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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Effects of thermal pretreatment and catalyst on biomass gasification efficiency and syngas composition

This work explores the combined effects of thermal pretreatment and using a catalyst in situ on gasification carbon conversion efficiency, as well as product gas and tar content and compositions. To compare the effects of thermal pretreatment, pelletized and ground oak with three different levels of thermal pretreatment were gasified in a fluidized bed reactor. The pretreatments applied to the oak were (1) pelletization, (2) drying at 180 °C in air, and (3) torrefaction at 270 °C in nitrogen. The oak dried at 180 °C produced syngas of similar quality and approximately the same amount of char as untreated oak. Torrefaction at 270 °C resulted in syngas with a higher hydrogen to CO ratio, lower methane, and less than half of the total tar -- all of which are desirable properties in terms of product gas quality. However, the oak torrefied at 270 °C also produced more than two times the amount of char as the untreated, pelletized oak. To determine the effect of catalyst, a series of experiments were conducted using olivine impregnated with nickel and cerium as the fluidized bed material in the gasifier. These tests showed that modified olivine can improve hydrogen production and reduce methane and tar levels in the syngas. The result was observed for both treated and untreated oak; although the effect was more substantial for untreated oak, for which the use of modified olivine reduced tar concentrations in the product gas by 60%, with a larger reduction in heavier tars than lighter tars. Furthermore, this result is important because reduction in heavier tar plays a more important role in benefitting downstream operations.

09 BIOMASS FUELS↗
DOE OSTI2026

Opportunities and challenges in thermochemical conversion of municipal solid waste: A comprehensive review

Recent advancements in thermochemical conversion processes have elucidated new pathways for converting municipal solid waste into valuable resources. This review explores the primary thermochemical conversion methods, including combustion, gasification, pyrolysis, torrefaction, hydrothermal carbonization, and hydrothermal liquefaction, emphasizing their potential roles in waste management and energy recovery. Key challenges including feedstock variability, ash behavior, and scale-up limitations are discussed alongside opportunities for hybrid systems and circular economy integration. A comparative analysis of research publications indicates a significant focus on thermochemical pathways within the broader context of municipal solid waste research, underscoring the growing interest in these technologies. Recent advancements in each thermochemical process, alongside their operational, technical, and economic challenges, are discussed. Comparative data reveal that torrefaction enhances the hydrophobicity and grindability of municipal solid waste components, though its energy densification benefits are more modest than those observed in biomass. Hydrothermal carbonization and liquefaction are highlighted for their ability to process high-moisture and heterogeneous waste streams. The review also synthesizes recent findings on reactor configurations, emissions control, and synergistic effects in co-processing municipal solid waste fractions. The findings underscore the importance of developing standardized protocols for municipal solid waste characterization and the need for innovative hybrid systems to improve efficiency.

99 - GENERAL AND MISCELLANEOUS↗
DOE OSTI2021

Environmental and Economic Assessment of Portable Systems: Production of Wood-Briquettes and Torrefied-Briquettes to Generate Heat and Electricity

This study assessed the environmental impacts and economic feasibility of generating heat using wood-briquettes (WBs), and heat and electricity using torrefied-wood-briquettes (TWBs). WBs and TWBs were manufactured from forest residues using portable systems and delivered to either residential consumers or power plants in the United States. An integrated cradle-to-grave life-cycle assessment (LCA) and techno-economic analysis (TEA) approach was used to quantify environmental impacts and minimum-selling prices (MSPs) of heat and electricity, respectively. Results illustrated that 82% and 59% of the cradle-to-grave global warming (GW) impact of producing heat resulted from the feedstock preparation in WBs and torrefaction in TWBs, respectively. About 46–54% of total cost in the production of heat were from labor and capital costs only. The GW impact of electricity production with TWBs was dominated by the torrefaction process (48% contribution). Capital cost (50%) was a major contributor to the total cost of electricity production using TWBs. The GW impacts of producing heat were 7–37 gCO₂eq/MJ for WBs, and 14–51 gCO₂eq/MJ for TWBs, whereas producing electricity using TWBs was 146–443 gCO₂eq/kWhe. MSPs of generating heat from WBs and TWBs were €1.09–€1.73 and €1.60–€2.26/MJ, respectively, whereas the MSP of electricity from TWBs was €20–€25/kWhe. Considering carbon and pile-burn credits, MSPs of heat and electricity were reduced by 60–90% compared to the base-case.

