EPIC (Environmental Policy Integrated Climate) was used to understand the net energy (NE) and soil organic carbon (SOC) implications of cultivating different annual and perennial production systems.

  9. The semi-empirical tight-binding model for carbon allotropes between diamond and graphite

    SciTech Connect (OSTI)

    Lytovchenko, V.; Kurchak, A.; Strikha, M.

    2014-06-28

    The new carbon allotropes between diamond and graphite have come under intensive examination during the last decade due to their numerous technical applications. The modification of energy gap in thin films of these allotropes was studied experimentally using optical methods. The proposed simple model of carbon clusters with variable lengths of chemical bonds allows us to imitate the transfer from diamond and diamond-like to graphite-like structures, as well as the corresponding modification of hybridization sp{sup 3}/sp{sup 2} for diamond-like and sp{sub z} for graphite-like phases. This enables us to estimate various allotropes parameters, like the gap E{sub g}, energies of valence E{sub v}, and conduction E{sub c} band edges, and the value of electronic affinity, i.e., optical work function X, which are all of practical importance. The obtained estimations correspond to the experimental data.

  10. Water, Energy and Carbon Sequestration Model (WECSsim) v. 1.0

    SciTech Connect (OSTI)

    2011-11-14

    The national Water, Energy and Carbon Sequestration Simulation Model (WECSsim) is an analysis tool that can be used at the local, regional and national scale to address a potentially combined system using a coal or natural gas-fired power plant, a geologic carbon sequestration system in saline formations, and water extraction and treatment. With this combined system for geologic storage of CO2 in saline formations, the treated saline formation water could be used as cooling water in the power plant. The key areas addressed in this tool include applying a data reduction process to existing NatCarb saline formation data to select the most viable formations for CO2 injection, water withdrawal and treatment metrics, and developing a national model to address the multiple combinations of power plants and saline formations. This model can be utilized by decision makers to understand the economic benefits and tradeoffs of this combined system. WECSsim allows for sensitivity analyses for capital costs, variables costs, CO2 sequestration and water treatment systems’ costs. The main goal of the WECSsim model is to allow interested individuals or groups the ability to run custom power plant, CO2 sequestration and water use scenarios for different regions of the country and understand the associated economics, longevity and potential of the CO2 sequestration and water extraction systems.

  11. Water, Energy and Carbon Sequestration Model (WECSsim) v. 1.0

    Energy Science and Technology Software Center (OSTI)

    2011-11-14

    The national Water, Energy and Carbon Sequestration Simulation Model (WECSsim) is an analysis tool that can be used at the local, regional and national scale to address a potentially combined system using a coal or natural gas-fired power plant, a geologic carbon sequestration system in saline formations, and water extraction and treatment. With this combined system for geologic storage of CO2 in saline formations, the treated saline formation water could be used as cooling watermore » in the power plant. The key areas addressed in this tool include applying a data reduction process to existing NatCarb saline formation data to select the most viable formations for CO2 injection, water withdrawal and treatment metrics, and developing a national model to address the multiple combinations of power plants and saline formations. This model can be utilized by decision makers to understand the economic benefits and tradeoffs of this combined system. WECSsim allows for sensitivity analyses for capital costs, variables costs, CO2 sequestration and water treatment systems’ costs. The main goal of the WECSsim model is to allow interested individuals or groups the ability to run custom power plant, CO2 sequestration and water use scenarios for different regions of the country and understand the associated economics, longevity and potential of the CO2 sequestration and water extraction systems.« less

  12. Comparison of Global Model Results from the Carbon-Land Model Intercomparison Project (C-LAMP) with Free-Air Carbon Dioxide Enrichment (FACE) Manipulation Experiments

    SciTech Connect (OSTI)

    Hoffman, Forrest M; Randerson, Jim; Fung, Inez; Thornton, Peter E; Covey, Curtis; Bonan, Gordon; Running, Steven; Norby, Richard J

    2008-01-01

    Free-Air CO{sub 2} Enrichment (FACE) manipulation experiments have been carried out at a handful of sites to gauge the response of the biosphere to significant increases in atmospheric [CO{sub 2}]. Early synthesis results from four temperate forest sites suggest that the response of net primary productivity (NPP) is conserved across a broad range of productivity with a stimulation at the median of 23 {+-} 2% when the surrounding air [CO{sub 2}] was raised to 550{approx}ppm. As a part of the Carbon-Land Model Intercomparison Project (C-LAMP), a community-based model-data comparison activity, the authors have performed a global FACE modeling experiment using two terrestrial biogeochemistry modules, CLM3-CASA and CLM3-CN, coupled to the National Center for Atmospheric Research (NCAR) Community Climate System Model (CCSM). The two models were forced with an improved NCEP/NCAR reanalysis data set and reconstructed atmospheric [CO{sub 2}] and N deposition data through 1997. At the beginning of 1997 in the transient simulations, global atmospheric [CO{sub 2}] was abruptly raised to 550{approx}ppm, the target value used at the FACE sites. In the control runs, [CO{sub 2}] continued to rise following observations until 2004, after which it was held constant out to year 2100. In both simulations, the last 25 years of reanalysis forcing and a constant N deposition were applied after year 2004. Across all forest biomes, the NPP responses from both models are weaker than those reported for the four FACE sites. Moreover, model responses vary widely geographically with a decreasing trend of NPP increases from 40{sup o}N to 70{sup o}N. For CLM3-CASA, the largest responses occur in arid regions of western North America and central Asia, suggesting that responses are most strongly influenced by increased water use efficiency for this model. CLM3-CN exhibits consistently weaker responses than CLM3-CASA' with the strongest responses in central Asia, but significantly constrained by N

  13. Predicting long-term carbon sequestration in response to CO2 enrichment: How and why do current ecosystem models differ?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Walker, Anthony P.; Zaehle, Sönke; Medlyn, Belinda E.; De Kauwe, Martin G.; Asao, Shinichi; Hickler, Thomas; Parton, William; Ricciuto, Daniel M.; Wang, Ying -Ping; Wårlind, David; et al

    2015-04-27

    Large uncertainty exists in model projections of the land carbon (C) sink response to increasing atmospheric CO2. Free-Air CO2 Enrichment (FACE) experiments lasting a decade or more have investigated ecosystem responses to a step change in atmospheric CO2 concentration. To interpret FACE results in the context of gradual increases in atmospheric CO2 over decades to centuries, we used a suite of seven models to simulate the Duke and Oak Ridge FACE experiments extended for 300 years of CO2 enrichment. We also determine key modeling assumptions that drive divergent projections of terrestrial C uptake and evaluate whether these assumptions can bemore » constrained by experimental evidence. All models simulated increased terrestrial C pools resulting from CO2 enrichment, though there was substantial variability in quasi-equilibrium C sequestration and rates of change. In two of two models that assume that plant nitrogen (N) uptake is solely a function of soil N supply, the net primary production response to elevated CO2 became progressively N limited. In four of five models that assume that N uptake is a function of both soil N supply and plant N demand, elevated CO2 led to reduced ecosystem N losses and thus progressively relaxed nitrogen limitation. Many allocation assumptions resulted in increased wood allocation relative to leaves and roots which reduced the vegetation turnover rate and increased C sequestration. Additionally, self-thinning assumptions had a substantial impact on C sequestration in two models. As a result, accurate representation of N process dynamics (in particular N uptake), allocation, and forest self-thinning is key to minimizing uncertainty in projections of future C sequestration in response to elevated atmospheric CO2.« less

  14. A Finite-Element Model for Simulation of Carbon Dioxide Sequestration

    SciTech Connect (OSTI)

    Bao, Jie; Xu, Zhijie; Fang, Yilin

    2014-09-01

    Herein, we present a coupled thermal-hydro-mechanical model for geological sequestration of carbon dioxide followed by the stress, deformation, and shear-slip failure analysis. This fully coupled model considers the geomechanical response, fluid flow, and thermal transport relevant to geological sequestration. Both analytical solutions and numerical approach via finite element model are introduced for solving the thermal-hydro-mechanical model. Analytical solutions for pressure, temperature, deformation, and stress field were obtained for a simplified typical geological sequestration scenario. The finite element model is more general and can be used for arbitrary geometry. It was built on an open-source finite element code, Elmer, and was designed to simulate the entire period of CO2 injection (up to decades) both stably and accuratelyeven for large time steps. The shear-slip failure analysis was implemented based on the numerical results from the finite element model. The analysis reveals the potential failure zone caused by the fluid injection and thermal effect. From the simulation results, the thermal effect is shown to enhance well injectivity, especially at the early time of the injection. However, it also causes some side effects, such as the appearance of a small failure zone in the caprock. The coupled thermal-hydro-mechanical model improves prediction of displacement, stress distribution, and potential failure zone compared to the model that neglects non-isothermal effects, especially in an area with high geothermal gradient.

  15. From Microbes to Global Carbon Models | U.S. DOE Office of Science...

    Office of Science (SC) Website

    Understanding microbial community processes improves predictions of soil carbon dynamics. ... from Wieder, Bonan, and Allison. "Global soil carbon projections are improved by ...

  16. Carbon Capture Simulation Initiative: A Case Study in Multi-Scale Modeling and New Challenges

    SciTech Connect (OSTI)

    Miller, David; Syamlal, Madhava; Mebane, David; Storlie, Curtis; Bhattacharyya, Debangsu; Sahinidis, Nikolaos V.; Agarwal, Deborah A.; Tong, Charles; Zitney, Stephen E.; Sarkar, Avik; Sun, Xin; Sundaresan, Sankaran; Ryan, Emily M.; Engel, David W.; Dale, Crystal

    2014-04-01

    Advanced multi-scale modeling and simulation has the potential to dramatically reduce development time, resulting in considerable cost savings. The Carbon Capture Simulation Initiative is a partnership among national laboratories, industry and universities that is developing and deploying a suite of multi-scale modeling and simulation tools including basic data submodels, steady-state and dynamic process models, process optimization and uncertainty quantification tools, an advanced dynamic process control framework, high-resolution filtered computational-fluid-dynamic (CFD) submodels, validated high-fidelity device-scale CFD models with quantified uncertainty, and a risk analysis framework. These tools and models enable basic data submodels, including thermodynamics and kinetics, to be used within detailed process models to synthesize and optimize a process. The resulting process informs the development of process control systems and more detailed simulations of potential equipment to improve the design and reduce scale-up risk. Quantification and propagation of uncertainty across scales is an essential part of these tools and models.

  17. Carbon Capture Simulation Initiative: A Case Study in Multi-Scale Modeling and New Challenges

    SciTech Connect (OSTI)

    Miller, David C; Syamlal, Madhava; Zitney, Stephen E.

    2014-06-07

    Abstract: Advanced multi-scale modeling and simulation has the potential to dramatically reduce development time, resulting in considerable cost savings. The Carbon Capture Simulation Initiative is a partnership among national laboratories, industry and universities that is developing and deploying a suite of multi-scale modeling and simulation tools including basic data submodels, steady-state and dynamic process models, process optimization and uncertainty quantification tools, an advanced dynamic process control framework, high-resolution filtered computational-fluid-dynamic (CFD) submodels, validated high-fidelity device-scale CFD models with quantified uncertainty, and a risk analysis framework. These tools and models enable basic data submodels, including thermodynamics and kinetics, to be used within detailed process models to synthesize and optimize a process. The resulting process informs the development of process control systems and more detailed simulations of potential equipment to improve the design and reduce scale-up risk. Quantification and propagation of uncertainty across scales is an essential part of these tools and models.

  18. Extinction properties of single-walled carbon nanotubes: Two-fluid model

    SciTech Connect (OSTI)

    Moradi, Afshin

    2014-03-15

    The extinction spectra of a single-walled carbon nanotube are investigated, within the framework of the vector wave function method in conjunction with the hydrodynamic model. Both polarizations of the incident plane wave (TE and TM with respect to the x-z plane) are treated. Electronic excitations on the nanotube surface are modeled by an infinitesimally thin layer of a two-dimensional electron gas represented by two interacting fluids, which takes into account the different nature of the σ and π electrons. Numerical results show that strong interaction between the fluids gives rise to the splitting of the extinction spectra into two peaks in quantitative agreement with the π and σ + π plasmon energies.

  19. Modeling microbial dynamics in heterogeneous environments: Growth on soil carbon sources

    SciTech Connect (OSTI)

    Resat, Haluk; Bailey, Vanessa L.; McCue, Lee Ann; Konopka, Allan

    2012-01-01

    We have developed a new hybrid model to study how microbial dynamics are affected by the heterogeneity in the physical structure of the environment. The modeling framework can represent porous media such as soil. The individual based biological model can explicitly simulate microbial diversity, and cell metabolism is regulated via optimal allocation of cellular resources to enzyme synthesis, control of growth rate by protein synthesis capacity, and shifts to dormancy. This model was developed to study how microbial community functioning is influenced by local environmental conditions and by the functional attributes of individual microbes. Different strategies for acquisition of carbon from polymeric cellulose were investigated. Bacteria that express membrane-associated hydrolase had different growth and survival dynamics in soil pores than bacteria that release extracellular hydrolases. The kinetic differences may suggest different functional roles for these two classes of microbes in cellulose utilization. Our model predicted an emergent behavior in which co-existence led to higher cellulose utilization efficiency and reduced stochasticity. Microbial community dynamics were simulated at two spatial scales: micro-pores that resemble 6-20 {micro}m size portions of the soil physical structure and in 111 {micro}m size soil aggregates with a random pore structure. Trends in dynamic properties were very similar at these two scales, implying that micro-scale studies can be useful approximations to aggregate scale studies when local effects on microbial dynamics are studied.

  20. Seismic model of a progradational carbonate platform, Picco di Vallandro, the Dolomites, northern Italy

    SciTech Connect (OSTI)

    Biddle, K.T.; Bush, T.L. ); Schlager, W. ); Rudolph, K.W. )

    1992-01-01

    The authors present a seismic model of a well-exposed carbonate platform-to-basin transition from the Triassic succession at Picco di Vallandro, the Dolomites, northern Italy. The core of this model is a detailed lithologic cross section that represents 1,500 m of stratigraphic section over a distance of 3.5 km. The cross section is based on detailed measured sections, photo interpretation, and careful projection of surface mapping into the plane of section. Samples from the measured sections provide control on velocity and density distribution, and these data were used to generate an impedance model from the cross section. The impedance model was convolved with a zero-phase, 25-Hz peak-frequency wavelet to produce the seismic model. The results illustrate how the platform-to-basin transition might be imaged by conventional seismic reflection data, how the reflections relate to the distribution of lithology and through-going geological surfaces, and how constructive and destructive interference and seismic resolution combine to produce individual reflections.

  1. The costs of different energy taxes for stabilizing U. S. carbon dioxide emissions: An application of the Gemini model

    SciTech Connect (OSTI)

    Leary, N.A.; Scheraga, J.D. . Climate Change Div.)

    1993-09-01

    In the absence of policies to mitigate emissions of carbon dioxide, US emissions will grow substantially over the period 1990 to 2030. One option for mitigation of carbon dioxide emissions is to tax energy use. For example, fossil energy might be taxed according to its carbon content, heating value, or market value. Using a partial equilibrium model of US energy markets that combines detailed representation of technological processes with optimizing behavior by energy users and suppliers, the authors compare the costs of using carbon, Btu, and ad valorem taxes as instruments to implement a policy of emission stabilization. The authors also examine the differential impacts of these taxes on the mix of primary energy consumed in the US. The carbon tax induces the substitution of renewables and natural gas for coal and stabilizes carbon dioxide emissions at an estimated annual cost of $125 billion. The Btu tax induces the substitution of renewables for coal, but does not encourage the use of natural gas. The estimated cost of stabilization with the Btu tax is $210 billion per year. The ad valorem tax, like the Btu tax, does not encourage the substitution of natural gas for coal. It also causes a significant shift away from oil in comparison to the carbon tax. The cost of stabilizing emissions with the ad valorem tax is estimated at $450 billion per year.

  2. Modeling polychlorinated biphenyl mass transfer after amendment of contaminated sediment with activated carbon

    SciTech Connect (OSTI)

    David Werner; Upal Ghosh; Richard G. Luthy

    2006-07-01

    The sorption kinetics and concentration of polychlorinated biphenyls (PCBs) in historically polluted sediment is modeled to assess a remediation strategy based on in situ PCB sequestration by mixing with activated carbon (AC). The authors extend their evaluation of a model based on intraparticle diffusion by including a biomimetic semipermeable membrane device (SPMD) and a first-order degradation rate for the aqueous phase. The model predictions are compared with the previously reported experimental PCB concentrations in the bulk water phase and in SPMDs. The simulated scenarios comprise a marine and a freshwater sediment, four PCB congeners, two AC grain sizes, four doses of AC, and comparison with laboratory experiments. The modeling approach distinguishes between two different sediment particles types: a light-density fraction representing carbonaceous particles such as charcoal, coal, coke, cenospheres, or wood, and a heavy-density fraction representing the mineral phase with coatings of organic matter. A third particle type in the numerical model is AC. The model qualitatively reproduces the observed shifts in the PCB distribution during repartitioning after AC amendment but overestimates the overall effect of the treatment in reducing aqueous and SPMD concentrations of PCBs by a factor of 2-6. For the AC application in sediment, competitive sorption of the various solutes apparently requires a reduction by a factor of 16 of the literature values for the AC-water partitioning coefficient measured in pure aqueous systems. With this correction, model results and measurements agree within a factor of 3. After AC amendment is homogeneously mixed into the sediment and then left undisturbed, aqueous PCB concentrations tend toward the same reduction after 5 years. 19 refs., 5 figs., 4 tabs.

  3. Simulating the Impacts of Disturbances on Forest Carbon Cycling in North America: Processes, Data, Models, and Challenges

    SciTech Connect (OSTI)

    Liu, Shuguang; Bond-Lamberty, Benjamin; Hicke, J.; Vargas, Rodrigo; Zhao, Shuqing; Chen, Jing Ming; Edburg, Steve; Hu, Yueming; Liu, Jinxun; McGuire, A. David; Xiao, Jingfeng; Keane, Robert; Yuan, Wenping; Tang, Jianwu; Luo, Yiqi; Potter, Christopher; Oeding, Jennifer

    2011-11-08

    Disturbances disrupt the forest structures and alter forest resources, substrate availability, or the physical environment. Understanding disturbances and their impacts is critical for a better quantification of North American carbon dynamics. We reviewed the status and major challenges in simulating the impacts of disturbances on forest carbon cycling in North America from the perspectives of process understanding, disturbance characterization, and modeling, and found some major issues. First, we do not have adequate continentally-consistent disturbance databases to support the NACP missions. Community effort, in collaborating with the modeling community, should be designated to systematically define international standards for disturbance databases with explicit inclusion of uncertainty measurements, adequate spatial and temporal resolutions, and explicit and quantifiable linkages with model simulations. Second, there is a need to develop effective and comprehensive process-based procedures or algorithms that can be used to quantify the immediate and long-term impacts of disturbances on forest succession, soils, microclimate, and cycles of carbon, water, and nutrients. These algorithms should be evaluated not only on the carbon cycle but also on the simulations of vegetation succession, alterations of soil and microclimate, and water and nutrients dynamics because adequate simulations of carbon dynamics rely on the correct quantification of the changes of soil and vegetation conditions. Third, the scaling challenges have rarely been addressed at the continental scale. We do not understand which processes and properties at a given temporal or spatial scales are critical while others can be simplified when we try to balance the North American carbon budget. Previous and current model simulations at the continental scale did not incorporate a full suite of disturbances information (because they do not exist as described above), and therefore provided little insight

  4. Modifying the Soil and Water Assessment Tool to Simulate Cropland Carbon Flux: Model Development and Initial Evaluation

    SciTech Connect (OSTI)

    Zhang, Xuesong; Izaurralde, Roberto C.; Arnold, Jeffrey; Williams, Jimmy R.; Srinivasan, Raghavan

    2013-10-01

    Climate change is one of the most compelling modern issues and has important implications for almost every aspect of natural and human systems. The Soil and Water Assessment Tool (SWAT) model has been applied worldwide to support sustainable land and water management in a changing climate. However, the inadequacies of the existing carbon algorithm in SWAT limit its application in assessing impacts of human activities on CO2 emission, one important source of greenhouse gases (GHGs) that traps heat in the earth system and results in global warming. In this research, we incorporate a revised version of the CENTURY carbon model into SWAT to describe dynamics of soil organic matter (SOM)- residue and simulate land-atmosphere carbon exchange.

  5. Regional scale cropland carbon budgets: evaluating a geospatial agricultural modeling system using inventory data

    SciTech Connect (OSTI)

    Zhang, Xuesong; Izaurralde, Roberto C.; Manowitz, David H.; Sahajpal, Ritvik; West, Tristram O.; Thomson, Allison M.; Xu, Min; Zhao, Kaiguang; LeDuc, Stephen D.; Williams, Jimmy R.

    2015-01-01

    Accurate quantification and clear understanding of regional scale cropland carbon (C) cycling is critical for designing effective policies and management practices that can contribute toward stabilizing atmospheric CO2 concentrations. However, extrapolating site-scale observations to regional scales represents a major challenge confronting the agricultural modeling community. This study introduces a novel geospatial agricultural modeling system (GAMS) exploring the integration of the mechanistic Environmental Policy Integrated Climate model, spatially-resolved data, surveyed management data, and supercomputing functions for cropland C budgets estimates. This modeling system creates spatially-explicit modeling units at a spatial resolution consistent with remotely-sensed crop identification and assigns cropping systems to each of them by geo-referencing surveyed crop management information at the county or state level. A parallel computing algorithm was also developed to facilitate the computationally intensive model runs and output post-processing and visualization. We evaluated GAMS against National Agricultural Statistics Service (NASS) reported crop yields and inventory estimated county-scale cropland C budgets averaged over 2000–2008. We observed good overall agreement, with spatial correlation of 0.89, 0.90, 0.41, and 0.87, for crop yields, Net Primary Production (NPP), Soil Organic C (SOC) change, and Net Ecosystem Exchange (NEE), respectively. However, we also detected notable differences in the magnitude of NPP and NEE, as well as in the spatial pattern of SOC change. By performing crop-specific annual comparisons, we discuss possible explanations for the discrepancies between GAMS and the inventory method, such as data requirements, representation of agroecosystem processes, completeness and accuracy of crop management data, and accuracy of crop area representation. Based on these analyses, we further discuss strategies to improve GAMS by updating input

  6. Detection of long-term trends in carbon accumulation by forests in Northeastern U. S. and determination of causal factors: Final report

    SciTech Connect (OSTI)

    J. William Munger; Steven C. Wofsy; David R. Foster

    2012-01-31

    The overall project goal was to quantify the trends and variability for Net ecosystem exchange of CO{sub 2}, H{sub 2}O, and energy by northeastern forests, with particular attention to the role of succession, differences in species composition, legacies of past land use, and disturbances. Measurements included flux measurements and observations of biomass accumulation using ecosystem modeling as a framework for data interpretation. Continuation of the long-term record at the Environmental Measurement Site (EMS) Tower was a priority. The final quality-assured CO{sub 2}-flux data now extend through 2010. Data through 2011 are collected but not yet finalized. Biomass observations on the plot array centered on the tower are extended to 2011. Two additional towers in a hemlock stand (HEM) and a younger deciduous stand (LPH) complement the EMS tower by focusing on stands with different species composition or age distribution and disturbance history, but comparable climate and soil type. Over the period since 1993 the forest has added 24.4 Mg-C ha{sup -1} in the living trees. Annual net carbon uptake had been increasing from about 2 Mg-C ha{sup -1}y{sup -1} in the early 1990s to nearly 6 Mg-C ha{sup -1}y{sup -1} by 2008, but declined in 2009-2010. We attribute the increasing carbon uptake to a combination of warmer temperatures, increased photosynthetic efficiency, and increased influence by subcanopy hemlocks that are active in the early spring and late autumn when temperatures are above freezing but the deciduous canopy is bare. Not all of the increased carbon accumulation was found in woody biomass. Results from a study using data to optimize parameters in an ecosystem process model indicate that significant changes in model parameters for photosynthetic capacity and shifts in allocation to slow cycling soil organic matter are necessary for the model to match the observed trends. The emerging working hypothesis is that the pattern of increasing carbon uptake over the

  7. ON THE CARBON-TO-OXYGEN RATIO MEASUREMENT IN NEARBY SUN-LIKE STARS: IMPLICATIONS FOR PLANET FORMATION AND THE DETERMINATION OF STELLAR ABUNDANCES

    SciTech Connect (OSTI)

    Fortney, Jonathan J.

