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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Biological response of eelgrass epifauna, Taylor's Sea hare ( Phyllaplysia taylori ) and eelgrass isopod ( Idotea resecata ), to elevated ocean alkalinity

Abstract. Marine carbon dioxide removal (mCDR) approaches are under development to mitigate the effects of climate change by sequestering carbon in stable reservoirs, with the potential co-benefit of local reductions in coastal acidification impacts. One such method is ocean alkalinity enhancement (OAE). A specific OAE method is the generation of aqueous alkalinity via electrochemistry to enhance the alkalinity of the receiving water by the extraction of acid from seawater, thereby avoiding the issues of solid dissolution kinetics and the release of impurities into the ocean from alkaline minerals. While electrochemical acid extraction is a promising method for increasing the carbon dioxide sequestration potential of the ocean, the biological effects of increasing seawater alkalinity and pH within an OAE project site are relatively unknown. This study aims to address this knowledge gap by testing the effects of increased pH and alkalinity, delivered in the form of aqueous NaOH, on two eelgrass epifauna in the US Pacific Northwest, Taylor's sea hare (Phyllaplysia taylori) and eelgrass isopod (Idotea resecata), chosen for their ecological importance as salmon prey and for their role in eelgrass ecosystems. Four-day experiments were conducted in closed bottles to allow measurements of the evolution of carbonate species throughout the experiment, with water refreshed twice daily to maintain elevated pH, across pHNBS (NBS standard scale) treatments ranging from 7.8 to 9.3. Sea hares experienced mortality in all pH treatments, ranging from 37 % mortality at pHNBS 7.8 to 100 % mortality at pHNBS 9.3. Isopods experienced lower mortality rates in all treatment groups, ranging from 13 % at pHNBS 7.8 to 21 % at pHNBS 9.3, which did not significantly increase with higher pH treatments. These experiments represent an extreme of constant exposure to elevated pH and alkalinity, which should be considered in the context of both the natural variation and the dilution of alkalinity experienced by marine communities across an OAE project site. Different invertebrate species will likely have different responses to increased pH and alkalinity, depending on their physiological vulnerabilities. Investigation of the potential vulnerabilities of local marine species will help inform the decision-making process regarding mCDR planning and permitting.

marine carbon dioxide removal↗
DOE OSTI2022

Geothermal Hydraulic Stimulation: Overview of Methods and Best Practices

This paper outlines important information related to the hydraulic stimulation of geothermal wells and considerations for regulators responsible for evaluating applications to conduct these operations. Hydraulic stimulation applied to geothermal wells is an evolving technology that is different from the hydraulic fracturing process widely used to complete unconventional oil and gas wells. Important differences relate to operating pressures, variations in rock and fracture processes, and characteristics and disposal of hydraulic fracture fluids. Hydraulic stimulation is not widely used in the geothermal industry; however, future development of enhanced geothermal systems (EGS) will require hydraulic stimulation in order to enhance and create fracture permeability to allow wells to deliver sufficient heat and fluid to power plants. Gigawatts of EGS potential have been identified (U.S. Department of Energy 2019), so it is expected that the use of hydraulic stimulation of geothermal wells will be more common in the future. At present, there are no formal regulations guiding drilling programs or sundry notices that propose hydraulic stimulation of geothermal wells. On federal lands, important constraints and oversight are embedded in the process for obtaining Geothermal Drilling Permits outlined in the Code of Federal Regulations (43 CFR Section 3262.11); in Geothermal Resource Order 2 (GRO 2) guidance for assessment and mitigation of impacts of geothermal operations as well as construction and testing of geothermal wells; and in a Bureau of Land Management (BLM) Induced Seismicity Instruction Memorandum (BLM 2018). Additionally, local knowledge from BLM field offices and expertise of BLM engineers, or that of state regulators for operations on private and state lands, will be applied to fully assess operator applications to conduct geothermal hydraulic stimulation activities. Significant research effort has been directed toward EGS, so geothermal hydraulic stimulation techniques, impacts, and results are evolving and becoming better understood, including adaptation of decades of oil and gas industry experience with hydraulic fracturing of unconventional reservoirs. Recent EGS activities in the United States provide details about hydraulic stimulation with respect to oversight, stimulation design, execution, and results. Based on experience to date, the important issues to address when hydraulically stimulating a geothermal well include the following: 1. Wellbore construction and integrity must be appropriate to protect groundwater and manage stimulation pressures. 2. Understanding of lithology, faults, fractures, and subsurface stress state is necessary to design stimulation plans and predict results. 3. Seismic monitoring allows for observation and mitigation of induced seismicity.

