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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Finite element modeling of biomass hopper flow

Hoppers are widely used biomass handling devices that channel bulk biomass from storage to subsequent handling equipment. Jenike’s longstanding approach, based on the Mohr-Coulomb model, has been successfully used to design hoppers handling cohesionless granular materials such as grains and other agricultural produces. However, designing a hopper to ensure reliable biomass flow is found to be challenging due to cohesion, irregular particle shape, and bulk material elastoplasticity. This study aims to address the biomass handling engineering challenge with alternative constitutive material models concerning the flow behavior of bulk solids. Finite element modeling is an approach that allows for implementation of different material models, whose underlying constitutive theories assist in investigating the origin and manifestation of bulk mechanical behavior of granular materials. This study focuses on the incipient gravity hopper flow of two types of biomass feedstocks, i.e., ground corn stover and Douglas fir wood. Three widely used constitutive material models, i.e., Mohr-Coulomb model, modified Cam-Clay model, and Drucker-Prager/Cap model, are implemented. Using the flow pattern represented by the volume of biomass exhibiting more than 7% of axial strain (Kamath and Puri, 1999), the finite element model predicts that the bulk corn stover particulate material forms an arch, which represents a hampered transition from the static state to the dynamic flow-state out of the hopper, whereas bulk Douglas fir wood particulate material develops a reliable mass flow pattern. A laboratory scale hopper was used to experimentally determine the biomass flow conditions, which were subsequently compared with the predicted onset of flow by a finite element model (FEM). The developed FEM was found to correctly predict the initiation of mass flow for the milled Douglas fir wood, whereas corn stover was predicted to establish a strong core flow suggesting an unreliable handling characteristic. This observation aligns with the reported poor handling of milled corn stover.

09 BIOMASS FUELS↗
DOE OSTI2017

Multiscale analyses of solar‐induced florescence and gross primary production

Abstract Solar‐induced fluorescence (SIF) has shown great promise for probing spatiotemporal variations in terrestrial gross primary production (GPP), the largest component flux of the global carbon cycle. However, scale mismatches between SIF and ground‐based GPP have posed challenges toward fully exploiting these data. We used SIF obtained at high spatial sampling rates and resolution by NASA's Orbiting Carbon Observatory‐2 satellite to elucidate GPP‐SIF relationships across space and time in the U.S. Corn Belt. Strong linear scaling functions ( R 2 ≥ 0.79) that were consistent across instantaneous to monthly time scales were obtained for corn ecosystems and for a heterogeneous landscape based on tall tower observations. Although the slope of the corn function was ~56% higher than for the landscape, SIF was similar for corn ( C 4 ) and soybean ( C 3 ). Taken together, there is strong observational evidence showing robust linear GPP‐SIF scaling that is sensitive to plant physiology but insensitive to the spatial or temporal scale.

Wood, Jeffrey D.↗
DOE OSTI2020

Predicted annual biomass input to maintain soil organic carbon under contrasting management

Corn (Zea mays L.) residue is an important source of lignocellulosic feedstocks for meeting the US renewable energy goals. However, there is uncertainty in how much biomass can be sustainably harvested. The objectives of this study were to (i) simulate soil organic carbon (SOC) dynamics in the 0–20, 20–30, and 0–30 cm soil depths for the 2005–2015 study period using CQESTR, a process-based C model; (ii) establish trends in SOC with residue removal and tillage management over the predictive period of 2016–2035; and (iii) recommend practices to maintain SOC stocks in a corn–soybean (Glycine max L. [Merr.]) rotation with corn residue removal in western Minnesota. The residue removal treatments in the conventional tillage since 1995 (CT 95 ) and no tillage since 1995 (NT 95 ) were initiated in 2005, and in 2006 for the no tillage since 2005 (NT 05 ). Corn residue removal treatments were none, cob removal, ~50% removal, and ~75% removal (R0, RCob, R50, and R75, respectively). Only R0 in NT 05 increased SOC (0.32 Mg C ha –1 yr –1 ) stocks in the top 30 cm soil depth by 2035 with annual aboveground biomass input of 6.30 Mg ha –1 yr –1 . It was concluded that only the NT 05 field has the potential to maintain SOC at the current rate of biomass addition, and a minimal annual aboveground C (MSC) input of 3.75 Mg C ha –1 yr –1 is required to maintain SOC until 2035. These simulation results indicate that caution should be used in removing residue especially under conventional tillage.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Optimal blending management of biomass resources used for biochemical conversion

