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Water content modulation enables selective ion transport in 2D MXene membranes

Separation membranes are critical for a range of processes, including but not limited to water desalination, chemical and fuel production, and recycling and recovery applications. Fundamentally, there are intrinsic trade-offs between permeability and selectivity. Local water organization and content can impact membrane structure (short- and long-range) in laminar transition metal carbide (MXene) membranes and impact selective ion permeation. Intercalation of chaotropic cesium (Cs + ) ions within the layers reduces the water content in the membrane and at the surface which cannot be found in the intercalation of other ions. Additionally, 3D imaging using focused ion beam scanning electron microscopy showed fewer defects in the Cs-MXene membrane, due to reduced local water content, leading to more efficient ion sieving. X-ray diffraction and density functional theory calculations on the nanochannel structure demonstrated that the chaotropic ion results in the smallest nanochannel size and induces a stronger resistance to water-induced nanochannel swelling. With a narrower nanochannel, the Cs-MXene membrane limits ion transport pathways, resulting in more selective transport of lithium over other metal cations, as evidenced in both experiment and molecular dynamics simulations. In conclusion, our findings highlight the potential for controlling the structural organization of 2D MXene membranes to enable on-demand transport of ions for diverse applications.

36 MATERIALS SCIENCE↗

Electron ptychography reveals a ferroelectricity dominated by anion displacements

Sodium niobate, a lead-free ferroic material, hosts delicately balanced, competing order parameters, including ferroelectric states that can be stabilized by epitaxial strain. Here we show that the resulting macroscopic ferroelectricity exhibits an unconventional microscopic structure using multislice electron ptychography. This technique overcomes multiple scattering artefacts limiting conventional electron microscopy, enabling both lateral spatial resolution beyond the diffraction limit and recovery of three-dimensional structural information. These imaging capabilities allow us to separate the ferroelectric interior of the sample from the relaxed surface structure and identify the soft phonon mode and related structural distortions with picometre precision. Unlike conventional ferroelectric perovskites, we find that the polar distortion in this material involves minimal distortions of the cation sublattices and is instead dominated by anion displacements relative to the niobium sublattice. We establish limits on film thickness for interfacial octahedral rotation engineering and directly visualize a random octahedral rotation pattern, arising from the flat dispersion of the associated phonon mode.

ferroelectrics and multiferroics↗

Criteria Considered in Selecting Feed Items for Americium-241 Oxide Production Operations

The analysis in this document serves the purpose of defining a number of attributes in selection of feed items to be utilized in recovery/recycle of Pu and also production operations of 241 AmO 2 material intended to meet specification requirements. This document was written in response to a specific request on the part of the 2014 annual program review which took place over the dates of October 28-29, 2014. A number of feed attributes are noted including: (1) Non-interference with existing Pu recovery operations; (2) Content of sufficient 241 Am to allow process efficiency in recovery operations; (3) Absence of indications that 243 Am might be mixed in with the Pu/ 241 Am material; (4) Absence of indications that Cm might be mixed in with the Pu/ 241 Am material; (5) Absence of indications of other chemical elements that would present difficulty in chemical separation from 241 Am; (6) Feed material not expected to present difficulty in dissolution; (7) Dose issues; (8) Process efficiency; (9) Size; (10) Hazard associated with items and package configuration in the vault; (11) Within existing NEPA documentation. The analysis in this document provides a baseline of attributes considered for feed materials, but does not presume to replace the need for technical expertise and judgment on the part of individuals responsible for selecting the material feed to be processed. This document is not comprehensive as regards all attributes that could prove to be important. The value of placing a formal QA hold point on accepting feed items versus more informal management of feed items is discussed in the summation of this analysis. The existing planned QA hold points on 241 AmO 2 products produced and packaged may be adequate as the entire project is based on QA of the product rather than QA of the process. The probability of introduction of items that would inherently cause the 241 AmO 2 products produced to be outside of specification requirements appears to be rather small.

07 ISOTOPE AND RADIATION SOURCES↗

Improved Ion Resistance for III-V Photocathodes in High Current Guns

The two photocathode test systems were modified, baked and recommissioned. The first system was dedicated to ion studies and the second to electron stimulated recovery (ESR) work. The demonstration system for the electron beam rejuvenation was set up, tested and demonstrated to one of the SSRL team (Dr. Kirby) during a site visit. The requisite subsystems were transferred to SSRL, installed and photoemission studies conducted on activated surfaces following electron beam exposure. Little surface chemistry change was detected in the photoemission spectra following the ESR process. The yield mapping system for the ion (and later, the electron beam rejuvenation) studies was implemented and use made routine. Ion species and flux measurements were performed for H, He, Ne, Ar, Kr and Xe ions at energies of 0.5, 1.0 and 2.0 kV. Gas induced photoyield measurements followed each ion exposure measurement. These data permit the extraction of photoyield induced change per ion (by species) at the measured energies. Electron beam induced rejuvenation was first demonstrated in the second chamber with primary electron beam energy and dependency investigations following. A Hiden quadrupole mass spectrometer for the electron stimulated desorption (ESD) measurements was procured. The UHV test systems needed for subsequent measurements were configured, baked, commissioned and utilized for their intended purposes. Measurements characterizing the desorption products from the ESD process and secondary electron (SE) yield at the surfaces of negative electron affinity GaAs photocathodes have been performed. One US Utility Patent was granted covering the ESR process.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Analysis of Drought Impacts on Electricity Production in the Western and Texas Interconnections of the United States