    2012-03-10

    Recent high-resolution spectroscopic analysis of nearby FGK stars suggests that a high C/O ratio of greater than 0.8, or even 1.0, is relatively common. Two published catalogs find C/O > 0.8 in 25%-30% of systems, and C/O > 1.0 in {approx}6%-10%. It has been suggested that in protoplanetary disks with C/O > 0.8 that the condensation pathways to refractory solids will differ from what occurred in our solar system, where C/O = 0.55. The carbon-rich disks are calculated to make carbon-dominated rocky planets, rather than oxygen-dominated ones. Here we suggest that the derived stellar C/O ratios are overestimated. One constraint on the frequency of high C/O is the relative paucity of carbon dwarf stars (10{sup -3}-10{sup -5}) found in large samples of low-mass stars. We suggest reasons for this overestimation, including a high C/O ratio for the solar atmosphere model used for differential abundance analysis, the treatment of a Ni blend that affects the O abundance, and limitations of one-dimensional LTE stellar atmosphere models. Furthermore, from the estimated errors on the measured stellar C/O ratios, we find that the significance of the high C/O tail is weakened, with a true measured fraction of C/O > 0.8 in 10%-15% of stars, and C/O > 1.0 in 1%-5%, although these are still likely overestimates. We suggest that infrared T-dwarf spectra could show how common high C/O is in the stellar neighborhood, as the chemistry and spectra of such objects would differ compared to those with solar-like abundances. While possible at C/O > 0.8, we expect that carbon-dominated rocky planets are rarer than others have suggested.

  8. Unveiling Stability Criteria of DNA-Carbon Nanotubes Constructs by Scanning Tunneling Microscopy and Computational Modeling

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kilina, Svetlana; Yarotski, Dzmitry A.; Talin, A. Alec; Tretiak, Sergei; Taylor, Antoinette J.; Balatsky, Alexander V.

    2011-01-01

    We present a combined approach that relies on computational simulations and scanning tunneling microscopy (STM) measurements to reveal morphological properties and stability criteria of carbon nanotube-DNA (CNT-DNA) constructs. Application of STM allows direct observation of very stable CNT-DNA hybrid structures with the well-defined DNA wrapping angle of 63.4 ° and a coiling period of 3.3 nm. Using force field simulations, we determine how the DNA-CNT binding energy depends on the sequence and binding geometry of a single strand DNA. This dependence allows us to quantitatively characterize the stability of a hybrid structure with an optimal π-stacking between DNA nucleotides andmore » the tube surface and better interpret STM data. Our simulations clearly demonstrate the existence of a very stable DNA binding geometry for (6,5) CNT as evidenced by the presence of a well-defined minimum in the binding energy as a function of an angle between DNA strand and the nanotube chiral vector. This novel approach demonstrates the feasibility of CNT-DNA geometry studies with subnanometer resolution and paves the way towards complete characterization of the structural and electronic properties of drug-delivering systems based on DNA-CNT hybrids as a function of DNA sequence and a nanotube chirality.« less

  9. Experiments and modeling of variably permeable carbonate reservoir samples in contact with CO₂-acidified brines

    SciTech Connect (OSTI)

    Smith, Megan M.; Hao, Yue; Mason, Harris E.; Carroll, Susan A.

    2014-12-31

    Reactive experiments were performed to expose sample cores from the Arbuckle carbonate reservoir to CO₂-acidified brine under reservoir temperature and pressure conditions. The samples consisted of dolomite with varying quantities of calcite and silica/chert. The timescales of monitored pressure decline across each sample in response to CO₂ exposure, as well as the amount of and nature of dissolution features, varied widely among these three experiments. For all samples cores, the experimentally measured initial permeability was at least one order of magnitude or more lower than the values estimated from downhole methods. Nondestructive X-ray computed tomography (XRCT) imaging revealed dissolution features including “wormholes,” removal of fracture-filling crystals, and widening of pre-existing pore spaces. In the injection zone sample, multiple fractures may have contributed to the high initial permeability of this core and restricted the distribution of CO₂-induced mineral dissolution. In contrast, the pre-existing porosity of the baffle zone sample was much lower and less connected, leading to a lower initial permeability and contributing to the development of a single dissolution channel. While calcite may make up only a small percentage of the overall sample composition, its location and the effects of its dissolution have an outsized effect on permeability responses to CO₂ exposure. The XRCT data presented here are informative for building the model domain for numerical simulations of these experiments but require calibration by higher resolution means to confidently evaluate different porosity-permeability relationships.

  10. Global patterns and controls of soil organic carbon dynamics as simulated by multiple terrestrial biosphere models: Current status and future directions

    SciTech Connect (OSTI)

    Tian, Hanqin; Lu, Chaoqun; Yang, Jia; Banger, Kamaljit; Huntzinger, Deborah N.; Schwalm, Christopher R.; Michalak, Anna M.; Cook, Robert; Ciais, Philippe; Hayes, Daniel; Huang, Maoyi; Ito, Akihiko; Jain, Atul K.; Lei, Huimin; Mao, Jiafu; Pan, Shufen; Post, Wilfred M.; Peng, Shushi; Poulter, Benjamin; Ren, Wei; Ricciuto, Daniel; Schaefer, Kevin; Shi, Xiaoying; Tao, Bo; Wang, Weile; Wei, Yaxing; Yang, Qichun; Zhang, Bowen; Zeng, Ning

    2015-06-05

    Soil is the largest organic carbon (C) pool of terrestrial ecosystems, and C loss from soil accounts for a large proportion of land-atmosphere C exchange. Therefore, a small change in soil organic C (SOC) can affect atmospheric carbon dioxide (CO₂) concentration and climate change. In the past decades, a wide variety of studies have been conducted to quantify global SOC stocks and soil C exchange with the atmosphere through site measurements, inventories, and empirical/process-based modeling. However, these estimates are highly uncertain, and identifying major driving forces controlling soil C dynamics remains a key research challenge. This study has compiled century-long (1901–2010) estimates of SOC storage and heterotrophic respiration (Rh) from 10 terrestrial biosphere models (TBMs) in the Multi-scale Synthesis and Terrestrial Model Intercomparison Project and two observation-based data sets. The 10 TBM ensemble shows that global SOC estimate ranges from 425 to 2111 Pg C (1 Pg = 10¹⁵ g) with a median value of 1158 Pg C in 2010. The models estimate a broad range of Rh from 35 to 69 Pg C yr⁻¹ with a median value of 51 Pg C yr⁻¹ during 2001–2010. The largest uncertainty in SOC stocks exists in the 40–65°N latitude whereas the largest cross-model divergence in Rh are in the tropics. The modeled SOC change during 1901–2010 ranges from –70 Pg C to 86 Pg C, but in some models the SOC change has a different sign from the change of total C stock, implying very different contribution of vegetation and soil pools in determining the terrestrial C budget among models. The model ensemble-estimated mean residence time of SOC shows a reduction of 3.4 years over the past century, which accelerate C cycling through the land biosphere. All the models agreed that climate and land use changes decreased SOC stocks, while elevated atmospheric CO₂ and nitrogen deposition over intact ecosystems increased SOC stocks—even though the responses varied significantly

  11. Global patterns and controls of soil organic carbon dynamics as simulated by multiple terrestrial biosphere models: Current status and future directions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tian, Hanqin; Lu, Chaoqun; Yang, Jia; Banger, Kamaljit; Huntzinger, Deborah N.; Schwalm, Christopher R.; Michalak, Anna M.; Cook, Robert; Ciais, Philippe; Hayes, Daniel; et al

    2015-06-05

    Soil is the largest organic carbon (C) pool of terrestrial ecosystems, and C loss from soil accounts for a large proportion of land-atmosphere C exchange. Therefore, a small change in soil organic C (SOC) can affect atmospheric carbon dioxide (CO₂) concentration and climate change. In the past decades, a wide variety of studies have been conducted to quantify global SOC stocks and soil C exchange with the atmosphere through site measurements, inventories, and empirical/process-based modeling. However, these estimates are highly uncertain, and identifying major driving forces controlling soil C dynamics remains a key research challenge. This study has compiled century-longmore » (1901–2010) estimates of SOC storage and heterotrophic respiration (Rh) from 10 terrestrial biosphere models (TBMs) in the Multi-scale Synthesis and Terrestrial Model Intercomparison Project and two observation-based data sets. The 10 TBM ensemble shows that global SOC estimate ranges from 425 to 2111 Pg C (1 Pg = 10¹⁵ g) with a median value of 1158 Pg C in 2010. The models estimate a broad range of Rh from 35 to 69 Pg C yr⁻¹ with a median value of 51 Pg C yr⁻¹ during 2001–2010. The largest uncertainty in SOC stocks exists in the 40–65°N latitude whereas the largest cross-model divergence in Rh are in the tropics. The modeled SOC change during 1901–2010 ranges from –70 Pg C to 86 Pg C, but in some models the SOC change has a different sign from the change of total C stock, implying very different contribution of vegetation and soil pools in determining the terrestrial C budget among models. The model ensemble-estimated mean residence time of SOC shows a reduction of 3.4 years over the past century, which accelerate C cycling through the land biosphere. All the models agreed that climate and land use changes decreased SOC stocks, while elevated atmospheric CO₂ and nitrogen deposition over intact ecosystems increased SOC stocks—even though the responses varied

  12. The Water, Energy, and Carbon Dioxide Sequestration Simulation Model (WECSsim). A user's manual

    SciTech Connect (OSTI)

    Kobos, Peter Holmes; Roach, Jesse Dillon; Klise, Geoffrey Taylor; Heath, Jason E.; Dewers, Thomas A.; Gutierrez, Karen A.; Malczynski, Leonard A.; Borns, David James; McNemar, Andrea

    2014-01-01

    The Water, Energy, and Carbon Sequestration Simulation Model (WECSsim) is a national dynamic simulation model that calculates and assesses capturing, transporting, and storing CO2 in deep saline formations from all coal and natural gas-fired power plants in the U.S. An overarching capability of WECSsim is to also account for simultaneous CO2 injection and water extraction within the same geological saline formation. Extracting, treating, and using these saline waters to cool the power plant is one way to develop more value from using saline formations as CO2 storage locations. WECSsim allows for both one-to-one comparisons of a single power plant to a single saline formation along with the ability to develop a national CO2 storage supply curve and related national assessments for these formations. This report summarizes the scope, structure, and methodology of WECSsim along with a few key results. Developing WECSsim from a small scoping study to the full national-scale modeling effort took approximately 5 years. This report represents the culmination of that effort. The key findings from the WECSsim model indicate the U.S. has several decades' worth of storage for CO2 in saline formations when managed appropriately. Competition for subsurface storage capacity, intrastate flows of CO2 and water, and a supportive regulatory environment all play a key role as to the performance and cost profile across the range from a single power plant to all coal and natural gas-based plants' ability to store CO2. The overall system's cost to capture, transport, and store CO2 for the national assessment range from $74 to $208 / tonne stored ($96 to 272 / tonne avoided) for the first 25 to 50% of the 1126 power plants to between $1,585 to well beyond $2,000 / tonne stored ($2,040 to well beyond $2,000 / tonne avoided) for the remaining 75 to 100% of the plants. The latter range, while extremely

  13. Reduced-Order Model for the Geochemical Impacts of Carbon Dioxide, Brine and Trace Metal Leakage into an Unconfined, Oxidizing Carbonate Aquifer, Version 2.1

    SciTech Connect (OSTI)

    Bacon, Diana H.

    2013-03-31

    The National Risk Assessment Partnership (NRAP) consists of 5 U.S DOE national laboratories collaborating to develop a framework for predicting the risks associated with carbon sequestration. The approach taken by NRAP is to divide the system into components, including injection target reservoirs, wellbores, natural pathways including faults and fractures, groundwater and the atmosphere. Next, develop a detailed, physics and chemistry-based model of each component. Using the results of the detailed models, develop efficient, simplified models, termed reduced order models (ROM) for each component. Finally, integrate the component ROMs into a system model that calculates risk profiles for the site. This report details the development of the Groundwater Geochemistry ROM for the Edwards Aquifer at PNNL. The Groundwater Geochemistry ROM for the Edwards Aquifer uses a Wellbore Leakage ROM developed at LANL as input. The detailed model, using the STOMP simulator, covers a 5x8 km area of the Edwards Aquifer near San Antonio, Texas. The model includes heterogeneous hydraulic properties, and equilibrium, kinetic and sorption reactions between groundwater, leaked CO2 gas, brine, and the aquifer carbonate and clay minerals. Latin Hypercube sampling was used to generate 1024 samples of input parameters. For each of these input samples, the STOMP simulator was used to predict the flux of CO2 to the atmosphere, and the volume, length and width of the aquifer where pH was less than the MCL standard, and TDS, arsenic, cadmium and lead exceeded MCL standards. In order to decouple the Wellbore Leakage ROM from the Groundwater Geochemistry ROM, the response surface was transformed to replace Wellbore Leakage ROM input parameters with instantaneous and cumulative CO2 and brine leakage rates. The most sensitive parameters proved to be the CO2 and brine leakage rates from the well, with equilibrium coefficients for calcite and dolomite, as well as the number of illite and kaolinite

  14. Determination of modeling parameters for power IGBTs under pulsed power conditions

    SciTech Connect (OSTI)

    Dale, Gregory E; Van Gordon, Jim A; Kovaleski, Scott D

    2010-01-01

    While the power insulated gate bipolar transistor (IGRT) is used in many applications, it is not well characterized under pulsed power conditions. This makes the IGBT difficult to model for solid state pulsed power applications. The Oziemkiewicz implementation of the Hefner model is utilized to simulate IGBTs in some circuit simulation software packages. However, the seventeen parameters necessary for the Oziemkiewicz implementation must be known for the conditions under which the device will be operating. Using both experimental and simulated data with a least squares curve fitting technique, the parameters necessary to model a given IGBT can be determined. This paper presents two sets of these seventeen parameters that correspond to two different models of power IGBTs. Specifically, these parameters correspond to voltages up to 3.5 kV, currents up to 750 A, and pulse widths up to 10 {micro}s. Additionally, comparisons of the experimental and simulated data will be presented.

  15. Prospective life-cycle modeling of a carbon capture and storage system using metal-organic frameworks for CO2 capture

    SciTech Connect (OSTI)

    Sathre, R; Masanet, E

    2013-01-01

    Metal-organic frameworks (MOFs) are promising new material media for carbon dioxide (CO2) capture. Their tunable adsorption patterns may allow relatively efficient separation of gases, e.g. from power plant exhaust. Here we conduct scenario-based prospective life-cycle system modeling to estimate the potentials and implications of large-scale MOF application for post-combustion carbon capture and storage (CCS), and estimate the source and magnitude of uncertainties. The methodological approach includes parametric system modeling to quantify relations between system components; scenario projections of plausible pathways for system scale-up; proxy data on analogous materials and processes; and uncertainty analysis of parameter significance. We estimate the system-wide material and energy flows and economic costs associated with projected large-scale CCS deployment. We compare the performance of a MOF-based system to currently more mature amine-based capture technology. We discuss balancing two critical factors that determine the success of CO2 capture media: thermodynamic efficiency of the capture/regeneration cycle, and life-cycle embodied energy and cost of the material and its ancillary systems.

  16. OPTIMIZATION OF THE CATHODE LONG-TERM STABILITY IN MOLTEN CARBONATE FUEL CELLS: EXPERIMENTAL STUDY AND MATHEMATICAL MODELING

    SciTech Connect (OSTI)

    Dr. Ralph E. White; Dr. Branko N. Popov

    2002-04-01

    The dissolution of NiO cathodes during cell operation is a limiting factor to the successful commercialization of molten carbonate fuel cells (MCFCs). Lithium cobalt oxide coating onto the porous nickel electrode has been adopted to modify the conventional MCFC cathode which is believed to increase the stability of the cathodes in the carbonate melt. The material used for surface modification should possess thermodynamic stability in the molten carbonate and also should be electro catalytically active for MCFC reactions. Two approaches have been adopted to get a stable cathode material. First approach is the use of LiNi{sub 0.8}Co{sub 0.2}O{sub 2}, a commercially available lithium battery cathode material and the second is the use of tape cast electrodes prepared from cobalt coated nickel powders. The morphology and the structure of LiNi{sub 0.8}Co{sub 0.2}O{sub 2} and tape cast Co coated nickel powder electrodes were studied using scanning electron microscopy and X-Ray diffraction studies respectively. The electrochemical performance of the two materials was investigated by electrochemical impedance spectroscopy and polarization studies. A three phase homogeneous model was developed to simulate the performance of the molten carbonate fuel cell cathode. The homogeneous model is based on volume averaging of different variables in the three phases over a small volume element. The model gives a good fit to the experimental data. The model has been used to analyze MCFC cathode performance under a wide range of operating conditions.

  17. Experiments and modeling of variably permeable carbonate reservoir samples in contact with CO₂-acidified brines

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Smith, Megan M.; Hao, Yue; Mason, Harris E.; Carroll, Susan A.

    2014-12-31

    Reactive experiments were performed to expose sample cores from the Arbuckle carbonate reservoir to CO₂-acidified brine under reservoir temperature and pressure conditions. The samples consisted of dolomite with varying quantities of calcite and silica/chert. The timescales of monitored pressure decline across each sample in response to CO₂ exposure, as well as the amount of and nature of dissolution features, varied widely among these three experiments. For all samples cores, the experimentally measured initial permeability was at least one order of magnitude or more lower than the values estimated from downhole methods. Nondestructive X-ray computed tomography (XRCT) imaging revealed dissolution featuresmore » including “wormholes,” removal of fracture-filling crystals, and widening of pre-existing pore spaces. In the injection zone sample, multiple fractures may have contributed to the high initial permeability of this core and restricted the distribution of CO₂-induced mineral dissolution. In contrast, the pre-existing porosity of the baffle zone sample was much lower and less connected, leading to a lower initial permeability and contributing to the development of a single dissolution channel. While calcite may make up only a small percentage of the overall sample composition, its location and the effects of its dissolution have an outsized effect on permeability responses to CO₂ exposure. The XRCT data presented here are informative for building the model domain for numerical simulations of these experiments but require calibration by higher resolution means to confidently evaluate different porosity-permeability relationships.« less

  18. EXPERIMENTAL DESIGN APPLICATIONS FOR MODELING AND ASSESSING CARBON DIOXIDE SEQUESTRATION IN SALINE AQUIFERS

    SciTech Connect (OSTI)

    Rogers, John

    2014-08-31

    determine the limitations of both the commercial simulator and the Lawrence Berkeley National Laboratory (LBNL) R&D simulator, TOUGHREACT available to the project. A simplified layer cake model approximating the volume of the RMOTC targeted reservoirs was defined with 1-3 minerals eventually modeled with limited success. Modeling reactive transport in porous media requires significant computational power. In this project, up to 24 processors were used to model a limited mineral set of 1-3 minerals. In addition, geomechanical aspects of injecting CO2 into closed, semi-open, and open systems in various well completion methods was simulated. Enhanced Oil Recovery (EOR) as a storage method was not modeled. A robust and stable simulation dataset or base case was developed and used to create a master dataset with embedded instructions for input to the ED/RSM software. Little success was achieved toward the objective of the project using the commercial simulator or the LBNL simulator versions available during the time of this project. Several hundred realizations were run with the commercial simulator and ED/RSM software, most having convergence problems and terminating prematurely. A proxy model for full field CO2 injection sequestration utilization and storage was not capable of being developed with software available for this project. Though the chemistry is reasonably known and understood, based on the amount of effort and huge computational time required, predicting CO2 sequestration storage capacity in geologic formations to within the program goals of ±30% proved unsuccessful.

  19. Development and Integration of Genome-Enabled Techniques to Track and Predict the Cycling of Carbon in Model Microbial Communities

    SciTech Connect (OSTI)

    Banfield, Jillian

    2014-11-26

    The primary objective of this project was to establish widely applicable, high-throughput omics methods for tracking carbon flow in microbial communities at a strain-resolved molecular level. We developed and applied these methods to study a well-established microbial community model system with a long history of omics innovation: chemoautotrophic biofilms grown in an acid mine drainage (AMD) environment. The methods are now being transitioned (in a new project) to study soil. Using metagenomics, stable-isotope proteomics, stable-isotope metabolomics, transcriptomics, and microscopy, we tracked carbon flow during initial biofilm growth involving CO2 fixation, through the maturing biofilm community consisting of multiple trophic levels, and during an anaerobic degradative phase after biofilms sink. This work included explicit consideration of the often overlooked roles of archaea and microbial eukaryotes (fungi) in carbon turnover. We also analyzed where the eosystem begins to fail in response to thermal perturbation, and how perturbation propagates through a carbon cycle. We investigated the form of strain variation in microbial communities, the importance of strain variants, and the rate and form of strain evolution. Overall, the project generated an array of new, integrated omics approaches and provided unprecedented insight into the functioning of a natural ecosystem. This project supported graduate training for five Ph.D. students and three post doctoral fellows and contributed directly to at least 26 publications (two in Science).