This research develops an optimization model to describe the tradeoff among blend components in the least-cost biomass blend, based on resource availability, quality requirements, and logistics cost for a biochemical conversion. A mixed-integer linear programming model is developed to determine the least-cost blend from a set of candidate feedstocks. A case study – based on a biorefinery located in western Kansas that uses three-pass corn stover, two-pass corn stover, switchgrass, miscanthus, and municipal solid waste fractions to meet biochemical conversion specifications and feedstock demand – shows that the delivered cost of an optimal blend that meets carbohydrate and ash specifications is 12.12% higher than the delivered cost of optimal blend that meets a carbohydrate specification only. The results indicate that a least-cost blend that meets both carbohydrate and ash specifications consists of miscanthus (48.2%) and switchgrass (29.4%) whereas the least-cost blend meeting carbohydrate specification only comprises three-pass corn stover (55.4%) and two-pass corn stover (20.4%). Here an optimal blend uses a low-cost municipal solid waste fraction in all cases, implying that blending could be a potential strategy to reduce delivered feedstock cost.

09 BIOMASS FUELS↗
DOE OSTI2019

Setting a baseline for Integrated Landscape Design: Cost and risk assessment in herbaceous feedstock supply chains

The literature on bioenergy has pointed out that financial risks and limited performance benchmarks are leading barriers to wide-spread industry expansion. The purpose of this paper is to document a baseline cost and risk assessment from the perspective of biorefinery management for two herbaceous feedstocks, switchgrass and corn stover, in an application of Integrated Landscape Design (ILD). Integrating energy crops into row crops has attracted considerable attention leading to a variety of ways to implement ILD. However, variation in production conditions, different methods of implementing unit operations, and technology performance variability are among many factors leading to financial risk facing biorefineries from feedstock supply based on ILD. Utilizing data from field-based trials on switchgrass and corn stover in Virginia and Iowa in the United States, we estimate feedstock logistics cost and characterize it by a distribution of potential outcomes. The results show that, across fields included in the study, logistics cost for switchgrass vary from 73 per Mg to 171 per Mg. For corn stover, the inter-field variation in cost ranges from 83 per Mg to 105 per Mg. Results for intra-field uncertainty show that the cost for switchgrass ranges from 58 per Mg to 74 per Mg, and for corn stover they range from 50 per Mg to 65 per Mg. Furthermore, these results inform a baseline from which improvements in ILD can be compared, and provide biorefinery management with a starting point for cost and risk estimates of feedstock from ILD.

09 BIOMASS FUELS↗
DOE OSTI2022

Plant litter traits control microbial decomposition and drive soil carbon stabilization

Efforts to manage soils for carbon (C) sequestration remain limited by our understanding of how differences in plant traits and microbial traits mechanistically drive soil organic C (SOC) storage. Addressing this uncertainty is particularly critical in bioenergy agriculture, due to its potential to enhance soil C and provide a C neutral fuel. As such, we examined differences between two contrasting feedstocks, Zea mays (corn) and Miscanthus x giganteus (miscanthus), in the ability of their litter to form new chemically resistant particulate SOC vs. physically protected mineral associated SOC and used this data to improve the parameterization of a microbial SOC model. We tested a hypothesized conceptual model whereby easy to decompose corn litters drive greater microbial carbon use efficiency (CUE) and the formation of more mineral associated SOC over particulate SOC than more complex miscanthus litters. To do this, we performed a soil microcosm experiment where we added 13 C enriched aboveground and belowground litters to soils and traced the fate of the 13 C into microbial respiration and SOC pools. We found that corn litters promoted higher microbial CUE (0.37) than miscanthus litters (0.24). In turn, corn litter formed approximately 50% more mineral associated SOC than miscanthus litters. Similarly, structurally complex root litters promoted a lower CUE and formed less mineral associated SOC than leaf and shoot litters for both crops. When we used our data to parameterize the SOC model, we found that modelling microbial trait differences uniquely allowed the model to capture the fate of litter C in SOC. Collectively, we found a robust link between litter quality, microbial efficiency, and the formation of SOC. This link bridges the empirical uncertainty in how different crops can form new soil C and provides an empirical basis for modelling SOC transformations.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Life Cycle Emissions and Health Cost Impacts of Producing Ethanol and Electricity from Willow and Switchgrass in the Riparian Buffers of Mid-Atlantic United States

