20 Search Results

We present that a sodium thermal electrochemical converter (Na-TEC) generates electricity directly from heat through isothermal expansion of sodium ions across a beta"-alumina solid-electrolyte. This heat engine has been considered for use with conventional concentrating solar power (CSP) systems before. However, unlike previous single-stage devices, the improved design uses two stages with an interstage reheat, allowing more economical and efficient conversion up to 29% at a hot side temperature of 850 °C. Herein, a cost-performance analysis for this improved design assesses opportunities for distributed-CSP in the context of micro-combined heat and power systems. A high-level techno-economic analysis (TEA) is presentedmore » that explores four scenarios where a Na-TEC is used as the heat engine for a distributed-CSP system. Overnight capital cost and levelized cost of electricity (LCOE) are estimated for a system lifetime of 30 years, revealing that overnight capital costs in a range from $3.57 to $17.71 per W_e are feasible, which equate to LCOEs from 6.9 to 17.2 cents kWh_e^-1. This analysis makes a significant contribution by concurrently quantifying the efficiency and unit costs for a range of multistage configurations, and demonstrating that a Na-TEC may be a promising alternative to Stirling engines for distributed-CSP systems at residential scale of 1–5 kW_e.« less

Energy efficiency is widely recognized as a cost-effective strategy to meet energy demand. The U.S. energy service company (ESCO) industry generates significant energy savings and other benefits through installing and maintaining energy efficiency, renewable and other types of projects. In this study, we evaluate factors that may explain trends in the economic performance of U.S. ESCO projects by analyzing project level data for ~7000 U.S. ESCO industry projects. We find that real project investment levels normalized for floor area have increased over time in ESCO projects across market segments. However, the dollar value of energy savings and other reported benefitsmore » have not kept pace with increases in real project investment levels over time. The latter have increased 100%–500% in various market segments from 1990 to 2017. We conduct an econometric analysis to decompose the drivers of these underlying trends. Number of measures and a changing mix of conservation measures are the primary factors that correlate with the long-term increase in project investment levels. However, our analysis is only able to account for less than 50% of the increase in real investment levels. Finally, we discuss additional factors, and conclude discussing policy implications and outlining long-term research needs.« less

For many decades, integration of concentrated solar power (CSP) and desalination relied solely on the use of conventional steam Rankine cycles with thermally based desalination technologies. However, CSP research focus is shifting toward the use of supercritical CO₂ Brayton cycles due to the significant improvement in thermal efficiencies. Here, we present a techno-economic study that compares the generated power and freshwater produced from a CSP system operated with a Rankine and Brayton cycle. Such a study facilitates co-analysis of the costs of producing both electricity and water among the other trade-off assessments. To minimize the levelized cost of water (LCOW),more » a desalination facility utilizing multi-effect distillation with thermal vapor compression (MED/TVC) instead of multistage flash distillation (MSF) is most suitable. The techno-economic analysis reveals that in areas where water production is crucial to be optimized, although levelized cost of electricity (LCOE) values are lowest for wet-cooled recompression closed Brayton cycle (RCBR) with MSF (12.1 cents/kWh_e) and MED/TVC (12.4 cents/kWh_e), there is only a 0.35 cents/kWh_e increase for dry-cooled RCBR with MED/TVC to a cost of 12.8 cents/kWh_e. In conclusion, this suggests that the best candidate for optimizing water production while minimizing both LCOW and LCOE is dry-cooled RCBR with MED/TVC desalination.« less

Lithium-ion batteries (LIBs) are currently the most suitable energy storage device for powering electric vehicles (EVs) owing to their attractive properties including high energy efficiency, lack of memory effect, long cycle life, high energy density and high power density. These advantages allow them to be smaller and lighter than other conventional rechargeable batteries such as lead–acid batteries, nickel–cadmium batteries (Ni–Cd) and nickel–metal hydride batteries (Ni–MH). Modern EVs, however, still suffer from performance barriers (range, charging rate, lifetime, etc.) and technological barriers (high cost, safety, reliability, etc.), limiting their widespread adoption. Given these facts, this review sets the extensive market penetrationmore » of LIB-powered EVs as an ultimate objective and then discusses recent advances and challenges of electric automobiles, mainly focusing on critical element resources, present and future EV markets, and the cost and performance of LIBs. Finally, novel battery chemistries and technologies including high-energy electrode materials and all-solid-state batteries are also evaluated for their potential capabilities in next-generation long-range EVs.« less

