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At least 109 records · Page 6

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DOE OSTI2025

Unlocking the biofuel power of cover crop in Washington State: Enhancing potential through hydrothermal liquefaction

This study evaluates cover crops in Washington State (WA) as a renewable feedstock for hydrothermal liquefaction (HTL), supported by techno-economic (TEA) and life cycle (LCA) analysis. In the Pacific Northwest, fallow land is the common winter practice, generating no income for farmers. Over three years, field trials at two representative sites—Puyallup (cool, wet) and Othello (irrigated, no-till)tested triticale, hairy vetch, crimson clover, winter pea, and fava bean preceding cash crops. Biomass yields, composition, soil impacts, and net revenue were assessed across removal treatments. HTL conversion produced 32–37 wt% biocrude, lower than 48 wt% for sewage sludge, with modeled cradle-to-grave carbon intensities of 26–31 g CO 2 e/MJ and minimum fuel selling prices (MFSP) of $\$$6.75–$\$$7.18 per gallon gasoline equivalent (GGE), comparable to other lignocellulosic feedstocks. No significant changes were observed in soil carbon, nitrogen, or subsequent cash crop yields after cover crop removal. Farmer profitability was possible, particularly for triticale and hairy vetch at $\$$60 per dry ton. To address seasonal variability, blending with wastewater sludge was evaluated. All scenarios delivered >70 % carbon intensity reductions relative to fossil fuels, and with Renewable Identification Number (RIN) credits, MFSPs below $\$$2.5 GGE were achievable. These results demonstrate that cover crops can generate new revenue streams for farmers while serving as a flexible, low-carbon feedstock. Integrating cover crops with waste biomass offers a practical pathway to expand the bioeconomy and support year-round renewable fuel production.

Biofuels↗

DOE OSTI2022

Ionic-liquid-Assisted Fabrication of Lignocellulosic Thin Films with Tunable Hydrophobicity

Thin films with enhanced water repellency and mechanical strength can be fabricated from renewable lignocellulosic feedstock as a replacement for petrochemical-derived synthetic polymers, such that it minimizes life cycle impact on the environment and human health. In this work, hybrid poplar wood, either untreated (control) or pretreated with hot water at 160 °C for 20 min (HWE-20), 60 min (HWE-60), and 90 min (HWE-90), was dissolved in 1-ethyl-3-methylimidazolium acetate and regenerated to fabricate thin films. The HWE-90 films were enriched in lignin by 74%, specifically on the surface, which along with hemicellulose depletion imparted hydrophobicity (108° water contact angle) when compared to the control (56°), HWE-20 (77°), and HWE-60 (84°) films. They also exhibited 86% reduced water vapor sorption hysteresis and 75% improved storage modulus compared to the control. Thus, we demonstrate how to tune the lignocellulosic film properties via a combination of hot water pretreatment and ionic liquid dissolution.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2025

Computational analysis of interface-driven spin-orbit coupling in molecular adsorbates on transition metal dichalcogenides

Spin-orbit coupling (SOC) lifts molecular orbital degeneracy, enabling bilevel electronic platforms suitable for next-generation digital devices. However, common light-atom molecular feedstocks exhibit weak SOC due to the absence of heavy elements. To enhance SOC without synthesizing new materials, we leverage interfacial interactions between molecules and transition-element-based solid-state materials. This computational study investigates SOC splitting in metal-phthalocyanine adsorbed on transition metal dichalcogenides (TMDs) using density functional theory (DFT). The enhanced SOC splitting is attributed to strong orbital hybridization at the molecule-substrate interface. Specifically, Zn-phthalocyanine (ZnPC) on monolayer Mo⁢S 2 achieves a notable SOC splitting of ∼8 meV. Furthermore, when ZnPC forms self-assembled chains on Mo⁢S 2 , the splitting increases to ∼20 meV, driven by the formation of hybrid bands modulated by molecular periodicity. Furthermore, these findings highlight the role of interfacial and intermolecular interactions in inducing and enhancing SOC in surface-adsorbed molecules, providing a new strategy for molecular spintronic materials without complex synthetic efforts.