The United States (US Mid-Atlantic Region (MAR) has the potential to grow a variety of perennial feedstocks such as switchgrass and shrub willow to increase domestic energy production. These cellulosic feedstocks have also shown improved ecosystem services, such as soil carbon sequestration, nitrate leaching reduction, and flood mitigation along rivers and streams as partially harvested riparian buffers. To examine the effects on greenhouse gases (GHGs) and criteria air pollutants (CAPs) from using these feedstocks to produce ethanol or electricity, we conducted a comprehensive life cycle assessment (LCA) and estimated the impact on human health costs when land use is changed from corn production for ethanol. Results indicate up to 54% reduced GHG per hectare from using willow and switchgrass feedstock sources to produce ethanol instead of corn. However, there was a trade-off in terms of CAP emission, as grass-based energy emitted more NO x and SO x compared to the corn ethanol pathway, except for SO X emissions from willow-based electricity. Electricity from cellulosic biomass had higher particulate matter (PM) emission compared to that from corn ethanol. Estimates for health cost to society ranged from $2498 ha –1 for electricity from switchgrass to a net benefit of $448 ha –1 for ethanol production from willow, depending on varying biomass yield under different market scenarios. Although using cellulosic feedstocks to produce bioenergy has great potential to reduce GHG emissions, CAP control measures are needed to manage CAP-induced health costs.

Bioenergy↗
DOE OSTI2021

Grassland-to-cropland conversion increased soil, nutrient, and carbon losses in the US Midwest between 2008 and 2016

After decades of declining cropland area, the United States (US) experienced a reversal in land use/land cover change in recent years, with substantial grassland conversion to cropland in the US Midwest. Although previous studies estimated soil carbon (C) loss due to cropland expansion, other important environmental indicators, such as soil erosion and nutrient loss, remain largely unquantified. In this study, we simulated the environmental impacts from the conversion of grassland to corn and soybeans for 12 US Midwestern states using the EPIC (Environmental Policy Integrated Climate) model. Between 2008 and 2016, over 2 Mha of grassland were converted to crop production in these states, with much less cropland concomitantly abandoned or retired from production. The net grassland-cropland conversion increased annual soil erosion by 7.9%, nitrogen (N) loss by 3.7%, and soil organic carbon loss by 5.6% relative to that of existing cropland, despite an associated increase in cropland area of only 2.5%. Notably, the above estimates represent the scenario of converting unmanaged grassland to tilled corn and soybeans, and impacts varied depending upon crop type and tillage regime. Corn and soybeans are dominant biofuel feedstocks, yet the grassland conversion and subsequent environmental impacts simulated in this study are likely not attributable solely to biofuel-driven land use change since other factors also contribute to corn and soybean prices and land use decisions. Nevertheless, our results suggest grassland conversion in the Upper Midwest has resulted in substantial degradation of soil quality, with implications for air and water quality as well. Additional conservation measures are likely necessary to counterbalance the impacts, particularly in areas with high rates of grassland conversion (e.g. the Dakotas, southern Iowa).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

Supplementing biofuel mandates with a carbon mitigation policy can lead to water quality co-benefits