  20. The North American Carbon Program Multi-scale Synthesis and Terrestrial Model Intercomparison Project – Part 2: Environmental driver data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wei, Yaxing; Liu, Shishi; Huntzinger, Deborah N.; Michalak, Anna M.; Viovy, Nicolas; Post, Wilfred M.; Schwalm, Christopher R.; Schaeffer, Kevin; Jacobson, Andrew R.; Lu, Chaoqun; et al

    2014-12-05

    Ecosystems are important and dynamic components of the global carbon cycle, and terrestrial biospheric models (TBMs) are crucial tools in further understanding of how terrestrial carbon is stored and exchanged with the atmosphere across a variety of spatial and temporal scales. Improving TBM skills, and quantifying and reducing their estimation uncertainties, pose significant challenges. The Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP) is a formal multi-scale and multi-model intercomparison effort set up to tackle these challenges. The MsTMIP protocol prescribes standardized environmental driver data that are shared among model teams to facilitate model model and model observation comparisons. Inmore » this article, we describe the global and North American environmental driver data sets prepared for the MsTMIP activity to both support their use in MsTMIP and make these data, along with the processes used in selecting/processing these data, accessible to a broader audience. Based on project needs and lessons learned from past model intercomparison activities, we compiled climate, atmospheric CO2 concentrations, nitrogen deposition, land use and land cover change (LULCC), C3 / C4 grasses fractions, major crops, phenology and soil data into a standard format for global (0.5⁰ x 0.5⁰ resolution) and regional (North American: 0.25⁰ x 0.25⁰ resolution) simulations. In order to meet the needs of MsTMIP, improvements were made to several of the original environmental data sets, by improving the quality, and/or changing their spatial and temporal coverage, and resolution. The resulting standardized model driver data sets are being used by over 20 different models participating in MsTMIP. Lastly, the data are archived at the Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC, http://daac.ornl.gov) to provide long-term data management and distribution.« less

  1. Modeling dolomitized carbonate-ramp reservoirs: A case study of the Seminole San Andres unit. Part 2 -- Seismic modeling, reservoir geostatistics, and reservoir simulation

    SciTech Connect (OSTI)

    Wang, F.P.; Dai, J.; Kerans, C.

    1998-11-01

    In part 1 of this paper, the authors discussed the rock-fabric/petrophysical classes for dolomitized carbonate-ramp rocks, the effects of rock fabric and pore type on petrophysical properties, petrophysical models for analyzing wireline logs, the critical scales for defining geologic framework, and 3-D geologic modeling. Part 2 focuses on geophysical and engineering characterizations, including seismic modeling, reservoir geostatistics, stochastic modeling, and reservoir simulation. Synthetic seismograms of 30 to 200 Hz were generated to study the level of seismic resolution required to capture the high-frequency geologic features in dolomitized carbonate-ramp reservoirs. Outcrop data were collected to investigate effects of sampling interval and scale-up of block size on geostatistical parameters. Semivariogram analysis of outcrop data showed that the sill of log permeability decreases and the correlation length increases with an increase of horizontal block size. Permeability models were generated using conventional linear interpolation, stochastic realizations without stratigraphic constraints, and stochastic realizations with stratigraphic constraints. Simulations of a fine-scale Lawyer Canyon outcrop model were used to study the factors affecting waterflooding performance. Simulation results show that waterflooding performance depends strongly on the geometry and stacking pattern of the rock-fabric units and on the location of production and injection wells.

  2. Integrating Remote Sensing, Field Observations, and Models to Understand Disturbance and Climate Effects on the Carbon Balance of the West Coast U.S., Final Report

    SciTech Connect (OSTI)

    Beverly E. Law

    2011-10-05

    As an element of NACP research, the proposed investigation is a two pronged approach that derives and evaluates a regional carbon (C) budget for Oregon, Washington, and California. Objectives are (1) Use multiple data sources, including AmeriFlux data, inventories, and multispectral remote sensing data to investigate trends in carbon storage and exchanges of CO2 and water with variation in climate and disturbance history; (2) Develop and apply regional modeling that relies on these multiple data sources to reduce uncertainty in spatial estimates of carbon storage and NEP, and relative contributions of terrestrial ecosystems and anthropogenic emissions to atmospheric CO2 in the region; (3) Model terrestrial carbon processes across the region, using the Biome-BGC terrestrial ecosystem model, and an atmospheric inverse modeling approach to estimate variation in rate and timing of terrestrial uptake and feedbacks to the atmosphere in response to climate and disturbance.

  3. Integrating Remote Sensing, Field Observations, and Models to Understand Disturbance and Climate Effects on the Carbon Balance of the West Coast U.S.

    SciTech Connect (OSTI)

    Cohen, Warren

    2014-07-03

    As an element of NACP research, the proposed investigation is a two pronged approach that derives and evaluates a regional carbon (C) budget for Oregon, Washington, and California. Objectives are (1) Use multiple data sources, including AmeriFlux data, inventories, and multispectral remote sensing data to investigate trends in carbon storage and exchanges of CO2 and water with variation in climate and disturbance history; (2) Develop and apply regional modeling that relies on these multiple data sources to reduce uncertainty in spatial estimates of carbon storage and NEP, and relative contributions of terrestrial ecosystems and anthropogenic emissions to atmospheric CO2 in the region; (3) Model terrestrial carbon processes across the region, using the Biome-BGC terrestrial ecosystem model, and an atmospheric inverse modeling approach to estimate variation in rate and timing of terrestrial uptake and feedbacks to the atmosphere in response to climate and disturbance.

  4. Experimental determination of electrical characteristics and circuit models of superconducting dipole magnets

    SciTech Connect (OSTI)

    Smedley, K.M. . Dept. of Electrical and Computer Engineering); Shafer, R.E. )

    1994-09-01

    Superconducting magnets are used very extensively in modern science and technology to produce high intensity magnetic fields. In many application, magnets are used in non-dc conditions and are subject to current ramping. The magnets studied in this paper were intended to be used in the Superconducting Supercollider with a ramping rate of 4A/sec and a maximum current of 7000A. Due to the effects of eddy currents and parasitic capacitance, the electrical characteristics of superconducting magnets are not completely inductive; instead, they are frequency dependent functions. This paper develops a method of accurately measuring the ac characteristics and determining the circuit models of superconducting magnets that characterize the eddy currents and the parasitic capacitance. This measurement method can be used to analyze eddy current and the resulting circuit model can be used to study the transmission line effect of long magnet strings.

  5. The thin section rock physics: Modeling and measurement of seismic wave velocity on the slice of carbonates

    SciTech Connect (OSTI)

    Wardaya, P. D. Noh, K. A. B. M. Yusoff, W. I. B. W.; Ridha, S.; Nurhandoko, B. E. B.

    2014-09-25

    This paper discusses a new approach for investigating the seismic wave velocity of rock, specifically carbonates, as affected by their pore structures. While the conventional routine of seismic velocity measurement highly depends on the extensive laboratory experiment, the proposed approach utilizes the digital rock physics view which lies on the numerical experiment. Thus, instead of using core sample, we use the thin section image of carbonate rock to measure the effective seismic wave velocity when travelling on it. In the numerical experiment, thin section images act as the medium on which wave propagation will be simulated. For the modeling, an advanced technique based on artificial neural network was employed for building the velocity and density profile, replacing image's RGB pixel value with the seismic velocity and density of each rock constituent. Then, ultrasonic wave was simulated to propagate in the thin section image by using finite difference time domain method, based on assumption of an acoustic-isotropic medium. Effective velocities were drawn from the recorded signal and being compared to the velocity modeling from Wyllie time average model and Kuster-Toksoz rock physics model. To perform the modeling, image analysis routines were undertaken for quantifying the pore aspect ratio that is assumed to represent the rocks pore structure. In addition, porosity and mineral fraction required for velocity modeling were also quantified by using integrated neural network and image analysis technique. It was found that the Kuster-Toksoz gives the closer prediction to the measured velocity as compared to the Wyllie time average model. We also conclude that Wyllie time average that does not incorporate the pore structure parameter deviates significantly for samples having more than 40% porosity. Utilizing this approach we found a good agreement between numerical experiment and theoretically derived rock physics model for estimating the effective seismic wave

  6. Coupled modeling of a directly heated tubular solar receiver for supercritical carbon dioxide Brayton cycle: Optical and thermal-fluid evaluation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ortega, Jesus; Khivsara, Sagar; Christian, Joshua; Ho, Clifford; Yellowhair, Julius; Dutta, Pradip

    2016-05-30

    In single phase performance and appealing thermo-physical properties supercritical carbon dioxide (s-CO2) make a good heat transfer fluid candidate for concentrating solar power (CSP) technologies. The development of a solar receiver capable of delivering s-CO2 at outlet temperatures ~973 K is required in order to merge CSP and s-CO2 Brayton cycle technologies. A coupled optical and thermal-fluid modeling effort for a tubular receiver is undertaken to evaluate the direct tubular s-CO2 receiver’s thermal performance when exposed to a concentrated solar power input of ~0.3–0.5 MW. Ray tracing, using SolTrace, is performed to determine the heat flux profiles on the receivermore » and computational fluid dynamics (CFD) determines the thermal performance of the receiver under the specified heating conditions. Moreover, an in-house MATLAB code is developed to couple SolTrace and ANSYS Fluent. CFD modeling is performed using ANSYS Fluent to predict the thermal performance of the receiver by evaluating radiation and convection heat loss mechanisms. Understanding the effects of variation in heliostat aiming strategy and flow configurations on the thermal performance of the receiver was achieved through parametric analyses. Finally, a receiver thermal efficiency ~85% was predicted and the surface temperatures were observed to be within the allowable limit for the materials under consideration.« less

  7. Predicting long-term carbon sequestration in response to CO2 enrichment: How and why do current ecosystem models differ?

    SciTech Connect (OSTI)

    Walker, Anthony P.; Zaehle, Sönke; Medlyn, Belinda E.; De Kauwe, Martin G.; Asao, Shinichi; Hickler, Thomas; Parton, William; Ricciuto, Daniel M.; Wang, Ying -Ping; Wårlind, David; Norby, Richard J.

    2015-04-27

    Large uncertainty exists in model projections of the land carbon (C) sink response to increasing atmospheric CO2. Free-Air CO2 Enrichment (FACE) experiments lasting a decade or more have investigated ecosystem responses to a step change in atmospheric CO2 concentration. To interpret FACE results in the context of gradual increases in atmospheric CO2 over decades to centuries, we used a suite of seven models to simulate the Duke and Oak Ridge FACE experiments extended for 300 years of CO2 enrichment. We also determine key modeling assumptions that drive divergent projections of terrestrial C uptake and evaluate whether these assumptions can be constrained by experimental evidence. All models simulated increased terrestrial C pools resulting from CO2 enrichment, though there was substantial variability in quasi-equilibrium C sequestration and rates of change. In two of two models that assume that plant nitrogen (N) uptake is solely a function of soil N supply, the net primary production response to elevated CO2 became progressively N limited. In four of five models that assume that N uptake is a function of both soil N supply and plant N demand, elevated CO2 led to reduced ecosystem N losses and thus progressively relaxed nitrogen limitation. Many allocation assumptions resulted in increased wood allocation relative to leaves and roots which reduced the vegetation turnover rate and increased C sequestration. Additionally, self-thinning assumptions had a substantial impact on C sequestration in two models. As a result, accurate representation of N process dynamics (in particular N uptake), allocation, and forest self-thinning is key to minimizing uncertainty in projections of future C sequestration in response to elevated atmospheric CO2.

  8. Modeling global atmospheric CO2 with improved emission inventories and CO2 production from the oxidation of other carbon species

    SciTech Connect (OSTI)

    Nassar, Ray; Jones, DBA; Suntharalingam, P; Chen, j.; Andres, Robert Joseph; Wecht, K. J.; Yantosca, R. M.; Kulawik, SS; Bowman, K; Worden, JR; Machida, T; Matsueda, H

    2010-01-01

    The use of global three-dimensional (3-D) models with satellite observations of CO2 in inverse modeling studies is an area of growing importance for understanding Earth s carbon cycle. Here we use the GEOS-Chem model (version 8-02-01) CO2 mode with multiple modifications in order to assess their impact on CO2 forward simulations. Modifications include CO2 surface emissions from shipping (0.19 PgC yr 1), 3-D spatially-distributed emissions from aviation (0.16 PgC yr 1), and 3-D chemical production of CO2 (1.05 PgC yr 1). Although CO2 chemical production from the oxidation of CO, CH4 and other carbon gases is recognized as an important contribution to global CO2, it is typically accounted for by conversion from its precursors at the surface rather than in the free troposphere. We base our model 3-D spatial distribution of CO2 chemical production on monthly-averaged loss rates of CO (a key precursor and intermediate in the oxidation of organic carbon) and apply an associated surface correction for inventories that have counted emissions of CO2 precursors as CO2. We also explore the benefit of assimilating satellite observations of CO into GEOS-Chem to obtain an observation-based estimate of the CO2 chemical source. The CO assimilation corrects for an underestimate of atmospheric CO abundances in the model, resulting in increases of as much as 24% in the chemical source during May June 2006, and increasing the global annual estimate of CO2 chemical production from 1.05 to 1.18 Pg C. Comparisons of model CO2 with measurements are carried out in order to investigate the spatial and temporal distributions that result when these new sources are added. Inclusion of CO2 emissions from shipping and aviation are shown to increase the global CO2 latitudinal gradient by just over 0.10 ppm (3%), while the inclusion of CO2 chemical production (and the surface correction) is shown to decrease the latitudinal gradient by about 0.40 ppm (10%) with a complex spatial structure

  9. Experimental Determination and Thermodynamic Modeling of Electrical Conductivity of SRS Waste Tank Supernate

    SciTech Connect (OSTI)

    Pike, J.; Reboul, S.

    2015-06-01

    SRS High Level Waste Tank Farm personnel rely on conductivity probes for detection of incipient overflow conditions in waste tanks. Minimal information is available concerning the sensitivity that must be achieved such that that liquid detection is assured. Overly sensitive electronics results in numerous nuisance alarms for these safety-related instruments. In order to determine the minimum sensitivity required of the probe, Tank Farm Engineering personnel need adequate conductivity data to improve the existing designs. Little or no measurements of liquid waste conductivity exist; however, the liquid phase of the waste consists of inorganic electrolytes for which the conductivity may be calculated. Savannah River Remediation (SRR) Tank Farm Facility Engineering requested SRNL to determine the conductivity of the supernate resident in SRS waste Tank 40 experimentally as well as computationally. In addition, SRNL was requested to develop a correlation, if possible, that would be generally applicable to liquid waste resident in SRS waste tanks. A waste sample from Tank 40 was analyzed for composition and electrical conductivity as shown in Table 4-6, Table 4-7, and Table 4-9. The conductivity for undiluted Tank 40 sample was 0.087 S/cm. The accuracy of OLI Analyzer™ was determined using available literature data. Overall, 95% of computed estimates of electrical conductivity are within ±15% of literature values for component concentrations from 0 to 15 M and temperatures from 0 to 125 °C. Though the computational results are generally in good agreement with the measured data, a small portion of literature data deviates as much as ±76%. A simplified model was created that can be used readily to estimate electrical conductivity of waste solution in computer spreadsheets. The variability of this simplified approach deviates up to 140% from measured values. Generally, this model can be applied to estimate the conductivity within a factor of two. The comparison of the

  10. Ocean acidification over the next three centuries using a simple global climate carbon-cycle model: projections and sensitivities

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hartin, Corinne A.; Bond-Lamberty, Benjamin; Patel, Pralit; Mundra, Anupriya

    2016-08-01

    Continued oceanic uptake of anthropogenic CO2 is projected to significantly alter the chemistry of the upper oceans over the next three centuries, with potentially serious consequences for marine ecosystems. Relatively few models have the capability to make projections of ocean acidification, limiting our ability to assess the impacts and probabilities of ocean changes. In this study we examine the ability of Hector v1.1, a reduced-form global model, to project changes in the upper ocean carbonate system over the next three centuries, and quantify the model's sensitivity to parametric inputs. Hector is run under prescribed emission pathways from the Representative Concentrationmore » Pathways (RCPs) and compared to both observations and a suite of Coupled Model Intercomparison (CMIP5) model outputs. Current observations confirm that ocean acidification is already taking place, and CMIP5 models project significant changes occurring to 2300. Hector is consistent with the observational record within both the high- (> 55°) and low-latitude oceans (< 55°). The model projects low-latitude surface ocean pH to decrease from preindustrial levels of 8.17 to 7.77 in 2100, and to 7.50 in 2300; aragonite saturation levels (ΩAr) decrease from 4.1 units to 2.2 in 2100 and 1.4 in 2300 under RCP 8.5. These magnitudes and trends of ocean acidification within Hector are largely consistent with the CMIP5 model outputs, although we identify some small biases within Hector's carbonate system. Of the parameters tested, changes in [H+] are most sensitive to parameters that directly affect atmospheric CO2 concentrations – Q10 (terrestrial respiration temperature response) as well as changes in ocean circulation, while changes in ΩAr saturation levels are sensitive to changes in ocean salinity and Q10. We conclude that Hector is a robust tool well suited for rapid ocean acidification projections and sensitivity analyses, and it is capable of emulating both current observations

  11. Characterizing the three-orbital Hubbard model with determinant quantum Monte Carlo

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kung, Y. F.; Chen, C. -C.; Wang, Yao; Huang, E. W.; Nowadnick, E. A.; Moritz, B.; Scalettar, R. T.; Johnston, S.; Devereaux, T. P.

    2016-04-29

    Here, we characterize the three-orbital Hubbard model using state-of-the-art determinant quantum Monte Carlo (DQMC) simulations with parameters relevant to the cuprate high-temperature superconductors. The simulations find that doped holes preferentially reside on oxygen orbitals and that the (π,π) antiferromagnetic ordering vector dominates in the vicinity of the undoped system, as known from experiments. The orbitally-resolved spectral functions agree well with photoemission spectroscopy studies and enable identification of orbital content in the bands. A comparison of DQMC results with exact diagonalization and cluster perturbation theory studies elucidates how these different numerical techniques complement one another to produce a more complete understandingmore » of the model and the cuprates. Interestingly, our DQMC simulations predict a charge-transfer gap that is significantly smaller than the direct (optical) gap measured in experiment. Most likely, it corresponds to the indirect gap that has recently been suggested to be on the order of 0.8 eV, and demonstrates the subtlety in identifying charge gaps.« less

  12. Predicting reservoir facies distribution using high resolution forward stratigraphic modeling (upper Permian Zechstein 2 carbonate, North Germany)

    SciTech Connect (OSTI)

    Leyrer, K.; Strohmenger, C.; Rockenbauch, K.

    1995-08-01

    To improve the prediction of facies within the Upper Permian Zechstein 2 Carbonate (Ca2), high resolution forward stratigraphic modeling was performed. The results show differences in the sedimentary history of various parts of the Southern Permian Basin, permitting a better prediction of reservoir facies distribution. The Zechstein 2 Carbonate contains North Germany`s largest hydrocarbon accumulation. The reservoir overlies the anhydrites of the first Zechstein cycle (Werra Anhydrite, or A1) and is sealed by the anhydrites of the second Zechstein cycle (Basal Anhydrite, or A2). The Ca2 can be subdivided into platform, upper slope, middle slope, lower slope, and basina1 facies with a total of 26 subfacies types. It comprises the transgressive and highstand systems tract, of the third Zechstein sequence (ZS3) and the lowstand systems tract of the fourth Zechstein sequence (ZS4). Furthermore the Ca2 can be subdivided into seven parasequences indicating high-order fluctuations. Although the Ca2 in both Northwest and Northeast Germany share this geological framework, many differences concerning reservoir distribution exist between the two areas. A general stratigraphic, simulation program (PHIL{sup TM} 1.5) was used for two-dimensional modeling of the Ca2 throughout North Germany. Using well data along with published data and modifying the sedimentation-governing factors, it was possible to simulate the current sequence stratigraphic and facies model. Sedimentation during Ca2-time can be characterized as a highly complex system; thus, only slight variations of the input data result in vastly different facies and stratigraphic patterns. This sensitivity offers the possibility to test depositional models and to estimate the relative influences of the sediment-controlling parameters during Ca2-time in different paleotopographic settings.

  13. Carbonation Mechanism of Reservoir Rock by Supercritical Carbon Dioxide |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy Carbonation Mechanism of Reservoir Rock by Supercritical Carbon Dioxide Carbonation Mechanism of Reservoir Rock by Supercritical Carbon Dioxide Project Objectives: Elucidate comprehensively the carbonation reaction mechanisms between supercritical carbon dioxide (scCO2) and reservoir rocks consisting of different mineralogical compositions in aqueous and non-aqueous environments at temperatures of up to 250ºC, and to develop chemical modeling of CO2-reservior rock

  14. Coupled modeling of a directly heated tubular solar receiver for supercritical carbon dioxide Brayton cycle: Structural and creep-fatigue evaluation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ortega, Jesus; Khivsara, Sagar; Christian, Joshua; Ho, Clifford; Dutta, Pradip

    2016-06-06

    A supercritical carbon dioxide (sCO2) Brayton cycle is an emerging high energy-density cycle undergoing extensive research due to the appealing thermo-physical properties of sCO2 and single phase operation. Development of a solar receiver capable of delivering sCO2 at 20 MPa and 700 °C is required for implementation of the high efficiency (~50%) solar powered sCO2 Brayton cycle. In this work, extensive candidate materials are review along with tube size optimization using the ASME Boiler and Pressure Vessel Code. Moreover, temperature and pressure distribution obtained from the thermal-fluid modeling (presented in a complementary publication) are used to evaluate the thermal andmore » mechanical stresses along with detailed creep-fatigue analysis of the tubes. For resulting body stresses were used to approximate the lifetime performance of the receiver tubes. A cyclic loading analysis is performed by coupling the Strain-Life approach and the Larson-Miller creep model. The structural integrity of the receiver was examined and it was found that the stresses can be withstood by specific tubes, determined by a parametric geometric analysis. The creep-fatigue analysis display the damage accumulation due to cycling and the permanent deformation on the tubes showed that the tubes can operate for the full lifetime of the receiver.« less

  15. Determination of High-Frequency Current Distribution Using EMTP-Based Transmission Line Models with Resulting Radiated Electromagnetic Fields

    SciTech Connect (OSTI)

    Mork, B; Nelson, R; Kirkendall, B; Stenvig, N

    2009-11-30

    Application of BPL technologies to existing overhead high-voltage power lines would benefit greatly from improved simulation tools capable of predicting performance - such as the electromagnetic fields radiated from such lines. Existing EMTP-based frequency-dependent line models are attractive since their parameters are derived from physical design dimensions which are easily obtained. However, to calculate the radiated electromagnetic fields, detailed current distributions need to be determined. This paper presents a method of using EMTP line models to determine the current distribution on the lines, as well as a technique for using these current distributions to determine the radiated electromagnetic fields.

