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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Jamaican Domestic Ethanol Fuel Feasibility and Benefits Analysis

The Government of Jamaica asked the National Renewable Energy Laboratory (NREL) to determine if the use of domestically produced ethanol motor fuel could help them achieve their goals to develop its economy and to reduce greenhouse gas (GHG) emissions. The first step was to determine how much ethanol could be used by Jamaican vehicles in blends of 10% (E10 – current blend level), 15% (E15), or 25% (E25). All blend levels make for feasible automotive fuels and are being used or pursued in multiple countries. Building on gross domestic product (GDP)-related projections made by the Johnson et al. (2019) business as usual scenario, the quantity of ethanol to be used in future years and blend levels is shown in Table ES1. All blend levels are assumed to achieve the same volumetric fuel economy because of verified efficiency improvements enabled by increased octane levels.

09 BIOMASS FUELS↗
DOE OSTI2024

Production of 1,3-Butadiene from Renewable Feedstocks Ethanol and 1,3-Butanediol - CRADA 560 (Final Report)

1,3-butadiene is a commodity chemical currently produced from petroleum sources. Producing 1,3-butadiene from renewable resources will contribute to decarbonization, provide new green jobs, and reduce our dependance on oil. Development of multifunctional catalysts that are active, selective, and stable for this reaction has been an area of research and development. This effort reported here builds on our prior work for the 1-step conversion of ethanol to butadiene. The goal of the additional scope performed here was to accelerate the commercial deployment of sustainable butadiene production. We demonstrated that the PNNL Ag-based catalyst is significantly more active than the WWII-era catalyst when operated under the same conditions. A butadiene selectivity of 68% was obtained at 64% conversion for the production of butadiene from ethanol. It was found that ethanol feedstock is preferred over 1,3-butanediol feedstock to produce butadiene due to higher yield resulting in lower butadiene selling price (i.e., $\$$0.4-1.7/ lb). Production of 3.0 Liter of butadiene solution in hexane containing 100 grams of butadiene was achieved and delivered to Bridgestone for producing a butadiene-derived test piece.

09 BIOMASS FUELS↗
DOE OSTI2025

Sustainable Tire Production: Catalytic Upgrading of Ethanol into Butadiene (CRADA 636) Abstract

Bridgestone aims to minimize resource depletion and greenhouse gas (GHG) emissions by using 100% sustainable materials by 2050. As part of this goal Bridgestone is working to develop a first-of-kind end-of-life recycling process for tire material circularity and the decarbonization of new tire production. Used tires can be gasified to produce intermediate syngas (H 2 + CO) that can be further converted into ethanol using mature technology. The ethanol can then be converted into butadiene, a key precursor of new tires, using patented PNNL technology, enabling circularity for end-of-life tires. Indeed, PNNL has developed a new patented thermocatalytic-based technology for the conversion of ethanol into butadiene that allows for high carbon efficiency and improved catalyst longevity compared to World War II baseline catalyst. The objective here is to continue the development of this processing with the goal of commercial deployment. This includes development of engineered catalysts (e.g., extrudates) and their evaluation under industrially relevant conditions for deployment of a pilot scale. If successful, Bridgestone will subsequently utilize this catalyst technology at pilot and then commercialization scale creating jobs in both construction sector and industry sector in a chosen location that promotes greater diversity, equity, and inclusion through key policies, training, and recruiting practices. Taken together, this work will support the U.S. Department of Energy goal for production of renewable chemicals with > 70% GHG emissions reduction relative to petroleum-derived counterparts and supporting > 1 MMT/ yr CO 2 e emissions reduction by 2030.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Direct Catalytic Conversion of Ethanol to C 5+ Ketones: Role of Pd–Zn Alloy on Catalytic Activity and Stability

Abstract Ethanol can be used as a platform molecule for synthesizing valuable chemicals and fuel precursors. Direct synthesis of C 5+ ketones, building blocks for lubricants and hydrocarbon fuels, from ethanol was achieved over a stable Pd‐promoted ZnO‐ZrO 2 catalyst. The sequence of reaction steps involved in the C 5+ ketone formation from ethanol was determined. The key reaction steps were found to be the in situ generation of the acetone intermediate and the cross‐aldol condensation between the reaction intermediates acetaldehyde and acetone. The formation of a Pd–Zn alloy in situ was identified to be the critical factor in maintaining high yield to the C 5+ ketones and the stability of the catalyst. A yield of >70 % to C 5+ ketones was achieved over a 0.1 % Pd‐ZnO‐ZrO 2 mixed oxide catalyst, and the catalyst was demonstrated to be stable beyond 2000 hours on stream without any catalyst deactivation.