geothermal↗
DOE OSTI2019

Cameco Corporation's Approach to Legacy and Ongoing Waste Management Within the Fuel Services Division - 19124

Since 2011, a Fuel Services Division (FSD) employee has been dedicated to oversee divisional waste management with the goal of accelerating the recycle/disposal of accumulated legacy radioactive wastes stored at its Ontario operations in Blind River and Port Hope. The Blind River Refinery (BRR) and Port Hope Conversion Facility (PHCF) were previously owned by the federal Crown Corporation, Eldorado Nuclear, becoming part of Cameco in 1988 and Cameco Fuel Manufacturing (CFM), previously known as Zircatec Precision Industries, becoming part of Cameco in 2006. Accumulated legacy radioactive waste is stored at each of the facilities. This radioactive waste has accumulated from operations beginning in the 1930's in Port Hope and the 1980's in Blind River. Due to minimal commercially available outlets for the disposal and/or treatment of these wastes, the waste was managed onsite by storage in underutilized space in buildings, trailers and/or in the secured yard. This relatively low-cost practice meant that over decades, the inventory increased at an unsustainable rate until available space became a limiting factor. During this time, the labelling, inventory records, characterization details and other history of many of the waste materials was not maintained adequately. Due to the volume of waste that had accumulated, campaigns to address these deficiencies in information were not considered feasible, sustaining the issue of accumulation of low-level radioactive waste. Since 2011, FSD has completed annual campaigns to address the accumulated legacy waste, which has included processing of material for decontamination to meet the unrestricted release criteria under the Canadian Nuclear Substance and Radiation Devices Regulations (NSRDR), disposal of marginally contaminated wastes (<500 ppm uranium) at a permitted landfill in the United States, processing of contaminated materials to reduce the volume of low-level radioactive waste and disposal at a designated facility in Port Hope. In addition FSD has undertaken significant changes to radioactive waste management practices at each of the facilities. Multiple characterization techniques, including visual observation, review of process and other historical records, laboratory analysis and radiation scanning have been utilized in campaign planning to identify the scope and appropriate waste management technique(s) to reduce the inventory of stored material. This divisional waste management program has resulted in a significant change to how radioactive waste is generated, inventoried, characterized and managed within FSD and has increased the visibility within the leadership team of the opportunities and challenges of waste management, such as alignment with decommissioning planning, project planning and budgeting. The heightened awareness has led to better financial and physical resource planning to execute waste projects with a current projected elimination of the legacy waste within FSD by 2025. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

How Do Microphysical Processes Influence Large-Scale Precipitation Variability and Extremes?

Convection permitting simulations using the Model for Prediction Across Scales-Atmosphere (MPAS-A) are used to examine how microphysical processes affect large-scale precipitation variability and extremes. An episode of the Madden-Julian Oscillation is simulated using MPAS-A with a refined region at 4-km grid spacing over the Indian Ocean. It is shown that cloud microphysical processes regulate the precipitable water (PW) statistics. Because of the non-linear relationship between precipitation and PW, PW exceeding a certain critical value (PWcr) contributes disproportionately to precipitation variability. However, the frequency of PW exceeding PWcr decreases rapidly with PW, so changes in microphysical processes that shift the column PW statistics relative to PWcr even slightly have large impacts on precipitation variability. Furthermore, precipitation variance and extreme precipitation frequency are approximately linearly related to the difference between the mean and critical PW values. Thus observed precipitation statistics could be used to directly constrain model microphysical parameters as this study demonstrates using radar observations from DYNAMO field campaign.

