41 Search Results

Ethanol is a promising feedstock for sustainable aviation fuel production; however, conventional routes face significant energy and cost challenges, particularly due to the ethanol dehydration step to ethylene. Here, this study leverages breakthrough experimental data to perform comprehensive techno-economic and life-cycle assessments of an innovative ethanol-to-jet process. The process employs a single-step catalytic conversion, enabled by multifunctional Cu-ZrO₂/SBA-16 catalyst, to directly upgrade ethanol into a mixed olefin stream rich in n-butene. The single-step conversion eliminates the costly ethanol dehydration step in the conventional process. High selectivity toward n-butene offers key advantages: it simplifies downstream oligomerization into jet-range hydrocarbons and enablesmore » the co-production of renewable n-butene alongside sustainable aviation fuel. The analysis estimates a minimum fuel selling price as low as $$\$$$$2.50 per gallon, whether using corn ethanol or cellulosic ethanol from corn stover. Life cycle CO₂ equivalent emissions are projected to be as low as 10.6 g CO₂eq/MJ sustainable aviation fuel, representing over 70% reduction compared to conventional petroleum-based jet fuel. This one-step ethanol upgrading approach not only facilitates SAF and n-butene co-production but also provides operational flexibility. The ability to tailor product outputs allows the ethanol-to-jet process to adapt to varying feedstocks, incentive programs, and market dynamics, ultimately enhancing the economic viability of sustainable aviation fuel production.« less

Introduction: Volatile organic compounds (VOCs) are small, low-vapor-pressure molecules emitted from the surface ocean into the atmosphere. In the atmosphere, VOCs can change OH reactivity and condense onto particles to become cloud condensation nuclei. VOCs are produced by phytoplankton, but the conditions leading to VOC accumulation in the surface ocean are poorly understood.Methods: In this study, VOC accumulation was measured in real time over a 12 h day−12 h night cycle in the model diatom Phaeodactylum tricornutum during exponential growth.Results: Sixty-three m/z signals were produced in higher concentrations than in cell-free controls. All VOCs, except methanol, were continuously produced overmore » 24 h. All VOCs accumulated to higher concentrations during the day compared to the night, and 11 VOCs exhibited distinct accumulation patterns during the morning hours. Twenty-seven VOCs were associated with known metabolic pathways in P. tricornutum, with most VOCs involved in amino acid and fatty acid metabolism.Discussion: Patterns of VOC production were strongly associated with diel shifts in cell physiology and the cell cycle. Diel VOC production patterns give a fundamental understanding of the first steps in VOC accumulation in the surface ocean.« less

Global CO₂ emissions are increasing at about a 1.5% rate per year. Fossil fuel-based plants are one of the main contributors to this rise. In the power generation industry, fossil fuel plants are dominant, and many plants are under development. In this study, a natural gas combined cycle (NGCC) power plant with postcombustion capture using a leading water-lean solvent is considered. For optimal design and operating schedule, large-scale dynamic optimization is undertaken for net present value (NPV) optimization. The first principle dynamic model of NGCC is developed, including a model of the highly efficient H-class gas turbines. For computational tractabilitymore » of the dynamic optimization problem, a reduced-order model is developed by using the Hankel singular value decomposition. A waterlean solvent, N-(2-ethoxyethyl)-3-morpholinopropan-1-amine, is used for carbon capture. A model of the capture system is developed in Aspen Plus, which is used to develop a reduced-order model by using ALAMO, a machine learning software. In addition, a reduced model of the CO₂ compression system with a dehydration unit is also considered. The integrated system is used for NPV optimization by using the Python-based PYOMO platform. The PCC process is analyzed for three configurations-conventional packed bed, rotating packed bed (RPB), and a combination of RPB and direct contact cooler. The NPV optimization is performed for 14 regional markets by considering year-long clustered and continuous locational marginal price data with a 1 h interval. Optimization results show that the PCC can achieve 90% CO₂ capture with a positive NPV for six regions. Sensitivity studies conducted by using the PCC configurations indicate that the process is economically feasible for 9 regions out of 14 regional electricity markets with NPV values in the range of 33−540 $MM.« less

A three-step synthesis was used to convert waste polyethylene terephthalate (PET) into the high value polymer, poly-para-phenylene terephthalamide (PPTA), used in the production of high strength aramid fiber, such as Kevlar. Improvements to the polymerization reaction by addition of calcium chloride to the solvent, N-methyl-2-pyrrolidone (NMP), and rigorous anhydrous conditions enabled the production of a PET-derived PPTA with a 4.15 dL/g inherent viscosity in sulfuric acid that is amenable to fiber spinning. PPTA fibers were spun using a wet spinning apparatus under varied process parameters to assess their impact on fiber surface morphology, diameter, and the mechanical properties of themore » fibers. Select fibers were subjected to a post-spinning heat treatment at 150 °C , which improved the tensile strength and modulus by 100% and 30%, respectively, relative to the as-spun fibers. Techno-economic and life cycle analyses were conducted to evaluate the economic feasibility and the life-cycle greenhouse gases (GHG) emissions of the approach. In conclusion, the results suggest the potential for up to a 30% cost reduction, and comparable GHG emissions against conventional petroleum-based processes.« less