Subramaniam, Senthil↗
DOE OSTI2020

Understanding the Deactivation of Ag–ZrO 2 /SiO 2 Catalysts for the Single-step Conversion of Ethanol to Butenes

Ag–ZrO 2 /SBA-16 has recently been found to be efficient for catalyzing the single-step conversion of ethanol to butene (1- and 2-butene mixtures) in the presence of H 2 . The reaction proceeds via a cascading sequence of reactions over mixed metal and Lewis sites, with the catalyst composition tuned to selectively favor butene formation. However, the catalyst slowly deactivates when evaluated over long reaction times. Here, we evaluated the lifetime of the Ag–ZrO 2 /SBA-16 catalyst system for ethanol-to-butene conversion at 325 °C for up to 800 hours on stream. Several characterization techniques were used to elucidate the mechanism(s) by which catalyst deactivation occurs. Coke deposition, Ag particle sintering, and Ag 0 -to-Ag + oxidation state change were identified to be the major causes of catalyst deactivation. Coke deposits cover primarily Lewis acid sites which are responsible for aldol condensation, Meerwein-Ponndorf-Verley (MPV) reduction, and dehydration reactions. Ag particle sintering and Ag oxidation state change leads to a reduction in the number of metallic Ag sites responsible for the dehydrogenation/hydrogenation steps. The fresh catalyst likely experiences hydrothermal sintering in the early stage of reaction and permanently loses some active Lewis acid sites before reaching a new structural steady state. The deactivation of Lewis acid sites leads to a decrease in overall ethanol conversion, whereas the deactivation of the metallic Ag sites decreases the butene selectivity. For catalyst regeneration, oxidative calcination (at 500 °C) followed by reduction (at 325 °C) successfully removes all the coke species on the catalyst surface and restores the metallic Ag particles of the 4Ag–4ZrO 2 /SBA-16 catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

The Ethanol–Ethyl Acetate System as a Biogenic Hydrogen Carrier

Liquid organic hydrogen carriers will likely be a key element of a future hydrogen economy by enabling the storage and transport of large quantities of hydrogen. Ethanol is a liquid organic hydrogen carrier that is readily available from biological resources, which undergoes a reversible reaction to yield hydrogen and ethyl acetate. The objective of the present study is to obtain a better understanding of the thermodynamic and environmental suitability of the ethanol–ethyl acetate cycle for hydrogen storage applications. The analysis covers three aspects: thermodynamics of the chemical reaction, energy balance of the process, and a first‐order assessment of greenhouse gas emissions. Thermodynamics of the reaction are characterized by a standard Gibbs energy of reaction close to zero which allows the reaction to be shifted between hydrogenation and dehydrogenation within a moderate window of temperature and pressure conditions. The energy demand for dehydrogenation is comparatively small, resulting in an overall system efficiency of 88%. A life cycle greenhouse gas analysis over a 20‐year storage system lifetime gives a carbon intensity of 7.0 kg‐CO 2eq /kg‐H 2 delivered. These results indicate that the ethanol–ethyl acetate system has considerable promise as a hydrogen carrier and should be the subject of further research.

08 HYDROGEN↗
DOE OSTI2022

Assessing the impact of substrate-level enzyme regulations limiting ethanol titer in Clostridium thermocellum using a core kinetic model