Sahoo, Kamalakanta (ORCID:0000000277635296)↗
DOE OSTI2017

Impact of Thermal Pretreatment Temperatures on Woody Biomass Chemical Composition, Physical Properties and Microstructure

Thermal pretreatment of biomass by torrefaction and low temperature pyrolysis has the potential for generating high quality and more suitable fuels. To utilize a model to describe the complex and dynamic changes taking place during these two treatments for process design, optimization and scale-up, detailed data is needed on the property evolution during treatment of well-defined individual biomass particles. The objectives of this study are to investigate the influence of thermal pretreatment temperatures on wood biomass biochemical compositions, physical properties and microstructure. Wild cherry wood was selected as a model biomass and prepared for this study. The well-defined wood particle samples were consecutively heated at 220, 260, 300, 350, 450 and 550 °C for 0.5 h under nitrogen. Untreated and treated samples were characterized for biochemical composition changes (cellulose, hemicellulose, and lignin) by thermogravimetric analyzer (TGA), physical properties (color, dimensions, weight, density and grindablity), chemical property (proximate analysis and heating value) and microstructural changes by scanning electron microscopy (SEM). Hemicellulose was mostly decomposed in the samples treated at 260 and 300 °C and resulted in the cell walls weakening resulting in improved grindability. The dimensions of the wood were reduced in all directions and shrinkage increased with increased treatment temperature and weight loss. With increased treatment temperature, losses of weight and volume increased and bulk density decreased. The low temperature pyrolyzed wood samples improved solid fuel property with high fuel ratio, which are close to lignite/bituminous coal. Morphology of the wood remained intact through the treatment range but the cell walls were thinner. Lastly, these results will improve the understanding of the property changes of the biomass during pretreatment and will help to develop models for process simulation and potential application of the treated biomass.

09 BIOMASS FUELS↗
DOE OSTI2019

Negative Emission Energy Production Technologies: A Techno‐Economic and Life Cycle Analyses Review

Negative emission technologies (NETs) are of growing importance for society to meet the atmospheric carbon levels required to maintain global temperatures under sustainable limits. A wide range of NETs have been proposed, but there are limited NET assessments that integrate life cycle analysis (LCA) and techno‐economic analysis (TEA). This Review gathers NET TEA/LCA findings and compares their costs and greenhouse gas emissions. Eight different NET‐producing transportation fuels and power‐generation technologies are considered: anaerobic digestion (lignocellulosic), fermentation, torrefaction, combustion, fast pyrolysis, gasification, and hydrothermal liquefaction. Most of these technologies sequester carbon either as carbon dioxide or as biochar. Some are carbon negative by virtue of avoided or displaced emissions. Overall, results indicate that NET energy production costs range between $20 and $80 GJ −1 and have emissions from −400 to 100 kg CO 2,eq GJ −1 . These results suggest that there are potential tradeoffs to consider when developing NETs. These results also show that future TEA/LCA studies of NETs are needed to decrease their uncertainty and improve their technology readiness level.

Li, Wenqin↗
DOE OSTI2018

Strategies for Reducing Moisture Content in Forest Residues at the Harvest Site

Abstract. The moisture content (MC) of biomass derived from forest residues can pose a challenge to biomass utilization. It plays a significant role in determining the cost of transportation and subsequent market price. Additionally, emerging biomass conversion technologies, such as gasification, torrefaction, and briquetting, have very narrow specifications for the MC (e.g., <15%) in their feedstocks. The goal of this study was to develop strategies for reducing moisture content by evaluating different arrangement patterns of forest residues and its effect on MC reduction at the harvest site. The study compared four different arrangement patterns including criss-cross, teepees, traditional piling (processor piled), and scattered residues in three different timber harvest units in northern California. Two of the arrangement patterns (criss-cross and processor piled) were also covered with a plastic cover. Samples were collected from each treatment using a transect method and were recorded for 12 months. There was an overall drop of MC from 52% (freshly cut) to 12% between all arrangements over the study period. The cost of construction per pile, averaged $37, $41, and $48 for teepees, criss-cross, and processor piles, respectively. Even though, there was no significant difference in MC reduction between piles (except scattered), each pile arrangement of forest residues directly affected biomass feedstock operations, logistics, and costs. Keywords: Feedstock quality, Logging slash, Transect sampling method, Woody biomass energy.