2-dimensional systems↗

NASA NTRSDate not supplied

Additive Manufacture of Refractory Metals for Aerospace Applications

High temperature refractory metals are required for a number of high temperature propulsion applications. Refractory metals are expensive, difficult to manufacture with high buy-to-fly ratios, and few vendors. Additive manufacture (AM) is used to produce C103, Molybdenum (Mo), and Tungsten (W) reaction chamber and thrust stand-off as well as Iridium ultra-fine lattice catalysts for integration into 1 N green propulsion thrusters. Refractory AM is in development and like traditional AM alloys requires substantial post-processing to include powder heat treatment, surface finish enhancement, inspection, and machining before placed in service. The combination of limited feedstock sources, high temperature processing, oxygen sensitivity, fracture prone nature, and need for elevated temperature mechanical testing limit the number of qualified facilities capable of post-processing AM refractory materials, which add to cost and schedule constraints. However, properly implemented refractory metal AM can overcome existing manufacture limitations by greatly increasing design flexibility, new material options, reduced price, decreased lead-time, and leverage the ever growing AM commercial supply base.

Refractory metal additive manufacture↗

NASA NTRSDate not supplied

Additive Manufacture of Refractory Metals for Aerospace Applications

Refractory metal additive manufacture↗

DOE OSTI2022

Systems and methods for additive manufacturing to encapsulate transformative colloidal suspensions

The present disclosure relates to an energy absorbing three dimensional (3D) structure. The structure may have an outer shell formed from a shell material. The outer shell may have a void forming a core volume. A transformative feedstock is contained in the void. The transformative feedstock is encapsulated within the outer shell, within the void, and provides enhanced energy absorbing properties to the 3D structure.

Mancini, Julie A.↗

DOE OSTI2025

Reducing Coke and Increasing Bio-Oil Yield during Catalytic Fast Pyrolysis of Biomass Using Phosphorus-Modified Zeolite Catalysts

Catalytic fast pyrolysis (CFP) is a promising strategy for producing hydrocarbon transportation fuels from biomass feedstocks. However, catalyst development is needed to increase bio-oil yields and enhance process economics. In this work, we demonstrate how post synthetic modification of formed ZSM-5 with phosphorus shifts CFP selectivity from coke and light gases toward the desired bio-oil product. Microscale experiments demonstrated reduced coke production relative to unmodified ZSM-5 and identified an optimal P loading. Extensive catalyst characterization revealed that P interacted with Al sites to reduce the acid site density, with preferential binding to the strongest acid sites. Insights from the microscale experiments were leveraged to produce kilogram quantities of formed P-ZSM-5 for evaluation in a larger semi-integrated process. These experiments generated liters of bio-oil that was hydrotreated and fractionated into gasoline, diesel, and jet cuts. The phosphorus-modified ZSM-5 improved CFP bio-oil yield, resulting in an 11% relative increase in the carbon yield from biomass to aviation fuel and a 14% decrease in the minimum fuel selling price. These results highlight the impact targeted changes in catalyst acidity, achieved by adding 2.5 wt % P, can have on the carbon efficiency and feasibility of fuel production from biomass feedstocks.

09 BIOMASS FUELS↗

DOE OSTI2024

Insights into Sustainable Nitrogen Fixation by Gas-phase Spectroscopic Measurements and Global Modeling of Reaction Intermediates in Humid Nitrogen Plasma

In this article, there is growing interest in reacting molecular nitrogen and water to sustainably synthesize fixed forms of nitrogen such as ammonia. In particular, low-temperature plasmas can activate these relatively inert feedstocks at or near room temperature without a catalyst. However, because of the enhanced reactivity and nonequilibrium chemistry, a diverse range of products is formed, and the underlying reaction mechanisms are exceedingly complex. In this work, we studied a simplified reactor consisting of a gaseous plasma containing controlled mixtures of nitrogen gas and water vapor. Densities of key chemical species such as N, H, OH, NH, and NO were measured by emission and laser-based spectroscopy as a function of the relative humidity. A global model was constructed and the reaction network was validated by comparing calculated species densities with experiments. We discover that N, a key initial intermediate for ammonia, strongly decreases in the presence of water vapor, and as a result, ammonia formation becomes limited at high relative humidity. This decrease is surprisingly not because N itself reacts, but because one of its main sources, an excited molecular nitrogen state, is reacted away. In addition, oxidation pathways for nitrogen, which lead to NO and related products, are found to be favored over reduction pathways because the corresponding reverse reactions are less significant. Together, this understanding helps explain previously reported observations of selectivity toward nitrogen oxides over ammonia, particularly at higher relative humidities.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

Identification of microRNAs responsive to arbuscular mycorrhizal fungi in Panicum virgatum (switchgrass)