Electricity generation relies heavily on water resources and their availability. To examine the interdependence of energy and water in the electricity context, the impacts of a severe drought to assess the risk posed by drought to electricity generation within the western and Texas interconnections has been examined. The historical drought patterns in the western United States were analyzed, and the risk posed by drought to electricity generation within the region was evaluated. The results of this effort will be used to develop scenarios for medium- and long-term transmission modeling and planning efforts by the Western Electricity Coordination Council (WECC) and the Electric Reliability Council of Texas (ERCOT). The study was performed in response to a request developed by the Western Governors Association in conjunction with the transmission modeling teams at the participating interconnections. It is part of a U.S. Department of Energy-sponsored, national laboratory-led research effort to develop tools related to the interdependency of energy and water as part of a larger interconnection-wide transmission planning project funded under the American Recovery and Reinvestment Act. This study accomplished three main objectives. It provided a thorough literature review of recent studies of drought and the potential implications for electricity generation. It analyzed historical drought patterns in the western United States and used the results to develop three design drought scenarios. Finally, it quantified the risk to electricity generation for each of eight basins for each of the three drought scenarios and considered the implications for transmission planning. Literature on drought impacts on electricity generation describes a number of examples where hydroelectric generation capacity has been limited because of drought but only a few examples of impact on thermoelectric generation. In all documented cases, shortfalls of generation were met by purchasing power from the market, albeit at higher prices. However, sufficient excess generation and transmission must be available for this strategy to work. Although power purchase was the most commonly discussed drought mitigation strategy, a total of 12 response strategies were identified in the literature, falling into four main categories: electricity supply, electricity demand response, alternative water supplies, and water demand response. Three hydrological drought scenarios were developed based on a literature review and historical data analysis. The literature review helped to identify key drought parameters and data on drought frequency and severity. Historical hydrological drought data were analyzed for the western United States to identify potential drought correlations and estimate drought parameters. The first scenario was a West-wide drought occurring in 1977; it represented a severe drought in five of the eight basins in the study area. A second drought scenario was artificially defined by selecting the conditions from the 10th-percentile drought year for each individual basin; this drought was defined in this way to allow more consistent analysis of risk to electricity generation in each basin. The final scenario was based upon the current low-flow hydro modeling scenario defined by WECC, which uses conditions from the year 2001. These scenarios were then used to quantify the risk to electricity generation in each basin. The risk calculations represent a first-order estimate of the maximum amount of electricity generation that might be lost from both hydroelectric and thermoelectric sources under a worst-case scenario. Even with the conservative methodology used, the majority of basins showed a limited amount of risk under most scenarios. The level of risk in these basins is likely to be amenable to mitigation by known strategies, combined with existing reserve generation and transmission capacity. However, the risks to the Pacific Northwest and Texas Basins require further study. The Pacific Northwest is vulnerable because of its heavy reliance on hydroelectric generation. Texas, conversely, is vulnerable because of its heavy dependence on thermoelectric generation, which relies on surface water for cooling, along with the fact that this basin seems to experience more severe drought events on average. Further modeling analysis will be performed in conjunction with the modeling teams at the participating interconnections (WECC and ERCOT) to explore the transmission implications of the drought scenarios in more detail. Given the first-order nature of this analysis, more detailed study of the potential impacts of drought on electricity generation is recommended. Future analyses should attempt to model the potential impacts of drought at the power-plant level, including potential mitigation strategies; include the effects of drought duration; understand the impacts of climate change; and consider economic impacts.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Lake Charles CCS Project (Final Technical Report, Phase 2)

In late September 2014 development of the Lake Charles Clean Energy (LCCE) Plant was abandoned resulting in termination of Lake Charles Carbon Capture and Sequestration (CCS) Project which was a subset the LCCE Plant. As a result, the project was only funded through Phase 2A (Design) and did not enter Phase 2B (Construction) or Phase 2C (Operations). This report was prepared relying on information prepared and provided by engineering companies which were engaged by Leucadia Energy, LLC to prepare or review Front End Engineering and Design (FEED) for the Lake Charles Clean Energy Project, which includes the Carbon Capture and Sequestration (CCS) Project in Lake Charles, Louisiana. The Lake Charles Carbon Capture and Sequestration (CCS) Project was to be a large-scale industrial CCS project intended to demonstrate advanced technologies that capture and sequester carbon dioxide (CO 2 ) emissions from industrial sources into underground formations. The Scope of work was divided into two discrete sections; 1) Capture and Compression prepared by the Recipient Leucadia Energy, LLC, and 2) Transport and Sequestration prepared by sub-Recipient Denbury Onshore, LLC. Capture and Compression-The Lake Charles CCS Project Final Technical Report describes the systems and equipment that would be necessary to capture CO 2 generated in a large industrial gasification process and sequester the CO 2 into underground formations. The purpose of each system is defined along with a description of its equipment and operation. Criteria for selection of major equipment are provided and ancillary utilities necessary for safe and reliable operation in compliance with environmental regulations are described. Construction considerations are described including a general arrangement of the CCS process units within the overall gasification project. A cost estimate is provided, delineated by system area with cost breakdown showing equipment, piping and materials, construction labor, engineering, and other costs. The CCS Project Final Technical Report is based on a Front End Engineering and Design (FEED) study prepared by SK E&C, completed in [June] 2014. Subsequently, Fluor Enterprises completed a FEED validation study in mid-September 2014. The design analyses indicated that the FEED package was sufficient and as expected. However, Fluor considered the construction risk based on a stick-build approach to be unacceptable, but construction risk would be substantially mitigated through utilization of modular construction where site labor and schedule uncertainty is minimized. Fluor’s estimate of the overall EPC project cost utilizing the revised construction plan was comparable to SKE&C’s value after reflecting Fluor’s assessment of project scope and risk characteristic. Development was halted upon conclusion of Phase 2A FEED and the project was not constructed.Transport and Sequestration – The overall objective of the pipeline project was to construct a pipeline to transport captured CO 2 from the Lake Charles Clean Energy project to the existing Denbury Green Line and then to the Hastings Field in Southeast Texas to demonstrate effective geologic sequestration of captured CO 2 through commercial EOR operations. The overall objective of the MVA portion of the project was to demonstrate effective geologic sequestration of captured CO 2 through commercial Enhanced Oil Recovery (EOR) operations in order to evaluate costs, operational processes and technical performance. The DOE target for the project was to capture and implement a research MVA program to demonstrate the sequestration through EOR of approximately one million tons of CO 2 per year as an integral component of commercial operations.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