Agriculture↗
DOE OSTI2014

Jointly Sponsored Research Program on Energy Related Research

Cooperative Agreements, DE-FC26-08NT43293, DOE-WRI Cooperative Research and Development Program for Fossil Energy-Related Resources began in June 2009. The goal of the Program was to develop, commercialize, and deploy technologies of value to the nation’s fossil and renewable energy industries. To ensure relevancy and early commercialization, the involvement of an industrial partner was encouraged. In that regard, the Program stipulated that a minimum of 20% cost share be achieved in a fiscal year. This allowed WRI to carry a diverse portfolio of technologies and projects at various development technology readiness levels. Depending upon the maturity of the research concept and technology, cost share for a given task ranged from none to as high as 67% (two-thirds). Over the course of the Program, a total of twenty six tasks were proposed for DOE approval. Over the period of performance of the Cooperative agreement, WRI has put in place projects utilizing a total of $\$$7,089,581 in USDOE funds. Against this funding, cosponsors have committed $\$$7,398,476 in private funds to produce a program valued at $\$$14,488,057. Tables 1 and 2 presented at the end of this section is a compilation of the funding for all the tasks conducted under the program. The goal of the Cooperative Research and Development Program for Fossil Energy-Related Resources was to through collaborative research with the industry, develop or assist in the development of innovative technology solutions that will: • Increase the production of United States energy resources – coal, natural gas, oil, and renewable energy resources; • Enhance the competitiveness of United States energy technologies in international markets and assist in technology transfer; • Reduce the nation's dependence on foreign energy supplies and strengthen both the United States and regional economies; and • Minimize environmental impacts of energy production and utilization. Success of the Program can be measured by several criteria. Using the deployment of the federal funding with industrial participation as a performance criterion, over the course of the program, the cosponsors contributed more dollars than the federal funds. As stated earlier, a little more than half of the funding for the Program was derived from industrial partners. The industrial partners also enthusiastically supported the research and development activities with cash contribution of $\$$4,710,372.67, nearly 65% of the required cost share. Work on all of the tasks proposed under the Cooperative Agreement has been completed. This report summarizes and highlights the results from the Program. Under the Cooperative Agreement Program, energy-related tasks emphasized petroleum processing, upgrading and characterization, coal and biomass beneficiation and upgrading, coal combustion systems development including oxy-combustion, emissions monitoring and abatement, coal gasification technologies including gas clean-up and conditioning, hydrogen and liquid fuels production, and the development of technologies for the utilization of renewable energy resources. Environmental-related activities emphasized cleaning contaminated soils using microbial fuel cells, development of processes and sorbents for emissions reduction and recovery of water from power plant flue gas, and biological carbon capture and reuse. Technology enhancement activities included resource characterization studies, development of improved methods, monitors and sensors. In general the goals of the tasks proposed were to enhance competitiveness of U.S. technology, increase production of domestic resources, and reduce environmental impacts associated with energy production and utilization. Technologies being brought to commercialization as a result of the funds provided by the Cooperative Agreement contribute to the overall goals of the USDOE and the nation. Each has broad applicability both within the United States and abroad, thereby helping to enhance the competitiveness of U.S. energy technologies in international markets and assisting in technology transfer. Under the Cooperative Agreement Program, WRI has furthered the development of two different coal upgrading technologies. River Basin Energy technology was scaled-up and demonstrated at a nominal 40 tpd size. Similarly, WRI’s patented mercury removal technology further developed into WRITE Coal technology which was then integrated into oxy-combustion and gasification systems for IGCC and fuels production. Integrated systems with WRITE Coal technology applied at the front end represent substantial environmental and efficiency gains. A variation of the RBE coal upgrading technology is being commercialized as a torrefaction technology for woody biomass. WRI worked with EPRI and NIST to develop and improve mercury calibration standards for emissions monitoring. Working with Chart Energy and Chemicals, WRI scaled-up compact reactor technology for the synthesis of fuels and chemicals from syngas. Compact reactor technology represents a five-fold increase in productivity over conventional reactors making smaller-scale distributed synthesis plants an economical viability. Similarly, WRI's patented mixed alcohol synthesis catalyst production is being scaled-up in collaboration with a commercial catalyst manufacturer.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2026

