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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Renewable low viscosity polyester-polyols for biodegradable thermoplastic polyurethanes

In the transition to renewably sourced, biodegradable polymers, the preparation of low viscosity polyester-polyols has posed a challenge for renewable polyurethane (PU) development. Low viscosity polyols not only reduce the requirement for high process temperatures but also decrease manufacturing time. In our efforts to incorporate increasing ratios of bio-based monomers into renewable PUs, we mixed diacids such as even carbon sebacic acid and odd carbon azelaic acid along with a renewable diol. This provided library of 2000 g/mol molecular weight polyester-polyols, and structures were established by 1 H and 13 C NMR analysis. The prepared polyester-polyols offered lower viscosity and enable lower fabrication temperatures to make TPUs, and their structure and material metrics were evaluated. The formation of TPUs is ascertained from FTIR and NMR analysis. The final TPUs displayed good physical and mechanical properties. Further, these TPUs exhibited T g in the range of -56.5 to -39.7°C, corresponding to TPU soft block structure, and T m between 98.3 and 105.1°C originating from the hard segment. Prepared TPUs exhibit excellent biodegradation under compost environmental conditions. These TPUs showed up to 57% decrease in molecular weight by GPC analysis after 9 weeks of biodegradation, and respirometer analysis displayed up to 97% biodegradation over 120 days.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Enzymatic depolymerization of polyester: Foaming as a pretreatment to increase specific surface area

Abstract Poly(ethylene terephthalate) (PET) is widely used for its high strength‐to‐weight ratio, gas barrier properties, and chemical resistance. The growing PET use highlights the demand for a better recycling system. Enzymatic recycling, alongside mechanical and chemical methods, is eco‐friendly and yields properties similar to virgin PET. Substrate properties ( T g , crystallinity, and specific surface area [SSA]) and enzyme stability significantly impact conversion efficiency. Higher SSA and lower crystallinity tend to yield improved depolymerization when employing leaf compost‐cutinase (LCC‐ICCG) enzymes. This study explored melt extrusion and foaming as pretreatment techniques to modify PET structural properties, using a low‐cost chemical foaming agent (CFA). The monomer conversion rate and efficiency during depolymerization were measured and related to the processing, extrudate micro‐ and meso‐structure, and polyester type. Pretreated PET substrates showed reduced T g , crystallinity, density, and enhanced SSA, resulting in a 90% mass loss for foamed RPET and VPET substrates within 2 days. In contrast, PET with ~30% of cyclohexanedimethanol comonomer exhibited a nearly 50% lower depolymerization rate, with zero BHET production. It indicates that the combination of low crystallinity, low T g , and high SSA leads to improved monomer conversion. These findings emphasize the significance of amorphization and foaming in enhancing PET enzymatic depolymerization.

42 ENGINEERING↗
DOE OSTI2024

In‐Situ Product Removal for the Enzymatic Depolymerization of Poly(ethylene terephthalate) via a Membrane Reactor

Poly(ethylene terephthalate) (PET) is a common single-use plastic and a major contributor to plastic waste. PET upcycling through enzymatic depolymerization has drawn significant interests, but lack of robust enzymes in acidic environments remains a challenge. This study investigates in-situ product removal (ISPR) of protons and monomers from enzymatic PET depolymerization via a membrane reactor, focusing on the ICCG variant of leaf branch compost cutinase. More than two-fold improvements in overall PET depolymerization and terephthalic acid yields were achieved employing ISPR for an initial PET loading of 10 mgPET ml buffer −1 . The benefit of ISPR was reduced for a lower initial loading of 1 mgPET ml buffer −1 due to decreased need for pH stabilization of the enzyme-containing solutions. A back-of-envelop analysis suggests that at a modest dilution ratio, ISPR could help achieve savings on caustic base solutions used for pH control in a bioreactor. Our study provides valuable insights for future ISPR developments for enzymatic PET depolymerization, addressing the pressing need for more sustainable solutions towards plastic recycling and environmental conservation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Phosphorus budgets of intensively managed row crops at a long–term agroecosystem research site in the upper US Midwest