Clostridium thermocellum is a promising candidate for consolidated bioprocessing because it can directly ferment cellulose to ethanol. Despite significant efforts, achieved yields and titers fall below industrially relevant targets. This implies that there still exist unknown enzymatic, regulatory, and/or possibly thermodynamic bottlenecks that can throttle back metabolic flow. By (i) elucidating internal metabolic fluxes in wild-type C. thermocellum grown on cellobiose via 13 C-metabolic flux analysis ( 13 C-MFA), (ii) parameterizing a core kinetic model, and (iii) subsequently deploying an ensemble-docking workflow for discovering substrate-level regulations, this paper aims to reveal some of these factors and expand our knowledgebase governing C. thermocellum metabolism. Generated 13 C labeling data were used with 13 C-MFA to generate a wild-type flux distribution for the metabolic network. Notably, flux elucidation through MFA alluded to serine generation via the mercaptopyruvate pathway. Using the elucidated flux distributions in conjunction with batch fermentation process yield data for various mutant strains, we constructed a kinetic model of C. thermocellum core metabolism (i.e. k-ctherm138). Subsequently, we used the parameterized kinetic model to explore the effect of removing substrate-level regulations on ethanol yield and titer. Upon exploring all possible simultaneous (up to four) regulation removals we identified combinations that lead to many-fold model predicted improvement in ethanol titer. In addition, by coupling a systematic method for identifying putative competitive inhibitory mechanisms using K-FIT kinetic parameterization with the ensemble-docking workflow, we flagged 67 putative substrate-level inhibition mechanisms across central carbon metabolism supported by both kinetic formalism and docking analysis.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Advanced fuels from ethanol – a superstructure optimization approach

We develop a superstructure framework for the design of biorefineries for ethanol upgrading into advanced biofuels to replace gasoline, jet fuel or diesel. The framework integrates catalysis, process synthesis, and fuel property modelling towards the design of biorefineries producing fuels with specified properties. The proposed framework is applied to identify strategies for the upgrading of ethanol into one or more fuels with specific properties. We discuss the trade-off between profit and biorefinery complexity, as well as the relation among fuel property constraints, the optimal upgrading strategy selected, and process economics. Lastly, we show how to find the optimal biorefinery associated with a particular chemistry or catalyst. The results presented constitute the first systematic study of ethanol upgrading considering, simultaneously, fuel and process design.

09 BIOMASS FUELS↗
DOE OSTI2022

A System Level Analysis of Ethanol Upgrading to Middle Distillates

We systematically study the upgrading of ethanol toward middle distillates with desired properties. To survey the large design space, we introduce a novel superstructure-based optimization framework integrating process design and fuel formulation. We show that biorefineries that produce middle distillates by upgrading lignocellulosic ethanol can have an energy return on investment (EROI) greater than 1. Additionally, we show that technological improvements can lead to significant increases in EROI. Furthermore, trade-offs between fuel properties and biorefinery profitability are established, showing how process economics are strongly influenced by fuel properties. In the case of diesel, the feasibility of producing high cetane number biofuels is demonstrated, coupled with a discussion of the technological requirements and costs to produce these superior fuels. It is also shown that the minimum fuel selling price (MFSP) can be reduced by increasing the biorefinery complexity. Lastly, we discuss the possibility of satisfying current and projected middle distillates demand in the U.S. using biofuels produced by ethanol upgrading, and we estimate the potential CO2 mitigation of these technologies.

09 BIOMASS FUELS↗
DOE OSTI2023

Guerbet upgrading of ethanol to n -butanol using Ru( iii ) catalysts under air

A series of in situ prepared Ru(III) complexes supported by easily accessible N-donor organic pincer ligands were used as catalysts in the Guerbet upgrading reaction of ethanol under aerobic conditions. Tridentate bis(benzimidazole) ligand systems containing amino-dimethyl (L1) and pyridine (L2) backbones were found to make more efficient catalyst systems as compared to the bidentate bis(benzimidazole) ligand systems containing phenyl (L3) and ethene (L4) backbones. Potassium t-butoxide was found to be the most compatible base for this catalyst system. Reaction with 0.1 mol% of the catalyst and 10 mol% of potassium t-butoxide yielded 27% of n-butanol at 71% selectivity (150 °C, 24 h). Increase in the catalyst or base loading mostly resulted in increased reactivity but selectivity towards the key product n-butanol was found to decrease. On the other hand, reducing the reaction period to 12 h resulted in slightly decreased reactivity but the reaction provides n-butanol with high selectivity (76%). Contrarily, increased reaction period resulted in enhanced conversion of ethanol to higher alcohols. Under moderate and aerobic reaction conditions, the catalytic system was found to efficiently upgrade ethanol to higher alcohols. Furthermore, the decrease in the catalytic activity of the system over time was speculated to be due to the gradual deactivation of the base upon reaction with water (by-product of the Guerbet reaction). Poor solubility of the catalytic system in aqueous solutions makes it unsuitable for direct Guerbet reaction of fermentation broth.