A Comprehensive Greenhouse Gas Assessment of Biomass-Based Carbon Dioxide Removal and Storage

Biomass-based Carbon Removal and Storage (BiCRS) is a suite of technological pathways that provide a relatively affordable and high-potential way to remove carbon dioxide from the atmosphere and simultaneously re-purpose residual biomass. BiCRS technologies are individually optimized to different biomass feedstocks, temperatures and oxygen, with the primary goal of capturing a high percentage of biomass-derived carbon dioxide and storing it in permanent below-ground storage (i.e. geologic storage), and a secondary goal of producing renewable energy. The current standard for BiCRS life cycle assessments does not account for greenhouse gas (carbon dioxide, methane and nitrous oxide) fluxes from surface soil amendment of BiCRS byproducts (e.g. char, ash) and their alternate fates. This is partly due to a paucity of empirical data due to the novelty of BiCRS conversion technologies, the range in feedstocks, and the heterogeneity of soils to which they might be amended. To fill this gap in in the life-cycle assessment and provide a realistic range of parameters for a soil amendment component of the BiCRS life cycle assessment, we conducted an incubation experiment to measure soil carbon changes, microbial respiration, methane fluxes, and nitrous oxide fluxes from two different soils amended with char- and ash- byproducts from biomass after gasification to hydrogen, fast pyrolysis to bio-oil, and torrefaction. Our results suggest that nitrous oxide and methane emission or consumption from BiCRS char amendments to soil are context dependent. Nitrous oxide emissions from amendments are higher in soils with higher pH, whereas some char amendments to low pH soil can reduce N 2 O emissions relative to control. In contrast, methane is emitted from BiCRS char amended to low pH soil, but consumed or neutral relative to control when amended to high pH soil. We present carbon and nitrogen mass balance throughout the experiment to help understand short-term durability of BiCRS chars and their counterfactuals, and preliminary suggestions for revisions to the broader BiCRS Measurement, Reporting, and Verification framework.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

A Comprehensive Greenhouse Gas Assessment of Biomass-Based Carbon Dioxide Removal and Storage

Biomass with Carbon Removal and Sequestration (BiCRS) is a suite of technological pathways that provide a relatively affordable and high-potential way to remove carbon dioxide from the atmosphere and simultaneously re-purpose residual biomass. BiCRS technologies are individually optimized to different biomass feedstocks, temperatures and oxygen, with the goal of capturing a high percentage of biomass-derived carbon dioxide and storing it in permanent below-ground storage (i.e. geologic storage). The current standard for BiCRS life cycle assessments does not account for carbon dioxide, methane and nitrous oxide (CO 2 , CH 4 , and N 2 O) fluxes from surface soil amendment of BiCRS byproducts (e.g. char, ash) and their alternate fates. This is partly due to a paucity of empirical data due to the novelty of BiCRS conversion technologies, the range in feedstocks, and the heterogeneity of soils to which they might be amended. To fill this gap in in the life-cycle assessment (LCA) and provide a realistic range of parameters for a soil amendment component of the BiCRS LCA, we conducted an incubation experiment to measure soil carbon changes, microbial respiration, methane fluxes, and nitrous oxide fluxes from two different soils amended with char- and ash- byproducts from biomass after gasification to hydrogen, fast pyrolysis to bio-oil, and torrefaction.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Integrating Biomass Conversion Technologies with Recovery Operations In-Woods: Modeling Supply Chain