Freight rail is more energy-efficient than truck transport over long-haul distances, offering a low-energy and emissions-intensive option for transporting freight. This study evaluates techno-economic analysis and life cycle assessment of seven alternative unblended fuels for freight locomotive engines─biodiesel, renewable diesel (RD), bio-oils, methanol, dimethyl ether (DME), ethanol, and ammonia─across 16 fuel pathways utilizing soybean, corn, woody biomass, renewable hydrogen, and waste sources, e.g., sludge, manure, and industrial CO₂, and compares these to conventional diesel. The minimum fuel selling price (MFSP) ranged from $$\$$2.05$ to $$\$$8.27$ per diesel gallon equivalent (2020 US dollars), with biocrude and RDs produced from hydrothermal liquefactionmore » (HTL) of sludge having the lowest MFSPs due to coproduct credits and avoided waste treatment cost. Life cycle GHG emissions ranged from −41 to 53 g of CO₂e/MJ. RD from waste via HTL achieves negative emissions by diverting sludge/manure from GHG-intensive conventional management. Few pathways such as biocrude, methanol, and DME require additional control for SO_X emissions in the refinery, while ethanol, FT-diesel, and bio-oil require additional control for particulate matter emissions. Bio-oil and RD from sludge have lower marginal abatement cost or MAC (–$$\$$38$/tonne CO₂ lowest) while methanol and ammonia with renewable hydrogen have higher MAC ($$\$$490$/tonne CO₂ maximum).« less

Anthropogenic emissions of CO₂ have nearly exhausted our carbon budget, putting the world on a trajectory toward irreversible climate change. CO₂ emissions must be reversed in coming decades to avoid global warming past the 2 °C target. Recent approaches have focused on recycling CO₂ into fuels and chemicals to create sufficient financial incentives to pay for CO₂ removal and geological sequestration. These technologies aim to produce fuels and chemicals at quantities relevant to global markets while also recycling a meaningful amount of CO₂. While promising, these technologies are CO₂-neutral at best. Truly negative emission technologies will require significant quantities ofmore » durable, fungible products that sequester hundreds of millions of tonnes of CO₂. We present an economically viable approach to sequestering hundreds of thousands of tonnes of CO₂ per year in polymer composites made from CO₂-functionalized lignin or lignite fillers mixed with a high-density polyethylene (HDPE) matrix. CO₂ is chemically fixed to polymeric phenols via C–C bond formation at the lignin or lignite surface, storing about 2–4.2 wt% of CO₂. Composites produced with the CO₂-functionalized fillers and HDPE have mechanical properties that meet international building code standards for decking, a multi-billion-dollar market. A techno-economic analysis and life cycle assessment suggest that CO₂-functionalized lignin and lignite fillers have favorable economic potential. These composites could reduce greenhouse gas emissions up to 62% over conventional wood plastic composites or be CO₂-negative within 20 years when manufactured with renewable electricity, recycled high-density polyethylene and if extra CO₂ is captured and sequestered in the ground. The composites can achieve a net-negative global warming potential after 54 years for the CO₂ solely stored in the composites.« less

A single sorbent-catalytic (non-noble metal) material has been developed for the integrated direct air capture and catalytic conversion of captured CO ₂  into C-C coupled products.

Hydrothermal liquefaction (HTL) is a technology capable of producing sustainable hydrocarbon fuels from wet waste, reducing volumes of that waste as an added benefit. However, sustainable fuel production through HTL has yet to reach commercial scale and opportunities for improvements to process safety remain. This work describes low-pressure, low-temperature, two-stage solvent extraction and separation of HTL products utilizing naphtha range hydrocarbons. The similar qualitative solubility behavior of bitumen and biocrude (BC) with respect to paraffin versus naphthene or aromatic solvent composition allows us to examine a process comparable to solvent processing of bitumen. Lab-scale experiments were carried out to demonstratemore » the basic process and evaluate key parameters. The laboratory work indicates that using aliphatic/aromatic solvent mixtures at 80 °C results in a recovery of nearly 100% of the biocrude from the product mixture with reduced carbon content on the hydro-char. The findings illustrate the potential of solvent extraction for HTL biocrude processing. On a commercial scale, such a process may de-risk HTL, improving prospects for commercialization, opening the door to widespread conversion of wet-waste and waste biomass to sustainable fuels by HTL.« less

Here we demonstrate the proof-of-concept for microchannel reactive distillation for alcohol-to-jet application: combining ethanol/water separation and ethanol dehydration in one unit operation. Ethanol is first distilled into the vapor phase, converted to ethylene and water, and then the water co-product is condensed to shift the reaction equilibrium. Process intensification is achieved through rapid mass transfer—ethanol stripping from thin wicks using novel microchannel architectures—leading to lower residence time and improved separation efficiency. Energy savings are realized with integration of unit operations. For example, heat of condensing water can offset vaporizing ethanol. Furthermore, the dehydration reaction equilibrium shifts towards completion by immediatemore » removal of the water byproduct upon formation while maintaining aqueous feedstock in the condensed phase. For aqueous ethanol feedstock (40%_w), 71% ethanol conversion with 91% selectivity to ethylene was demonstrated at 220 °C, 600 psig, and 0.28 h^-1 wt hour space velocity. 2.7 stages of separation were also demonstrated, under these conditions, using a device length of 8.3 cm. This provides a height equivalent of a theoretical plate (HETP), a measure of separation efficiency, of ~3.3 cm. By comparison, conventional distillation packing provides an HETP of ~30 cm. Thus, 9.1× reduction in HETP was demonstrated over conventional technology, providing a means for significant energy savings and an example of process intensification. Finally, preliminary process economic analysis indicates that by using microchannel reactive distillation technology, the operating and capital costs for the ethanol separation and dehydration portion of an envisioned alcohol-to-jet process could be reduced by at least 35% and 55%, respectively, relative to the incumbent technology, provided future improvements to microchannel reactive distillation design and operability are made.« less