09 BIOMASS FUELS↗
DOE OSTI2021

Techno‐economic feasibility analysis of engineered energycane‐based biorefinery co‐producing biodiesel and ethanol

Abstract High feedstock cost and low oil yields per unit of land from temperate oilseed crops limit the growth of commercial‐scale biodiesel production. Recently, highly productive crops, such as sugarcane and energycane, have been engineered to accumulate triacylglycerides (TAGs) that allow the production of far more industrial vegetable oil than previously possible. A proof‐of‐concept suggests that biodiesel production from engineered energycane will be possible. However, before making efforts for scale‐up, it is critical to understand the commercial feasibility and economic competitiveness of this process. This study performs techno‐economic analysis of a unique biorefinery processing energycane to co‐produce biodiesel and ethanol. Comprehensive process simulation models were developed for two scenarios: (i) biodiesel from TAGs and ethanol from fermentation of sugars in juice and (ii) biodiesel from TAGs and ethanol from fermentation of sugars in juice and hydrolysis of carbohydrates in bagasse. Based on the target levels, the analysis was performed for energycane containing 0%, 5%, and 7.7% TAGs (d.b.). The biodiesel from engineered energycane was found economically viable and competitive to soybean biodiesel. Although the capital investment is higher compared to the soybean biodiesel plant, the biodiesel production costs ($0.66–$0.9/L) were lower than soybean biodiesel ($0.91/L). Biorefinery‐scenario‐1 processing energycane containing 7.7% TAG produces biodiesel with profitability (IRR 7.84) slightly lower than soybean biodiesel (IRR 8.3), but yields five times of biodiesel per unit land and is self‐sustainable for energy requirements. The surplus electricity can displace fossil electricity and provide environmental benefits. Monte Carlo simulation indicated that biorefinery is profitable with a 29%–65% probability (NPV > 0) which is largely controlled by feedstock composition and biodiesel market price. It is important to note that energycane can be grown on the marginal rainfed lands in S.E. USA, where soybean would not be viable. Biodiesel from engineered energycane would therefore be complementary to soydiesel in the United States.

09 BIOMASS FUELS↗
DOE OSTI2024

Potential for Combined Heat and Power with Carbon Capture and Storage at U.S. Ethanol Facilities

Conference paper presented at 17th International Conference on Greenhouse Gas Control Technologies (GHGT-17), Calgary, Alberta, Canada, October 20–24, 2024. Economic conditions in the United States have positioned ethanol producers as early adopters of industrial CO 2 capture and storage (CCS) from fermentation processes, creating an opportunity to further reduce emissions. Replacing fossil fired energy with biogenic combined heat and power (CHP) coupled with CCS could enable ethanol production to achieve net negative CO 2 emissions, with gasification based CHP better matching ethanol facilities’ heat and power needs than combustion based systems. Pilot scale testing showed that while 100% biomass gasification increased tar formation, cofeeding corn stover with coal and optimizing gasifier configurations offered promising pathways to reduce tar and improve operational performance.

09 BIOMASS FUELS↗
DOE OSTI2025

Integrated Biorefinery of Brewer’s Spent Grain for Second-Generation Ethanol, Mycoprotein, and Bioactive Vinasse Production

Brewer’s spent grain (BSG), the main lignocellulosic by-product of the beer industry, represents an abundant yet underutilized resource with high potential for valorization. This study presents an integrated biorefinery approach to convert BSG into second-generation (2G) ethanol, bioactive vinasse for plant growth promotion, and fungal biomass as a potential mycoprotein source. The biomass was first subjected to biological delignification using the white-rot fungus Ganoderma lucidum, after which two valorization routes were explored: (i) evaluation of the fungal biomass as a mycoprotein candidate and (ii) alcoholic fermentation for ethanol production. For the latter, three pretreatment strategies were assessed (diluted sulfuric acid and two deep eutectic solvents (DESs) based on choline chloride combined with either glycerol or lactic acid) followed by a one-pot enzymatic saccharification and fermentation using Kluyveromyces marxianus SLP1. The highest ethanol yield on substrate (YP/S) was achieved with [Ch]Cl:lactic acid pretreatment (0.46 g/g, 89.32% of theoretical). Vinasse, recovered after distillation, was characterized for organic acid content and tested on Solanum lycopersicum seed germination, showing promising biostimulant activity. Overall, this work highlights the potential of BSG as a sustainable feedstock within circular economy models, enabling the production of multiple bio-based products from a single residue.