CHP REGIONAL APPLICATION CENTERS: ACTIVITIES AND SELECTED RESULTS

Between 2001 and 2005, the U.S. Department of Energy (DOE) created a set of eight Regional Application Centers (RACs) to facilitate the development and deployment of Combined Heat and Power (CHP) technologies. By utilizing the thermal energy that is normally wasted when electricity is produced at central generating stations, Combined Heat and Power installations can save substantial amounts of energy compared to more traditional technologies. In addition, the location of CHP facilities at or near the point of consumption greatly reduces or eliminates electric transmission and distribution losses. The regional nature of the RACs allows each one to design and provide services that are most relevant to the specific economic and market conditions in its particular geographic area. Between them, the eight RACs provide services to all 50 states and the District of Columbia. Through the end of the federal 2009 fiscal year (FY 2009), the primary focus of the RACs was on providing CHP-related information to targeted markets, encouraging the creation and adoption of public policies and incentives favorable to CHP, and providing CHP users and prospective users with technical assistance and support on specific projects. Beginning with the 2010 fiscal year, the focus of the regional centers broadened to include district energy and waste heat recovery and these entities became formally known as Clean Energy Application Centers, as required by the Energy Independence and Security Act (EISA) of 2007. In 2007, ORNL led a cooperative effort to establish metrics to quantify the RACs accomplishments. That effort began with the development of a detailed logic model describing RAC operations and outcomes, which provided a basis for identifying important activities and accomplishments to track. A data collection spreadsheet soliciting information on those activities for FY 2008 and all previous years of RAC operations was developed and sent to the RACs in the summer of 2008. This represents the first systematic attempt at RAC program measurement in a manner consistent with approaches used for other efforts funded by DOE's Industrial Technologies Program (ITP). In addition, data on CHP installations and associated effects were collected for the same years from a state-by-state database maintained for DOE by ICF international. A report documenting the findings of that study was produced in September, 2009. The purpose of the current report is to present the findings from a new study of RAC activities and accomplishments which examined what the Centers did in FY 2009, the last year in which they concentrated exclusively on CHP technologies. This study focused on identifying and describing RAC activities and was not designed to measure how those efforts influenced CHP installations or other outcomes.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Real-Time Partitioning of Diurnal Stem CO 2 Efflux into Local Stem Respiration and Xylem Transport Processes

The apparent respiratory quotient (ARQ) of tree stems, defined as the ratio of net stem CO 2 efflux (E S_CO2 ) to net stem O 2 influx (E S_O2 ), offers insights into the balance between local respiratory CO 2 production and CO 2 transported via the xylem. Traditional static chamber methods for measuring ARQ can introduce artifacts and obscure natural diurnal variations. Here, we employed an open flow-through stem chamber with ambient air coupled with cavity ring-down spectrometry, which uses the molecular properties of CO 2 and O 2 molecules to continuously measure E S_CO2 , E S_O2 , and ARQ, at the base of a California cherry tree (Prunus ilicifolia) during the 2024 growing season. Measurements across three stem chambers over 3–11-day periods revealed strong correlations between E S_CO2 and E S_O2 and mean ARQ values ranging from 1.3 to 2.9, far exceeding previous reports. Two distinct diurnal ARQ patterns were observed: daytime suppression with nighttime recovery, and a morning peak followed by gradual decline. Partitioning E S_CO2 into local respiration and xylem-transported CO 2 indicated that the latter can dominate when ARQ exceeds 2.0. Furthermore, transported CO 2 exhibited a higher temperature sensitivity than local respiration, with both processes showing declining temperature sensitivity above 20 °C. These findings underscore the need to differentiate stem CO 2 flux components to improve our understanding of whole-tree carbon cycling.

59 BASIC BIOLOGICAL SCIENCES↗

25 Years Of Environmental Remediation In The General Separations Area Of The Savannah River Site: Lessons Learned About What Worked And What Did Not Work In Soil And Groundwater Cleanup