  16. Mathematical modeling of the lithium deposition overcharge reaction in lithium-ion batteries using carbon-based negative electrodes

    SciTech Connect (OSTI)

    Arora, P.; Doyle, M.; White, R.E.

    1999-10-01

    Two major issues facing lithium-ion battery technology are safety and capacity grade during cycling. A significant amount of work has been done to improve the cycle life and to reduce the safety problems associated with these cells. This includes newer and better electrode materials, lower-temperature shutdown separators, nonflammable or self-extinguishing electrolytes, and improved cell designs. The goal of this work is to predict the conditions for the lithium deposition overcharge reaction on the negative electrode (graphite and coke) and to investigate the effect of various operating conditions, cell designs and charging protocols on the lithium deposition side reaction. The processes that lead to capacity fading affect severely the cycle life and rate behavior of lithium-ion cells. One such process is the overcharge of the negative electrode causing lithium deposition, which can lead to capacity losses including a loss of active lithium and electrolyte and represents a potential safety hazard. A mathematical model is presented to predict lithium deposition on the negative electrode under a variety of operating conditions. The Li{sub x}C{sub 6} {vert{underscore}bar} 1 M LiPF{sub 6}, 2:1 ethylene carbonate/dimethyl carbonate, poly(vinylidene fluoride-hexafluoropropylene) {vert{underscore}bar} LiMn{sub 2}O{sub 4} cell is simulated to investigate the influence of lithium deposition on the charging behavior of intercalation electrodes. The model is used to study the effect of key design parameters (particle size, electrode thickness, and mass ratio) on the lithium deposition overcharge reaction. The model predictions are compared for coke and graphite-based negative electrodes. The cycling behavior of these cells is simulated before and after overcharge to understand the hazards and capacity fade problems, inherent in these cells, can be minimized.

  17. EA-1835: Environmental Assessment Determination | Department...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    35: Environmental Assessment Determination EA-1835: Environmental Assessment Determination Midwest Regional Carbon Sequestration Partnership (MRCSP) Phase II Michigan Basin Project ...

  18. Elevated carbon dioxide is predicted to promote coexistence among competing species in a trait-based model

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ali, Ashehad A.; Medlyn, Belinda E.; Aubier, Thomas G.; Crous, Kristine Y.; Reich, Peter B.

    2015-10-06

    Differential species responses to atmospheric CO2 concentration (Ca) could lead to quantitative changes in competition among species and community composition, with flow-on effects for ecosystem function. However, there has been little theoretical analysis of how elevated Ca (eCa) will affect plant competition, or how composition of plant communities might change. Such theoretical analysis is needed for developing testable hypotheses to frame experimental research. Here, we investigated theoretically how plant competition might change under eCa by implementing two alternative competition theories, resource use theory and resource capture theory, in a plant carbon and nitrogen cycling model. The model makes several novelmore » predictions for the impact of eCa on plant community composition. Using resource use theory, the model predicts that eCa is unlikely to change species dominance in competition, but is likely to increase coexistence among species. Using resource capture theory, the model predicts that eCa may increase community evenness. Collectively, both theories suggest that eCa will favor coexistence and hence that species diversity should increase with eCa. Our theoretical analysis leads to a novel hypothesis for the impact of eCa on plant community composition. In this study, the hypothesis has potential to help guide the design and interpretation of eCa experiments.« less

  19. Seismic models of a carbonate foreslope-to-basin transition, Picco di Vallandro, Dolomite Alps, northern Italy

    SciTech Connect (OSTI)

    Rudolph, K.W. ); Schlager, W. ); Biddle, K.T. )

    1989-05-01

    Detailed geologic cross sections, augmented by laboratory calibration of lithology and acoustic impedance, have been used to produce synthetic reflection seismic sections of a carbonate foreslope-to-basin transition. Two areas from the Picco di Vallandro region of the Dolomite Alps were modeled: a progradational section and a retrogradational (backstepping) section. The resulting models show how these complex areas of strata interfingering might be displayed on conventional reflection seismic lines. In the area of progradation, rapid stratigraphic thinning below seismic detectibility, coupled with abrupt impedance changes, produces a reflection discontinuity between steeply dipping reflections of the foreslope and gently dipping paralle reflections of the basin section. This apparent downlap surface marks the toe-of-slope for successive clinoforms but dose not correspond to a discrete stratigraphic surface. In the backstepping example, similar stratigraphic thinning and impedance changes create an apparent onlap surface. Wavelet interference causes complications in both examples. These models indicate how stratigraphic complexity can be simplified by the seismic reflection process and suggest that caution should be exercised when using seismic data to construct general models in areas of complex depositional geometries and rapidly changing facies.

  20. Carbon nanotube nanoelectrode arrays

    DOE Patents [OSTI]

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  1. Vehicle Technologies Office Merit Review 2014: Validation of Material Models for Automotive Carbon Fiber Composite Structures

    Broader source: Energy.gov [DOE]

    Presentation given by General Motors at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about validation of material models...

  2. A Sensitivity Study on Modeling Black Carbon in Snow and its Radiative Forcing over the Arctic and Northern China

    SciTech Connect (OSTI)

    Qian, Yun; Wang, Hailong; Zhang, Rudong; Flanner, M. G.; Rasch, Philip J.

    2014-06-02

    Black carbon in snow (BCS) simulated in the Community Atmosphere Model (CAM5) is evaluated against measurements over Northern China and the Arctic, and its sensitivity to atmospheric deposition and two parameters that affect post-depositional enrichment is explored. The BCS concentration is overestimated (underestimated) by a factor of two in Northern China (Arctic) in the default model, but agreement with observations is good over both regions in the simulation with improvements in BC transport and deposition. Sensitivity studies indicate that uncertainty in the melt-water scavenging efficiency (MSE) parameter substantially affects BCS and its radiative forcing (by a factor of 2-7) in the Arctic through post-depositional enrichment. The MSE parameter has a relatively small effect on the magnitude of BCS seasonal cycle but can alter its phase in Northern China. The impact of the snow aging scaling factor (SAF) on BCS, partly through the post-depositional enrichment effect, shows more complex latitudinal and seasonal dependence. Similar to MSE, SAF affects more significantly the magnitude (phase) of BCS season cycle over the Arctic (Northern China). While uncertainty associated with the representation of BC transport and deposition processes in CAM5 is more important than that associated with the two snow model parameters in Northern China, the two uncertainties have comparable effect in the Arctic.

  3. Modelled Black Carbon Radiative Forcing and Atmospheric Lifetime in AeroCom Phase II Constrained by Aircraft Observations

    SciTech Connect (OSTI)

    Samset, B. H.; Myhre, G.; Herber, Andreas; Kondo, Yutaka; Li, Shao-Meng; Moteki, N.; Koike, Makoto; Oshima, N.; Schwarz, Joshua P.; Balkanski, Y.; Bauer, S.; Bellouin, N.; Berntsen, T.; Bian, Huisheng; Chin, M.; Diehl, Thomas; Easter, Richard C.; Ghan, Steven J.; Iversen, T.; Kirkevag, A.; Lamarque, Jean-Francois; Lin, Guang; Liu, Xiaohong; Penner, Joyce E.; Schulz, M.; Seland, O.; Skeie, R. B.; Stier, P.; Takemura, T.; Tsigaridis, Kostas; Zhang, Kai

    2014-11-27

    Black carbon (BC) aerosols absorb solar radiation, and are generally held to exacerbate global warming through exerting a positive radiative forcing1. However, the total contribution of BC to the ongoing changes in global climate is presently under debate2-8. Both anthropogenic BC emissions and the resulting spatial and temporal distribution of BC concentration are highly uncertain2,9. In particular, long range transport and processes affecting BC atmospheric lifetime are poorly understood, leading to large estimated uncertainty in BC concentration at high altitudes and far from emission sources10. These uncertainties limit our ability to quantify both the historical, present and future anthropogenic climate impact of BC. Here we compare vertical profiles of BC concentration from four recent aircraft measurement campaigns with 13 state of the art aerosol models, and show that recent assessments may have overestimated present day BC radiative forcing. Further, an atmospheric lifetime of BC of less than 5 days is shown to be essential for reproducing observations in transport dominated remote regions. Adjusting model results to measurements in remote regions, and at high altitudes, leads to a 25% reduction in the multi-model median direct BC forcing from fossil fuel and biofuel burning over the industrial era.

  4. Electromagnetic model for near-field microwave microscope with atomic resolution: Determination of tunnel junction impedance

    SciTech Connect (OSTI)

    Reznik, Alexander N.

    2014-08-25

    An electrodynamic model is proposed for the tunneling microwave microscope with subnanometer space resolution as developed by Lee et al. [Appl. Phys. Lett. 97, 183111 (2010)]. Tip-sample impedance Z{sub a} was introduced and studied in the tunneling and non-tunneling regimes. At tunneling breakdown, the microwave current between probe and sample flows along two parallel channels characterized by impedances Z{sub p} and Z{sub t} that add up to form overall impedance Z{sub a}. Quantity Z{sub p} is the capacitive impedance determined by the near field of the probe and Z{sub t} is the impedance of the tunnel junction. By taking into account the distance dependences of effective tip radius r{sub 0}(z) and tunnel resistance R{sub t}(z)?=?Re[Z{sub t}(z)], we were able to explain the experimentally observed dependences of resonance frequency f{sub r}(z) and quality factor Q{sub L}(z) of the microscope. The obtained microwave resistance R{sub t}(z) and direct current tunnel resistance R{sub t}{sup dc}(z) exhibit qualitatively similar behavior, although being largely different in both magnitude and the characteristic scale of height dependence. Interpretation of the microwave images of the atomic structure of test samples proved possible by taking into account the inductive component of tunnel impedance ImZ{sub t}?=??L{sub t}. Relation ?L{sub t}/R{sub t}???0.235 was obtained.

  5. Model-independent determination of the astrophysical S factor in laser-induced fusion plasmas

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lattuada, D.; Barbarino, M.; Bonasera, A.; Bang, W.; Quevedo, H. J.; Warren, M.; Consoli, F.; De Angelis, R.; Andreoli, P.; Kimura, S.; et al

    2016-04-01

    In this paper, we present a new and general method for measuring the astrophysical S factor of nuclear reactions in laser-induced plasmas and we apply it to 2H(d,n)3He. The experiment was performed with the Texas Petawatt Laser, which delivered 150–270 fs pulses of energy ranging from 90 to 180 J to D2 or CD4 molecular clusters (where D denotes 2H). After removing the background noise, we used the measured time-of-flight data of energetic deuterium ions to obtain their energy distribution. We derive the S factor using the measured energy distribution of the ions, the measured volume of the fusion plasma,more » and the measured fusion yields. This method is model independent in the sense that no assumption on the state of the system is required, but it requires an accurate measurement of the ion energy distribution, especially at high energies, and of the relevant fusion yields. In the 2H(d,n)3He and 3He(d,p)4He cases discussed here, it is very important to apply the background subtraction for the energetic ions and to measure the fusion yields with high precision. While the available data on both ion distribution and fusion yields allow us to determine with good precision the S factor in the d+d case (lower Gamow energies), for the d+3He case the data are not precise enough to obtain the S factor using this method. Our results agree with other experiments within the experimental error, even though smaller values of the S factor were obtained. This might be due to the plasma environment differing from the beam target conditions in a conventional accelerator experiment.« less

  6. CO2 CAPTURE BY ABSORPTION WITH POTASSIUM CARBONATE (Technical...

    Office of Scientific and Technical Information (OSTI)

    Subject: 54 ENVIRONMENTAL SCIENCES; CARBON DIOXIDE; ABSORPTION; SORPTIVE PROPERTIES; POTASSIUM CARBONATES; THERMODYNAMIC MODEL; VAPOR PRESSURE; AIR POLLUTION CONTROL Word Cloud ...

  7. CO2 Capture by Absorption with Potassium Carbonate (Technical...

    Office of Scientific and Technical Information (OSTI)

    ... Subject: 54 ENVIRONMENTAL SCIENCES; CARBON DIOXIDE; ABSORPTION; POTASSIUM CARBONATES; SORPTIVE PROPERTIES; AMINES; MATERIALS RECOVERY; AIR POLLUTION CONTROL; MATHEMATICAL MODELS ...

  8. Study of behavior and determination of customer lifetime value(CLV) using Markov chain model

    SciTech Connect (OSTI)

    Permana, Dony; Indratno, Sapto Wahyu; Pasaribu, Udjianna S.

    2014-03-24

    Customer Lifetime Value or CLV is a restriction on interactive marketing to help a company in arranging financial for the marketing of new customer acquisition and customer retention. Additionally CLV can be able to segment customers for financial arrangements. Stochastic models for the fairly new CLV used a Markov chain. In this model customer retention probability and new customer acquisition probability play an important role. This model is originally introduced by Pfeifer and Carraway in 2000 [1]. They introduced several CLV models, one of them only involves customer and former customer. In this paper we expand the model by adding the assumption of the transition from former customer to customer. In the proposed model, the CLV value is higher than the CLV value obtained by Pfeifer and Caraway model. But our model still requires a longer convergence time.

  9. PRODUCTION OF THE p-PROCESS NUCLEI IN THE CARBON-DEFLAGRATION MODEL FOR TYPE Ia SUPERNOVAE

    SciTech Connect (OSTI)

    Kusakabe, Motohiko; Iwamoto, Nobuyuki; Nomoto, Ken'ichi E-mail: iwamoto.nobuyuki@jaea.go.jp

    2011-01-01

    We calculate the nucleosynthesis of proton-rich isotopes in the carbon-deflagration model for Type Ia supernovae (SNe Ia). The seed abundances are obtained by calculating the s-process nucleosynthesis that is expected to occur in the repeating helium shell flashes on the carbon-oxygen (CO) white dwarf (WD) during mass accretion from a binary companion. When the deflagration wave passes through the outer layer of the CO WD, p-nuclei are produced by photodisintegration reactions on s-nuclei in a region where the peak temperature ranges from 1.9 to 3.6 x 10{sup 9} K. We confirm the sensitivity of the p-process on the initial distribution of s-nuclei. We show that the initial C/O ratio in the WD does not affect much the yield of p-nuclei. On the other hand, the abundance of {sup 22}Ne left after s-processing has a large influence on the p-process via the {sup 22}Ne({alpha},n) reaction. We find that about 50% of p-nuclides are co-produced when normalized to their solar abundances in all adopted cases of seed distribution. Mo and Ru, which are largely underproduced in Type II supernovae (SNe II), are produced more than in SNe II although they are underproduced with respect to the yield levels of other p-nuclides. The ratios between p-nuclei and iron in the ejecta are larger than the solar ratios by a factor of 1.2. We also compare the yields of oxygen, iron, and p-nuclides in SNe Ia and SNe II and suggest that SNe Ia could make a larger contribution than SNe II to the solar system content of p-nuclei.

  10. Elevated carbon dioxide is predicted to promote coexistence among competing species in a trait-based model

    SciTech Connect (OSTI)

    Ali, Ashehad A.; Medlyn, Belinda E.; Aubier, Thomas G.; Crous, Kristine Y.; Reich, Peter B.

    2015-10-06

    Differential species responses to atmospheric CO2 concentration (Ca) could lead to quantitative changes in competition among species and community composition, with flow-on effects for ecosystem function. However, there has been little theoretical analysis of how elevated Ca (eCa) will affect plant competition, or how composition of plant communities might change. Such theoretical analysis is needed for developing testable hypotheses to frame experimental research. Here, we investigated theoretically how plant competition might change under eCa by implementing two alternative competition theories, resource use theory and resource capture theory, in a plant carbon and nitrogen cycling model. The model makes several novel predictions for the impact of eCa on plant community composition. Using resource use theory, the model predicts that eCa is unlikely to change species dominance in competition, but is likely to increase coexistence among species. Using resource capture theory, the model predicts that eCa may increase community evenness. Collectively, both theories suggest that eCa will favor coexistence and hence that species diversity should increase with eCa. Our theoretical analysis leads to a novel hypothesis for the impact of eCa on plant community composition. In this study, the hypothesis has potential to help guide the design and interpretation of eCa experiments.

  11. Economic and Physical Modeling of Land Use in GCAM 3.0 and an Application to Agricultural Productivity, Land, and Terrestrial Carbon

    SciTech Connect (OSTI)

    Wise, Marshall A.; Calvin, Katherine V.; Kyle, G. Page; Luckow, Patrick; Edmonds, James A.

    2014-09-01

    We explore the impact of changes in agricultural productivity on global land use and terrestrial carbon using the new agriculture and land use modeling approach developed for Global Change Assessment Model (GCAM) version 3.0. This approach models economic land use decisions with regional, physical, and technological specificity while maintaining economic and physical integration with the rest of the GCAM model. Physical land characteristics and quantities are tracked explicitly, and crop production practices are modeled discretely to facilitate coupling with physical models. Economic land allocation is modeled with non-linear functions in a market equilibrium rather than through a constrained optimization. In this paper, we explore three scenarios of future agriculture productivity in all regions of the globe over this century, ranging from a high growth to a zero growth level. The higher productivity growth scenario leads to lower crop prices, increased production of crops in developing nations, preservation of global forested lands and lower terrestrial carbon emissions. The scenario with no productivity improvement results in higher crop prices, an expansion of crop production in the developed world, loss of forested lands globally, and higher terrestrial carbon emissions.

  12. X-ray absorption spectroscopy of LiBF 4 in propylene carbonate. A model lithium ion battery electrolyte

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Smith, Jacob W.; Lam, Royce K.; Sheardy, Alex T.; Shih, Orion; Rizzuto, Anthony M.; Borodin, Oleg; Harris, Stephen J.; Prendergast, David; Saykally, Richard J.

    2014-08-20

    Since their introduction into the commercial marketplace in 1991, lithium ion batteries have become increasingly ubiquitous in portable technology. Nevertheless, improvements to existing battery technology are necessary to expand their utility for larger-scale applications, such as electric vehicles. Advances may be realized from improvements to the liquid electrolyte; however, current understanding of the liquid structure and properties remains incomplete. X-ray absorption spectroscopy of solutions of LiBF4 in propylene carbonate (PC), interpreted using first-principles electronic structure calculations within the eXcited electron and Core Hole (XCH) approximation, yields new insight into the solvation structure of the Li+ ion in this model electrolyte.more » By generating linear combinations of the computed spectra of Li+-associating and free PC molecules and comparing to the experimental spectrum, we find a Li+–solvent interaction number of 4.5. This result suggests that computational models of lithium ion battery electrolytes should move beyond tetrahedral coordination structures.« less

  13. Effects of harvest management practices on forest biomass and soil carbon in eucalypt forests in New South Wales, Australia: Simulations with the forest succession model LINKAGES

    SciTech Connect (OSTI)

    Ranatunga, Kemachandra; Keenan, Rodney J.; Wullschleger, Stan D; Post, Wilfred M; Tharp, M Lynn

    2008-01-01

    Understanding long-term changes in forest ecosystem carbon stocks under forest management practices such as timber harvesting is important for assessing the contribution of forests to the global carbon cycle. Harvesting effects are complicated by the amount, type, and condition of residue left on-site, the decomposition rate of this residue, the incorporation of residue into soil organic matter and the rate of new detritus input to the forest floor from regrowing vegetation. In an attempt to address these complexities, the forest succession model LINKAGES was used to assess the production of aboveground biomass, detritus, and soil carbon stocks in native Eucalyptus forests as influenced by five harvest management practices in New South Wales, Australia. The original decomposition sub-routines of LINKAGES were modified by adding components of the Rothamsted (RothC) soil organic matter turnover model. Simulation results using the new model were compared to data from long-term forest inventory plots. Good agreement was observed between simulated and measured above-ground biomass, but mixed results were obtained for basal area. Harvesting operations examined included removing trees for quota sawlogs (QSL, DBH >80 cm), integrated sawlogs (ISL, DBH >20 cm) and whole-tree harvesting in integrated sawlogs (WTH). We also examined the impact of different cutting cycles (20, 50 or 80 years) and intensities (removing 20, 50 or 80 m{sup 3}). Generally medium and high intensities of shorter cutting cycles in sawlog harvesting systems produced considerably higher soil carbon values compared to no harvesting. On average, soil carbon was 2-9% lower in whole-tree harvest simulations whereas in sawlog harvest simulations soil carbon was 5-17% higher than in no harvesting.

  14. Stereochemical determination of carbon partitioning between photosynthesis and photorespiration in C3 plants: use of (3R)-D-(3-3H1, 3-14C)glyceric acid

    SciTech Connect (OSTI)

    Hanson, K.R.

    1984-07-01

    When (3R)-D-(3-3H1,3-14C)glyceric acid is supplied in tracer amounts to illuminated tobacco leaf discs, the acid penetrates to the chloroplasts without loss of 3H, and is phosphorylated there. Subsequent metabolism associated with the reductive photosynthetic cycle fully conserves 3H. Oxidation of ribulose bisphosphate (RuBP) by RuBP carboxylase-oxygenase (EC 4.1.1.39) results in the formation of (2R)-(2-3H1, 14C)glycolic acid which, on oxidation by glycolate oxidase (EC 1.1.3.1), releases 3H to water. Loss of 3H from the combined photosynthetic and photorespiratory systems is, therefore, associated with the oxidative photorespiratory loop. Assuming steady-state conditions and a basic metabolic model, the fraction of RuBP oxidized and the photorespiratory carbon flux relative to gross or net CO2 fixation can be calculated from the fraction of supplied 3H retained in the triose phosphates exported from the chloroplasts. This retention can be determined from the 3H:14C ratio for glucose obtained from isolated sucrose. The dependence of 3H retention upon O2 and CO2 concentrations can be deduced by assuming simple competitive kinetics for RuBP carboxylase-oxygenase. The experimental results confirmed the stereochemical assumptions made. Under conditions of negligible photorespiration 3H retention was essentially complete. The change in 3H retention with O2 and CO2 concentrations were investigated. For leaf discs (upper surface up) in normal air, it was estimated that 39% of the RuBP was oxidized, 32% of the fixed CO2 was photorespired, and the photorespiration rate was 46% of the net photosynthetic CO2 fixation rate. These are minimal estimates, as it is assumed that the only source of photorespired CO2 is glycine decarboxylation.

  15. Differences in carbon cycle and temperature projections from emission- and concentration-driven earth system model simulations

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Shao, P.; Zeng, X.; Zeng, X.