Phosphorus (P) budgets for cropping systems provide insights for keeping soil P at optimal levels for crops while avoiding excess inputs. We quantified 12 years of P inputs (fertilizer and atmospheric deposition) and outputs (harvest and leaching losses) for replicated maize (Zea mays L.)—soybean (Glycine max L.)—wheat (Triticum aestivum) crop rotations under conventional, no-till, reduced input, and biologically based (organic without compost or manure) management systems at the Kellogg Biological Station LTAR site in southwest Michigan. Conventional, no-till, and reduced input systems were fertilized between 13 and 50 kg P ha –1 depending on year. Soil test phosphorus (STP) was measured at 0- to 25-cm depth every autumn. Leached P was measured as dissolved P in the soil solution sampled beneath the rooting depth and combined with modeled percolation. Fertilization and harvest were the predominant P fluxes in the fertilized systems, whereas only harvest dominated P flux in the unfertilized organic system. Leaching losses were minor terms in the budgets, but leachate concentrations were nevertheless close to the range of concern for downstream eutrophication. Over the 12-year study period, the organic system exhibited a negative P balance (–82.0 kg P ha –1 ), coinciding with suboptimal STP levels, suggesting a need for P supplementation. In contrast, the fertilized systems showed positive P balances (mean: 70.1 kg P ha –1 ) with STP levels well above agronomic optima. Results underscore the importance of tailored P management strategies to sustain crop productivity while mitigating environmental impacts.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

Effects of Copolymer Structure on Enzyme-Catalyzed Polyester Recycling

Polyesters are an omnipresent material used for a variety of applications (e.g., bottles, packaging, textile, windshield), roughly comprising 8% of plastics produced worldwide. Enzymatic recycling is an emerging solution to deal with the increasingly diverse polyesters that are not suitable for mechanical recycling. However, enzyme activity and efficiency are still the limiting factors impeding enzymatic recycling for different plastic waste forms. The effects of thermal and structural properties (e.g., glass transition temperature, crystallinity, specific surface area), which are determined by chemical composition and preprocessing, directly influence enzyme recycling efficiency. This work investigates two extrusion methods (single screw and twin-screw extrusion) to pretreat a range of copolyesters (RPET, PETG, Ecozen, Tritan and PBT) and modify their properties (i.e., glass transition temperature (T g ), crystallinity (%), and molecular weight (M n )). A PET-specific enzyme, leaf-branch compost cutinase (LCC ICCG ), produced from a fed-batch fermentation of Escherichia coli BL21(DE3), was used for the enzymatic depolymerization of different polyesters. Several copolyesters showed improved depolymerization after pretreatment, as measured by rate and amount of monomers produced. Furthermore, those that did not depolymerize were found to have exceptionally high glass transition temperature or percent crystallinity, highlighting the importance of these physical parameters on conversion efficiency.

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

The role of binding modules in enzymatic poly(ethylene terephthalate) hydrolysis at high-solids loadings

In nature, enzymes that deconstruct biological polymers, such as cellulose and chitin, often exhibit multi-domain architectures, comprising a catalytic domain and a non-catalytic binding module; the latter serves to increase the enzyme concentration at the substrate surface. This multi-domain architecture has been shown to improve the hydrolysis of poly(ethylene terephthalate) (PET) using engineered cutinase enzymes. Here, we examine the role of accessory binding modules at industrially relevant PET solids loadings necessary for cost-effective enzymatic recycling. Using a thermostable variant of leaf compost cutinase (LCC), we produced synthetic fusion constructs of LCC with five type A carbohydrate-binding modules (CBMs). At solids loadings below 10 wt%, the CBMs improve aromatic monomer yield from PET, but above this threshold, conversion extents up to 97% are reached with no added benefits from the presence of CBM fusions. This suggests that fusion constructs with the herein studied CBMs are not necessary for industrial enzymatic PET recycling.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Extraction of valuable chemicals from food waste via computational solvent screening and experiments

About 1.3 billion tons of global food production end up in landfills and composting, leading to significant anthropogenic greenhouse gas (GHG) emissions. Extracting antioxidant and antimicrobial chemicals (flavonoids, phenolic acids, etc.) from food waste is an economically lucrative valorization strategy but is hindered by efficient solvent selection. Here we perform in silico high throughput screening to identify high solubility solvents for key phenolics and reveal more than 100+ higher-performing solvents than the traditional ethanol and methanol. Solubilities of nine shortlisted solvents are measured and found in reasonable agreement with model predictions. Analysis of the Conductor like Screening Model for Real Solvents (COSMO-RS) σ-profiles and Hansen Solubility Parameters reveals that polarity and hydrogen bonding make dimethylformamide (DMF) an excellent single solvent. We showcase the replacement of high-solubility toxic solvents with green mixtures and demonstrate the approach to potato peel waste. As a result, our work provides a blueprint for solvent selection and generates new insights into extraction from food waste.