The Savannah River Site (SRS) is owned and administered by the US Department of Energy (DOE). SRS covers an area of approximately 900 square kilometers. The General Separation Area (GSA) is located roughly in the center of the SRS and includes: radioactive material chemical separations facilities, radioactive waste tank farms, a variety of radioactive seepage basins, and the radioactive waste burial grounds. Radioactive wastes were disposed in the GSA from the mid-1950s through the mid-1990s. Radioactive operations at the F Canyon began in 1954; radioactive operations at H Canyon began in 1955. Waste water disposition to the F and H Seepage Basins began soon after operations started in the canyons. The Old Radioactive Waste Burial Ground (ORWBG) began operations in 1952 to manage solid waste that could be radioactive from all the site operations, and ceased receiving waste in 1972. The Mixed Waste Management Facility (MWMF) and Low Level Radioactive Waste Disposal Facility (LLRWDF) received radioactive solid waste from 1969 until 1995. Environmental legislation enacted in the 1970s, 1980s, and 1990s led to changes in waste management and environmental cleanup practices at SRS. The US Congress passed the Clean Air Act in 1970, and the Clean Water Act in 1972; the Resource Conservation and Recovery Act (RCRA) was enacted in 1976; the Comprehensive Environmental Response Compensation, and Liability Act (CERCLA) was enacted by Congress in 1980; the Federal Facilities Compliance Act (FFCA) was signed into law in 1992. Environmental remediation at the SRS essentially began with a 1987 Settlement Agreement between the SRS and the State of South Carolina (under the South Carolina Department of Health and Environmental Control - SCDHEC), which recognized linkage between many SRS waste management facilities and RCRA. The SRS manages several of the larger groundwater remedial activities under RCRA for facilities recognized early on as environmental problems. All subsequent environmental remediation projects tend to be managed under tri-party agreement (DOE, Environmental Protection Agency, and SCDHEC) through the Federal Facilities Agreement. During 25 years of environmental remediation SRS has stabilized and capped seepage basins, and consolidated and capped waste units and burial grounds in the GSA. Groundwater activities include: pump and treat systems in the groundwater, installation of deep subsurface barrier systems to manage groundwater flow, in situ chemical treatments in the groundwater, and captured contaminated groundwater discharges at the surface for management in a forest irrigation system. Over the last 25 years concentrations of contaminants in the aquifers beneath the GSA and in surface water streams in the GSA have dropped significantly. Closure of 65 waste sites and 4 RCRA facilities has been successfully accomplished. Wastes have been successfully isolated in place beneath a variety of caps and cover systems. Environmental clean-up has progressed to the stage where most of the work involves monitoring, optimization, and maintenance of existing remedial systems. Many lessons have been learned in the process. Geotextile covers outperform low permeability clay caps, especially with respect to the amount of repairs required to upkeep the drainage layers as the caps age. Passive, enhanced natural processes to address groundwater contamination are much more cost effective than pump and treat systems. SRS operated two very large pump and treat systems at the F and H Seepage Basins to attempt to limit the release of tritium to Fourmile Branch, a tributary of the Savannah River. The systems were designed to extract contaminated acidic groundwater, remove all contamination except tritium (not possible to remove the tritium from the water), and inject the tritiated groundwater up-gradient of the source area and the plume. The concept was to increase the travel time of the injected water for radioactive decay of the tritium. The two systems were found to be non-effective and potentially mobilizing more contamination. SRS invested approximately $50 million in construction and approximately $100 million in 6 years of operation. The H Seepage Basin pump and treat system was replaced by a series of subsurface barriers that alters the groundwater velocity; the F Seepage Basin pump and treat system was replaced by subsurface barriers forming a funnel and gate augmented by chemical treatment within the gates. These replacement systems are mostly passive and cost approximately $13 million to construct, and have reduced the tritium flux to Fourmile Branch, in these plumes, by over 70%. SRS manages non-acidic tritiated groundwater releases to Fourmile Branch from the southwest plume of the MWMF with a forest irrigation system. Tritiated water is captured with a sheetpile dam below the springs that caused releases to Fourmile Branch. Water from the irrigation pond is pumped to a filter plant prior to irrigation of approximately 26 hectares of mixed forest and developing pine plantation. SRS has almost achieved a 70% reduction in tritium flux to the Branch from this plume. The system cost approximately $5 million to construct with operation cost of approximately $500K per year. In conclusion, many lessons have been learned in 25 years of relatively aggressive remedial activities in the GSA. Geotextile covers outperform low permeability clay caps, especially with respect to the amount of repairs required to upkeep the drainage layers as the caps age. Passive, enhanced natural processes to address groundwater contamination are much more cost effective than pump and treat systems. In water management situations with non-accumulative contaminants (tritium, VOCs, etc.) irrigation in a forest setting can be very effective.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Advanced Stirling Convertor Control Unit Testing at NASA Glenn Research Center in the Radioisotope Power Systems System Integration Laboratory

Future NASA missions could include long-duration flyby, orbital, lander, or rover applications where generating power from sunlight may be limited. Radioisotope power systems (RPSs) provide a dependable power source for missions where inadequate sunlight or operational requirements make other power systems impractical. Over the past 16 years, NASA Glenn Research Center has been supporting the development of RPSs. The advanced Stirling radioisotope generator (ASRG) utilized a pair of advanced Stirling convertors (ASCs). Although flight development of the ASRG has been canceled, much of the technology and hardware continued development and testing to guide future activities. Specifically, a controller for the convertor(s) is an integral part of a Stirling-based RPS. For the ASRG design, the controller maintains stable operation of the convertors, regulates the alternating current produced by the linear alternator of the convertor, provides a specified direct-current output voltage for the spacecraft, and synchronizes the piston motion of the two convertors to minimize vibration as well as manage and maintain operation with a stable piston amplitude and hot-end temperature. It not only provides power to the spacecraft but also must regulate convertor operation to avoid damage to internal components and maintain safe thermal conditions after fueling. Lockheed Martin Coherent Technologies, Inc., has designed, developed, and tested an ASC control unit engineering development unit (ACU EDU) to support this effort. GRC used the ACU EDU as part of its nonnuclear representation of a RPS that also consists of a Dual advanced Stirling convertor simulator (DASCS), and associated support equipment to perform a test in the Radioisotope Power Systems System Integration Laboratory (RSIL). The RSIL was designed and built with flexibility to evaluate hardware utilizing RPS technology. The RSIL provides insight into the electrical interactions between as many as three radioisotope power generators, associated control strategies, and typical electric system loads. The first phase of testing included a DASCS that was developed by Johns Hopkins University Applied Physics Laboratory and simulates the operation and electrical behavior of a pair of ASCs in real time via a combination of hardware and software. Testing included the following spacecraft electrical energy storage configurations: capacitor, battery, and supercapacitor. Testing of the DASCS and ACU in each energy storage configuration included simulation of a typical mission profile and transient voltage and current data during load turnon and turnoff. Testing for these devices also included the initiation of several system faults such as short circuits, electrical bus overvoltage, undervoltage, and a "dead bus" recovery to restore normal power operations. The goal of this testing was to verify operation of the ACU(s) when connected to a spacecraft electrical bus. The results of these tests are presented here.