Background: MicroRNAs (miRNAs) are important post-transcriptional regulators involved in the control of a range of processes, including symbiotic interactions in plants. MiRNA involvement in arbuscular mycorrhizae (AM) symbiosis has been mainly studied in model species, and our study is the first to analyze global miRNA expression in the roots of AM colonized switchgrass ( Panicum virgatum ), an emerging biofuel feedstock. AM symbiosis helps plants gain mineral nutrition from the soil and may enhance switchgrass biomass production on marginal lands. Our goals were to identify miRNAs and their corresponding target genes that are controlling AM symbiosis in switchgrass. Results: Through genome-wide analysis of next-generation miRNA sequencing reads generated from switchgrass roots, we identified 122 mature miRNAs, including 28 novel miRNAs. By comparing miRNA expression profiles of AM-inoculated and control switchgrass roots, we identified 15 AM-responsive miRNAs across lowland accession “Alamo”, upland accession “Dacotah”, and two upland/lowland F 1 hybrids. We used degradome sequencing to identify target genes of the AM-responsive miRNAs revealing targets of miRNAs residing on both K and N subgenomes. Notably, genes involved in copper ion binding were targeted by downregulated miRNAs, while upregulated miRNAs mainly targeted GRAS family transcription factors. Conclusion: Through miRNA analysis and degradome sequencing, we revealed that both upland and lowland switchgrass genotypes as well as upland-lowland hybrids respond to AM by altering miRNA expression. We demonstrated complex GRAS transcription factor regulation by the miR171 family, with some miR171 family members being AM responsive while others remained static. Copper miRNA downregulation was common amongst the genotypes tested and we identified superoxide dismutases and laccases as targets, suggesting that these Cu-miRNAs are likely involved in ROS detoxification and lignin deposition, respectively. Other prominent targets of the Cu miRNAs were blue copper proteins. Overall, the potential effect of AM colonization on lignin deposition pathways in this biofuel crop highlights the importance of considering AM and miRNA in future biofuel crop development strategies.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2024

Synergistic Thermo-Microbial-Electrochemical (T-MEC) Approach for Drop-In Fuel Production from Wet Waste

This project successfully developed and demonstrated the synergistic thermo-microbial-electrochemical (T-MEC) process, converting food waste into sustainable biofuels while achieving self-sustaining wastewater treatment and hydrogen production. By integrating hydrothermal liquefaction (HTL) and microbial electrolysis cells (MECs), the project advanced waste-to-fuel technology and expanded the understanding of sustainable waste valorization. It established a scalable framework for achieving high carbon efficiency, effective pollutant removal, and energy recovery, showcasing the potential of combining biological, thermal, and electrochemical systems to optimize resource recovery and reduce environmental impacts. The project demonstrated the technical effectiveness of the T-MEC process, achieving over 50% improvement in carbon efficiency and reducing waste processing costs by more than 25% compared to anaerobic digestion (AD). The HTL pilot reactor processed food waste at 90 kg/h, producing up to 200 L/day of biocrude oil with high conversion efficiency. A critical desalting step in pretreatment prevented catalyst fouling, enabling efficient hydrotreating with 100% deoxygenation and denitrogenation and sulfur reduction to <15 ppm. This positioned the kerosene fraction as a strong candidate for sustainable aviation fuel (SAF). The MECs achieved rapid startup, 86.4% COD removal, and hydrogen production rates of 1.8 L H 2 /L cat /day, among the highest recorded for pilot-scale systems. The integrated process achieved 65% carbon efficiency to biocrude and 58% to finished fuels, outperforming AD's 41% and 33% efficiencies for biogas and natural gas vehicle fuels. System analysis highlighted economic potential, with minimum fuel selling prices (MFSP) decreasing from $\$$25/GGE at 5 tpd to $\$$10/GGE at 500 tpd due to economies of scale. Future work will focus on reducing MEC material and membrane costs, enhancing performance through higher current densities, and creating tailored operational strategies for diverse feedstocks. Optimization of the integrated system will improve scalability and feasibility, positioning the T-MEC process as a competitive solution for converting wet waste into sustainable fuels and clean water. Beyond its technical and economic achievements, the project offers significant public benefits. The T-MEC process provides a sustainable alternative to landfilling and incineration, reducing greenhouse gas emissions and conserving resources. Converting waste into SAF and renewable fuels supports decarbonization in the transportation sector, advancing energy independence and reducing reliance on fossil fuels. Additionally, the process minimizes environmental pollutants, transforming them into valuable products like hydrogen and fuels, contributing to a cleaner and more sustainable future.