09 BIOMASS FUELS↗
DOE OSTI2022

Prospects for carbon-negative biomanufacturing

Biomanufacturing has the potential to reduce demand for petrochemicals and mitigate climate change. Recent studies have also suggested that some of these products can be net carbon negative, effectively removing CO 2 from the atmosphere and locking it up in products. This review explores the magnitude of carbon removal achievable through biomanufacturing and discusses the likely fate of carbon in a range of target molecules. Solvents, cleaning agents, or food and pharmaceutical additives will likely re-release their carbon as CO 2 at the end of their functional lives, while carbon incorporated into non-compostable polymers can result in long-term sequestration. Future research can maximize its impact by focusing on reducing emissions, achieving performance advantages, and enabling a more circular carbon economy.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Environmental life cycle assessment of treatment and management strategies for food waste and sewage sludge

A consequential life cycle assessment (LCA) was utilized to compare the environmental impacts of food waste and sewage sludge management strategies. The strategies included a novel two-phase anaerobic digestion (AD) system and alternatives including landfill, waste-to-energy, composting, anaerobic membrane bioreactor, and conventional AD (wet continuous stirred-tank reactor [CSTR]). The co-management of food waste with sewage sludge was also considered for the two-phase AD system and for a conventional AD reactor. Further, a multidimensional LCA approach was taken, considering the five-midpoint impact categories of global warming, smog, human health particulate, acidification, and eutrophication estimated using the U.S. EPA Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts. Co-management of food waste and sewage sludge using the novel two-phase AD system was shown to maximize energy recovery and had a net global warming benefit while reducing other environmental impacts compared with the alternative management strategies. It had similar relative environmental advantages across all categories as conventional AD, with the advantage of a smaller physical footprint. However, both approaches featured net environmental burdens when the background electric grid intensity fell below 0.25 kg CO 2 -eq kWh -1 , as could be expected in a decarbonized electric future. Upgrading the biogas produced from AD to renewable natural gas can displace the use of fossil natural gas for other non-electricity energy requirements that are difficult to decarbonize and may extend the time period of significant environmental benefits of utilizing AD for organic waste management. Treatment of the nutrient-rich supernatant generated by the novel two-phase AD system could be an obstacle for utilities with stringent nutrient discharge limits. Future research and full-scale implementation are needed to demonstrate the benefits of the two-phase AD system predicted through this analysis.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Renewable and Biodegradable Polyurethane Foams with Aliphatic Diisocyanates

The transition to renewable plastics will require the development of substitutes with existing industrial standards and manufacturing processes. Polyurethanes (PU), versatile plastics, are traditionally dominated by aromatic diisocyanates, which are challenging to derive from renewable sources. However, for higher biocontent, it is crucial to utilize aliphatic diisocyanates, which can be sourced from renewable plant or algae waste streams. Historically, PU foams relied on aromatic diisocyanates for essential hard segments, resulting in desired physical properties. Here, we report the generation of high-performance renewable and biodegradable PU foams utilizing aliphatic diisocyanates and aromatic polyols, translating hard segments into the polyester polyol component using biosourced furan dicarboxylic acid (FDCA) monomers. We demonstrate that an FDCA-based PU is suitable for foams with performance characteristics that meet commercial tolerances and can biodegrade under backyard compost conditions. Here, this demonstrates steps toward redesigning traditional petrochemical-based polymers to accommodate new biological monomers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Enhanced Weathering May Benefit From Co‐Application With Organic Amendments

Abstract Enhanced weathering has emerged as a promising natural climate solution that has the potential to remove billions of tons of carbon from the atmosphere if widely adopted in agricultural settings. Despite this potential, few field trials have been published that verify the carbon dioxide removal (CDR) potential of enhanced weathering in croplands and, until now, none had been published in grazing lands. Anthony et al. (2025, https://doi.org/10.1029/2024AV001480 ) conducted the first trial of enhanced weathering in a California rangeland and showed weathering of ground silicate rocks despite drought conditions in an already dry climate. Co‐application of inorganic (silicate rocks) with organic (biochar and compost) amendments revealed not just additive, but synergistic effects whereby organic amendments increased rates of weathering. This is important because field CDR rates were <10% of the theoretical maximum (i.e., the rate if basalt was completely weathered); thus, methods to improve weathering rates will be necessary for this practice to scale in a meaningful way. Multi‐carbon pool measurements revealed not only how co‐application of soil amendments heightened net carbon benefits, but also how soil amendments complemented each other to produce net benefits for soil carbon, biomass growth, and greenhouse gas emission reductions. Anthony et al. (2025, https://doi.org/10.1029/2024AV001480 ) produce new insights toward our understanding of enhanced weathering as well as introduce paths for future research concerning combined amendment applications, synergistic mechanisms for carbon storage, and deployment in various agricultural contexts. While questions remain about the fate of weathering products in arid regions, Anthony et al. (2025, https://doi.org/10.1029/2024AV001480 ) present novel findings on the potential for significant weathering to occur even under suboptimal conditions.