The widespread implementation of plug-in electric vehicles (PEVs) will depend on public appreciation of the potential savings in ownership costs that PEVs offer over conventional, internal combustion energy vehicles (ICEVs) and hybrid electric vehicles (HEVs), including fuel savings. This study compares the energy consumption and estimated ownership costs of various technologies for multiple drive cycles in the United States and the European Union; identifies and quantifies the impacts of the main parameters influencing the ownership costs of PEVs in comparison with other powertrains for different timeframes, vehicle classes, and technologies; and assesses under what combinations of parameters the cost ofmore » PEVs can be competitive with other powertrains.« less

Power consumption and associated carbon emissions are increasingly critical challenges for large-scale computing. Recent research proposes exploiting stranded power-uneconomic renewable power-for green supercomputing in a system called Zero-Carbon Cloud (ZCCloud). These efforts studied production supercomputing workloads on stranded-power based computing resources, demonstrating their achievable productivity. We explore economic viability of stranded-power based supercomputing, using three datacenter total-cost-of-ownership (TOO) models to study cost-effectiveness. These studies show that ZCCloud's approach can be cost-effective in the USA today, and is even more attractive in regions with higher power prices (e.g., Japan, Germany), achieving cost advantages as large as 50 percent. Environmental and power-gridmore » benefits are a further advantage. We also explore the sensitivity of these results to changes in hardware TOO; cheaper hardware or longer lifetimes magnify the attractiveness of stranded-power based approaches, yielding advantages as large as 91 percent. These results are robust across different TCO models. Lastly, we study extreme-scale supercomputers ( >100 MW), finding stranded-power can increase peak capability per cost by as much as 80 percent.« less

This paper presents a review of the main electrical components that are expected to be present in marine renewable energy arrays. The review is put in context by appraising the current needs of the industry and identifying the key components required in both device and array-scale developments. For each component, electrical, mechanical and cost considerations are discussed; with quantitative data collected during the review made freely available for use by the community via an open access online repository. Here, this data collection updates previous research and addresses gaps specific to emerging offshore technologies, such as marine and floating wind, andmore » provides a comprehensive resource for the techno-economic assessment of offshore energy arrays.« less