Biofuel mandates can impact the environment in multiple ways that may be positive or negative, including affecting life-cycle greenhouse gas (GHG) emissions by displacing fossil fuels, affecting soil carbon stocks due to accompanying land use change, and water quality due to changes in fertilizer requirements and the mix of crops used as feedstocks. To achieve desired environmental outcomes in the presence of a biofuel mandate, additional policy instruments must be adopted to supplement the mandate. We develop an integrated and spatially explicit ecosystem-economic modeling framework to analyze the cost-effectiveness of alternative policies to achieve desired targets for GHG emissions reduction from the agricultural and fuel sectors in the USA and nitrate leaching reduction in the Gulf of Mexico below the levels that would be achieved by a corn ethanol and/or a cellulosic ethanol mandate in the USA. We find that while a corn ethanol mandate lowers GHG emissions, it increases nitrate leaching due to the expansion of corn production; a cellulosic ethanol mandate lowers both GHG emissions and nitrate leaching relative to a corn ethanol mandate, but the additional carbon and nitrate prices are needed to achieve anticipated GHG reduction and nitrate reduction targets. We also find that accompanying a biofuel mandate with a GHG reduction target alone leads to substantial nitrate reduction co-benefits, but a nitrate reduction target alone is less effective in reducing GHG emissions. Combining a GHG standard with a nitrate standard can achieve GHG and nitrate reduction targets at lower carbon and nitrate prices as compared to implementing each of these policies independently. Furthermore, our findings show that disregarding policy co-benefits can overestimate the GHG and nitrate prices needed to achieve policy targets and higher policy costs.

09 BIOMASS FUELS↗
DOE OSTI2018

Land management change greatly impacts biofuels’ greenhouse gas emissions

Harvesting corn stover for biofuel production may decrease soil organic carbon (SOC) and increase greenhouse gas (GHG) emissions. Adding additional organic matter into soil or reducing tillage intensity, however, could potentially offset this SOC loss. Here, by using SOC and life cycle analysis (LCA) models, we evaluated the impacts of land management change (LMC), i.e., stover removal, organic matter addition, and tillage on spatially explicit SOC level and biofuels’ overall life-cycle GHG emissions in U.S. corn-soybean production systems. Results indicate that under conventional tillage (CT), 30% stover removal (dry weight) may reduce SOC by 0.04 t C ha-1yr-1 over a 30-year simulation period. Growing a cover crop during the fallow season or applying manure, on the other hand, could add to SOC and further reduce biofuels’ life-cycle GHG emissions. With 30% stover removal in a CT system, cover crop and manure application can increase SOC at the national level by about 0.06 and 0.02 t C ha-1yr-1, respectively, compared to cases without such measures. With contributions from this SOC increase, the life-cycle GHG emissions for stover ethanol are more than 80% lower than those of gasoline, exceeding the U.S. Renewable Fuel Standard mandate of 60% emissions reduction for cellulosic biofuels. Reducing tillage intensity while removing stover could also limit SOC loss or lead to SOC gain, which would lower stover ethanol life-cycle GHG emissions to near or under the mandated 60% reduction. Without these organic matter inputs or reduced tillage intensity, however, the emissions will not meet this mandate. More efforts are still required to further identify key practical LMCs, improve SOC modeling, and accounting for LMCs in biofuel LCAs that incorporate stover removal.

Qin, Zhangcai↗
DOE OSTI2022

BrzostekEcologyLab/CORPSE-soil-jars

Efforts to manage soils for carbon (C) sequestration remain limited by our understanding of how differences in plant traits and microbial traits mechanistically drive soil organic C (SOC) storage. Addressing this uncertainty is particularly critical in bioenergy agriculture, due to its potential to enhance soil C and provide a C neutral fuel. As such, we examined differences between two contrasting feedstocks, Zea mays (corn) and Miscanthus x giganteus (miscanthus), in the ability of their litter to form new chemically resistant particulate SOC vs. physically protected mineral associated SOC and used this data to improve the parameterization of a microbial SOC model. We tested a hypothesized conceptual model whereby easy to decompose corn litters drive greater microbial carbon use efficiency (CUE) and the formation of more mineral associated SOC over particulate SOC than more complex miscanthus litters. To do this, we performed a soil microcosm experiment where we added 13C enriched aboveground and belowground litters to soils and traced the fate of the 13C into microbial respiration and SOC pools. We found that corn litters promoted higher microbial CUE (0.37) than miscanthus litters (0.24). In turn, corn litter formed approximately 50% more mineral associated SOC than miscanthus litters. Similarly, structurally complex root litters promoted a lower CUE and formed less mineral associated SOC than leaf and shoot litters for both crops. When we used our data to parameterize the SOC model, we found that modeling microbial trait differences uniquely allowed the model to capture the fate of litter C in SOC. Collectively, we found a robust link between litter quality, microbial efficiency, and the formation of SOC. This link bridges the empirical uncertainty in how different crops can form new soil C and provides an empirical basis for modeling SOC transformations.