General↗

Advanced Stirling Convertor Control Unit Testing at NASA Glenn Research Center in the Radioisotope Power Systems System Integration Laboratory

Future NASA missions could include establishing Lunar or Martian base camps, exploring Jupiters moons and travelling beyond where generating power from sunlight may be limited. Radioisotope Power Systems (RPS) provide a dependable power source for missions where inadequate sunlight or operational requirements make other power systems impractical. Over the past decade, NASA Glenn Research Center (GRC) has been supporting the development of RPSs. The Advanced Stirling Radioisotope Generator (ASRG) utilized a pair of Advanced Stirling Convertors (ASC). While flight development of the ASRG has been cancelled, much of the technology and hardware continued development and testing to guide future activities. Specifically, a controller for the convertor(s) is an integral part of a Stirling-based RPS. For the ASRG design, the controller maintains stable operation of the convertors, regulates the alternating current produced by the linear alternator of the convertor, provides a specified direct current output voltage for the spacecraft, synchronizes the piston motion of the two convertors in order to minimize vibration as well as manage and maintain operation with a stable piston amplitude and hot end temperature. It not only provides power to the spacecraft but also must regulate convertor operation to avoid damage to internal components and maintain safe thermal conditions after fueling. Lockheed Martin Coherent Technologies has designed, developed and tested an Engineering Development Unit (EDU) Advanced Stirling Convertor Control Unit (ACU) to support this effort. GRC used the ACU EDU as part of its non-nuclear representation of a RPS which also consists of a pair of Dual Advanced Stirling Convertor Simulator (DASCS), and associated support equipment to perform a test in the Radioisotope Power Systems System Integration Laboratory (RSIL). The RSIL was designed and built to evaluate hardware utilizing RPS technology. The RSIL provides insight into the electrical interactions between as many as 3 radioisotope power generators, associated control strategies, and typical electric system loads. The first phase of testing included a DASCS which was developed by Johns Hopkins UniversityApplied Physics Laboratory and simulates the operation and electrical behavior of a pair of ASCs in real time via a combination of hardware and software. Testing included the following spacecraft electrical energy storage configurations: capacitive, battery, and supercapacitor. Testing of the DASCS and ACU in each energy storage configuration included simulation of a typical mission profile, and transient voltage and current data during load turn-on/turn-off. Testing for these devices also included the initiation of several system faults such as short circuits, electrical bus over-voltage, under-voltage and a dead bus recovery to restore normal power operations. The goal of this testing was to verify operation of the ACU(s) when connected to a spacecraft electrical bus.

Dugala, Gina M.↗

Gridded thermionic gun and integral superconducting ballistic bunch compression cavity

Electron-Ion colliders such as the Medium energy Electron Ion Collider (MEIC) being developed by JLAB require high current electrons with low energy spread for electron cooling of the collider ring. Accelerator techniques for improving bunch charge, average current, emittance, and energy spread are required for Energy Recovery Linacs (ERLs) and Circulator Rings (CR) for next generation colliders for nuclear physics experiments. Example candidates include thermionic-cathode electron guns with RF accelerating structures. Thermionic cathodes are known to produce high currents and have excellent lifetime. The success of the IR and THz Free-Electron Laser (FEL) designed and installed by Advanced Energy Systems at the Fritz Haber Institute (FHI) of the Max Planck Society in Berlin [1,2] demonstrates that gridded thermionic cathodes and rf systems be considered for next generation collider technology. In Phase 1 Advanced Energy Systems (AES) developed and analyzed a design concept using a superconducting cavity pair and gridded thermionic cathode. Analysis included Beam Dynamics and thermal analysis to show that a design of this type is feasible. The latest design goals for the MEIC electron cooler were for electron bunches of 420 pC at a frequency of 952.6 MHz with a magnetic field on the cathode of 2kG. This field magnetizes the beam imparting angular momentum that provides for helical motion of the electrons in the cooling solenoid. The helical motion increases the interaction time and improves the cooling efficiency. A coil positioned around the cathode providing 2kG field was developed. Beam dynamics simulations were run to develop the particle dynamics near the cathode and grid. Lloyd Young added capability to Tstep to include space charge effects between two plates and include image charge effects from the grid. He also added new pepper-pot geometry capability to account for honeycomb grids. These additions were used to develop the beam dynamics for this gun. The general design is a modified ballistic compression cavity pair with two independently powered cells [3]. The first is a cathode cell that includes the thermionic cathode and grid to provide for beam bunching. The second is a full cell with independent phasing and field levels designed to minimize energy spread. The primary goal for Phase II is to manufacture a superconducting gun with a thermionic cathode and imbedded coil. The system developed here is applicable to many high current electron accelerators. The analysis and design constraints imposed by the magnetized cathode make the cathode system developed here more complicated and limited than one without the magnetized beam constraints. High power ERLs would benefit by a gun with the capabilities shown here, 400 mA or more of current. ERLs hold great promise for electron cooling experiments, advanced light sources and Free Electron Lasers. This high current electron injector is a technological advance that will place the requirements for an ERL capable of providing quality bunches needed for cooling within the MEIC circulator ring within reach. This injector would have application to future ERLs around the world.