Almaraz, Maya [Yale Center for Natural Carbon Capt↗
DOE OSTI2024

Biocomposite thermoplastic polyurethanes containing evolved bacterial spores as living fillers to facilitate polymer disintegration

The field of hybrid engineered living materials seeks to pair living organisms with synthetic materials to generate biocomposite materials with augmented function since living systems can provide highly-programmable and complex behavior. Engineered living materials have typically been fabricated using techniques in benign aqueous environments, limiting their application. In this work, biocomposite fabrication is demonstrated in which spores from polymer-degrading bacteria are incorporated into a thermoplastic polyurethane using high-temperature melt extrusion. Bacteria are engineered using adaptive laboratory evolution to improve their heat tolerance to ensure nearly complete cell survivability during manufacturing at 135 °C. Furthermore, the overall tensile properties of spore-filled thermoplastic polyurethanes are substantially improved, resulting in a significant improvement in toughness. The biocomposites facilitate disintegration in compost in the absence of a microbe-rich environment. Finally, embedded spores demonstrate a rationally programmed function, expressing green fluorescent protein. This research provides a scalable method to fabricate advanced biocomposite materials in industrially-compatible processes.

36 MATERIALS SCIENCE↗
DOE OSTI2022

A chemical approach for the future of PLA upcycling: from plastic wastes to new 3D printing materials

As the demand for PLA increases, post-consumer disposal strategies must be carefully considered. While we would love to embrace a bioplastic future, we also need to tread carefully. Though PLA is widely claimed to be biodegradable, full degradation often requires conditions not typically found in landfills or industrial composting. Therefore, it will negatively impact the environment if treated carelessly. Here, in this work, we report a simple PLA upcycling path to turn existing PLA wastes into new 3D printable materials within 48 hours. The ester bonds of PLA can be cleaved efficiently via aminolysis. The obtained monomeric compound was derivatized with methacrylic anhydride, which introduces double bonds and thus a cross-linkable monomer is obtained. In combination with a comonomer and initiator, a photocurable resin is produced. The resin can be fed into any commercially available photocuring 3D printer. The 3D printed parts derived from PLA wastes exhibit impressive performances with a tensile strength of 58.6 MPa, Young's modulus of 2.8 GPa, and glass transition at ~180 °C. Our work demonstrates a new route to active upcycling of PLA while minimizing the need for disposal.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Polyhydroxyalkanoates in emerging recycling technologies for a circular materials economy

Circular polymer systems, specifically polyesters operating through chemical and biological technologies, are approaching a critical moment of industrial adoption and scale-up feasibility. At the same time, polyhydroxyalkanoate (PHA) production, scale-up, and resulting material development is converging toward commodity applications. The current PHA end-of-life philosophy, however, focalizes leveraging inherent biodegradability to circumvent plastic waste accumulation. If indeed a substantial replacement of incumbent single-use plastics with PHA alternatives is to be met in commercial manufacture, we emphasize the importance of linking PHA development with feasible polymer recycling technologies. In other words, a PHA materials economy is significantly more carbon- and cost-favorable when efficient mechanical (reprocessing), chemical (deconstruction, depolymerization), or biological (enzymatic) recycling is prioritized over biodegradation or composting. In this perspective, we discuss strategies for PHA recyclable-by-design principles, guidable by developing machine learning tools, as well as material compatibility with closed-loop recycling technologies. Additionally, we posit compelling life-cycle assessment incentives for adopting polymer reclamation over competing pathways. Ultimately, we hope this narrative further inspires the alignment between PHA design with growing calls for a circular material economy.