Mitigating the spread of infectious disease is of great importance for policy makers. Taking the recent outbreak of Ebola as an example, it was difficult for policy makers to identify the best course of action based on the cost-effectiveness of what was available. In effort to address the needs of policy makers to mitigate the spread of infectious disease before an outbreak becomes uncontrollable, we have devised a cost-benefit disease control model to simulate the effect of various control methods on disease incidence and the cost associated with each of the scenarios. Here, we present a case study of Ebolamore » used to quantify the cost effectiveness of vaccination and isolation methods to minimize the spread of the disease. We evaluate the impact of changing strategy levels on the incidence of the disease and address the benefits of choosing one strategy over the other with regards to cost of vaccine and isolation. Disease. We use a general SEIRJ model for disease transmission. Here, S-Susceptible, E- Exposed (latent), IA– Infected (asymptomatic),IM– Infected (mild symptoms), IS– Infected (severe symptoms),JM– Isolated (mild symptoms at home), JS– Isolated (severe symptoms in hospital), and R- Recovered individuals. In this model, we consider the dynamics of the system and the effect of the relative transmissibility of isolated individuals (L) compared to other infected individuals. Cost. Ebola vaccination and treatment are very expensive and not widely available. Some preliminary data shows that it will take$73 million (M) to produce 27 M vaccines plus the cost for vaccine delivery and health care professionals (not included here). On the other hand, the treatment for Ebola in the U.S. would cost $25,000dollars a day per person to ensure proper isolation and adequate care(treatment, health care professionals, facilities and special equipment).Although not included in this research, the proper isolation of Ebola patients would also lead to a loss in hospital revenue of $148,000per day due to reduced patient capacity3. Here, we use $27,000 per individual hospitalized per day and $2.70 per person vaccinated. Model. To evaluate the cost-effectiveness of control methods on disease transmission, we assessed the affect of different levels of vaccination coverage on the resulting number of infected individuals. Then, we calculated the overall estimated cost of vaccination and resulting hospitalization for each scenario to identify the lowest cost-benefit ratio. Using a base population of 10 M individuals, we ran scenarios for different levels of vaccination (μ= 0.01, 0.05, 0.1) while varying the relative transmissibility of isolated individuals (L = 0.5, 0.6, 0.65).For each combination, we calculated the incidence, vaccination and hospitalization cost per individual per day (Fig 1). We note that an increase in the relative transmissibility of isolated individuals leads to a higher number of infected people and, therefore, a reduced number of candidates for vaccination and an overall increase in cost. Since the cost of vaccination is 1 ten-thousandth of the cost of hospitalization, our results clearly show the cost-benefit of vaccinating over hospital treatment. In every scenario studied, we observed a measurable reduction in disease incidence when vaccinating a higher fraction of the population compared to isolating individuals post infection. Given these preliminary results, we plan to extend the framework of our model to a dynamic control system where we consider the cost of vaccination and isolation embedded in the system of differential equations. This approach will allow us see the best available control implementation while minimizing the cost of treatment and vaccination.« less

Flow batteries are a promising technology for storing and discharging megawatt hours of electrical energy on the time scale of hours. The separator between the positive and negative electrodes strongly affects technical and economic performance. However, requirements for separators have not been reported in a general manner that enables quantitative evaluation of new systems such as nonaqueous flow batteries. This gap is addressed by deriving specifications for transport properties that are chemistry agnostic and align with aggressive capital cost targets. Three key transport characteristics are identified: area-specific resistance R_Ω, crossover current density i_x, and the coupling between crossover and capacitymore » loss Ψ. Suggested maximum area-specific resistances are 0.29 and 2.3 Ω·cm² for aqueous and nonaqueous batteries, respectively. Allowable crossover rates are derived by considering the possible fates of active molecules that cross the separator and the coupling between Coulombic efficiency (CE) and capacity decline. The CE must exceed 99.992% when active species are unstable at the opposing electrode, while a CE of 97% can be tolerated when active molecules can be recovered from the opposing electrode. The contributions of diffusion, migration, and convection are discussed, quantified, and related to the physical properties of the separator and the active materials.« less

Successful project management has been defined as balancing the triangle of the cost, schedule, and cjuality criteria (Kerzner, 1989). For example, if the project manager must meet a tighter schedule, he or she must know the effect on specifications and/or cost. Except in cases of greater efficiency, the specifications must relax and/or the cost mast increase. This classical triangle applies to all levels of management, including program management. Today, successful project management cannot be secured by meeting just these three traditional criteria. We must meet the cost, schedule, and quality criteria and, in doing so, we must satisfy the stakeholdersmore » of the project. Why are stakeholders now an issue? Haven't project managers always had to contend with stakeholders? I'll address why stakeholders have risen in visibility, power, and influence in project management. To satisfy our stakeholders, we must know who they are. I'll identify categories of stakeholders, identify their main interests, assess the power of each category, locate the channels this power is exercised through, design ways to address stakeholder expectations, and discuss how stakeholder satisfaction strategy can be implemented in project management. I argue that satisfying stakeholders is a compromise. Stakeholder satisfaction relies on information about the three success criteria plus assurances on data and information accuracy and reliability (and also assurances past problems have been fixed and reoccurrence minimized). Project managers will dramatically increase their potential to manage projects successfully if they understand who their stakeholders are, each stakeholder's agenda, stakeholder power and how it's used, how to satisfy stakeholders, and ways to actively and sincerely seek and address stakeholder concerns.« less