09 BIOMASS FUELS↗

DOE OSTI2022

A toolkit for plant lipid engineering: surveying the efficacies of lipogenic factors for accumulating specialty lipids

Plants produce energy-dense lipids from carbohydrates using energy acquired via photosynthesis, making plant oils an economically and sustainably attractive feedstock for conversion to biofuels and value-added bioproducts. A growing number of strategies have been developed and optimized in model plants, oilseed crops and high-biomass crops to enhance the accumulation of storage lipids (mostly triacylglycerols, TAGs) for bioenergy applications and to produce specialty lipids with increased uses and value for chemical feedstock and nutritional applications. Most successful metabolic engineering strategies involve heterologous expression of lipogenic factors that outperform those from other sources or exhibit specialized functionality. In this review, we summarize recent progress in engineering the accumulation of triacylglycerols containing - specialized fatty acids in various plant species and tissues. We also provide an inventory of specific lipogenic factors derived from a wide variety of organisms, along with their reported efficacy in supporting the accumulation of desired lipids. A review of previously obtained results serves as a foundation to guide future efforts to optimize combinations of factors to achieve further enhancements to the production and accumulation of desired lipids in a variety of plant tissues and species.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2024

Enhancing Electrochemical CO2 Conversion by Controlling Electrocatalysts' Structure

Electrochemical reduction of CO2 (CO2R) to valuable, carbon-neutral chemical feedstocks and storable fuels driven by renewable electricity has been recognized as one of the promising pathways to mitigate the greenhouse effect, reduce global demand for fossil fuels, achieve carbon neutrality, and create sustainable energy. Tremendous ongoing efforts have focused on controlling the morphology, composition, structure, size, defects, etc., of the electrocatalysts to improve product selectivity, activity, and durability to approach the feasibility of practical applications (current density higher than 200 mA/cm2 and lifetime ~1,000 hr+). This presentation will discuss how the geometry and surface composition of novel copper- and tin-based catalysts would maximize the CO2 conversion to carbon monoxide and liquid formic acid/formate in both common aqueous H-cell and electrolyzer configurations. Several spectroscopic, microscopic, and electrochemical characterization tools have been utilized to correlate the changes in the structural, physico-chemical, and electronic properties with the catalytic activity. Our work provides additional electrocatalyst design considerations for high-performance CO2 electrolysis.

Nguyen Phan, Thuy Duong↗

DOE OSTI2023

Lipid–enhanced Oilcane does not impact soil carbon dynamics compared with wild–type Sugarcane

The carbon neutral potential of bioenergy relies in part on the ability of feedstocks to sequester carbon (C) in the soil. Sugarcane is one of the most widely used bioenergy crops, yet there remain unknowns about how it impacts soil C dynamics. In addition, Oilcane, a genetically modified version of Sugarcane has been produced to accumulate more energy-dense oils and less soluble lignin, which enhances conversion efficiency but may also impact soil C cycling. Thus, our objectives were to examine the impact of Sugarcane litter decomposition on soil C formation and losses and determine if the genetic modifications to produce Oilcane alter these dynamics. To do this, we incubated bagasse (processed stem litter) and leaf litter from Sugarcane and Oilcane in microcosms with forest soil for 11 weeks. We used differences in natural abundance δ 13 C between C 3 forest soil and C 4 litter to trace the fate of the litter into respiratory losses as well as stable and unstable soil C pools. Our results show that genetic modifications to Oilcane did not substantially alter soil C dynamics. Sugarcane and Oilcane litter both led to net soil C gains dominated by an accumulation of the added litter as unstable, particulate organic C (POC). Oilcane litter led to small but significantly greater net soil C gains than Sugarcane litter due to greater POC formation, but the formation of stable, mineral associated organic matter (MAOC) did not differ between crop types. Sugarcane and Oilcane had opposing effects on tissue type where Sugarcane bagasse formed more MAOC, while Oilcane leaves preferentially remained as POC which may have important management implications. These results suggest that genetic modifications to Sugarcane will not significantly impact soil C dynamics; however, this may not be universal to other crops particularly if modifications lead to greater differences in litter chemistry.