    2014-08-29

    The influence of prognostic and prescribed atmospheric CO2 concentrations ([CO2]) on the carbon uptake and temperature is investigated using all eight Earth System Models (ESMs) with relevant output variables from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Under the RCP8.5 scenario, the projected [CO2] differences in 2100 vary from -19.7 to +207.3 ppm in emission-driven ESMs. Incorporation of the interactive concentrations also increases the range of global warming, computed as the 20 year average difference between 20812100 and 18501869/18611880, by 49% from 2.36 K (i.e. ranging from 3.11 to 5.47 K) in the concentration-driven simulations to 3.51 K inmorethe emission-driven simulations. The observed seasonal amplitude of global [CO2] from 19802011 is about 1.25.3 times as large as those from the eight emission-driven ESMs, while the [CO2] seasonality is simply neglected in concentration-driven ESMs, suggesting the urgent need of ESM improvements in this area. The temperature-concentration feedback parameter ? is more sensitive to [CO2] (e.g. during 19802005 versus 20752100) than how [CO2] is handled (i.e. prognostic versus prescribed). This sensitivity can be substantially reduced by using a more appropriate parameter ?' computed from the linear regression of temperature change versus that of the logarithm of [CO2]. However, the inter-model relative variations of both ? and ?' remain large, suggesting the need of more detailed studies to understand and hopefully reduce these discrepancies.less

  16. Expanding the potential for saline formations : modeling carbon dioxide storage, water extraction and treatment for power plant cooling.

    SciTech Connect (OSTI)

    Not Available

    2011-04-01

    The National Water, Energy and Carbon Sequestration simulation model (WECSsim) is being developed to address the question, 'Where in the current and future U.S. fossil fuel based electricity generation fleet are there opportunities to couple CO{sub 2} storage and extracted water use, and what are the economic and water demand-related impacts of these systems compared to traditional power systems?' The WECSsim collaborative team initially applied this framework to a test case region in the San Juan Basin, New Mexico. Recently, the model has been expanded to incorporate the lower 48 states of the U.S. Significant effort has been spent characterizing locations throughout the U.S. where CO{sub 2} might be stored in saline formations including substantial data collection and analysis efforts to supplement the incomplete brine data offered in the NatCarb database. WECSsim calculates costs associated with CO{sub 2} capture and storage (CCS) for the power plant to saline formation combinations including parasitic energy costs of CO{sub 2} capture, CO{sub 2} pipelines, water treatment options, and the net benefit of water treatment for power plant cooling. Currently, the model can identify the least-cost deep saline formation CO{sub 2} storage option for any current or proposed coal or natural gas-fired power plant in the lower 48 states. Initial results suggest that additional, cumulative water withdrawals resulting from national scale CCS may range from 676 million gallons per day (MGD) to 30,155 MGD depending on the makeup power and cooling technologies being utilized. These demands represent 0.20% to 8.7% of the U.S. total fresh water withdrawals in the year 2000, respectively. These regional and ultimately nation-wide, bottom-up scenarios coupling power plants and saline formations throughout the U.S. can be used to support state or national energy development plans and strategies.

  17. Modeling reservoir heterogeneity within outer ramp carbonate facies using an outcrop analog, San Andres Formation of the Permian Basin

    SciTech Connect (OSTI)

    Eisenberg, R.A.; Harris, P.M.; Grant, C.W.

    1994-09-01

    Variably cyclic, fusulinid-rich, outer ramp facies of the Permian San Andres Formation are exposed along the Algerita escarpment, Guadalupe Mountains, New Mexico. We have used the outcrop exposures and cored wells drilled adjacent to the outcrop to assess reservoir- and interwell-scale variability of permeability as a potential analog for carbonate reservoirs in the Permian basin and elsewhere. Permeability distribution was evaluated using a field permeameter and conventional measurements on small core plugs taken along vertical and horizontal outcrop traverses and from the slim-hole cores. Geostatistical models of permeability variation, honoring the geologic and petrophysical data, were constructed and input into a waterflood simulator to understand the interactions between heterogeneity and flow. Different vertical variogram characteristics are displayed by cyclic and less distinctly cyclic parts of the San Andres. Variograms constructed for horizontal transect data from three distinct stratigraphic units have nearly identical properties. Overall, the ranges of correlation are short (3-3.5 in; 10-12 ft) when compared to typical interwell distances, supporting a nearly uncorrelated and highly variable permeability model. Using observed short ranges of vertical and horizontal correlation and honoring the vertical transect data, cross sectional, conditionally simulated permeability fields were generated and used in simulated waterfloods to investigate the sensitivities to an oil recovery model and overall fluid injection rate for this style of stratigraphy and cyclicity. Cyclic parts of the section are characterized by a potential for early water breakthrough and relatively high vertical sweep efficiencies. Within the less distinctly cyclic section, waterflood fronts have a fingerlike profile and vertical sweep efficiency is generally poorer.

  18. Method of and apparatus for determining the similarity of a biological analyte from a model constructed from known biological fluids

    DOE Patents [OSTI]

    Robinson, Mark R.; Ward, Kenneth J.; Eaton, Robert P.; Haaland, David M.

    1990-01-01

    The characteristics of a biological fluid sample having an analyte are determined from a model constructed from plural known biological fluid samples. The model is a function of the concentration of materials in the known fluid samples as a function of absorption of wideband infrared energy. The wideband infrared energy is coupled to the analyte containing sample so there is differential absorption of the infrared energy as a function of the wavelength of the wideband infrared energy incident on the analyte containing sample. The differential absorption causes intensity variations of the infrared energy incident on the analyte containing sample as a function of sample wavelength of the energy, and concentration of the unknown analyte is determined from the thus-derived intensity variations of the infrared energy as a function of wavelength from the model absorption versus wavelength function.

  19. Carbonic Acid Pretreatment of Biomass

    SciTech Connect (OSTI)

    G. Peter van Walsum; Kemantha Jayawardhana; Damon Yourchisin; Robert McWilliams; Vanessa Castleberry

    2003-05-31

    acid compared to water alone. 6) Determine optimal conditions for carbonic acid pretreatment of aspen wood. Optimal severities appeared to be in the mid range tested. ASPEN-Plus modeling and economic analysis of the process indicate that the process could be cost competitive with sulfuric acid if the concentration of solids in the pretreatment is maintained very high (~50%). Lower solids concentrations result in larger reactors that become expensive to construct for high pressure applications.

  20. Carbonic Acid Retreatment of Biomass

    SciTech Connect (OSTI)

    Baylor university

    2003-06-01

    the use of carbonic acid compared to water alone. (6) Determine optimal conditions for carbonic acid pretreatment of aspen wood. Optimal severities appeared to be in the mid range tested. ASPEN-Plus modeling and economic analysis of the process indicate that the process could be cost competitive with sulfuric acid if the concentration of solids in the pretreatment is maintained very high ({approx}50%). Lower solids concentrations result in larger reactors that become expensive to construct for high pressure applications.

  1. MO-G-BRF-07: Anomalously Fast Diffusion of Carbon Nanotubes Carriers in 3D Tissue Model

    SciTech Connect (OSTI)

    Wang, Y; Bahng, J; Kotov, N

    2014-06-15

    Purpose: We aim to investigate and understand diffusion process of carbon nanotubes (CNTs) and other nanoscale particles in tissue and organs. Methods: In this research, we utilized a 3D model tissue of hepatocellular carcinoma (HCC)cultured in inverted colloidal crystal (ICC) scaffolds to compare the diffusivity of CNTs with small molecules such as Rhodamine and FITC in vitro, and further investigated the transportation of CNTs with and without targeting ligand, TGFβ1. The real-time permeation profiles of CNTs in HCC tissue model with high temporal and spatial resolution was demonstrated by using standard confocal microscopy. Quantitative analysis of the diffusion process in 3D was carried out using luminescence intensity in a series of Z-stack images obtained for different time points of the diffusion process after initial addition of CNTs or small molecules to the cell culture and the image data was analyzed by software ImageJ and Mathematica. Results: CNTs display diffusion rate in model tissues substantially faster than small molecules of the similar charge such as FITC, and the diffusion rate of CNTs are significantly enhanced with targeting ligand, TGFβ1. Conclusion: In terms of the advantages of in-vitro model, we were able to have access to measuring the rate of CNT penetration at designed conditions with variable parameters. And the findings by using this model, changed our understanding about advantages of CNTs as nanoscale drug carriers and provides design principles for making new drug carriers for both treatment and diagnostics. Additionally the fast diffusion opens the discussion of the best possible drug carriers to reach deep parts of cancerous tissues, which is often a prerequisite for successful cancer treatment. This work was supported by the Center for Photonic and Multiscale Nanomaterials funded by National Science Foundation Materials Research Science and Engineering Center program DMR 1120923. The work was also partially supported by NSF

  2. Multi-scale geospatial agroecosystem modeling: a case study on the influence of soil data resolution on carbon budget estimates

    SciTech Connect (OSTI)

    Zhang, Xuesong; Sahajpal, Ritvik; Manowitz, D.; Zhao, Kaiguang; LeDuc, Stephen D.; Xu, Min; Xiong, Wei; Zhang, Aiping; Izaurralde, Roberto C.; Thomson, Allison M.; West, Tristram O.; Post, W. M.

    2014-05-01

    The development of effective measures to stabilize atmospheric CO2 concentration and mitigate negative impacts of climate change requires accurate quantification of the spatial variation and magnitude of the terrestrial carbon (C) flux. However, the spatial pattern and strength of terrestrial C sinks and sources remain uncertain. In this study, we designed a spatially-explicit agroecosystem modeling system by integrating the Environmental Policy Integrated Climate (EPIC) model with multiple sources of geospatial and surveyed datasets (including crop type map, elevation, climate forcing, fertilizer application, tillage type and distribution, and crop planting and harvesting date), and applied it to examine the sensitivity of cropland C flux simulations to two widely used soil databases (i.e. State Soil Geographic-STATSGO of a scale of 1:250,000 and Soil Survey Geographic-SSURGO of a scale of 1:24,000) in Iowa, USA. To efficiently execute numerous EPIC runs resulting from the use of high resolution spatial data (56m), we developed a parallelized version of EPIC. Both STATSGO and SSURGO led to similar simulations of crop yields and Net Ecosystem Production (NEP) estimates at the State level. However, substantial differences were observed at the county and sub-county (grid) levels. In general, the fine resolution SSURGO data outperformed the coarse resolution STATSGO data for county-scale crop-yield simulation, and within STATSGO, the area-weighted approach provided more accurate results. Further analysis showed that spatial distribution and magnitude of simulated NEP were more sensitive to the resolution difference between SSURGO and STATSGO at the county or grid scale. For over 60% of the cropland areas in Iowa, the deviations between STATSGO- and SSURGO-derived NEP were larger than 1MgCha(-1)yr(-1), or about half of the average cropland NEP, highlighting the significant uncertainty in spatial distribution and magnitude of simulated C fluxes resulting from

  3. Greenhouse Gas Mitigation Options in ISEEM Global Energy Model: 2010-2050 Scenario Analysis for Least-Cost Carbon Reduction in Iron and Steel Sector

    SciTech Connect (OSTI)

    Karali, Nihan; Xu, Tengfang; Sathaye, Jayant

    2013-12-01

    The goal of the modeling work carried out in this project was to quantify long-term scenarios for the future emission reduction potentials in the iron and steel sector. The main focus of the project is to examine the impacts of carbon reduction options in the U.S. iron and steel sector under a set of selected scenarios. In order to advance the understanding of carbon emission reduction potential on the national and global scales, and to evaluate the regional impacts of potential U.S. mitigation strategies (e.g., commodity and carbon trading), we also included and examined the carbon reduction scenarios in China’s and India’s iron and steel sectors in this project. For this purpose, a new bottom-up energy modeling framework, the Industrial Sector Energy Efficiency Modeling (ISEEM), (Karali et al. 2012) was used to provide detailed annual projections starting from 2010 through 2050. We used the ISEEM modeling framework to carry out detailed analysis, on a country-by-country basis, for the U.S., China’s, and India’s iron and steel sectors. The ISEEM model applicable to iron and steel section, called ISEEM-IS, is developed to estimate and evaluate carbon emissions scenarios under several alternative mitigation options - including policies (e.g., carbon caps), commodity trading, and carbon trading. The projections will help us to better understand emission reduction potentials with technological and economic implications. The database for input of ISEEM-IS model consists of data and information compiled from various resources such as World Steel Association (WSA), the U.S. Geological Survey (USGS), China Steel Year Books, India Bureau of Mines (IBM), Energy Information Administration (EIA), and recent LBNL studies on bottom-up techno-economic analysis of energy efficiency measures in the iron and steel sector of the U.S., China, and India, including long-term steel production in China. In the ISEEM-IS model, production technology and manufacturing details are

  4. Reactive transport modeling of the enhancement of density-driven CO2 convective mixing in carbonate aquifers and its potential implication on geological carbon sequestration

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Islam, Akand; Sun, Alexander Y.; Yang, Changbing

    2016-04-20

    We study the convection and mixing of CO2 in a brine aquifer, where the spread of dissolved CO2 is enhanced because of geochemical reactions with the host formations (calcite and dolomite), in addition to the extensively studied, buoyancy-driven mixing. The nonlinear convection is investigated under the assumptions of instantaneous chemical equilibrium, and that the dissipation of carbonate rocks solely depends on flow and transport and chemical speciation depends only on the equilibrium thermodynamics of the chemical system. The extent of convection is quantified in term of the CO2 saturation volume of the storage formation. Our results suggest that the densitymore » increase of resident species causes significant enhancement in CO2 dissolution, although no significant porosity and permeability alterations are observed. Furthermore, early saturation of the reservoir can have negative impact on CO2 sequestration.« less

  5. Technosocial Modeling for Determining the Status and Nature of a State’s Nuclear Activities

    SciTech Connect (OSTI)

    Gastelum, Zoe N.; Harvey, Julia B.

    2009-09-25

    The International Atomic Energy Agency State Evaluation Process: The Role of Information Analysis in Reaching Safeguards Conclusions (Mathews et al. 2008), several examples of nonproliferation models using analytical software were developed that may assist the IAEA with collecting, visualizing, analyzing, and reporting information in support of the State Evaluation Process. This paper focuses on one of the examples a set of models developed in the Proactive Scenario Production, Evidence Collection, and Testing (ProSPECT) software that evaluates the status and nature of a state’s nuclear activities. The models use three distinct subject areas to perform this assessment: the presence of nuclear activities, the consistency of those nuclear activities with national nuclear energy goals, and the geopolitical context in which those nuclear activities are taking place. As a proof-of-concept for the models, a crude case study was performed. The study, which attempted to evaluate the nuclear activities taking place in Syria prior to September 2007, yielded illustrative, yet inconclusive, results. Due to the inconclusive nature of the case study results, changes that may improve the model’s efficiency and accuracy are proposed.

  6. Models for evaluation of energy technology and policy options to maximize low carbon source penetration in the United States energy supply.

    SciTech Connect (OSTI)

    Pickard, Paul S.; Kataoka, Dawn; Reno, Marissa Devan; Malczynski, Leonard A.; Peplinski, William J.; Roach, Jesse D.; Brainard, James Robert; West, Todd H.; Schoenwald, David Alan

    2009-12-01

    An initial version of a Systems Dynamics (SD) modeling framework was developed for the analysis of a broad range of energy technology and policy questions. The specific question selected to demonstrate this process was 'what would be the carbon and import implications of expanding nuclear electric capacity to provide power for plug in hybrid vehicles?' Fifteen SNL SD energy models were reviewed and the US Energy and Greenhouse gas model (USEGM) and the Global Nuclear Futures model (GEFM) were identified as the basis for an initial modeling framework. A basic U.S. Transportation model was created to model U.S. fleet changes. The results of the rapid adoption scenario result in almost 40% of light duty vehicles being PHEV by 2040 which requires about 37 GWy/y of additional electricity demand, equivalent to about 25 new 1.4 GWe nuclear plants. The adoption rate of PHEVs would likely be the controlling factor in achieving the associated reduction in carbon emissions and imports.

  7. Technical Approach for Determining Key Parameters Needed for Modeling the Performance of Cast Stone for the Integrated Disposal Facility Performance Assessment

    SciTech Connect (OSTI)

    Yabusaki, Steven B.; Serne, R. Jeffrey; Rockhold, Mark L.; Wang, Guohui; Westsik, Joseph H.

    2015-03-30

    Washington River Protection Solutions (WRPS) and its contractors at Pacific Northwest National Laboratory (PNNL) and Savannah River National Laboratory (SRNL) are conducting a development program to develop / refine the cementitious waste form for the wastes treated at the ETF and to provide the data needed to support the IDF PA. This technical approach document is intended to provide guidance to the cementitious waste form development program with respect to the waste form characterization and testing information needed to support the IDF PA. At the time of the preparation of this technical approach document, the IDF PA effort is just getting started and the approach to analyze the performance of the cementitious waste form has not been determined. Therefore, this document looks at a number of different approaches for evaluating the waste form performance and describes the testing needed to provide data for each approach. Though the approach addresses a cementitious secondary aqueous waste form, it is applicable to other waste forms such as Cast Stone for supplemental immobilization of Hanford LAW. The performance of Cast Stone as a physical and chemical barrier to the release of contaminants of concern (COCs) from solidification of Hanford liquid low activity waste (LAW) and secondary wastes processed through the Effluent Treatment Facility (ETF) is of critical importance to the Hanford Integrated Disposal Facility (IDF) total system performance assessment (TSPA). The effectiveness of cementitious waste forms as a barrier to COC release is expected to evolve with time. PA modeling must therefore anticipate and address processes, properties, and conditions that alter the physical and chemical controls on COC transport in the cementitious waste forms over time. Most organizations responsible for disposal facility operation and their regulators support an iterative hierarchical safety/performance assessment approach with a general philosophy that modeling provides

  8. Field Demonstration of Horizontal Infill Drilling Using Cost-effective Integrated Reservoir Modeling--Mississippian Carbonates, Central Kansas

    SciTech Connect (OSTI)

    Saibal Bhattacharya

    2005-08-31

    Mississippian carbonate reservoirs have produced in excess of 1 billion barrels of oil in Kansas accounting for over 16% of the state's production. With declining production from other age reservoirs, the contribution of Mississippian reservoirs to Kansas's oil production has risen to 43% as of 2004. However, solution-enhanced features such as vertical shale intervals extending from the karst erosional surface at the top introduce complexities/compartmentalizations in Mississippian carbonate reservoirs. Coupled with this, strong water drives charge many of these reservoirs resulting in limited drainage from vertical wells due to high water cuts after an initial period of low water production. Moreover, most of these fields are operated by small independent operators without access to the knowledge bank of modern research in field characterization and exploitation/development practices. Thus, despite increasing importance of Mississippian fields to Kansas production, these fields are beset with low recovery factors and high abandonment rates leaving significant resources in the ground. Worldwide, horizontal infill wells have been successful in draining compartmentalized reservoirs with limited pressure depletion. The intent of this project was to demonstrate the application of horizontal wells to successfully exploit the remaining potential in mature Mississippian fields of the mid-continent. However, it is of critical importance that for horizontal wells to be economically successful, they must be selectively targeted. This project demonstrated the application of initial and secondary screening methods, based on publicly available data, to quickly shortlist fields in a target area for detailed studies to evaluate their potential to infill horizontal well applications. Advanced decline curve analyses were used to estimate missing well-level production data and to verify if the well produced under unchanging bottom-hole conditions--two commonly occurring data

  9. Carbon Smackdown: Carbon Capture

    SciTech Connect (OSTI)

    Jeffrey Long

    2010-07-12

    In this July 9, 2010 Berkeley Lab summer lecture, Lab scientists Jeff Long of the Materials Sciences and Nancy Brown of the Environmental Energy Technologies Division discuss their efforts to fight climate change by capturing carbon from the flue gas of power plants, as well as directly from the air

  10. Carbon Smackdown: Carbon Capture

    ScienceCinema (OSTI)

    Jeffrey Long

    2010-09-01

    In this July 9, 2010 Berkeley Lab summer lecture, Lab scientists Jeff Long of the Materials Sciences and Nancy Brown of the Environmental Energy Technologies Division discuss their efforts to fight climate change by capturing carbon from the flue gas of power plants, as well as directly from the air

  11. Determination of Electrochemical Performance and Thermo-Mechanical-Chemical Stability of SOFCs from Defect Modeling

    SciTech Connect (OSTI)

    Eric Wachsman; Keith L. Duncan

    2006-09-30

    This research was focused on two distinct but related issues. The first issue concerned using defect modeling to understand the relationship between point defect concentration and the electrochemical, thermo-chemical and mechano-chemical properties of typical solid oxide fuel cell (SOFC) materials. The second concerned developing relationships between the microstructural features of SOFC materials and their electrochemical performance. To understand the role point defects play in ceramics, a coherent analytical framework was used to develop expressions for the dependence of thermal expansion and elastic modulus on point defect concentration in ceramics. These models, collectively termed the continuum-level electrochemical model (CLEM), were validated through fits to experimental data from electrical conductivity, I-V characteristics, elastic modulus and thermo-chemical expansion experiments for (nominally pure) ceria, gadolinia-doped ceria (GDC) and yttria-stabilized zirconia (YSZ) with consistently good fits. The same values for the material constants were used in all of the fits, further validating our approach. As predicted by the continuum-level electrochemical model, the results reveal that the concentration of defects has a significant effect on the physical properties of ceramic materials and related devices. Specifically, for pure ceria and GDC, the elastic modulus decreased while the chemical expansion increased considerably in low partial pressures of oxygen. Conversely, the physical properties of YSZ remained insensitive to changes in oxygen partial pressure within the studied range. Again, the findings concurred exactly with the predictions of our analytical model. Indeed, further analysis of the results suggests that an increase in the point defect content weakens the attractive forces between atoms in fluorite-structured oxides. The reduction treatment effects on the flexural strength and the fracture toughness of pure ceria were also evaluated at

  12. INTEGRATED GEOLOGIC-ENGINEERING MODEL FOR REEF AND CARBONATE SHOAL RESERVOIRS ASSOCIATED WITH PALEOHIGHS: UPPER JURASSIC SMACKOVER FORMATION, NORTHEASTERN GULF OF MEXICO

    SciTech Connect (OSTI)

    Ernest A. Mancini

    2002-09-25

    The University of Alabama in cooperation with Texas A&M University, McGill University, Longleaf Energy Group, Strago Petroleum Corporation, and Paramount Petroleum Company are undertaking an integrated, interdisciplinary geoscientific and engineering research project. The project is designed to characterize and model reservoir architecture, pore systems and rock-fluid interactions at the pore to field scale in Upper Jurassic Smackover reef and carbonate shoal reservoirs associated with varying degrees of relief on pre-Mesozoic basement paleohighs in the northeastern Gulf of Mexico. The project effort includes the prediction of fluid flow in carbonate reservoirs through reservoir simulation modeling which utilizes geologic reservoir characterization and modeling and the prediction of carbonate reservoir architecture, heterogeneity and quality through seismic imaging. The primary objective of the project is to increase the profitability, producibility and efficiency of recovery of oil from existing and undiscovered Upper Jurassic fields characterized by reef and carbonate shoals associated with pre-Mesozoic basement paleohighs. The principal research effort for Year 2 of the project has been reservoir characterization, 3-D modeling and technology transfer. This effort has included six tasks: (1) the study of rockfluid interactions, (2) petrophysical and engineering characterization, (3) data integration, (4) 3-D geologic modeling, (5) 3-D reservoir simulation and (6) technology transfer. This work was scheduled for completion in Year 2. Overall, the project work is on schedule. Geoscientific reservoir characterization is essentially completed. The architecture, porosity types and heterogeneity of the reef and shoal reservoirs at Appleton and Vocation Fields have been characterized using geological and geophysical data. The study of rock-fluid interactions is near completion. Observations regarding the diagenetic processes influencing pore system development and

  13. Modeling LIDAR Detection of Biological Aerosols to Determine Optimum Implementation Strategy

    SciTech Connect (OSTI)

    Sheen, David M.; Aker, Pam M.