Economic potential of feedstock generated low-valued forest residue can be enhanced by emerging biomass conversion technologies (BCT), such as torrefaction, briquetting, and gasification. However, for implementing these emerging processes within the woods, several hurdles are to be overcome, among which a balanced supply chain is pivotal. Centralized biomass recovery operation (CBRO) could be an economically viable solution in accessing harvesting sites and allows integration of BCT into forest management. The goal of this study was to examine the logistic effects of integrating a BCT into a CBRO, under different in-wood scenarios based on variations in travel time between the facility locations, amount of raw materials handled, intermediate storage capacity, and duration (number of days) of annual operations. Specific objectives included analyzing the effects of forest residue recoverability (BDMT, bone dry metric ton/ha), total transportation time from the harvest unit to the market, and the annual number of in-woods production sites on the overall efficiency of the BCT operations. Concurrently, this study examined the forest managerial impacts due to such an integration. Location-allocation tool (maximize market share problem type) within the ArcGIS Network Analyst platform was utilized to model the scenarios and generate one-way travel times from the harvest site to final markets. Results from geospatial analysis showed that there were 89–159 and 64–136 suitable locations for the BCT for logistics model (LM) I and II, respectively. Total one-way travel time for all the models ranged between 1.0–1.7 h. Additionally, the annual numbers of BCT sites was inversely proportional to the total one-way travel time (i.e., harvest unit to market). Arranging CBRO and BCT operations to occur at the same in-woods site returned shorter total and average travel times than arranging the two activities at separate in-woods sites. The model developed for this study can be used by forest managers and entrepreneurs to identify sites for placing BCTs in the forest that minimizes transportation times.

Paulson, Jeffrey↗
NASA NTRSDate not supplied

A Review of Existing Policies Affecting the Jettison of Waste in Low Earth Orbit and Deep Space

The management of waste generated onboard spacecraft during future long-duration deep-space missions will require different solutions from those currently implemented on the International Space Station which consist exclusively of collecting, storing, and returning the waste to Earth. Alternative options for managing spacecraft waste are to process it for recycling and recovery of resources, and to jettison it overboard in a solid form (such as a compacted tile) or in a gaseous form after torrefaction or other trash-to-gas technologies. The waste generated during a deep-space mission is derived mainly from spacecraft logistics supplies, food and beverage residues, personal or scientific items used by the crew, human metabolic waste, and unused spare components. Uncontained and unprocessed trash is a potential health hazard and a habitat volume liability, which makes onboard long-term storage an inefficient and non-optimal option. However, the jettison of solid, processed waste appears to be an effective solution for crewed deep-space missions, leading not only to volume reduction and habitat safening, but also to considerable mass savings in the spacecraft’s propulsion system. However, the disposal of trash overboard also creates a navigation hazard for spacecraft and the potential risk of contamination of planetary bodies, interfering with the search for life. This paper investigates the requirements covered by existing policies that could affect the jettison concept of operations and system design.

Jettison↗
NASA NTRSDate not supplied

Design of a Jettison System For Space Transit Vehicles

Many options to re-use waste are currently being developed by NASA. These include combustion, compaction, torrefaction, and converting waste materials to an easily stored base polymer for future use. Human exploration missions require large amounts of supplies such as food, clothing and spare parts. A many-month journey to Mars will result in the generation of a substantial amount of problematic waste products. It is thought that this waste must be discarded to enable a Mars transit mission. The most cost-effective, reliable, and safest method to address this problem may be to simply jettison these materials from the spacecraft. The ability to jettison requires a multi-component integrated system design. Major components include a launcher, airlocks, trash bags, and tracking system. Depending upon mission requirements, a jettison dedicated airlock may be necessary. In other cases, the crew airlock might be all that’s needed. Examples of what to jettison include food waste, fecal containers, broken equipment, foam, expendables, hygiene products, health items, wipes, and clothing. The most important design factor is always crew safety. Other features to consider are loss of air due to the inefficiencies of vacuum pumps in the airlock, outgassing from the bags, and liquids condensing on the airlock that result in unwanted coatings. The launching system design must consider many different features: while in planetary orbit, a minimum exit velocity is necessary so the jettisoned material will not complete an orbit only to return and strike the ship. Also, for planetary protection issues, enabling waste to be sent to distant non-critical locations is highly desirable. When the space craft is in planetary transit to say, Mars, the jettison exit velocity should be low if the material is not released along the direction of travel. This is to minimize trajectory perturbations due to jettison-imposed torque on the spacecraft. Design considerations for the launcher include exit velocity, power consumption, volume and mass of material jettisoned, and frequency of jettison. Finally, the launcher must be able to handle many different types and shapes of waste products. This paper will discuss these design issues and give guidance to a pathway forward.