58 GEOSCIENCES↗
DOE OSTI2025

Nature of innovations affecting photovoltaic system costs

Innovations improve technology costs through various kinds of engineering advancements, including changes to materials choices and device or process designs. Understanding how these innovations relate to cost change can reveal aspects of the process of technology evolution, yet developing such understanding is often not possible with a strictly quantitative approach due to data limitations. In this paper we develop a hybrid quantitative-qualitative framework for relating specific innovations to cost change by using the variables in a quantitative technology cost change model as an organizing principle. We demonstrate this framework by applying it to the cost decline in photovoltaic (PV) systems over the last five decades. This framework generates new understanding of a set of innovations that contributed to PV modules’ sustained cost decline and the more modest trends observed in balance-of-system (BOS) costs. The results show the great diversity of innovations that affected PV costs, drawing on wide-ranging fields of expertise within scientific research and practice. We find that there are differences in the characteristics of innovations that reduced the cost of PV modules compared to innovations influencing BOS costs. Numerous module innovations reduced costs by advancing manufacturing tools and processes that improved material quality. Many BOS innovations reduced costs through a combination of component design changes, integration, automation, digitalization, and standardization. Overall, most innovations in our sample affected PV hardware. However, some also target ‘soft technologies’ such as task durations through innovations like fast-track permitting, which require improved collaboration and process streamlining. This framework also provides insight into the nature of knowledge spillovers between technologies. Both module and BOS hardware innovations show the benefits of PV’s position within an ‘ecosystem’ of continuously advancing technologies in many industries, in particular semiconductors and electronics, and also point to the importance of public institutions for accelerating testing, permitting, and training.

14 SOLAR ENERGY↗
DOE OSTI2020

In situ electrochemical scanning/transmission electron microscopy of electrode–electrolyte interfaces

Insights into the dynamics of electrochemical processes are critically needed to improve our fundamental understanding of electron, charge, and mass transfer mechanisms and reaction kinetics that influence a broad range of applications, from the functionality of electrical energy-storage and conversion devices (e.g., batteries, fuel cells, and supercapacitors), to materials degradation issues (e.g., corrosion and oxidation), and materials synthesis (e.g., electrodeposition). To unravel these processes, in situ electrochemical scanning/transmission electron microscopy (ec-S/TEM) was developed to permit detailed site-specific characterization of evolving electrochemical processes that occur at electrode–electrolyte interfaces in their native electrolyte environment, in real time and at high-spatial resolution. This approach utilizes “closed-form” microfabricated electrochemical cells that couple the capability for quantitative electrochemical measurements with high spatial and temporal resolution imaging, spectroscopy, and diffraction. Here, we review the state-of-the-art instrumentation for in situ ec-S/TEM and how this approach has resulted in new observations of electrochemical processes.

25 ENERGY STORAGE↗
DOE OSTI2018

Separation and Speciation of Mercury from Hanford 241-AP-107 Tank Waste Supernatant

Mercuric nitrate, Hg(NO 3 ) 2 , was introduced into the Hanford flowsheet when it was used to catalyze nitric acid dissolution of certain aluminum alloy fuels and to suppress radioiodine volatilization during nitric acid dissolution of short-cooled uranium metal fuel. Inventory estimates, based primarily on Hanford process-knowledge, suggest a total mercury inventory of 2,100 kg 1 in the Hanford Tank Farms. Aside from the obvious human exposure concerns via tank vapors, mercury species in the tank waste liquid and solid fraction pose risk to the implementation and execution of the River Protection Project mission due to mercury limits imposed under waste acceptance criteria, toxicity characteristic leaching procedure restrictions for secondary waste disposal, and air emission permits. Although there is currently no processing of tank waste at Hanford, waste processing is imminent and representative mercury inventory tracking will be important to anticipate and mitigate stack emissions and secondary liquid waste disposal issues like those experienced at the Savannah River Site.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Time-dependent THMC properties and microstructural evolution of damaged rocks in excavation damage zone