43 PARTICLE ACCELERATORS↗

Gasification of Coal and Biomass: The Route to Net-Negative-Carbon Power and Hydrogen

One promising process that is a candidate for meeting the goals of the US Department of Energy’s 21st Century Power Plant initiative is to gasify a mixture of coal and biomass to yield a syngas, which can have CO2 removed and then be used to produce hydrogen as well as an off-gas that can be used to flexibly produce power. This concept would overall be carbon net-negative and readily meet the 21st Century Power Plant initiative targets of smaller scale MW generation, high ramp rates and turndown, feedstock flexibility, and high efficiency—at a reasonable cost. Moreover, adding the large-scale production of “ultra-green” hydrogen yields a system tailored for the coming hydrogen economy, providing long-term energy storage and an attractive co-product for sale. The objective of the work being led by the Electric Power Research Institute, Inc. (EPRI), with support by Bechtel Corporation (Bechtel), Gas Technology Institute (GTI), Hamilton Mauer International, Inc. (HMI), Nebraska Public Power District (NPPD), NexantECA, Inc. (Nexant), and Wärtsilä, is to perform a front-end design and engineering (FEED) study on an oxygen-blown gasification system coupled with water-gas shift, pre-combustion CO2 capture, and pressure-swing adsorption working off a coal/biomass mix to yield high-purity hydrogen and a fuel off-gas that can generate power. Several designs are being considered that will be capable of producing 50 MW net from a flexible generator, over 8500 kg/hr of hydrogen, and net-negative CO2 emissions, at an efficiency of 50% net HHV. The plant would be hosted at an NPPD site, where opportunities for enhanced oil recovery and sequestration have been investigated and the need for low-carbon power and hydrogen is imminent. The principal biomass to be used is corn stover—prevalent in Nebraska where the plant will be located—mixed with Powder River Basin (PRB) coal, necessitating a gasifier that can use this feedstock and be flexible to allow other types. Waste plastics will also be reviewed for use. Two oxygen-blown gasifiers have been identified as candidates that have done testing with biomass including corn stover: the GTI gasifier—a high-pressure, fluidized-bed type—and HMI’s, a lower pressure moving-bed type. Both have relative advantages that were investigated in the Phase I design study, with a resultant down select of one system for which the FEED will be performed in Phase II. The technical tasks for the project are: • Design Development: Completion of design activities necessary to provide inputs for the FEED study. Multiple design cases will be assessed with the selection of the optimal one for the FEED. • Investment Case Preparation: Development of the draft investment case for the proposed process with business cases performed for the proposed host site and two other locations. • Host Site Selection: Evaluation of the two potential host sites within NPPD’s portfolio to select the preferred candidate based on technical, economic, and environmental considerations. • Environmental Information Volume (EIV) Development: Completion of the EIV for the host site. • FEED Study: Completion of a FEED study based on the design selected in Phase I. A Greenhouse Gas Life Cycle Analysis will also be performed for the process. • Update Investment Case: Finalization of the investment case based on findings from the FEED. The advantages of the proposed project are significant. Having an engaged U.S. power utility willing to provide a host site that will produce energy from coal plus a deep and experienced team is critical; the process meets all the goals of DOE’s 21st Century Power Plant initiative at an estimated total plant cost of ~$880M and a production cost of hydrogen of ~$2/kg-H2 while producing net-negative carbon power. If developed, this process has real commercial potential in the United States—supported by EPRI’s initial review of the considerable interest from selected U.S. utilities—and elsewhere around the globe. The process has fewer environmental hurdles compared to other concepts, lowering regulatory and protest risks—providing a pathway to preserving the viability of a critical indigenous energy source by transforming its use to match a changing world. This presentation outlines the motivation for the effort, summarizes project plans, work completed to date, results of the Phase I effort and, and detailed work scope for the remainder of the project in the Phase II FEED effort.

01 COAL, LIGNITE, AND PEAT↗

Gasification of Coal and Biomass: The Route to Net-Negative-Carbon Power and Hydrogen

One promising process that is a candidate for meeting the goals of the US Department of Energy’s 21st Century Power Plant initiative is to gasify a mixture of coal and biomass to yield a syngas, which can have CO2 removed and then be used to produce hydrogen as well as an off-gas that can be used to flexibly produce power. This concept would overall be carbon net-negative and readily meet the 21st Century Power Plant initiative targets of smaller scale MW generation, high ramp rates and turndown, feedstock flexibility, and high efficiency—at a reasonable cost. Moreover, adding the large-scale production of “ultra-green” hydrogen yields a system tailored for the coming hydrogen economy, providing long-term energy storage and an attractive co-product for sale. The objective of the work being led by the Electric Power Research Institute, Inc. (EPRI), with support by Bechtel Corporation (Bechtel), Gas Technology Institute (GTI), Hamilton Mauer International, Inc. (HMI), Nebraska Public Power District (NPPD), NexantECA, Inc. (Nexant), and Wärtsilä, is to perform a front-end design and engineering (FEED) study on an oxygen-blown gasification system coupled with water-gas shift, pre-combustion CO2 capture, and pressure-swing adsorption working off a coal/biomass mix to yield high-purity hydrogen and a fuel off-gas that can generate power. Several designs are being considered that will be capable of producing 50 MW net from a flexible generator, over 8500 kg/hr of hydrogen, and net-negative CO2 emissions, at an efficiency of 50% net HHV. The plant would be hosted at an NPPD site, where opportunities for enhanced oil recovery and sequestration have been investigated and the need for low-carbon power and hydrogen is imminent. The principal biomass to be used is corn stover—prevalent in Nebraska where the plant will be located—mixed with Powder River Basin (PRB) coal, necessitating a gasifier that can use this feedstock and be flexible to allow other types. Waste plastics will also be reviewed for use. Two oxygen-blown gasifiers have been identified as candidates that have done testing with biomass including corn stover: the GTI gasifier—a high-pressure, fluidized-bed type—and HMI’s, a lower pressure moving-bed type. Both have relative advantages that are being investigated in the Phase I design study, with a resultant down select of one system for which the FEED will be performed in Phase II. The technical tasks for the proposed project are: • Design Development: Completion of design activities necessary to provide inputs for the FEED study. Multiple design cases will be assessed with the selection of the optimal one for the FEED. • Investment Case Preparation: Development of the draft investment case for the proposed process with business cases performed for the proposed host site and two other locations. • Host Site Selection: Evaluation of the two potential host sites within NPPD’s portfolio to select the preferred candidate based on technical, economic, and environmental considerations. • Environmental Information Volume (EIV) Development: Completion of the EIV for the host site. • FEED Study: Completion of a FEED study based on the design selected in Phase I. A Greenhouse Gas Life Cycle Analysis will also be performed for the process. • Update Investment Case: Finalization of the investment case based on findings from the FEED. The advantages of the proposed project are significant. Having an engaged U.S. power utility willing to provide a host site that will produce energy from coal plus a deep and experienced team is critical; the process meets all the goals of DOE’s 21st Century Power Plant initiative at an estimated total plant cost of ~$880M and a production cost of hydrogen of ~$2/kg-H2 while producing net-negative carbon power. If developed, this process has real commercial potential in the United States—supported by EPRI’s initial review of the considerable interest from selected U.S. utilities—and elsewhere around the globe. The process has fewer environmental hurdles compared to other concepts, lowering regulatory and protest risks—providing a pathway to preserving the viability of a critical indigenous energy source by transforming its use to match a changing world. This presentation will outline the motivation for the effort, summarize project plans, work completed to date, results of the Design Development task, and detailed work scope for the remainder of the project.