Steve Sepka↗
DOE OSTI2021

Solid waste gasification: comparison of single- and multi-staged reactors

Interest in converting waste into renewable energy has increased recently due to concerns about sustainability and climate change. This solid waste is mainly derived from municipal solid waste (MSW), biomass residue, plastic waste, and their mixtures. Gasification is one commonly applied technology that can convert solid waste into usable gases, including H2, CO, CH4, and CO2. Single- and multi-staged reactors have been utilized for solid waste gasification. Comparison in reactor dimensions, operating factors (e.g., gasification agent, temperature, and feed composition), performance (e.g., syngas yield and selectivity), advantages, and disadvantages are discussed and summarized. Additionally, discussion will include economic and advanced catalysts which have been developed for use in solid waste gasification. The multi-staged reactor can not only be applied for gasification, but also for pyrolysis and torrefaction.

Zhao, Xianhui↗
DOE OSTI2025

Novel Preprocessing Techniques for Enhancing Flowability of Miscanthus

Purpose-grown energy crops possess significant potential as promising feedstocks for biofuel and biochemical production. However, similar to other biomass feedstocks, their utilization has been hindered by handling and feeding challenges such as clogging and segregation, which prevent biorefineries from operating at full capacity. These challenges arise primarily due to particle attributes including irregular shape, high flexibility, and high compressibility, leading to interlocking, high compaction, and significant friction under stress consolidation. To enhance operational reliability, it is crucial to focus on preprocessing techniques to address these issues, alongside accurately characterizing the mechanical and physical properties and flow performance of these feedstocks. This study investigates novel preprocessing techniques, including pelletization and torrefaction, to fundamentally alter these particle attributes and improve flowability. Miscanthus, an herbaceous energy crop, was the primary focus of this study. Samples were processed using a Forest Concepts Crumbler rotary shear system and an oscillating multi-stack screen bed to achieve two nominal (baseline) particle sizes: 6mm and 2mm. The study evaluated the efficiency and energy consumption of size reduction, revealing that while 2mm particles required more energy, they exhibited better flowability and higher yield strength compared to 6mm particles. Shear and compression tests assessed the material's shear strength, internal friction, and elastic modulus, while wedge-shaped hopper tests measured the critical arching distance and mass flow rate. The results provide valuable insights into the mechanical properties and processing efficiency of Miscanthus, contributing to the development of a preprocessing framework that enhances energy efficiency and material flowability in bioenergy production. However, further preprocessing and development are required to optimize this framework fully.

09 - BIOMASS FUELS↗
DOE OSTI2026

Are the U.S. Biorefineries Over the Hurdle of 2000 Ton Daily Throughput Yet?

The efficient utilization of lignocellulosic biomass for biofuel and biochemical production is hindered by material handling issues such as clogging and segregation among other challenges. Preprocessing methods such as drying, screening, and milling have improved conversion yield but have not sufficiently enhanced flowability, especially herbaceous biomass. The poor flowability of herbaceous biomass is rooted in some particle attributes that remain less altered by those methods, e.g., irregular particle shape, high roughness, and high compressibility, making it hard to scale up throughput to a key benchmark for a biorefinery – 2000 ton per day. Applying additional preprocessing methods like pelletization and torrefaction to drastically change those particle attributes can improve flow and handling but has not been comprehensively verified through test. The flowability of herbaceous biomass feedstock formats generated by three different preprocessing methods was recently assessed at Idaho National Laboratory’s Biomass Feedstock National User Facility: first, loose particles size reduced from as-received materials; second, pellets produced from an efficient densification process; and third, powders milled from torrefied pellets. Benchmarking tests including static angle of repose, basic flow energy measured in a powder rheometer, and discharge flow in an adjustable hopper, were conducted to evaluate those feedstock formats. Beyond the capacity of existing experimental apparatuses, a digital engineering approach involving flow simulations and AI models were used to identity the material attributes and processing parameters that have dominant influences on flow throughput. Techno-economic analysis focusing on hopper flow as a typical material handling operation was conducted for those feedstock formats. Perspectives will be discussed on whether the 2000-ton daily throughput for a biorefinery is achievable at an acceptable cost by using any of the tested preprocessing methods.