Modeling coupled thermo-hydro-mechanical-chemical (THMC) processes in host rocks near high-level nuclear waste (HLW) repositories at various time scales is an extremely challenging task. The current study integrates experimental, theoretical, and numerical methods in assessing the evolution of excavation damage zone (EDZ) over time and its implication on the long-term migration of hazardous species. Argillite and rock salt and are the focus of this study. The first part of the report presents a novel time-dependent directional microcrack damage theory for generic brittle rocks. It features detailed statistical description of the microcracks within a damaged solid, permitting a direct upscaling of microscale processes such as crack growth kinetics, crack closure/opening, sliding friction to explain the macroscopic creep, nonlinear elasticity, shear dilation, and loading-unloading hysteresis. This provides a basic platform for describing the anisotropic mechanical and transport properties of damaged rocks during excavation and subsequent THMC loadings. The model is validated and numerically implemented to Finite Element (FE) package ABAQUS through the user-defined material (UMAT) interface and have demonstrated great potential in resolving the time-dependent and anisotropic evolution of damage in the EDZ. The second part of the report presents a multi-scale experimental effort in characterizing the thermal, hydraulic, and mechanical properties of Mancos shale and Avery Island salt. For the Mancos shale, triaxial compression tests are performed at different confining pressures and temperatures to probe its thermomechanical properties relevant to HLW repositories. The obtained stress-strain data are interpreted using the proposed directional damage theory. Post-test specimens are subjected to gas permeability tests to reveal the correlation between permeability and the degree of microcracking. At microscale, temperature-controlled nanoindentation tests are performed and found a linear correlation between fracture toughness and elastic modulus from 25°C to 300°C. For Avery Island salt, we have designed and manufactured a novel relative-humidity controlled uniaxial creep device. Long-term creep tests at low stresses (< 5 MPa) are performed at different levels of relative humidity (RH). Besides confirming the much higher creep rates as one would expect through extrapolating the high-stress creep data, the results reveal that the steady-state creep rate of rock salt is strongly dependent on the ambient RH, an aspect that is often neglected in the literature. Both behaviors can be attributed to the pressure-solution creep mechanism which dominates at low stress and high RH levels. The third part of the report explores a set of numerical strategies in modeling the THMC behavior of porous geomaterials. A fully implicit, monolithic FE solution that can flexibly interface with different material models and coupling mechanisms for THMC problems is developed and verified through the ABAQUS user-defined element (UEL) interface. The scheme is used to study the THM response of a hypothetical HLW storage site with reference to an existing in-situ heater test. Strategies for integrating the UEL and the microcrack UMAT are suggested. Another numerical endeavor of this study is to implement a higher-order asymptotic homogenization method to account for the heterogeneous porous structures. The same method is then extended to perform microstructure-informed thermo-mechanical modeling of generalized continua. The above outcomes of this project provide a strong thrust towards enhancing the fundamental understanding and modeling capability of the long-term evolution of host rocks in EDZ, thus helping achieve the design goal of 1-million-year isolation of high-level nuclear wastes.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Laser Intensity Profile Effects on the Solidification Microstructure of Ti-6Al-4V and Ti-5553

Traditional machining of Ti-6Al-4V and Ti-5Al-5Mo-5V-3Cr (Ti-5553) is challenging due to high chemical reactivity, adiabatic shear band formation, and material cost. Titanium is attractive because of its high tensile strength, low density, corrosion resistance, and ability to withstand extreme temperatures. Selective Laser Melting (SLM) is capable of manufacturing geometrically complicated parts at a lower expense. Exceptional tolerances can be obtained with properly tuned processing parameters. Alterations on scan parameters permit microstructure and melt pool control. Single track laser melting experiments were performed on Ti-6Al-4V and Ti- 5553 using elliptical intensity profiles. Results show that maintaining constant energy density but increasing power results in a melt pool failing to penetrate the substrate for Ti-5553. Increasing laser energy density increases melt pool width and can increase powder bed denudation. Comparing Ti64 and Ti-5553 microstructures contributes to a better understanding of rapid solidification in titanium.

36 MATERIALS SCIENCE↗
DOE OSTI2021

UKy-CAER Heat Integrated Transformative CO 2 Capture Process in Pulverized Coal Power Plants

The goal of this Phase II Topical Report is to summarize the work for public domain conducted on project DE-FE0031583. Building upon the Design Basis completed during Phase I and in accordance with the Statement of Project Objectives (SOPO), the University of Kentucky (UK) Center for Applied Energy Research (CAER) (Recipient) along with team members has completed the Front End Engineering Design (FEED) for its advanced, versatile post-combustion CO 2 capture system (CCS) at the 10 MWe large pilot scale to be installed at the Wyoming (WY) Integrated Test Center (ITC), using a heat integrated process with split-rich fed, two-stage stripping and any advanced solvent to enhance the CO 2 absorber performance and lower the cost of CO 2 capture. The proposed project (Phases I-III) involves the design, fabrication, installation, testing and evaluation of a large pilot scale facility that will demonstrate the UK CAER transformative CCS integrated with an operating power plant. The work performed in Phase I, detailed in the Phase I Topical Report that was submitted in March 2019, included formation of a project team, securing the host site, and completing pre-FEED design basis, a cost estimation, a preliminary techno-economic analysis (TEA) and an environmental information volume (EIV). The work performed in Phase II, detailed in this Phase II Topical Report, includes completion of FEEDs, completion of a process risk analysis (PRA), obtaining necessary permits, updating the EIV and TEA, updating the cost and schedule estimate for the Phase III scope of work (SOW) and securing the necessary cost share. Updated information is provided on the current status of the UK CAER CCS technology and the project is ready to begin immediately detailed design, construction and operation of the proposed pilot.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2020