    2007-09-19

    This report summarizes work performed for a larger multi-laboratory project named the Background Interferent Measurement and Standards project. While originally tasked to develop algorithms to optimize biological warfare agent detection using UV fluorescence LIDAR, the current uncertainties in the reported fluorescence profiles and cross sections the development of any meaningful models. It was decided that a better approach would be to model the wavelength-dependent elastic backscattering from a number of ambient background aerosol types, and compare this with that generated from representative sporulated and vegetative bacterial systems. Calculations in this report show that a 266, 355, 532 and 1064 nm elastic backscatter LIDAR experiment will allow an operator to immediately recognize when sulfate, VOC-based or road dust (silicate) aerosols are approaching, independent of humidity changes. It will be more difficult to distinguish soot aerosols from biological aerosols, or vegetative bacteria from sporulated bacteria. In these latter cases, the elastic scattering data will most likely have to be combined with UV fluorescence data to enable a more robust categorization.

  14. Experimental determination and thermodynamic modeling of the Ni-Re binary system

    SciTech Connect (OSTI)

    Yaqoob, Khurram; Joubert, Jean-Marc

    2012-12-15

    The phase diagram of the Ni-Re binary system has been partially reinvestigated by chemical, structural and thermal characterization of the arc melted alloys. The experimental results obtained during the present investigation were combined with the literature data and a new phase diagram of the Ni-Re binary system is proposed. In comparison with the Ni-Re phase diagram proposed by Nash et al. in 1985 [1], significant differences in the homogeneity domains, freezing ranges and peritectic reaction temperature were evidenced. On the other hand, thermodynamic modeling of the studied system by using the new experimental information has also been carried out with the help of the CALPHAD method. The calculated Ni-Re phase diagram showed a good agreement with the selected experimental information. - Graphical abstract: Ni-Re phase diagram according to the present study. Highlights: Black-Right-Pointing-Pointer Re-investigation of the Ni-Re phase diagram. Black-Right-Pointing-Pointer Extended phase field of the hcp phase. Black-Right-Pointing-Pointer Different freezing ranges and peritectic reaction temperature. Black-Right-Pointing-Pointer Thermodynamic modeling of the studied system by using the CALPHAD method.

  15. Symmetric structure of field algebra of G-spin models determined by a normal subgroup

    SciTech Connect (OSTI)

    Xin, Qiaoling Jiang, Lining

    2014-09-15

    Let G be a finite group and H a normal subgroup. D(H; G) is the crossed product of C(H) and CG which is only a subalgebra of D(G), the double algebra of G. One can construct a C*-subalgebra F{sub H} of the field algebra F of G-spin models, so that F{sub H} is a D(H; G)-module algebra, whereas F is not. Then the observable algebra A{sub (H,G)} is obtained as the D(H; G)-invariant subalgebra of F{sub H}, and there exists a unique C*-representation of D(H; G) such that D(H; G) and A{sub (H,G)} are commutants with each other.

  16. RECONCILING MODELS OF LUMINOUS BLAZARS WITH MAGNETIC FLUXES DETERMINED BY RADIO CORE-SHIFT MEASUREMENTS

    SciTech Connect (OSTI)

    Nalewajko, Krzysztof; Begelman, Mitchell C.; Sikora, Marek

    2014-11-20

    Estimates of magnetic field strength in relativistic jets of active galactic nuclei, obtained by measuring the frequency-dependent radio core location, imply that the total magnetic fluxes in those jets are consistent with the predictions of the magnetically arrested disk (MAD) scenario of jet formation. On the other hand, the magnetic field strength determines the luminosity of the synchrotron radiation, which forms the low-energy bump of the observed blazar spectral energy distribution (SED). The SEDs of the most powerful blazars are strongly dominated by the high-energy bump, which is most likely due to the external radiation Compton mechanism. This high Compton dominance may be difficult to reconcile with the MAD scenario, unless (1) the geometry of external radiation sources (broad-line region, hot-dust torus) is quasi-spherical rather than flat, or (2) most gamma-ray radiation is produced in jet regions of low magnetization, e.g., in magnetic reconnection layers or in fast jet spines.

  17. Radiological Modeling for Determination of Derived Concentration Levels of an Area with Uranium Residual Material - 13533

    SciTech Connect (OSTI)

    Perez-Sanchez, Danyl [CIEMAT, Avenida Complutense 40, 28040, Madrid (Spain)] [CIEMAT, Avenida Complutense 40, 28040, Madrid (Spain)

    2013-07-01

    As a result of a pilot project developed at the old Spanish 'Junta de Energia Nuclear' to extract uranium from ores, tailings materials were generated. Most of these residual materials were sent back to different uranium mines, but a small amount of it was mixed with conventional building materials and deposited near the old plant until the surrounding ground was flattened. The affected land is included in an area under institutional control and used as recreational area. At the time of processing, uranium isotopes were separated but other radionuclides of the uranium decay series as Th-230, Ra-226 and daughters remain in the residue. Recently, the analyses of samples taken at different ground's depths confirmed their presence. This paper presents the methodology used to calculate the derived concentration level to ensure that the reference dose level of 0.1 mSv y-1 used as radiological criteria. In this study, a radiological impact assessment was performed modeling the area as recreational scenario. The modelization study was carried out with the code RESRAD considering as exposure pathways, external irradiation, inadvertent ingestion of soil, inhalation of resuspended particles, and inhalation of radon (Rn-222). As result was concluded that, if the concentration of Ra-226 in the first 15 cm of soil is lower than, 0.34 Bq g{sup -1}, the dose would not exceed the reference dose. Applying this value as a derived concentration level and comparing with the results of measurements on the ground, some areas with a concentration of activity slightly higher than latter were found. In these zones the remediation proposal has been to cover with a layer of 15 cm of clean material. This action represents a reduction of 85% of the dose and ensures compliance with the reference dose. (authors)

  18. REDSHIFT DETERMINATION AND CO LINE EXCITATION MODELING FOR THE MULTIPLY LENSED GALAXY HLSW-01

    SciTech Connect (OSTI)

    Scott, K. S.; Lupu, R. E.; Aguirre, J. E.; Auld, R.; Eales, S.; Aussel, H.; Chanial, P.; Beelen, A.; Bock, J.; Bradford, C. M.; Carpenter, J. M.; Cooray, A.; Dowell, C. D.; Brisbin, D.; Burgarella, D.; Chapman, S. C.; Clements, D. L.; Conley, A.; Cox, P.

    2011-05-20

    We report on the redshift measurement and CO line excitation of HERMES J105751.1+573027 (HLSW-01), a strongly lensed submillimeter galaxy discovered in Herschel/SPIRE observations as part of the Herschel Multi-tiered Extragalactic Survey (HerMES). HLSW-01 is an ultra-luminous galaxy with an intrinsic far-infrared luminosity of L{sub FIR} = 1.4 x 10{sup 13} L{sub sun}, and is lensed by a massive group of galaxies into at least four images with a total magnification of {mu} = 10.9 {+-} 0.7. With the 100 GHz instantaneous bandwidth of the Z-Spec instrument on the Caltech Submillimeter Observatory, we robustly identify a redshift of z = 2.958 {+-} 0.007 for this source, using the simultaneous detection of four CO emission lines (J = 7 {yields} 6, J = 8 {yields} 7, J = 9 {yields} 8, and J = 10 {yields} 9). Combining the measured line fluxes for these high-J transitions with the J = 1 {yields} 0, J = 3 {yields} 2, and J = 5 {yields} 4 line fluxes measured with the Green Bank Telescope, the Combined Array for Research in Millimeter Astronomy, and the Plateau de Bure Interferometer, respectively, we model the physical properties of the molecular gas in this galaxy. We find that the full CO spectral line energy distribution is described well by warm, moderate-density gas with T{sub kin} = 86-235 K and n{sub H{sub 2}} = (1.1-3.5) x 10{sup 3} cm{sup -3}. However, it is possible that the highest-J transitions are tracing a small fraction of very dense gas in molecular cloud cores, and two-component models that include a warm/dense molecular gas phase with T{sub kin} {approx} 200 K, n{sub H{sub 2}}{approx}10{sup 5} cm{sup -3} are also consistent with these data. Higher signal-to-noise measurements of the J{sub up} {>=} 7 transitions with high spectral resolution, combined with high spatial resolution CO maps, are needed to improve our understanding of the gas excitation, morphology, and dynamics of this interesting high-redshift galaxy.

  19. Assessing the use of reflectance spectroscopy in determining CsCl stress in the model species Arabidopsis thaliana

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Martinez, N. E.; Sharp, J. L.; Kuhne, W. W.; Johnson, T. E.; Stafford, C. T.; Duff, M. C.

    2015-11-23

    Here, reflectance spectroscopy is a rapid and non-destructive analytical technique that may be used for assessing plant stress, and has potential applications for use in remediation. Changes in reflectance such as that due to metal stress may occur before damage is visible, and existing studies have shown that metal stress does cause changes in plant reflectance. To further investigate the potential use of reflectance spectroscopy as a method for assessing metal stress in plants, an exploratory study was conducted in which Arabidopsis thaliana plants were treated twice weekly in a laboratory setting with varying levels (0, 0.5, or 5 mMmore » (millimolar)) of caesium chloride (CsCl) solution, and reflectance spectra were collected every week for three weeks using an Analytical Spectral Devices FieldSpec Pro spectroradiometer with both a contact probe (CP) and a field of view (FOV) probe at 36.8 and 66.7 cm, respectively, above the plant. Plants were harvested each week after spectra collection for determination of relative water content and chlorophyll content. A visual assessment of the plants was also conducted using point observations on a uniform grid of 81 points. A mixed-effects model analysis was conducted for each vegetation index (VI) considered to determine the effects of length of treatment, treatment level, view with which spectra were acquired, and the interactions of these terms. Two-way analyses of variance (ANOVAs) were performed on the aforementioned endpoints (e.g. chlorophyll content) to determine the significance of the effects of treatment level and length of treatment. Multiple linear regression (MLR) was used to develop a predictive model for each endpoint, considering VI acquired at each view (CP, high FOV, and low FOV). Of the 14 VI considered, 8 were included in the MLR models. Contact probe readings and FOV readings differed significantly, but FOV measurements were generally consistent at each height.« less

  20. Quantitative Determination of the Hubbard Model Phase Diagram from Optical Lattice Experiments by Two-Parameter Scaling

    SciTech Connect (OSTI)

    Campo, V. L. Jr.; Capelle, K.; Quintanilla, J.; Hooley, C.

    2007-12-14

    We propose an experiment to obtain the phase diagram of the fermionic Hubbard model, for any dimensionality, using cold atoms in optical lattices. It is based on measuring the total energy for a sequence of trap profiles. It combines finite-size scaling with an additional 'finite-curvature scaling' necessary to reach the homogeneous limit. We illustrate its viability in the 1D case, simulating experimental data in the Bethe-ansatz local-density approximation. Including experimental errors, the filling corresponding to the Mott transition can be determined with better than 3% accuracy.

  1. Molecular Simulation of Carbon Dioxide Brine and Clay Mineral...

    Office of Scientific and Technical Information (OSTI)

    of Carbon Dioxide Brine and Clay Mineral Interactions and Determination of Contact Angles. Citation Details In-Document Search Title: Molecular Simulation of Carbon Dioxide ...

  2. Determining Plutonium Mass in Spent Fuel with Nondestructive Assay Techniques -- Preliminary Modeling Results Emphasizing Integration among Techniques

    SciTech Connect (OSTI)

    Tobin, S. J.; Fensin, M. L.; Ludewigt, B. A.; Menlove, H. O.; Quiter, B. J.; Sandoval, N. P.; Swinhoe, M. T.; Thompson, S. J.

    2009-08-03

    There are a variety of motivations for quantifying Pu in spent (used) fuel assemblies by means of nondestructive assay (NDA) including the following: strengthen the capabilities of the International Atomic Energy Agencies to safeguards nuclear facilities, quantifying shipper/receiver difference, determining the input accountability value at reprocessing facilities and providing quantitative input to burnup credit determination for repositories. For the purpose of determining the Pu mass in spent fuel assemblies, twelve NDA techniques were identified that provide information about the composition of an assembly. A key point motivating the present research path is the realization that none of these techniques, in isolation, is capable of both (1) quantifying the elemental Pu mass of an assembly and (2) detecting the diversion of a significant number of pins. As such, the focus of this work is determining how to best integrate 2 or 3 techniques into a system that can quantify elemental Pu and to assess how well this system can detect material diversion. Furthermore, it is important economically to down-select among the various techniques before advancing to the experimental phase. In order to achieve this dual goal of integration and down-selection, a Monte Carlo library of PWR assemblies was created and is described in another paper at Global 2009 (Fensin et al.). The research presented here emphasizes integration among techniques. An overview of a five year research plan starting in 2009 is given. Preliminary modeling results for the Monte Carlo assembly library are presented for 3 NDA techniques: Delayed Neutrons, Differential Die-Away, and Nuclear Resonance Fluorescence. As part of the focus on integration, the concept of"Pu isotopic correlation" is discussed and the role of cooling time determination.

  3. Deactivation by carbon of iron catalysts for indirect liquefaction

    SciTech Connect (OSTI)

    Bartholomew, C.H.

    1991-01-10

    Although promoted cobalt and iron catalysts for Fischer-Tropsch (FT) synthesis of gasoline feedstock were first developed more than three decades ago, a major technical problem still limiting the commercial use of these catalysts today is carbon deactivation. This report describes recent progress in a fundamental, three-year investigation of carbon formation and its effects on the activity and selectivity of promoted iron catalysts for FT synthesis, the objectives of which are to: determine rates and mechanisms of carbon deactivation of unsupported Fe and Fe/K catalysts during CO hydrogenation over a range of CO concentrations, CO:H{sub 2} ratios, and temperatures; and model the rates of deactivation of the same catalysts in fixed-bed reactors. To accomplish the above objectives, the project is divided into the following tasks: (1) determine the kinetics of reaction and of carbon deactivation during CO hydrogenation on Fe and Fe/K catalysts coated on monolith bodies. (2) Determine the reactivities and types of carbon deposited during reaction on the same catalysts from temperature-programmed-surface-reaction spectroscopy (TPSR) and transmission electron microscopy (TEM). Determine the types of iron carbides formed at various temperatures and H{sub 2}/CO ratios using x-ray diffraction and Moessbauer spectroscopy. (3) Develop mathematical deactivation models which include heat and mass transport contributions for FT synthesis is packed-bed reactors. Progress to date is described. 48 refs., 3 figs., 1 tab.

  4. Determination of the effects caused by different polymers on coal fluidity during carbonization using high-temperature {sup 1}H NMR and rheometry

    SciTech Connect (OSTI)

    Miguel Castro Diaz; Lucky Edecki; Karen M. Steel; John W. Patrick; Colin E. Snape

    2008-01-15

    The effects of blending polyethylene (PE), polystyrene (PS), poly(ethyleneterephthalate) (PET), a flexible polyurethane (FPU), and a car shredded fluff waste (CSF) on fluidity development of a bituminous coal during carbonization have been studied by means of high-torque, small-amplitude controlled-strain rheometry and in situ high-temperature {sup 1}H NMR spectroscopy. The most detrimental effects were caused by PET and PS, which completely destroyed the fluidity of the coal. The CSF had a deleterious effect on coal fluidity similar to that of PET, although the deleterious effect on the viscoelastic properties of the coal were less pronounced than those of PET and PS. On the contrary, the addition of 10 wt % PE caused a slight reduction in the concentration of fluid hydrogen and an increase in the minimum complex viscosity, and the addition of 10 wt % FPU reduced the concentration of fluid hydrogen without changing the viscoelastic properties of the coal. Although these results suggest that these two plastics could potentially be used as additives in coking blends without compromising coke porosity, it was found that the semicoke strengths were reduced by adding 2 wt % FPU and 5 wt % PE. Therefore, it is unlikely that more than 2 wt % of a plastic waste could be added to a coal blend without deterioration in coke quality. 35 refs., 11 figs., 3 tabs.

  5. INTEGRATED GEOLOGIC-ENGINEERING MODEL FOR REEF AND CARBONATE SHOAL RESERVOIRS ASSOCIATED WITH PALEOHIGHS: UPPER JURASSIC SMACKOVER FORMATION, NORTHEASTERN GULF OF MEXICO

    SciTech Connect (OSTI)

    Ernest A. Mancini

    2003-09-25

    The University of Alabama in cooperation with Texas A&M University, McGill University, Longleaf Energy Group, Strago Petroleum Corporation, and Paramount Petroleum Company are undertaking an integrated, interdisciplinary geoscientific and engineering research project. The project is designed to characterize and model reservoir architecture, pore systems and rock-fluid interactions at the pore to field scale in Upper Jurassic Smackover reef and carbonate shoal reservoirs associated with varying degrees of relief on pre-Mesozoic basement paleohighs in the northeastern Gulf of Mexico. The project effort includes the prediction of fluid flow in carbonate reservoirs through reservoir simulation modeling that utilizes geologic reservoir characterization and modeling and the prediction of carbonate reservoir architecture, heterogeneity and quality through seismic imaging. The primary objective of the project is to increase the profitability, producibility and efficiency of recovery of oil from existing and undiscovered Upper Jurassic fields characterized by reef and carbonate shoals associated with pre-Mesozoic basement paleohighs. The principal research effort for Year 3 of the project has been reservoir characterization, 3-D modeling, testing of the geologic-engineering model, and technology transfer. This effort has included six tasks: (1) the study of seismic attributes, (2) petrophysical characterization, (3) data integration, (4) the building of the geologic-engineering model, (5) the testing of the geologic-engineering model and (6) technology transfer. This work was scheduled for completion in Year 3. Progress on the project is as follows: geoscientific reservoir characterization is completed. The architecture, porosity types and heterogeneity of the reef and shoal reservoirs at Appleton and Vocation Fields have been characterized using geological and geophysical data. The study of rock-fluid interactions has been completed. Observations regarding the diagenetic

  6. Carbon Capture and Storage, 2008

    SciTech Connect (OSTI)

    2009-03-19

    The U.S. Department of Energy is researching the safe implementation of a technology called carbon sequestration, also known as carbon capture and storage, or CCS. Based on an oilfield practice, this approach stores carbon dioxide, or CO2 generated from human activities for millennia as a means to mitigate global climate change. In 2003, the Department of Energys National Energy Technology Laboratory formed seven Regional Carbon Sequestration Partnerships to assess geologic formations suitable for storage and to determine the best approaches to implement carbon sequestration in each region. This video describes the work of these partnerships.

  7. Carbon Capture and Storage, 2008

    ScienceCinema (OSTI)

    None

    2010-01-08

    The U.S. Department of Energy is researching the safe implementation of a technology called carbon sequestration, also known as carbon capture and storage, or CCS. Based on an oilfield practice, this approach stores carbon dioxide, or CO2 generated from human activities for millennia as a means to mitigate global climate change. In 2003, the Department of Energys National Energy Technology Laboratory formed seven Regional Carbon Sequestration Partnerships to assess geologic formations suitable for storage and to determine the best approaches to implement carbon sequestration in each region. This video describes the work of these partnerships.

  8. Carbon Capture

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Carbon capture involves the separation of carbon dioxide (CO2) from coal-based power plant ... are not ready for implementation on coal-based power plants because they have not ...

  9. A Carbon Flux Super Site. New Insights and InnovativeAtmosphere...

    Office of Scientific and Technical Information (OSTI)

    A Carbon Flux Super Site. New Insights and Innovative Atmosphere-Terrestrial Carbon Exchange Measurements and Modeling Citation Details In-Document Search Title: A Carbon Flux ...