09 BIOMASS FUELS↗

DOE OSTI2023

Simultaneously improved electrical and mechanical performance of hot-extruded bulk scale aluminum-graphene wires

Aluminum-based alloys are highly sought after as lightweight alternatives in electric grid applications. Improving the electrical conductivity of aluminum alloys has the potential to increase the energy efficiency of power transport. Here we used a hot extrusion process to synthesize AA1100 alloy with low-cost reduced graphene oxide nanoparticles to manufacture ultra-conductive aluminum composites in this study. The effects of graphene content on the electrical and mechanical performance of the composites were evaluated. The macroscale AA1100/graphene wires demonstrated a 2.1% enhancement in electrical conductivity at 20 °C, while the ultimate tensile strength increased by 6.1%. A Zener-Hollomon model was used to confirm the in-process exfoliation of the agglomerated graphene nanoparticle feedstock into high electrical conductivity graphene-like flakes during extrusion. They may have provided high-velocity carrier pathways leading to the enhanced electrical performance of the alloy. Transmission electron microscopy at aluminum-graphene interfaces ensures the preclusion of detrimental carbide formation during composite synthesis while confirming the structure graphene-like flakes. The in-process exfoliation provides an economically viable technique to produce bulk scale graphinated aluminum composites for advanced application and can be applied more generally to other alloy systems.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Hierarchical Cellulose Superinsulation Membrane

The environment-friendly components coupled with the ability to mimic the simplicity and originality of nature necessitate advanced sustainable materials with structural capabilities for energy-efficient applications. The use of feedstock deriving from plant-based, renewable organic material to produce nanofibril that embodies enhanced insulating properties and high mechanical strength constitutes an efficient development strategy. In this work, a free-standing, hierarchical superinsulation membrane by leveraging the principle of the bottom-up method is reported. The electrospun cellulose nanofibrils/aerogel-based core layer provides exceptional thermal properties with its thermal conductivity of 10.2 mW m –1 K –1 . The lightweight, flexible, and durable paper-like membrane features a tensile strength of 11.3 MPa and a bending rigidity in the order of 4.6 cN mm –1 . The hydrophobic superinsulation membrane material also exhibits a ΔT of ≈25 °C under continuous sunlight illumination and allows thermal runaway mitigation of rechargeable lithium-ion batteries. All the aforementioned properties position this hybrid superinsulation membrane as a promising material for energy-saving thermal management applications.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Improving biomass and lipid yields of Desmodesmus armatus and Chlorella vulgaris through mutagenesis and high-throughput screening

Advancement of microalgae for use as biofuel feedstock depends on bioprospecting novel strains and then applying classical strain improvement techniques to enhance desirable traits. Here we successfully demonstrate this approach using two novel strains of green algae, identified as Desmodesmus armatus and Chlorella vulgaris, to improve biomass and lipid yields. UV irradiation was utilized to generate random mutations and the resulting populations were analyzed via flow cytometry to quantify lipid fluorescence while enriching for high lipid variants using fluorescence activated cell sorting. Secondary screening was performed via in situ fluorescence staining to identify the single highest lipid producing mutants from each strain. This approach produced a Desmodesmus armatus mutant that exhibited both increased biomass productivity and higher lipid content, which doubled lipid yield from the culture. The resulting Chlorella vulgaris mutant exhibited an increase in growth only, resulting in a 33% increase in lipid yield.

09 BIOMASS FUELS↗

NASA NTRS1998

Enhanced Glow Discharge Production of Oxygen

Studies starting in late seventies have shown Mars atmosphere can be used as a feedstock for oxygen production using simple chemical processing systems during early phases of the Mars exploration program. This approach has been recognized as one of the most important in-situ resource utilization (ISRU) concepts for enabling future round trip Mars missions. It was determined a decade ago that separation of oxygen can be accomplished efficiently by permeation through a silver membrane at temperatures well below 1000 K. This process involves adsorption of atomic oxygen on the surface and its subsequent diffusion through a silver lattice via an oxygen concentration gradient. We have determined recently that glow discharge can be used to liberate atomic oxygen from Mars atmosphere and that the oxygen can be collected through a silver permeation membrane. Recently, we demonstrated a substantial increase in energy efficiency of the process by applying a radio frequency discharge in combination with a silver permeation membrane. The experiments were performed using pure carbon dioxide in the pressure range equal to Mars surface conditions. Energy efficiency was defined as the ratio of the energy required to dissociate a unit mass of oxygen from carbon dioxide to the (electrical) energy consumed by the overall system during the dissociation and collection process. The research effort, started at NASA Langley Research Center, continued with this project. Oxygen production apparatus, built and operated under the research grant NAG1-1140 was relocated to the Atomic Beams Laboratory at ODU in July 1996, being since then in fall operation.

Ash, Robert↗

DOE OSTI2025

Integrating AI and Multi-sensor Technology for better Bioenergy Preprocessing

Integrating multi-sensor identification with machine learning significantly enhances bioenergy preprocessing by using non-destructive, multi-spectral sensors to improve feedstock purity and quality. This approach not only reduces preprocessing costs but also ensures a more efficient and sustainable bioenergy production process.

09 - BIOMASS FUELS↗