Iodine Speciation Effects in LAW Feeds

Tests were conducted on a DM10 vitrification system with prototypical off-gas treatment system, which includes an SBS, WESP, and evaporator based on the design of the evaporator to be installed at the WTP for concentration of the liquid effluents. This allowed determination of the partitioning and speciation of iodine between the melter and the off gas system components, including liquid effluents from the SBS and WESP as well as in the evaporator condensate and concentrate. Evaporator testing was decoupled from melter testing to permit filtration and pH adjustments of process solutions prior to evaporation. In addition, a slip stream was pulled from the exhaust downstream of the WESP and High-Efficiency Particulate Air (HEPA) filters and passed through a caustic scrubber simulating the WTP caustic scrubber to assess iodine partitioning to the caustic scrubber liquid effluent. The tests were conducted using simulated Hanford LAW from tank AP-107, which is the planned first feed for Direct Feed LAW (DFLAW) operations, at a nominal feed concentration of 5.6 molar Na over about 120 hours of testing.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Development of a Trace Detection Method for Mercury Speciation in Hanford Tank Waste - 19014

The U.S. Department of Energy's (DOE) Hanford Site in southeast Washington State stores 56 million gallons of chemical and radioactive waste stored in underground tanks. Mercury species in liquid and solid fractions of Hanford tank waste pose a risk to the implementation and execution of DoE's River Protection Project mission due to mercury concentration limits imposed under waste acceptance criteria, toxicity characteristic leaching procedure restrictions for secondary waste disposal, and air emission permits. Although there is currently no processing of tank waste at Hanford, waste processing is imminent, and representative mercury inventory tracking will be important to anticipate and mitigate stack emissions and secondary liquid waste disposal issues. A methodology to accurately determine total mercury and mercury speciation in Hanford tank waste, while maintaining low mercury detection limits, currently does not exist at Hanford. Moreover, the mercury species in the waste solids are unknown and may be waste type-specific. The development of an analytical method to separate and speciate mercury in tank waste was undertaken by the Pacific Northwest National Laboratory (PNNL) while leveraging an existing non-radiological, ultra-trace mercury detection technique frequently performed at PNNL's Marine Sciences Laboratory in Sequim, Washington. The ultimate goal of this work is to develop an analytical method to obtain detailed mercury speciation information and update flowsheet modeling assumptions related to mercury partitioning at Hanford. The first phase of testing was completed in the development of an analytical methodology for the low-level determination of total mercury, elemental mercury, methylmercury, and dimethylmercury in Hanford tank waste. This paper presents Phase I testing which focused on determining whether mercury species can be preconcentrated from aqueous Hanford tank waste solution onto a solid substrate, while simultaneously eliminating or very significantly reducing the parent radionuclide activity. This was demonstrated by developing protocols for the separation and preconcentration of total mercury and methylmercury onto solid substrates, then measuring the substrates for radiological content at PNNL's Radiochemical Processing Laboratory on the Hanford Site. The mercury content was successfully separated onto stable substrates and the radionuclide activity reduction was significant enough that the preconcentrated samples could be subjected to quantification using far less restrictive handling and radiological controls than would be required for the parent sample (i.e., contamination area fume hood vs. hot cell). This mercury separation method required no sample dilution, which enables maximum mercury detectability, while still allowing mercury speciation. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Process Control Approach to Implement High Waste Loading Glass Formulations for Hanford Low Activity Waste Vitrification - 18435