  10. Carbon Storage

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Storage Fact Sheet Research Team Members Key Contacts Carbon Storage Carbon capture and storage (CCS) is a key component of the U.S. carbon management portfolio. Numerous studies have shown that CCS can account for up to 55 percent of the emissions reductions needed to stabilize and ultimately reduce atmospheric concentrations of CO2. NETL's Carbon Storage Program is readying CCS technologies for widespread commercial deployment by 2020. The program's goals are: By 2015, develop technologies

  11. INTEGRATED GEOLOGIC-ENGINEERING MODEL FOR REEF AND CARBONATE SHOAL RESERVOIRS ASSOCIATED WITH PALEOHIGHS: UPPER JURASSIC SMACKOVER FORMATION, NORTHEASTERN GULF OF MEXICO

    SciTech Connect (OSTI)

    Ernest A. Mancini

    2004-02-25

    The University of Alabama, in cooperation with Texas A&M University, McGill University, Longleaf Energy Group, Strago Petroleum Corporation, and Paramount Petroleum Company, has undertaken an integrated, interdisciplinary geoscientific and engineering research project. The project is designed to characterize and model reservoir architecture, pore systems and rock-fluid interactions at the pore to field scale in Upper Jurassic Smackover reef and carbonate shoal reservoirs associated with varying degrees of relief on pre-Mesozoic basement paleohighs in the northeastern Gulf of Mexico. The project effort includes the prediction of fluid flow in carbonate reservoirs through reservoir simulation modeling which utilizes geologic reservoir characterization and modeling and the prediction of carbonate reservoir architecture, heterogeneity and quality through seismic imaging. The primary goal of the project is to increase the profitability, producibility and efficiency of recovery of oil from existing and undiscovered Upper Jurassic fields characterized by reef and carbonate shoals associated with pre-Mesozoic basement paleohighs. Geoscientific reservoir property, geophysical seismic attribute, petrophysical property, and engineering property characterization has shown that reef (thrombolite) and shoal reservoir lithofacies developed on the flanks of high-relief crystalline basement paleohighs (Vocation Field example) and on the crest and flanks of low-relief crystalline basement paleohighs (Appleton Field example). The reef thrombolite lithofacies have higher reservoir quality than the shoal lithofacies due to overall higher permeabilities and greater interconnectivity. Thrombolite dolostone flow units, which are dominated by dolomite intercrystalline and vuggy pores, are characterized by a pore system comprised of a higher percentage of large-sized pores and larger pore throats. Rock-fluid interactions (diagenesis) studies have shown that although the primary control on

  12. Yucca Mountain Area Saturated Zone Dissolved Organic Carbon Isotopic Data

    SciTech Connect (OSTI)

    Thomas, James; Decker, David; Patterson, Gary; Peterman, Zell; Mihevc, Todd; Larsen, Jessica; Hershey, Ronald

    2007-06-25

    Groundwater samples in the Yucca Mountain area were collected for chemical and isotopic analyses and measurements of water temperature, pH, specific conductivity, and alkalinity were obtained at the well or spring at the time of sampling. For this project, groundwater samples were analyzed for major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC). The U.S. Geological Survey (USGS) performed all the fieldwork on this project including measurement of water chemistry field parameters and sample collection. The major ions dissolved in the groundwater, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) were analyzed by the USGS. All preparation and processing of samples for DOC carbon isotopic analyses and geochemical modeling were performed by the Desert Research Institute (DRI). Analysis of the DOC carbon dioxide gas produced at DRI to obtain carbon-13 and carbon-14 values was conducted at the University of Arizona Accelerator Facility (a NSHE Yucca Mountain project QA qualified contract facility). The major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of DIC were used in geochemical modeling (NETPATH) to determine groundwater sources, flow paths, mixing, and ages. The carbon isotopes of DOC were used to calculate groundwater ages that are independent of DIC model corrected carbon-14 ages. The DIC model corrected carbon-14 calculated ages were used to evaluate groundwater travel times for mixtures of water including water beneath Yucca Mountain. When possible, groundwater travel times were calculated for groundwater flow from beneath Yucca Mountain to down gradient sample sites. DOC carbon-14 groundwater ages were also calculated for groundwaters in the Yucca Mountain area. When possible, groundwater travel times were estimated for groundwater flow from beneath Yucca Mountain to down gradient groundwater sample sites using the DOC calculated

  13. Void morphology in polyethylene/carbon black composites

    SciTech Connect (OSTI)

    Marr, D.W.M.; Wartenberg, M.; Schwartz, K.B.

    1996-12-31

    A combination of small angle neutron scattering (SANS) and contrast matching techniques is used to determine the size and quantity of voids incorporated during fabrication of polyethylene/carbon black composites. The analysis used to extract void morphology from SANS data is based on the three-phase model of microcrack determination via small angle x-rayscattering (SAXS) developed by W.Wu{sup 12} and applied to particulate reinforced composites.

  14. Use of ARM observations and numerical models to determine radiative and latent heating profiles of mesoscale convective systems for general circulation models

    SciTech Connect (OSTI)

    Houze, Jr., Robert A.

    2013-11-13

    We examined cloud radar data in monsoon climates, using cloud radars at Darwin in the Australian monsoon, on a ship in the Bay of Bengal in the South Asian monsoon, and at Niamey in the West African monsoon. We followed on with a more in-depth study of the continental MCSs over West Africa. We investigated whether the West African anvil clouds connected with squall line MCSs passing over the Niamey ARM site could be simulated in a numerical model by comparing the observed anvil clouds to anvil structures generated by the Weather Research and Forecasting (WRF) mesoscale model at high resolution using six different ice-phase microphysical schemes. We carried out further simulations with a cloud-resolving model forced by sounding network budgets over the Niamey region and over the northern Australian region. We have devoted some of the effort of this project to examining how well satellite data can determine the global breadth of the anvil cloud measurements obtained at the ARM ground sites. We next considered whether satellite data could be objectively analyzed to so that their large global measurement sets can be systematically related to the ARM measurements. Further differences were detailed between the land and ocean MCS anvil clouds by examining the interior structure of the anvils with the satellite-detected the CloudSat Cloud Profiling Radar (CPR). The satellite survey of anvil clouds in the Indo-Pacific region was continued to determine the role of MCSs in producing the cloud pattern associated with the MJO.

  15. Determination of the effective diffusivity of water in a poly (methyl methacrylate) membrane containing carbon nanotubes using kinetic Monte Carlo simulations

    SciTech Connect (OSTI)

    Mermigkis, Panagiotis G.; Tsalikis, Dimitrios G.; Mavrantzas, Vlasis G.

    2015-10-28

    A kinetic Monte Carlo (kMC) simulation algorithm is developed for computing the effective diffusivity of water molecules in a poly(methyl methacrylate) (PMMA) matrix containing carbon nanotubes (CNTs) at several loadings. The simulations are conducted on a cubic lattice to the bonds of which rate constants are assigned governing the elementary jump events of water molecules from one lattice site to another. Lattice sites belonging to PMMA domains of the membrane are assigned different rates than lattice sites belonging to CNT domains. Values of these two rate constants are extracted from available numerical data for water diffusivity within a PMMA matrix and a CNT pre-computed on the basis of independent atomistic molecular dynamics simulations, which show that water diffusivity in CNTs is 3 orders of magnitude faster than in PMMA. Our discrete-space, continuum-time kMC simulation results for several PMMA-CNT nanocomposite membranes (characterized by different values of CNT length L and diameter D and by different loadings of the matrix in CNTs) demonstrate that the overall or effective diffusivity, D{sub eff}, of water in the entire polymeric membrane is of the same order of magnitude as its diffusivity in PMMA domains and increases only linearly with the concentration C (vol. %) in nanotubes. For a constant value of the concentration C, D{sub eff} is found to vary practically linearly also with the CNT aspect ratio L/D. The kMC data allow us to propose a simple bilinear expression for D{sub eff} as a function of C and L/D that can describe the numerical data for water mobility in the membrane extremely accurately. Additional simulations with two different CNT configurations (completely random versus aligned) show that CNT orientation in the polymeric matrix has only a minor effect on D{sub eff} (as long as CNTs do not fully penetrate the membrane). We have also extensively analyzed and quantified sublinear (anomalous) diffusive phenomena over small to moderate

  16. Precision Model Independent Determination of vertical bar V{sub ub} vertical bar from B{yields}{pi}l{nu}

    SciTech Connect (OSTI)

    Arnesen, Christian M.; Stewart, Iain W.; Grinstein, Benjamin; Rothstein, Ira Z.

    2005-08-12

    A precision method for determining vertical bar V{sub ub} vertical bar using the full range in q{sup 2} of B{yields}{pi}l{nu} data is presented. At large q{sup 2} the form factor is taken from unquenched lattice QCD, at q{sup 2}=0 we impose a model independent constraint obtained from B{yields}{pi}{pi} using the soft-collinear effective theory, and the shape is constrained using QCD dispersion relations. We find vertical bar V{sub ub} vertical bar=(3.54{+-}0.17{+-}0.44)x10{sup -3}. With 5% experimental error and 12% theory error, this is competitive with inclusive methods. Theory error is dominated by the input points, with negligible uncertainty from the dispersion relations.

  17. WTP Calculation Sheet: Determining the LAW Glass Former Constituents and Amounts for G2 and Acm Models. 24590-LAW-M4C-LFP-00002, Rev. B

    SciTech Connect (OSTI)

    Gimpel, Rodney F.; Kruger, Albert A.

    2013-12-16

    The purpose of this calculation is to determine the LAW glass former recipe and additives with their respective amounts. The methodology and equations contained herein are to be used in the G2 and ACM models until better information is supplied by R&T efforts. This revision includes calculations that determines the mass and volume of the bulk chemicals/minerals needed per batch. Plus, it contains calculations (for the G2 model) to help prevent overflow in LAW Feed Preparation Vessel.

  18. Determining Columbia and Snake River Project Tailrace and Forebay Zones of Hydraulic Influence using MASS2 Modeling

    SciTech Connect (OSTI)

    Rakowski, Cynthia L.; Serkowski, John A.; Richmond, Marshall C.; Perkins, William A.

    2010-12-01

    Although fisheries biology studies are frequently performed at US Army Corps of Engineers (USACE) projects along the Columbia and Snake Rivers, there is currently no consistent definition of the ``forebay'' and ``tailrace'' regions for these studies. At this time, each study may use somewhat arbitrary lines (e.g., the Boat Restriction Zone) to define the upstream and downstream limits of the study, which may be significantly different at each project. Fisheries researchers are interested in establishing a consistent definition of project forebay and tailrace regions for the hydroelectric projects on the lower Columbia and Snake rivers. The Hydraulic Extent of a project was defined by USACE (Brad Eppard, USACE-CENWP) as follows: The river reach directly upstream (forebay) and downstream (tailrace) of a project that is influenced by the normal range of dam operations. Outside this reach, for a particular river discharge, changes in dam operations cannot be detected by hydraulic measurement. The purpose of this study was to, in consultation with USACE and regional representatives, develop and apply a consistent set of criteria for determining the hydraulic extent of each of the projects in the lower Columbia and Snake rivers. A 2D depth-averaged river model, MASS2, was applied to the Snake and Columbia Rivers. New computational meshes were developed most reaches and the underlying bathymetric data updated to the most current survey data. The computational meshes resolved each spillway bay and turbine unit at each project and extended from project to project. MASS2 was run for a range of total river flows and each flow for a range of project operations at each project. The modeled flow was analyzed to determine the range of velocity magnitude differences and the range of flow direction differences at each location in the computational mesh for each total river flow. Maps of the differences in flow direction and velocity magnitude were created. USACE fishery biologists

  19. Evaluation of Preindustrial to Present-day Black Carbon and its Albedo Forcing from Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    SciTech Connect (OSTI)

    Lee, Y. H.; Lamarque, J.-F.; Flanner, M. G.; Jiao, C.; Shindell, Drew; Berntsen, T.; Bisiauxs, M.; Cao, J.; Collins, W. J.; Curran, M.; Edwards, R.; Faluvegi, G.; Ghan, Steven J.; Horowitz, L.; McConnell, J.R.; Ming, J.; Myhre, G.; Nagashima, T.; Naik, Vaishali; Rumbold, S.; Skeie, R. B.; Sudo, K.; Takemura, T.; Thevenon, F.; Xu, B.; Yoon, Jin-Ho

    2013-03-05

    As a part of the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), we evaluate the historical black carbon (BC) aerosols simulated by 8 ACCMIP models against the observations including 12 ice core records, a long-term surface mass concentrations and recent Arctic BC snowpack measurements. We also estimate BC albedo forcing by performing additional simulations using the NCAR Community Land and Sea-Ice model 4 with prescribed meteorology from 1996-2000, which includes the SNICAR BC-snow model. We evaluated the vertical profile of BC snow concentrations from these offline simulations to using recent BC snowpack measurements. Despite using the same BC emissions, global BC burden differs by approximately a factor of 3 among models due to the differences in aerosol removal parameterizations and simulated meteorology among models; 34 Gg to 103 Gg in 1850 and 82 Gg to 315 Gg in 2000. However,models agree well on 2.5~3 times increase in the global BC burden from preindustrial to present-day, which matches with the 2.5 times increase in BC emissions. We find a large model diversity at both NH and SH high latitude regions for BC burden and at SH high latitude regions for deposition fluxes. The ACCMIP simulations match the observed BC mass concentrations well in Europe and North America except at Jungfrauch and Ispra. However, the models fail to capture the Arctic BC seasonality due tosevere underestimations during winter and spring. Compared to recent snowpack measurements, the simulated vertically resolved BC snow concentrations are, on average, within a factor of 2-3 of observations except for Greenland and Arctic Ocean. However, model and observation differ widely due to missing interannual variations in emissions and possibly due to the choice of the prescribed meteorology period (i.e., 1996-2000).

  20. LANL Deliverable to the Big Sky Carbon Sequestration Partnership...

    Office of Scientific and Technical Information (OSTI)

    to the Big Sky Carbon Sequestration Partnership: Preliminary CO2-PENS model Citation Details In-Document Search Title: LANL Deliverable to the Big Sky Carbon Sequestration ...

  1. Scenarios for Deep Carbon Emission Reductions from Electricity by 2050 in Western North America using the Switch Electric Power Sector Planning Model: California's Carbon Challenge Phase II, Volume II

    SciTech Connect (OSTI)

    Nelson, James; Mileva, Ana; Johnston, Josiah; Kammen, Daniel; Wei, Max; Greenblatt, Jeffrey

    2014-01-01

    This study used a state-of-the-art planning model called SWITCH for the electric power system to investigate the evolution of the power systems of California and western North America from present-day to 2050 in the context of deep decarbonization of the economy. Researchers concluded that drastic power system carbon emission reductions were feasible by 2050 under a wide range of possible futures. The average cost of power in 2050 would range between $149 to $232 per megawatt hour across scenarios, a 21 to 88 percent increase relative to a business-as-usual scenario, and a 38 to 115 percent increase relative to the present-day cost of power. The power system would need to undergo sweeping change to rapidly decarbonize. Between present-day and 2030 the evolution of the Western Electricity Coordinating Council power system was dominated by implementing aggressive energy efficiency measures, installing renewable energy and gas-fired generation facilities and retiring coal-fired generation. Deploying wind, solar and geothermal power in the 2040 timeframe reduced power system emissions by displacing gas-fired generation. This trend continued for wind and solar in the 2050 timeframe but was accompanied by large amounts of new storage and long-distance high-voltage transmission capacity. Electricity storage was used primarily to move solar energy from the daytime into the night to charge electric vehicles and meet demand from electrified heating. Transmission capacity over the California border increased by 40 - 220 percent by 2050, implying that transmission siting, permitting, and regional cooperation will become increasingly important. California remained a net electricity importer in all scenarios investigated. Wind and solar power were key elements in power system decarbonization in 2050 if no new nuclear capacity was built. The amount of installed gas capacity remained relatively constant between present-day and 2050, although carbon capture and sequestration was

  2. Thermodynamic assessment of microencapsulated sodium carbonate slurry for carbon capture

    SciTech Connect (OSTI)

    Stolaroff, Joshuah K.; Bourcier, William L.

    2014-01-01

    Micro-encapsulated Carbon Sorbents (MECS) are a new class of carbon capture materials consisting of a CO?- absorbing liquid solvent contained within solid, CO?-permeable, polymer shells. MECS enhance the rate of CO? absorption for solvents with slow kinetics and prevent solid precipitates from scaling and fouling equipment, two factors that have previously limited the use of sodium carbonate solution for carbon capture. Here, we examine the thermodynamics of sodium carbonate slurries for carbon capture. We model the vapour-liquid-solid equilibria of sodium carbonate and find several features that can contribute to an energy-efficient capture process: very high CO? pressures in stripping conditions, relatively low water vapour pressures in stripping conditions, and good swing capacity. The potential energy savings compared with an MEA system are discussed.

  3. Thermodynamic assessment of microencapsulated sodium carbonate slurry for carbon capture

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Stolaroff, Joshuah K.; Bourcier, William L.

    2014-01-01

    Micro-encapsulated Carbon Sorbents (MECS) are a new class of carbon capture materials consisting of a CO₂- absorbing liquid solvent contained within solid, CO₂-permeable, polymer shells. MECS enhance the rate of CO₂ absorption for solvents with slow kinetics and prevent solid precipitates from scaling and fouling equipment, two factors that have previously limited the use of sodium carbonate solution for carbon capture. Here, we examine the thermodynamics of sodium carbonate slurries for carbon capture. We model the vapour-liquid-solid equilibria of sodium carbonate and find several features that can contribute to an energy-efficient capture process: very high CO₂ pressures in stripping conditions,more » relatively low water vapour pressures in stripping conditions, and good swing capacity. The potential energy savings compared with an MEA system are discussed.« less

  4. Global patterns and controls of soil organic carbon dynamics as simulated by multiple terrestrial biosphere models. Current status and future directions

    SciTech Connect (OSTI)

    Tian, Hanqin; Lu, Chaoqun; Yang, Jia; Banger, Kamaljit; Huntzinger, Deborah N.; Schwalm, Christopher R.; Michalak, A. M.; Cook, Robert B.; Ciais, Philippe; Hayes, Daniel J.; Huang, Maoyi; Ito, Akihiko; Jain, Atul K.; Lei, Huimin; Mao, Jiafu; Pan, Shufen; Post, W. M.; Peng, Shushi; Poulter, Benjamin; Ren, Wei; Ricciuto, Daniel M.; Schaefer, Kevin; Shi, Xiaoying; Tao, Bo; Wang, Weile; Wei, Yaxing; Yang, Qichun; Zhang, Bowen; Zeng, Ning

    2015-06-05

    Soil is the largest organic carbon (C) pool of terrestrial ecosystems, and loss from soil accounts for a large pro portion of land-atmosphere C exchange. Due to large pool size and variable residence time from years to millennia, even small changes in soil organic C(SOC) have substantial effects on the terrestrial C budget, thereby affecting atmospheric carbon dioxide (CO2)concentration and climate change. In the past decades, a wide variety of studies have been conducted to quantify global SOC stocks and soil exchange with the atmosphere through site measurements, inventories, and empirical/process-based modeling. However, these estimates are highly uncertain and identifying major driving forces controlling soil C storage and fluxes remains a key research challenge his study has compiled century-long (1901-2010)estimates of SOC storage and heterotrophic respiration (Rh) from ten terrestrial biosphere models (TBMs) in the Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP) and two observation based datasets. The ten-TBM ensemble shows that global SOC estimate range from 4 to 2111 Pg C (1 Pg = 1015g) with a median value of 1158 Pg C33 in 2010. Modeling approach estimates a broad range of Rh from 35 to 69 Pg C yr-1 with a median value of 51Pg C yr-1 during 200–2010. The largest uncertainty in SOC stocks exists in the 40–65°N latitude band while Rh differences are the largest in the tropics. All the models agreed that climate and land use changes have decreased SOC stocks while elevated CO2 and atmospheric nitrogen deposition have increased SOC stocks though the response varied significantly among models. Model representations of temperature and moisture sensitivity,nutrient limitation and land use partially explain the divergent estimates of global SOC stocks and soil fluxes in this study. In addition, major sources of uncertainty from model estimation include exclusion of SOC storage in

  5. Carbyne fiber synthesis within evaporating metallic liquid carbon

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Cannella, Christopher B.; Goldman, Nir

    2015-07-09

    Carbyne (e.g., linear chains of sp-bonded carbon) has been the subject of intense research focus due to its presence in astrophysical bodies, as well as its potential for use as a nanoelectronic device and superhard material. In this work, we discuss the formation of carbyne fiber bundles over a nanosecond time scale in laser pulse melting studies, using a previously determined density functional tight binding model for carbon coupled with a new correction for the dispersion energy. We determine our dispersion energy model by optimizing a modified Lennard-Jones potential to an experimentally determined equation of state for graphite, yielding excellentmore » results for the bulk modulus and density under ambient conditions. We then simulate previous experiments by heating graphite to high temperature, followed by expanding the ensuing liquid phase to low density. Our results indicate that the initial, hot liquid phase mainly consists of sp2-bonded carbon atoms, which form a system of sp-bonded strands bound together via dispersion interactions upon achieving low density and temperature. Lastly, the high computational efficiency of our approach allows for direct comparison with experiments that span a wide range of thermodynamic conditions and can help determine parameters for synthesis of carbon-based materials with potentially exotic properties.« less

  6. Carbon-enhanced metal-poor stars in SDSS/Segue. II. Comparison of CEMP-star frequencies with binary population-synthesis models

    SciTech Connect (OSTI)

    Lee, Young Sun; Suda, Takuma; Beers, Timothy C.; Stancliffe, Richard J.

    2014-06-20

    We present a comparison of the frequencies of carbon-enhanced metal-poor (CEMP) giant and main-sequence turnoff (MSTO) stars with predictions from binary population-synthesis models involving asymptotic giant-branch (AGB) mass transfer. The giant and MSTO stars are selected from the Sloan Digital Sky Survey and the Sloan Extension for Galactic Understanding and Exploration. We consider two initial mass functions (IMFs)a Salpeter IMF, and a mass function with a characteristic mass of 10 M {sub ?}. For giant stars, the comparison indicates a good agreement between the observed CEMP frequencies and the AGB binary model using a Salpeter IMF for [Fe/H] > 1.5, and a characteristic mass of 10 M {sub ?} for [Fe/H] < 2.5. This result suggests that the IMF shifted from high- to low-mass dominated in the early history of the Milky Way, which appears to have occurred at a 'chemical time' between [Fe/H] =2.5 and [Fe/H] =1.5. The CEMP frequency for the turnoff stars with [Fe/H] < 3.0 is much higher than the AGB model prediction from the high-mass IMF, supporting the previous assertion that one or more additional mechanisms, not associated with AGB stars, are required for the production of carbon-rich material below [Fe/H] =3.0. We also discuss possible effects of first dredge-up and extra mixing in red giants and internal mixing in turnoff stars on the derived CEMP frequencies.

  7. Monte Carlo determination of the low-energy constants of a spin-(1/2) Heisenberg model with spatial anisotropy

    SciTech Connect (OSTI)

    Jiang, F.-J.; Nyfeler, M.; Kaempfer, F.

    2009-07-15

    Motivated by the possible mechanism for the pinning of the electronic liquid crystal direction in YBa{sub 2}Cu{sub 3}O{sub 6.45} as proposed by Pardini et al. [Phys. Rev. B 78, 024439 (2008)], we use the first-principles Monte Carlo method to study the spin-(1/2) Heisenberg model with antiferromagnetic couplings J{sub 1} and J{sub 2} on the square lattice. In particular, the low-energy constants spin stiffness {rho}{sub s}, staggered magnetization M{sub s}, and spin wave velocity c are determined by fitting the Monte Carlo data to the predictions of magnon chiral perturbation theory. Further, the spin stiffnesses {rho}{sub s1} and {rho}{sub s2} as a function of the ratio J{sub 2}/J{sub 1} of the couplings are investigated in detail. Although we find a good agreement between our results with those obtained by the series expansion method in the weakly anisotropic regime, for strong anisotropy we observe discrepancies.

  8. The CPA Equation of State and an Activity Coefficient Model for Accurate Molar Enthalpy Calculations of Mixtures with Carbon Dioxide and Water/Brine

    SciTech Connect (OSTI)

    Myint, P. C.; Hao, Y.; Firoozabadi, A.