Ridgeway, Joanna↗
DOE OSTI2015

Biogeochemical consequences of regional land use change to a biofuel crop in the southeastern United States

Here, the United States has mandated the production of 80 billion liters of second–generation biofuel by 2022, and several approaches to meet this target focus on using ligno–cellulosic ethanol from perennial grasses and non–food crops. The large–scale deployment of biofuel agronomy should consider high–yielding crops that meet ethanol production goals, choose appropriate landscapes for biofuel crops from a climate and food production standpoint, and a full consideration of the environmental impact of large–scale land use change. The southeastern United States has a long growing season conducive for producing high–yielding crops, and is relatively less important to US food production than the rain–fed Midwestern states that have been extensively studied for biofuel crops. We use the DayCent biogeochemical model to run simulation experiments to test the hypotheses that converting a large swath of traditional agriculture in the southeastern United States that is already utilized for bioenergy production (assuming 35% of current corn–soy, and 10% of grazed pasture hectares; ~950,000 ha) to energy cane will result in greater biomass production, increased soil C storage, decreased soil N losses and lower greenhouse gas emissions than a landscape of corn–soy rotations and interspersed grazed pasture. Our simulations suggest that energy cane above–ground productivity on former pasture and corn–soy fields would be between 52–59 million Mg dry mass per year, resulting in 21.1–23.7 billion liters of ligno–cellulosic ethanol, or ~28% of the 2022 US government mandate. DayCent did not predict significant changes in soil C flux from land conversion to energy cane, but simulations predicted lower rates of N loss compared to current agriculture. GHG emissions from energy cane landscapes were substantially higher on former pasture, but an order of magnitude lower when compared to corn–soy hectares. While further study is needed to ascertain the full economic and industrial feasibility of converting nearly 1,000,000 ha of land to energy cane production, our results suggest that such an undertaking could meet a sizeable fraction of the US ethanol mandate, reduce N pollution and GHG emissions, and avoid compromising land devoted to food production in the southeastern United States.

southeastern United States↗
DOE OSTI2018

Perennialization and Cover Cropping Mitigate Soil Carbon Loss from Residue Harvesting

While the US Midwest is expected to serve as a primary feedstock source for cellulosic biofuel production, the impacts of residue harvesting on soil organic carbon (SOC) may greatly limit sustainable production capacity. However, viable feedstock production could be realized through adoption of management practices and cropping systems that offset residue‐harvest‐induced SOC losses. Sequestration of SOC can be enhanced by increasing the duration of crop soil cover through cover or double cropping or cultivation of dedicated perennials. However, assessing the efficacy of such options across sites and over long periods is experimentally challenging. Hence, we use the Environmental Productivity Integrated Climate (EPIC) model to provide such an assessment. Model‐data integration was used to calibrate and evaluate model suitability, which exhibited reasonable effectiveness through R 2 of 0.97 and 0.63 for SOC stock and yield, respectively. Long‐term simulations indicate considerable capacity for offsetting SOC loss. Incorporating rye ( Secale cereal L.) into continuous corn ( Zea mays L.) and corn–soybean [ Glycine max (L.) Merr.] systems offset the SOC losses induced by harvesting 21.2 and 38.3% of available stover, respectively. Similarly, converting 20.4% of corn–soybean land to miscanthus ( Miscanthus × giganteus J.M. Greef & Deuter ex Hodkinson & Renvoize) or 27.5% of land to switchgrass ( Panicum virgatum L.) offset the SOC impacts of harvesting 60% of stover from the remaining corn–soybean lands. These responses indicate that adoption of such measures would sizably affect the life cycle consequences of residue‐derived biofuels and expand estimates of sustainable cellulosic feedstock production capacity from the US Midwest. Core Ideas EPIC suitably assessed SOC under annual, cover, double, and perennial crops. Perennial cultivation offset the SOC losses of considerable residue harvesting. Rye double crops offset sizable residue‐induced SOC losses. Adoption could greatly expand Midwestern sustainable biofuel production capacity.