Acceptable glass formulations for vitrification of Hanford low activity waste (LAW) at The Hanford Tank Waste Treatment and Immobilization Plant (WTP) must meet a variety of product quality, processability, and waste loading requirements. The glass formulation development work underpinning the WTP baseline LAW glasses was captured in a vitrification process control approach developed by the Vitreous State Laboratory (VSL) and Atkins Energy Federal EPC, Inc. that permits the calculation of the glass formulation required for each particular batch of LAW delivered to the LAW vitrification facility. Since that time, we have developed a wide range of glass formulations that achieve considerably higher waste loadings and which therefore are more economically attractive in terms of reduced amounts of glass produced and decreased time for treatment. That work was done in support of the Department of Energy's Office of River Protection program that is examining options to optimize the LAW facility and LAW glass waste form. Implementation of these high waste loading formulations at the WTP requires the development of a new LAW vitrification process control algorithm, which is the subject of this paper. Waste loadings in LAW glasses are typically limited by either the alkali loading for LAW with low sulfate content or the SO{sub 3} loading for LAW with high sulfate content. In the former case, waste loadings are limited by refractory corrosion and glass corrosion on the vapor hydration test (VHT) and product consistency test (PCT), all of which tend to increase with higher alkali concentrations. In the latter case, waste loadings are limited by the formation of a molten sulfate phase in the melter, which has deleterious effects. The LAW vitrification process control strategy must mitigate these effects while optimizing waste loadings. Given the composition of any LAW stream, the new LAW vitrification process control algorithm permits the calculation of a suitable high waste loading glass composition and the required glass forming additives such that all processing, waste loading, and product quality requirements are met. This algorithm was developed from data for a large number of glasses that were formulated, and characterized with respect to a variety of properties affecting processability and product quality; many of these formulations were also subjected to melter testing to verify acceptable processing characteristics, processing rates, and the absence of secondary sulfate phase formation. This paper describes the development of the present algorithm, comparisons to the present lower waste loading baseline WTP process control approach, and plans for further development and testing. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Cellulosic biofuel production using emulsified simultaneous saccharification and fermentation (eSSF) with conventional and thermotolerant yeasts

Abstract Background Future expansion of corn-derived ethanol raises concerns of sustainability and competition with the food industry. Therefore, cellulosic biofuels derived from agricultural waste and dedicated energy crops are necessary. To date, slow and incomplete saccharification as well as high enzyme costs have hindered the economic viability of cellulosic biofuels, and while approaches like simultaneous saccharification and fermentation (SSF) and the use of thermotolerant microorganisms can enhance production, further improvements are needed. Cellulosic emulsions have been shown to enhance saccharification by increasing enzyme contact with cellulose fibers. In this study, we use these emulsions to develop an emulsified SSF (eSSF) process for rapid and efficient cellulosic biofuel production and make a direct three-way comparison of ethanol production between S. cerevisiae , O. polymorpha , and K. marxianus in glucose and cellulosic media at different temperatures. Results In this work, we show that cellulosic emulsions hydrolyze rapidly at temperatures tolerable to yeast, reaching up to 40-fold higher conversion in the first hour compared to microcrystalline cellulose (MCC). To evaluate suitable conditions for the eSSF process, we explored the upper temperature limits for the thermotolerant yeasts Kluyveromyces marxianus and Ogataea polymorpha , as well as Saccharomyces cerevisiae , and observed robust fermentation at up to 46, 50, and 42 °C for each yeast, respectively. We show that the eSSF process reaches high ethanol titers in short processing times, and produces close to theoretical yields at temperatures as low as 30 °C. Finally, we demonstrate the transferability of the eSSF technology to other products by producing the advanced biofuel isobutanol in a light-controlled eSSF using optogenetic regulators, resulting in up to fourfold higher titers relative to MCC SSF. Conclusions The eSSF process addresses the main challenges of cellulosic biofuel production by increasing saccharification rate at temperatures tolerable to yeast. The rapid hydrolysis of these emulsions at low temperatures permits fermentation using non-thermotolerant yeasts, short processing times, low enzyme loads, and makes it possible to extend the process to chemicals other than ethanol, such as isobutanol. This transferability establishes the eSSF process as a platform for the sustainable production of biofuels and chemicals as a whole.

09 BIOMASS FUELS↗
DOE OSTI2018

Methods of processing aromatic compounds

A method of processing a solution comprising aromatic compounds. The method includes culturing a first microorganism in the solution for a time sufficient to reduce an amount of an aromatic compound and thereby generate a processed solution. The culturing may remove an aromatic compound deleterious to growth of a second microorganism without substantially reducing fermentable sugars, thereby permitting enhanced growth of the second microorganism in the processed solution. The culturing may additionally or alternatively convert an aromatic compound into a commodity chemical. The methods of the present invention are advantageous for processing lignocellulosic biomass for upgrading to biofuel or for generating commodity chemicals therefrom.

Noguera, Daniel R,↗