    2015-03-27

    Thermodynamic property calculations of mixtures containing carbon dioxide (CO2) and water, including brines, are essential in theoretical models of many natural and industrial processes. The properties of greatest practical interest are density, solubility, and enthalpy. Many models for density and solubility calculations have been presented in the literature, but there exists only one study, by Spycher and Pruess, that has compared theoretical molar enthalpy predictions with experimental data [1]. In this report, we recommend two different models for enthalpy calculations: the CPA equation of state by Li and Firoozabadi [2], and the CO2 activity coefficient model by Duan and Sun [3]. We show that the CPA equation of state, which has been demonstrated to provide good agreement with density and solubility data, also accurately calculates molar enthalpies of pure CO2, pure water, and both CO2-rich and aqueous (H2O-rich) mixtures of the two species. It is applicable to a wider range of conditions than the Spycher and Pruess model. In aqueous sodium chloride (NaCl) mixtures, we show that Duan and Suns model yields accurate results for the partial molar enthalpy of CO2. It can be combined with another model for the brine enthalpy to calculate the molar enthalpy of H2O-CO2-NaCl mixtures. We conclude by explaining how the CPA equation of state may be modified to further improve agreement with experiments. This generalized CPA is the basis of our future work on this topic.

  9. Predictive model for the determination of the economic feasibility of construction and demolition waste recycling in the Air Force. Master's thesis

    SciTech Connect (OSTI)

    Dixon, B.L.

    1993-09-01

    This study created a model to be used at a CONUS Air Force base to determine the economic feasibility of Construction and Demolition (CD) waste recycling. Three areas investigated to develop this model: the methods to determine amounts and types of CD waste generated at a specific location, the markets for recycled CD wastes, and the recycling methods currently available. From this data, gathered through records searches and interviews, a procedure was developed to perform cost/benefit analyses on the available recycling options. A model was then created based on these calculations which can arm a manager with information to either support or reject a recycling program by indicating cost savings or losses from recycling CD waste. Also, the model aids managers in determining the approximate quantities of recyclable materials being generated, which could be valuable in reaching base recycling goals. To demonstrate the model, the feasibility of recycling CD waste at Hill AFB, Utah in 1994 was evaluated. In addition to determining recycling feasibility, a method was presented to perform sensitivity analyses on the base-specific input variables. This procedure can help determine when it will become feasible to create a CD waste recycling program.

  10. Nondestructive determination of plutonium mass in spent fuel: prelliminary modeling results using the passive neutron Albedo reactivity technique

    SciTech Connect (OSTI)

    Evans, Louise G; Tobin, Stephen J; Schear, Melissa A; Menlove, Howard O; Lee, Sang Y; Swinhoe, Martyn T

    2009-01-01

    There are a variety of motivations for quantifying plutonium (Pu) in spent fuel assemblies by means of nondestructive assay (NDA) including the following: strengthening the capability of the International Atomic Energy Agency (LAEA) to safeguard nuclear facilities, quantifying shipper/receiver difference, determining the input accountability value at pyrochemical processing facilities, providing quantitative input to burnup credit and final safeguards measurements at a long-term repository. In order to determine Pu mass in spent fuel assemblies, thirteen NDA techniques were identified that provide information about the composition of an assembly. A key motivation of the present research is the realization that none of these techniques, in isolation, is capable of both (1) quantifying the Pu mass of an assembly and (2) detecting the diversion of a significant number of rods. It is therefore anticipated that a combination of techniques will be required. A 5 year effort funded by the Next Generation Safeguards Initiative (NGSI) of the U.S. DOE was recently started in pursuit of these goals. The first two years involves researching all thirteen techniques using Monte Carlo modeling while the final three years involves fabricating hardware and measuring spent fuel. Here, we present the work in two main parts: (1) an overview of this NGSI effort describing the motivations and approach being taken; (2) The preliminary results for one of the NDA techniques - Passive Neutron Albedo Reactivity (PNAR). The PNAR technique functions by using the intrinsic neutron emission of the fuel (primarily from the spontaneous fission of curium) to self-interrogate any fissile material present. Two separate measurements of the spent fuel are made, both with and without cadmium (Cd) present. The ratios of the Singles, Doubles and Triples count rates obtained in each case are analyzed; known as the Cd ratio. The primary differences between the two measurements are the neutron energy spectrum

  11. Source Term Modeling for Evaluating the Potential Impacts to Groundwater of Fluids Escaping from a Depleted Oil Reservoir Used for Carbon Sequestration

    SciTech Connect (OSTI)

    Cantrell, Kirk J.; Brown, Christopher F.

    2014-06-13

    In recent years depleted oil reservoirs have received special interest as carbon storage reservoirs because of their potential to offset costs through collaboration with enhanced oil recovery projects. Modeling is currently being conducted to evaluate potential risks to groundwater associated with leakage of fluids from depleted oil reservoirs used for storage of CO2. Modeling results reported here focused on understanding how toxic organic compounds found in oil will distribute between the various phases within a storage reservoir after introduction of CO2, understanding the migration potential of these compounds, and assessing potential groundwater impacts should leakage occur. Two model scenarios were conducted to evaluate how organic components in oil will distribute among the phases of interest (oil, CO2, and brine). The first case consisted of 50 wt.% oil and 50 wt.% water; the second case was 90 wt.% CO2 and 10 wt.% oil. Several key organic compounds were selected for special attention in this study based upon their occurrence in oil at significant concentrations, relative toxicity, or because they can serve as surrogate compounds for other more highly toxic compounds for which required input data are not available. The organic contaminants of interest (COI) selected for this study were benzene, toluene, naphthalene, phenanthrene, and anthracene. Partitioning of organic compounds between crude oil and supercritical CO2 was modeled using the Peng-Robinson equation of state over temperature and pressure conditions that represent the entire subsurface system (from those relevant to deep geologic carbon storage environments to near surface conditions). Results indicate that for a typical set of oil reservoir conditions (75°C, and 21,520 kPa) negligible amounts of the COI dissolve into the aqueous phase. When CO2 is introduced into the reservoir such that the final composition of the reservoir is 90 wt.% CO2 and 10 wt.% oil, a significant fraction of the oil

  12. Factors affecting the retention of methyl iodide by iodide-impregnated carbon

    SciTech Connect (OSTI)

    Hyder, M.L.; Malstrom, R.A.

    1990-12-31

    Iodide-impregnated activated carbon that had been in use for up to 30 months was studied to characterize those factors that affect its interaction with and retention of methyl iodide. Humidity and competing organic sorbents were observed to decrease the residence time of the methyl iodide on the carbon bed. Additionally, changes in the effective surface area and the loss of iodide from the surface are both important in determining the effectiveness of the carbon for retaining radioactive iodine from methyl iodide. A simple model incorporating both factors gave a fairly good fit to the experimental data.

  13. Factors affecting the retention of methyl iodide by iodide-impregnated carbon

    SciTech Connect (OSTI)

    Hyder, M.L.; Malstrom, R.A.

    1990-01-01

    Iodide-impregnated activated carbon that had been in use for up to 30 months was studied to characterize those factors that affect its interaction with and retention of methyl iodide. Humidity and competing organic sorbents were observed to decrease the residence time of the methyl iodide on the carbon bed. Additionally, changes in the effective surface area and the loss of iodide from the surface are both important in determining the effectiveness of the carbon for retaining radioactive iodine from methyl iodide. A simple model incorporating both factors gave a fairly good fit to the experimental data.

  14. Building A Simulation Model For The Prediction Of Temperature Distribution In Pulsed Laser Spot Welding Of Dissimilar Low Carbon Steel 1020 To Aluminum Alloy 6061

    SciTech Connect (OSTI)

    Yousef, Adel K. M.; Taha, Ziad A.; Shehab, Abeer A.

    2011-01-17

    This paper describes the development of a computer model used to analyze the heat flow during pulsed Nd: YAG laser spot welding of dissimilar metal; low carbon steel (1020) to aluminum alloy (6061). The model is built using ANSYS FLUENT 3.6 software where almost all the environments simulated to be similar to the experimental environments. A simulation analysis was implemented based on conduction heat transfer out of the key hole where no melting occurs. The effect of laser power and pulse duration was studied.Three peak powers 1, 1.66 and 2.5 kW were varied during pulsed laser spot welding (keeping the energy constant), also the effect of two pulse durations 4 and 8 ms (with constant peak power), on the transient temperature distribution and weld pool dimension were predicated using the present simulation. It was found that the present simulation model can give an indication for choosing the suitable laser parameters (i.e. pulse durations, peak power and interaction time required) during pulsed laser spot welding of dissimilar metals.

  15. TECHNOLOGY IN AN INTEGRATED ASSESSMENT MODEL: THE POTENTIAL REGIONAL DEPLOYMENT OF CARBON CAPTURE AND STORAGE IN THE CONTEXT OF GLOBAL CO2 STABILIZATION

    SciTech Connect (OSTI)

    Edmonds, James A.; Dooley, James J.; Kim, Son H.; Friedman, S. Julio; Wise, Marshall A.

    2007-11-19

    Technology is a critically important determinant of the cost of meeting any environmental objective. In this paper we examine the role of a particular technology, carbon dioxide capture and storage (CCS), in the stabilization of the concentration of atmospheric carbon dioxide (CO2). While CCS is not presently deployed at scale, it has the potential to deploy extensively during the course of the 21st century if concentrations of atmospheric CO2 are to be stabilized. The existing research literature has focused largely on the cost of capturing CO2, with the implicit assumption that storage options would be relatively cheap, plentiful and located in close proximity to future CO2 point sources. However, CO2 capture and storage will take place at the local and regional scale and will compete with other mitigation options that also exhibit local or regional differences. This paper provides an initial examination of the implications of regionally disaggregated demand for and supply of CO2 storage reservoirs within the context of a globally disaggregated, long-term analysis of both the geology and economics of CCS. This analysis suggests that some regions will see their ability to deploy CCS systems constrained by a lack of quality target reservoirs relative to the demand for storage placed upon these candidate geologic storage reservoirs by large stationary CO2 point sources within the region. Other regions appear to have sufficient storage capacity to easily carry them into the 22nd century. We examined the regional and global economic implications of the distribution of these sources and sinks in meeting various potential limits to atmospheric CO2 concentrations. This analysis confirms that CCS is an important potential response to climate change throughout the 21st century and a technology that can play a key role in controlling the cost of addressing climate change.

  16. Carbon Fiber

    ScienceCinema (OSTI)

    McGetrick, Lee

    2014-07-23

    Lee McGetrick leads ORNL's effort to produce light, durable carbon fiber at lower cost -- a key to improvements in manufacturing that will produce more fuel-efficient vehicles and other advances.

  17. Carbon Fiber

    SciTech Connect (OSTI)

    McGetrick, Lee

    2014-04-17

    Lee McGetrick leads ORNL's effort to produce light, durable carbon fiber at lower cost -- a key to improvements in manufacturing that will produce more fuel-efficient vehicles and other advances.

  18. Carbon Sequestration

    SciTech Connect (OSTI)

    2013-05-06

    Carbon Sequestration- the process of capturing the CO2 released by the burning of fossil fuels and storing it deep withing the Earth, trapped by a non-porous layer of rock.

  19. Training and Research on Probabilistic Hydro-Thermo-Mechanical Modeling of Carbon Dioxide Geological Sequestration in Fractured Porous Rocks

    SciTech Connect (OSTI)

    Gutierrez, Marte

    2013-05-31

    Colorado School of Mines conducted research and training in the development and validation of an advanced CO{sub 2} GS (Geological Sequestration) probabilistic simulation and risk assessment model. CO{sub 2} GS simulation and risk assessment is used to develop advanced numerical simulation models of the subsurface to forecast CO2 behavior and transport; optimize site operational practices; ensure site safety; and refine site monitoring, verification, and accounting efforts. As simulation models are refined with new data, the uncertainty surrounding the identified risks decrease, thereby providing more accurate risk assessment. The models considered the full coupling of multiple physical processes (geomechanical and fluid flow) and describe the effects of stochastic hydro-mechanical (H-M) parameters on the modeling of CO{sub 2} flow and transport in fractured porous rocks. Graduate students were involved in the development and validation of the model that can be used to predict the fate, movement, and storage of CO{sub 2} in subsurface formations, and to evaluate the risk of potential leakage to the atmosphere and underground aquifers. The main major contributions from the project include the development of: 1) an improved procedure to rigorously couple the simulations of hydro-thermomechanical (H-M) processes involved in CO{sub 2} GS; 2) models for the hydro-mechanical behavior of fractured porous rocks with random fracture patterns; and 3) probabilistic methods to account for the effects of stochastic fluid flow and geomechanical properties on flow, transport, storage and leakage associated with CO{sub 2} GS. The research project provided the means to educate and train graduate students in the science and technology of CO{sub 2} GS, with a focus on geologic storage. Specifically, the training included the investigation of an advanced CO{sub 2} GS simulation and risk assessment model that can be used to predict the fate, movement, and storage of CO{sub 2} in

  20. Carbon Capture

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Capture Fact Sheet Key Contacts Carbon Capture Research & Development Carbon capture and storage from fossil-based power generation is a critical component of realistic strategies for arresting the rise in atmospheric CO2 concentrations, but capturing substantial amounts of CO2 using current technology would result in a prohibitive rise in the cost of producing energy. The National Energy Technology Laboratory Office of Research and Development (NETL-ORD), in collaboration with researchers

  1. COLLOQUIUM: The Fate of the Land Carbon Sink | Princeton Plasma...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Models of the global terrestrial biosphere in current Earth system models (climate models with coupled atmosphere, ocean and biosphere) uniformly predict a large current carbon ...

  2. CX-000373: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Measurements of 222 Radon, 220 Radon, and Carbon Dioxide Emissions in Natural Carbon Dioxide Fields in Wyoming: Monitoring, Verification, and Analysis Techniques for Determining Gas Transport and Caprock IntegrityCX(s) Applied: A1, A9, B3.6, B3.8Date: 11/20/2009Location(s): Laramie, WyomingOffice(s): Fossil Energy, National Energy Technology Laboratory

  3. X-ray absorption spectroscopy of LiBF 4 in propylene carbonate. A model lithium ion battery electrolyte

    SciTech Connect (OSTI)

    Smith, Jacob W.; Lam, Royce K.; Sheardy, Alex T.; Shih, Orion; Rizzuto, Anthony M.; Borodin, Oleg; Harris, Stephen J.; Prendergast, David; Saykally, Richard J.

    2014-08-20

    Since their introduction into the commercial marketplace in 1991, lithium ion batteries have become increasingly ubiquitous in portable technology. Nevertheless, improvements to existing battery technology are necessary to expand their utility for larger-scale applications, such as electric vehicles. Advances may be realized from improvements to the liquid electrolyte; however, current understanding of the liquid structure and properties remains incomplete. X-ray absorption spectroscopy of solutions of LiBF4 in propylene carbonate (PC), interpreted using first-principles electronic structure calculations within the eXcited electron and Core Hole (XCH) approximation, yields new insight into the solvation structure of the Li+ ion in this model electrolyte. By generating linear combinations of the computed spectra of Li+-associating and free PC molecules and comparing to the experimental spectrum, we find a Li+–solvent interaction number of 4.5. This result suggests that computational models of lithium ion battery electrolytes should move beyond tetrahedral coordination structures.

  4. CX-008905: Categorical Exclusion Determination

    Office of Energy Efficiency and Renewable Energy (EERE)

    Optimizing Accuracy of Determinations of Carbon Dioxide Storage Capacity and Permanence CX(s) Applied: A1, A9, B3.6 Date: 08/29/2012 Location(s): Wyoming Offices(s): National Energy Technology Laboratory

  5. Carbon supercapacitors

    SciTech Connect (OSTI)

    Delnick, F.M.

    1993-11-01

    Carbon supercapacitors are represented as distributed RC networks with transmission line equivalent circuits. At low charge/discharge rates and low frequencies these networks approximate a simple series R{sub ESR}C circuit. The energy efficiency of the supercapacitor is limited by the voltage drop across the ESR. The pore structure of the carbon electrode defines the electrochemically active surface area which in turn establishes the volume specific capacitance of the carbon material. To date, the highest volume specific capacitance reported for a supercapacitor electrode is 220F/cm{sup 3} in aqueous H{sub 2}SO{sub 4} (10) and {approximately}60 F/cm{sup 3} in nonaqueous electrolyte (8).

  6. Carbon particles

    DOE Patents [OSTI]

    Hunt, Arlon J.

    1984-01-01

    A method and apparatus whereby small carbon particles are made by pyrolysis of a mixture of acetylene carried in argon. The mixture is injected through a nozzle into a heated tube. A small amount of air is added to the mixture. In order to prevent carbon build-up at the nozzle, the nozzle tip is externally cooled. The tube is also elongated sufficiently to assure efficient pyrolysis at the desired flow rates. A key feature of the method is that the acetylene and argon, for example, are premixed in a dilute ratio, and such mixture is injected while cool to minimize the agglomeration of the particles, which produces carbon particles with desired optical properties for use as a solar radiant heat absorber.

  7. Quantifying sources of black carbon in Western North America using observationally based analysis and an emission tagging technique in the Community Atmosphere Model

    SciTech Connect (OSTI)

    Zhang, Rudong; Wang, Hailong; Hegg, D. A.; Qian, Yun; Doherty, Sarah J.; Dang, Cheng; Ma, Po-Lun; Rasch, Philip J.; Fu, Qiang

    2015-11-18

    The Community Atmosphere Model (CAM5), equipped with a technique to tag black carbon (BC) emissions by source regions and types, has been employed to establish source-receptor relationships for atmospheric BC and its deposition to snow over Western North America. The CAM5 simulation was conducted with meteorological fields constrained by reanalysis for year 2013 when measurements of BC in both near-surface air and snow are available for model evaluation. We find that CAM5 has a significant low bias in predicted mixing ratios of BC in snow but only a small low bias in predicted atmospheric concentrations over the Northwest USA and West Canada. Even with a strong low bias in snow mixing ratios, radiative transfer calculations show that the BC-in-snow darkening effect is substantially larger than the BC dimming effect at the surface by atmospheric BC. Local sources contribute more to near-surface atmospheric BC and to deposition than distant sources, while the latter are more important in the middle and upper troposphere where wet removal is relatively weak. Fossil fuel (FF) is the dominant source type for total column BC burden over the two regions. FF is also the dominant local source type for BC column burden, deposition, and near-surface BC, while for all distant source regions combined the contribution of biomass/biofuel (BB) is larger than FF. An observationally based Positive Matrix Factorization (PMF) analysis of the snow-impurity chemistry is conducted to quantitatively evaluate the CAM5 BC source-type attribution. While CAM5 is qualitatively consistent with the PMF analysis with respect to partitioning of BC originating from BB and FF emissions, it significantly underestimates the relative contribution of BB. In addition to a possible low bias in BB emissions used in the simulation, the model is likely missing a significant source of snow darkening from local soil found in the observations.

  8. Quantifying sources of black carbon in western North America using observationally based analysis and an emission tagging technique in the Community Atmosphere Model

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, R.; Wang, H.; Hegg, D. A.; Qian, Y.; Doherty, S. J.; Dang, C.; Ma, P.-L.; Rasch, P. J.; Fu, Q.

    2015-11-18

    The Community Atmosphere Model (CAM5), equipped with a technique to tag black carbon (BC) emissions by source regions and types, has been employed to establish source–receptor relationships for atmospheric BC and its deposition to snow over western North America. The CAM5 simulation was conducted with meteorological fields constrained by reanalysis for year 2013 when measurements of BC in both near-surface air and snow are available for model evaluation. We find that CAM5 has a significant low bias in predicted mixing ratios of BC in snow but only a small low bias in predicted atmospheric concentrations over northwestern USA and westernmore » Canada. Even with a strong low bias in snow mixing ratios, radiative transfer calculations show that the BC-in-snow darkening effect is substantially larger than the BC dimming effect at the surface by atmospheric BC. Local sources contribute more to near-surface atmospheric BC and to deposition than distant sources, while the latter are more important in the middle and upper troposphere where wet removal is relatively weak. Fossil fuel (FF) is the dominant source type for total column BC burden over the two regions. FF is also the dominant local source type for BC column burden, deposition, and near-surface BC, while for all distant source regions combined the contribution of biomass/biofuel (BB) is larger than FF. An observationally based positive matrix factorization (PMF) analysis of the snow-impurity chemistry is conducted to quantitatively evaluate the CAM5 BC source-type attribution. While CAM5 is qualitatively consistent with the PMF analysis with respect to partitioning of BC originating from BB and FF emissions, it significantly underestimates the relative contribution of BB. In addition to a possible low bias in BB emissions used in the simulation, the model is likely missing a significant source of snow darkening from local soil found in the observations.« less

  9. Quantifying sources of black carbon in Western North America using observationally based analysis and an emission tagging technique in the Community Atmosphere Model

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, R.; Wang, H.; Hegg, D. A.; Qian, Y.; Doherty, S. J.; Dang, C.; Ma, P.-L.; Rasch, P. J.; Fu, Q.

    2015-05-04

    The Community Atmosphere Model (CAM5), equipped with a technique to tag black carbon (BC) emissions by source regions and types, has been employed to establish source-receptor relationships for atmospheric BC and its deposition to snow over Western North America. The CAM5 simulation was conducted with meteorological fields constrained by reanalysis for year 2013 when measurements of BC in both near-surface air and snow are available for model evaluation. We find that CAM5 has a significant low bias in predicted mixing ratios of BC in snow but only a small low bias in predicted atmospheric concentrations over the Northwest USA andmore » West Canada. Even with a strong low bias in snow mixing ratios, radiative transfer calculations show that the BC-in-snow darkening effect is substantially larger than the BC dimming effect at the surface by atmospheric BC. Local sources contribute more to near-surface atmospheric BC and to deposition than distant sources, while the latter are more important in the middle and upper troposphere where wet removal is relatively weak. Fossil fuel (FF) is the dominant source type for total column BC burden over the two regions. FF is also the dominant local source type for BC column burden, deposition, and near-surface BC, while for all distant source regions combined the contribution of biomass/biofuel (BB) is larger than FF. An observationally based Positive Matrix Factorization (PMF) analysis of the snow-impurity chemistry is conducted to quantitatively evaluate the CAM5 BC source-type attribution. While CAM5 is qualitatively consistent with the PMF analysis with respect to partitioning of BC originating from BB and FF emissions, it significantly underestimates the relative contribution of BB. In addition to a possible low bias in BB emissions used in the simulation, the model is likely missing a significant source of snow darkening from local soil found in the observations.« less

  10. Carbon microtubes

    DOE Patents [OSTI]

    Peng, Huisheng (Shanghai, CN); Zhu, Yuntian Theodore (Cary, NC); Peterson, Dean E. (Los Alamos, NM); Jia, Quanxi (Los Alamos, NM)

    2011-06-14

    A carbon microtube comprising a hollow, substantially tubular structure having a porous wall, wherein the microtube has a diameter of from about 10 .mu.m to about 150 .mu.m, and a density of less than 20 mg/cm.sup.3. Also described is a carbon microtube, having a diameter of at least 10 .mu.m and comprising a hollow, substantially tubular structure having a porous wall, wherein the porous wall comprises a plurality of voids, said voids substantially parallel to the length of the microtube, and defined by an inner surface, an outer surface, and a shared surface separating two adjacent voids.