09 - BIOMASS FUELS↗
DOE OSTI2016

Thermal Pretreatment of a High Lignin SSF Digester Residue to Increase its Softening Point

Residues high in lignin and ash generated from the simultaneous saccharification and fermentation of corn stover were thermally pretreated in an inert (N2) atmosphere to study the effect of time and temperature on its softening point. These residues are difficult to feed into gasifiers due to premature thermal degradation and formation of reactive liquids in the feed lines, leading to plugging. The untreated and treated residues were characterized by proximate and ultimate analysis, and then analyzed via TGA, DSC, 13C NMR, Py-GC-MS, CHNO/S, and TMA. Interpretation of the compositional analysis indicates that the weight loss observed during pretreatment is mainly due to the thermal decomposition and volatilization of the hemicelluloses and amorphous cellulose fractions. Fixed carbon increases in the pretreated material, mostly due to a concentration effect rather than the formation of new poly-aromatic material. The optimal processing time and temperature to minimize the production of carbonyl groups in the pretreated samples was 300°C at a time of 30 minutes. Results showed that the softening point of the material could be increased from 187°C to 250°C, and that pretreatment temperature plays a more important role than time. The increase in softening point was mainly due to the formation of covalent bonds in the lignin structures and the removal of low molecular weight volatile intermediates.

Gasification, Lignin rich feedstocks, high lignin ↗
DOE OSTI2019

Stabilization of furanics to cyclic ketone building blocks in the vapor phase

Furanics are produced in high abundance from the decomposition of biomass. The thermal and chemical instability of these species leads to the formation of humins upon condensation. The ring rearrangement of furfural to form 2-cyclopentenone and cyclopentanone is known to occur in the condensed aqueous phase, but this requires operation in condensed acidic media where humin formation readily occurs. High hydrogen pressures are typically used to offset rapid polymerization reactions, limiting the yields of stable unsaturated products that result. We report that furfural can be selectively converted to 2-cyclopentenone and cyclopentanone in a single step over supported TiO 2 catalysts with both model compounds and real biomass-derived streams in the vapor phase. Selectivity for ring rearrangement vs. C—O cleavage over TiO 2 supported Ru and Pd catalysts can be tuned by manipulating the water partial pressure. The formation of these products in the absence of a condensed acidic stream also enables the tuning of reaction environments to favor the selective formation of unsaturated ketones, which could be valuable diolefin precursors. The incorporation of a TiO 2 support in the catalysts tested leads to the suppression of C—C hydrogenolysis/decarbonylation and enhancement of ring rearrangement reactions. The nature of the active sites for selective Csingle bondO cleavage as well as vapor phase ring rearrangement are discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

High temperature gasification of high heating-rate chars using a flat-flame reactor

The increasing interest in gasification and oxy-fuel combustion of biomass has heightened the need for a detailed understanding of char gasification in industrially relevant environments (i.e., high temperature and high-heating rate). Despite innumerable studies previously conducted on gasification of biomass, very few have focused on such conditions. Consequently, in this study the high-temperature gasification behaviors of biomass-derived chars were investigated using non-intrusive techniques. Two biomass chars produced at a heating rate of approximately 10 4 K/s were subjected to two gasification environments and one oxidation environment in an entrained flow reactor equipped with an optical particle-sizing pyrometer. A coal char produced from a common U.S. low sulfur subbituminous coal was also studied for comparison. Both char and surrounding gas temperatures were precisely measured along the centerline of the furnace. Despite differences in the physical and chemical properties of the biomass chars, they exhibited rather similar reaction temperatures under all investigated conditions. On the other hand, a slightly lower particle temperature was observed in the case of coal char gasification, suggesting a higher gasification reactivity for the coal char. A comprehensive numerical model was applied to aid the understanding of the conversion of the investigated chars under gasification atmospheres. In addition, a sensitivity analysis was performed on the influence of four parameters (gas temperature, char diameter, char density, and steam concentration) on the carbon conversion rate. Here, the results demonstrate that the gas temperature is the most important single variable influencing the gasification rate.

09 BIOMASS FUELS↗