Jones, Curtis D.↗
DOE OSTI2015

Manufacturing of Protected Lithium Electrodes for Advanced Lithium-Air, Lithium-Water & Lithium-Sulfur Batteries

The global demand for rechargeable batteries is large and growing rapidly. Assuming the adoption of electric vehicles continues to increase, the need for smaller, lighter, and less expensive batteries will become even more pressing. In this vein, PolyPlus Battery Company has developed ultra-light high performance batteries based on its proprietary protected lithium electrode (PLE) technology. The Company’s Lithium-Air and Lithium-Seawater batteries have already demonstrated world record performance (verified by third party testing), and we are developing advanced lithium-sulfur batteries which have the potential deliver high performance at low cost. In this program PolyPlus Battery Company teamed with Corning Incorporated to transition the PLE technology from bench top fabrication using manual tooling to a pre- commercial semi-automated pilot line. At the inception of this program PolyPlus worked with a Tier 1 battery manufacturing engineering firm to design and build the first-of-its-kind pilot line for PLE production. The pilot line was shipped and installed in Berkeley, California several months after the start of the program. PolyPlus spent the next two years working with and optimizing the pilot line and now produces all of its PLEs on this line. The optimization process successfully increased the yield, throughput, and quality of PLEs produced on the pilot line. The Corning team focused on fabrication and scale-up of the ceramic membranes that are key to the PLE technology. PolyPlus next demonstrated that it could take Corning membranes through the pilot line process to produce state-of-the-art protected lithium electrodes. In the latter part of the program the Corning team developed alternative membranes targeted for the large rechargeable battery market. PolyPlus is now in discussions with several potential customers for its advanced PLE-enabled batteries, and is building relationships and infrastructure for the transition into manufacturing. It is likely that the next step will be accomplished through a combination of joint venture partnering and licensing of the technology.

25 ENERGY STORAGE↗
DOE OSTI2016

Carbon Calculator for Land Use Change from Biofuels Production (CCLUB) Users’ Manual and Technical Documentation

The $\underline{C}$arbon $\underline{C}$alculator for $\underline{L}$and $\underline{U}$se Change from $\underline{B}$iofuels Production (CCLUB) calculates carbon emissions from land use change (LUC) for four different ethanol production pathways including corn grain ethanol and cellulosic ethanol from corn stover, Miscanthus, and switchgrass. This document discusses the version of CCLUB released September 30, 2014 which includes corn and three cellulosic feedstocks: corn stover, Miscanthus, and switchgrass.

09 BIOMASS FUELS↗
DOE OSTI2021

Demo 5: RapidClave Technology Demonstrations – Round II (Task 2)