Ganoderma lucidum↗
DOE OSTI2026

Catalytic Bias of NADH-Dependent Reduced Ferredoxin: NADP+ Oxidoreductase (Nfn) and its Relevance to Ethanol Production in Thermoanaerobacterium Saccharolyticum

NADH-dependent reduced ferredoxin: NADP+ oxidoreductase (Nfn) enzyme catalyzes an energy-conserving flavin-based electron bifurcation (FBEB) reaction. In microbial metabolism, Nfn links redox pools of three electron carriers - ferredoxin (Fd), NAD(H), and NADP(H) - through the following FBEB reaction: 2 NADPH + NAD+ + 2 Fdox 2 NADP+ + NADH + 2 Fdred + H+ The forward reaction is termed electron bifurcation, and the reverse reaction is electron confurcation. Catalytic bias describes an enzyme's tendency to favor one direction of a reversible reaction over the other and is expressed as the ratio of activities in the two directions. Thermoanaerobacterium saccharolyticum (Tsac) is a thermophilic, ethanologenic bacterium that ferments hemicellulose to ethanol at yields above 90%. Its Nfn enzyme is known to support ethanol production, presumably by operating in the confurcating direction to balance cellular cofactors, but this has not previously been demonstrated. To investigate the Tsac Nfn further, we heterologously expressed, purified, and reconstituted the proteins NfnS (NfnA), NfnL (NfnB), and the putative partner Fd with iron-sulfur cluster and/or FAD cofactors. Activity assays monitoring the oxidation or reduction of Fd showed that, across pH 5-10, Tsac Nfn is catalytically biased towards the confurcating direction, favoring NADPH generation over NADPH oxidation by at least fivefold. Using protein electrochemistry, we also determined the reduction potentials of the cofactors in NfnL and Fd. These results indicate that the energetic landscape of FBEB in Tsac Nfn is similar to that in an ortholog. However, Tsac Fd has redox properties distinct from previously assayed Fds, suggesting that the identity and redox properties of Fd may help determine the catalytic bias of Nfn. Additionally, we confirmed the standalone ferredoxin: NADP+ oxidoreductase (FNOR) activity of NfnL but found it to be low and likely insignificant for in vivo redox conversion. We also show how the catalytic bias of Nfn integrates with the hydrogen cycling mechanism proposed in Tsac to better explain cofactor balancing for ethanol production. Our work advances the understanding of electron transfer processes within metabolic networks for the generation of valuable bioproducts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1975

Anomalous volume change of gramicidin A in ethanol solutions

Results of studies aimed at clarifying the failure of gramicidin A (GA) to sediment in early experiments are analyzed. In the present work, no sedimentation was observed in pure pentanol or ethanol, while normal sedimentation was observed in ethanol-water mixtures. It is concluded that GA exists in two conformations that differ in volume. Since the apparent specific volume in absolute ethanol sinks to its lowest values on increasing concentration, the GA molecule probably unfolds completely in conditions favorable for dimerization.

Derechin, M.↗
NASA NTRS2016

Assessment of Ethanol Trends on the ISS

The International Space Station (ISS) Environmental Control and Life Support System (ECLSS) provides a working environment for six crewmembers through atmosphere revitalization and water recovery systems. In the last year, elevated ethanol levels have presented a unique challenge for the ISS ECLSS. Ethanol is monitored on the ISS by the Air Quality Monitor (AQM). The source of this increase is currently unknown. This paper documents the credible sources for the increased ethanol concentration, the monitoring provided by the AQM, and the impact on the atmosphere revitalization and water recovery systems.

Perry, Jay↗
NASA NTRS2017

An IR Investigation of Solid Amorphous Ethanol-Spectra, Properties, and Phase Changes

Mid- and far-infrared spectra of condensed ethanol (CH3CH2OH) at 10-160 K are presented, with a special focus on amorphous ethanol, the form of greatest astrochemical interest, and with special attention given to changes at 155-160 K. Infrared spectra of amorphous and crystalline forms are shown. The refractive index at 670 nm of amorphous ethanol at 16 K is reported, along with three IR band strengths and a density. A comparison is made to recent work on the isoelectronic compound ethanethiol (CH3CH2SH), and several astrochemical applications are suggested for future study.

Hudson, Reggie L.↗