36 MATERIALS SCIENCE↗
DOE OSTI2021

A multi-omics approach to lignocellulolytic enzyme discovery reveals a new ligninase activity from Parascedosporium putredinis NO1

Lignocellulose, the structural component of plant cells, is a major agricultural byproduct and the most abundant terrestrial source of biopolymers on Earth. The complex and insoluble nature of lignocellulose limits its conversion into value-added commodities, and currently, efficient transformation requires expensive pretreatments and high loadings of enzymes. In this work, we report on a fungus from the Parascedosporium genus, isolated from a wheat-straw composting community, that secretes a large and diverse array of carbohydrate-active enzymes (CAZymes) when grown on lignocellulosic substrates. We describe an oxidase activity that cleaves the major β-ether units in lignin, thereby releasing the flavonoid tricin from monocot lignin and enhancing the digestion of lignocellulose by polysaccharidase mixtures. We show that the enzyme, which holds potential for the biorefining industry, is widely distributed among lignocellulose-degrading fungi from the Sordariomycetes phylum.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Soil management practices can contribute to net carbon neutrality in California

Stabilizing climate requires reducing greenhouse gas (GHG) emissions and storing atmospheric carbon dioxide (CO 2 ) in land or ocean systems. Soil management practices can reduce GHG emissions or sequester atmospheric CO 2 into inorganic and organic forms. However, whether soil carbon strategies represent a viable and impactful climate mitigation pathway is uncertain. A specific question concerns the role that land-management practices and soil amendments can play in realizing California's ambition for carbon neutrality by 2045. Here we examine the carbon flux impacts of soil conservation (i.e., compost, reduced tillage, cover crop) and enhanced silicate rock weathering (EW) practices at different areal extents of implementation in cropland, grassland, and savanna in California under two climate change cases. We show that with implementation areas of 15% or 50% of private cultivated land, grassland, and savanna in California, soil conservation practices alone can contribute $1.4^{2.1}_{0.7}$% ($-1.8^{-2.7}_{ -0.9}$ Mt CO 2 eq y -1 ) and $4.6^{6.9}_{2.3}$% ($-6.0^{-8.9}_{-3.0}$ Mt CO 2 eq y -1 ) of the additional emissions reduction needed (beyond previous targets) to meet the 2045 net neutrality goal (-129.3 Mt CO 2 eq y -1 ), respectively, on an average annual basis, including climate uncertainty. Including EW in these scenarios increases the total contributions of management practices to $4.1^{5.6}_{2.5}$% ($-5.2^{-7.3}_{-3.2}$ Mt CO 2 eq y -1 ) and $13.5^{18.6}_{8.2}$% ($-17.5^{-24.2}_{-10.7}$ Mt CO 2 eq y -1 ), respectively, of this reduction. This highlights that the extent of implementation area is a major factor in determining benefits and that EW has the potential to make a real contribution to net reduction targets. Results are similar across climate cases, indicating that contemporary field data can be used to make future projections. With EW there remains mechanistic uncertainties, however, such as rock dissolution rate and environmental controls on weathering products, which require additional field research to improve understanding of the technological efficacy of this approach for California's 2045 carbon neutrality goal.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

Measuring impacts of California agri-environmental programs using field-scale satellite data

In the past decade, California has invested over $\$$200 million in direct grants to growers to support the adoption of agricultural practices that save water and/or improve soil health while also reducing greenhouse gas emissions. Ex-post evaluation of agri-environmental outcomes of these grant programs, however, is limited. We use satellite data to monitor changes in field-level consumptive water use and greenness (i.e. normalized difference vegetation index), a proxy for agricultural productivity, for the most frequently funded crop-types (almonds, grapes, and walnuts) in two California Department of Food and Agriculture programs. Nearly 600 fields receiving funding during the 2014–2022 period were analyzed using two causal inference methods. Fields that received grants to both upgrade irrigation systems and install irrigation water management sensors showed reduced consumptive water use and greenness by an average of 3.5% and 4.2%, respectively (significant at the 10% level). In contrast, we find that the adoption of only irrigation water management sensors, which are designed to inform irrigation scheduling and management, resulted in an average increase of 4.1% and 4.8% in consumptive water use and greenness respectively (significant at the 5% level). We find negligible effects for either consumptive water use or greenness when both pump efficiency upgrades and sensors were implemented. We further find that grants for compost addition and cover cropping led to small greenness increases of 1.7% and 2.8% respectively (significant at the 10% level) and had insignificant effects on consumptive water use. Our analysis of five agri-environmental program interventions reveals that several practice outcomes may be at odds with stated program goals of reducing water use while maintaining or improving agricultural productivity.

agriculture↗