The purpose of this project task was to make automotive composite part manufacturing more cost competitive for low volume production and thereby drive composite application innovation. The strategy was to incorporate low-cost preforming, snap cure resins, and RapidClave® processing to create an alternative to conventional automotive composite manufacturing based on SMC. The program used RapidClave® technology from Globe Machine Manufacturing, fast-curing (“snap cure”) epoxy resins from Hexion, and conformable/stretchable glass fiber reinforcement mats produced by Owens Corning for rapid preforming. O’Gara Armoring retrofits vehicles to meet special security needs, such as larger doors to facilitate easier entry into the vehicle. O’Gara has a variety of custom vehicles in need of custom doors that require affordable tooling to produce approximately 100 ship sets/year. The project focused on a composite door panel application provided by O’Gara that is currently made by manual chopped fiber spray-up processing. UDRI reverse-engineered the current composite door panel and created tooling for use in the RapidClave®. UDRI designed an improved composite door using MultiMat fiberglass reinforcement from Owens Corning. UDRI made snap cure resin films from Hexion resin. Finally, UDRI conducted molding trials to compare autoclave processing with RapidClave® processing. The technical goals of the project were to reduce tooling cost by 50% as compared to SMC compression molding and to reduce cycle time by 50% compared to current manual spray-up process. The approach to reduce tool costs is based on use of single sided tooling for use at 100 psi, as compared to matched metal SMC tooling. An added benefit realized from the program is that the Owens Corning mat provided more uniform thickness and improved performance. Tensile and flexural strengths and moduli were increased by at least 50%. This task also demonstrated a 75% decrease in cycle time. O’Gara is evaluating the technology demonstrated in this project for some of their current production. Additionally, there are new products O’Gara is pursuing which require higher production rates than their current products. O’Gara has identified these new products as good candidates for the RapidClave® technology. The cost advantages demonstrated by this project would then lead to significant economic development. In conclusion, this task successfully combined the RapidClave® technology from Globe with a snap cure epoxy resin film system from Hexion and preform material from Owens Corning. Further research is needed to better map the technical limits such as cycle time of these technologies. Additionally, the technology should be extended in terms of size and shape to include large parts outside of automotive applications, such as a small aircraft fuselage.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Perennializing marginal croplands: going back to the future to mitigate climate change with resilient biobased feedstocks

Managing annual row crops on marginally productive croplands can be environmentally unsustainable and result in variable economic returns. Incorporating perennial bioenergy feedstocks into marginally productive cropland can engender ecosystem services and enhance climate resiliency while also diversifying farm incomes. We use one of the oldest bioenergy-specific field experiments in North America to evaluate economically and environmentally sustainable management practices for growing perennial grasses on marginal cropland. This long-term field trial called 9804 was established in 1998 in eastern Nebraska and compared the productivity and sustainability of corn (Zea mays L.)—both corn grain and corn stover—and switchgrass (Panicum virgatum L.) bioenergy systems under different harvest strategies and nitrogen (N) fertilizer rates. This experiment demonstrated that switchgrass, compared to corn, is a reliable and sustainable bioenergy feedstock. This experiment has been a catalyst for other bioenergy projects which have also expanded our understanding of growing and managing bioenergy feedstocks on marginal cropland. We (1) synthesize research from this long-term experiment and (2) provide perspective concerning both the knowledge gained from this experiment and knowledge gaps and how to fill them as well as the role switchgrass will play in the future of bioenergy.

09 BIOMASS FUELS↗
DOE OSTI2019

Data from: Carbon debt of Conservation Reserve Program (CRP) grasslands converted to bioenergy production

Over 13 million ha of former cropland are enrolled in the US Conservation Reserve Program (CRP), providing well-recognized biodiversity, water quality, and carbon (C) sequestration benefits that could be lost on conversion back to agricultural production. Here we provide measurements of the greenhouse gas consequences of converting CRP land to continuous corn, corn–soybean, or perennial grass for biofuel production. No-till soybeans preceded the annual crops and created an initial carbon debt of 10.6 Mg CO2 equivalents (CO2e)·ha−1 that included agronomic inputs, changes in C stocks, altered N2O and CH4 fluxes, and foregone C sequestration less a fossil fuel offset credit. Total debt, which includes future debt created by additional changes in soil C stocks and the loss of substantial future soil C sequestration, can be constrained to 68 Mg CO2e·ha−1 if subsequent crops are under permanent no-till management. If tilled, however, total debt triples to 222 Mg CO2e·ha−1 on account of further soil C loss. Projected C debt repayment periods under no-till management range from 29 to 40 y for corn–soybean and continuous corn, respectively. Under conventional tillage repayment periods are three times longer, from 89 to 123 y, respectively. Alternatively, the direct use of existing CRP grasslands for cellulosic feedstock production would avoid C debt entirely and provide modest climate change mitigation immediately. Incentives for permanent no till and especially permission to harvest CRP biomass for cellulosic biofuel would help to blunt the climate impact of future CRP conversion.

09 BIOMASS FUELS↗