01 COAL, LIGNITE, AND PEAT↗

Carbon Life Cycle Analysis of CO 2 -EOR for Net Carbon Negative Oil (NCNO) Classification (Final Report)

This final report summarizes the work that was conducted to achieve the project’s general objective of developing a clear and repeatable methodology to determine whether the oil produced in a conventional CO 2 enhanced oil recovery (CO 2 -EOR) operation can be classified as Net Carbon Negative Oil (NCNO). The report also summarizes the reservoir mass accounting methodology and the monitoring, verification, and accounting (MVA) methodology, which are critical elements that support the general objective and were conceived as project goals. Because the purpose is to classify the EOR product (crude oil) and not the EOR project itself, and as the rate of crude oil production varies significantly with time, the methodology uses a novel dynamic carbon lifecycle analysis (d-LCA) that links instant energy demand and associated greenhouse gas (GHG) emissions to instant operational performance. The EOR operational performance is assessed through CO 2 utilization rates, which relate usage of CO 2 to oil production This dynamic method provides a better understanding of the evolution of the environmental impact (CO 2 emissions) and mitigation (geologic CO 2 storage) associated with an expanded carbon capture, utilization and storage (CCUS) system, from start to closure of operations. The dynamic interplay between operational and environmental performance forms the basis of our CCUS technology analysis. The LCA part of the work is meant to complement previous NETL LCA work, and so it focused on EOR/storage efficiency, its variability through time, and the impact of this variability on LCA results. The environmental impact of the CCUS system was assessed for 3 system boundaries: (1) gate-to-gate, (2) gate-to-grave, and (3) cradle-to-grave. The environmental impact was also assessed considering the electricity displacement from other generation facilities. Another goal of our study was to use results to make recommendations on EOR field development strategies that are conducive to producing NCNO. Because field operational strategies have a significant impact on reservoir engineering parameters that affect both CO 2 storage and oil production (e.g., sweep efficiency, flood conformance, fluid saturation distribution), we conducted a scenario analysis that assesses the operational and environmental performance of four common and novel CO 2 -EOR field development strategies. Results show that all CO 2 -EOR evaluated scenarios start operating with a negative carbon footprint and, years into the project, transition into operating with a positive carbon footprint. Having achieved a result that proves that all CO 2 -EOR operations produce NCNO during the first years of production is critical in the context of the urgency of climate change mitigation. Transition points are significantly different in each scenario. ii In a cradle-to-grave CCUS system, if the capture facility displaces a conventional power source and credits are added for displacement, the adverse impact caused by the system expansion not only is reversed but transformed into a significant environmental benefit. The effect of the displacement more than compensates the emissions associated with the electricity generation requirements for the production of CO 2 , as much more electricity will be displaced. Results provide an understanding of the evolution of the system’s net carbon balance of all four field development strategies studied. This information can be useful to CO 2 -EOR operators seeking value in storing more CO 2 through a carbon credit program (e.g., the 45Q federal carbon credit program). Most importantly, this study serves as confirmation that CO 2 -EOR can be operationally designed to both enhance oil production and reduce greenhouse gas emissions to the atmosphere.

02 PETROLEUM↗

Leveraging Existing Assets for Long Duration Energy Storage

Increased renewables penetration to electrical grid is necessary to reduce overall emissions from the electrical power generation sector. Nonetheless, its integration creates challenges to grid operators who must match the power being generated by intermittent renewables and other traditional energy sources with the demand from consumers, while ensuring the reliability and power quality for the entire system. Energy storage has been proposed as an alternative to natural gas peaking plants and a form to deliver excess renewable energy generation at times of peak demand. For energy storage to provide benefits to end customers (energy consumers), it must be reliable, efficient, and cost effective. The Illinois Sustainable Technology Center (ISTC), one of the surveys that integrate the Prairie Research Institute (PRI), aims to develop a Center for Energy Storage at Existing Assets (CESEA) at UIUC with the participation of Waste Pressure Corp and Ecotek Engineering USA LLC. CESEA will focus on LDES systems that can integrate to existing infrastructure in a manner that reduces the initial capital expenditure and demonstrates the ability to repurpose fossil assets that would otherwise become stranded, to serve the energy transition. CESEA aims to leverage UIUC’s unique facilities to validate LDES systems performance at a relevant operating environment. UIUC’s facilities include a 85-MW combined heat and power (CHP) power plant, two (2) solar PV plants totaling over 18 MWdc of installed capacity, an electrical grid along with a substation at transmission and distribution voltages, a 22-mile gas pipeline network operating at two pressure levels, along with steam and chilled water distribution networks. The new LDES systems will connect to the existing UIUC grid through a new test electrical station, which will have the capacity to accommodate additional connections to test new devices and technologies as part of future CESEA R&D activities. The test electrical station will contain meters, instrumentation, and controls to accurately capture data and allow optimization of control algorithms. CESEA will initially focus on technologies that: i) utilize existing equipment or facilities to perform at least one of the process steps in LDES (charging, storage, or discharging), ii) leverage mature or commercially available components or controls, iii) show potential for cost-leadership in 10+ hour storage at a commercial scale. Initial technologies that were identified to meet these criteria include Compressed Gas Energy Storage (CGES), and TES. CGES stores electricity by raising the pressure of a compressible gas inside a control volume and converting the stored energy to electricity via expansion-generation. CGES is a generalization of CAES that covers any working gas (not just air). A successful CGES demo will help to circumvent many challenges faced by CAES (long development times due to site prospecting, high cost of compression and storage, heat recovery management, etc.) by: 1) utilizing existing infrastructure (compressors, pipelines, underground storage or pressure vessels) used in the transportation and storage of industrial gases for LDES charging and storage; 2) deploying over sites already-developed for industrial applications with minor additional work; 3) leveraging the price structure of commercial industrial gas to cover the costs of electricity used during charging. A previous DOE-sponsored conceptual study (DE-FE-0032018) estimated the levelized cost of energy of a 1.1 MW / 17 MWh CGES system at $0.08/kWh, with a commercial 10x scale system cost estimated at <$0.04/kWh (Giardinella, 2022). The pilot-sized system was estimated to avoid up to 2693 tons of CO2/year.

25 ENERGY STORAGE↗

Path of Disposal for Hazardous and Non-hazardous Waste from Cradle to Grave

Hazardous waste is a threat to human health and the environment and must be managed and disposed of properly. A Solid Waste is defined as any material (solid, liquid, containerized gas) which has been discarded, abandoned (no longer needed), or recycled. The Resource Conservation Recovery Act (RCRA) is a law that creates the framework for the proper management of solid waste. Under RCRA, EPA has developed a program which ensures hazardous waste is managed safely from the moment it is generated to its final disposal (cradle-to-grave)2. To educate about how waste is handled at the Savannah River Research Campus (SRRC) under RCRA, the path it takes from point of generation (cradle) to disposal (grave), and the responsibilities of every person involved in the process. Researcher or other laboratory personnel that generates waste as a result of their work Responsibilities: - Fill out inventory log sheet and corresponding container sheet which includes the constituents of the waste; - Properly label waste container with SAA/WSA ID no., generator's name, what it is, the hazards, and date; - Place waste in designated waste storage area. Laboratory Custodian Responsibilities: - Ensures waste is handled and stored properly; - Ensures inventory is updated; - Ensures all container sheets are completed; - Ensures only authorized personal have access to waste storage areas. Environmental Compliance Authority Responsibilities: - Develops waste procedures; - Provide waste training; - Inspects for improperly handled waste; - Establishes or closes waste storage areas as needed; - Determines if waste can be recycled; - Determines if waste is RCRA hazardous: Is it U or P listed? - Unused commercial chemical products; Is it F listed - Spent solvents; Is it characteristic? - Flammable/Oxidizer, Corrosive, Reactive, Toxic; - Weighs waste to ensure laboratory has not exceeded its monthly or total storage limits; - Maintains waste records; - Determines how waste should be disposed: Trash - Nonhazardous solids; Drain - Nonhazardous Liquids; Labpack; - Prepares waste for shipment with Vendor and Department of Transportation (DOT) personnel. Packages, Transports, and Treats Hazardous Waste Responsibilities: - Must be EPA permitted and approved by the Department of Energy - Picks up hazardous waste for transport to a treatment, storage or disposal facility depending on waste disposal requirements - Must meet all Department of Transportation regulations for transporting hazardous waste - Dispose of waste according to RCRA regulations. Due to the potential risks to human health and the environment, waste must be handled safely through the chain of possession from cradle to grave. To ensure proper handling, there are many safety checks as required by RCRA and DOT regulations. This includes proper labeling, inventory, and characterization to ensure all hazards are known, inspections by the Custodian, ECA, and the state regulator (SCDHEC), and transportation verifications and manifesting. One of the best ways to reduce the risks that waste presents is to minimize or eliminate the creation of waste. This can be accomplished through source reduction which includes: Inventory control, material substitution, process modification, improved housekeeping, and preventative maintenance and recycling.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

A Comprehensive Review of Working Fluids for High-Temperature Heat Pumps: History, Selection, and Evaluation

High-temperature heat pumps (HTHPs) are essential for enhancing energy efficiency across various industrial applications, especially in terms of integrating with renewable energy sources and recovering waste heat. This article thoroughly investigates suitable working fluids for HTHPs, highlighting the evolution from traditional refrigerants to contemporary alternatives with low global warming potential (GWP). It proposes comprehensive selection criteria for these working fluids, pre-selects low-GWP working fluids, and outlines a screening methodology. The pre-selected low-GWP working fluids are evaluated for applications in three typical industrial scenarios involving HTHPs. Furthermore, this study demonstrates that regulatory compliance and environmental impacts significantly influence the development of next-generation refrigerants. The choice of working fluids is closely linked to the types of vapor compression cycles, tailored to the specific industrial applications for HTHPs. This study emphasizes areas for future research, including the development of innovative working fluids; integrated strategies that account for performance, safety, and regulatory standards; alignment of HTHP components; exploration of natural working fluids; and broadening the applications of existing working fluids.

Compression↗