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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

High-Temperature Thermochemical Storage with Redox-Stable Perovskites for Concentrating Solar Power, CRADA Number: CRD-14-554

As part of a Federal Opportunity Announcement (FOA) Award, the project will be led by Colorado School of Mines (CSM) to explore and demonstrate the efficacy of highly reducible, redox-stable oxides to provide efficient thermochemical energy storage for heat release at temperatures of 900 degrees Celcius or more. NREL will support the material development for its application in a concentrating solar power (CSP) plant. In the project, NREL will provide its inventive system design, chemical looping for CSP, and use it as a platform to accommodate the chemical processes using a cost effective perovskite materials identified by CSM. NREL will design a 5-10kW particle receiver for perovskite reduction to store solar energy and help the development of a fluidized-bed reoxidation reactor and system integration. NREL will develop the demonstration receiver for on-sun test in the 5-10 kWt range in NREL's high flux solar furnace. NREL will assist in system analysis and provide techno-economic inputs for the overall system configuration.

14 SOLAR ENERGY↗
DOE OSTI2016

Bench-Scale Development of a Non-Aqueous Solvent (NAS) CO 2 Capture Process for Coal-Fired Power Plants

The project aimed to advance RTI’s non-aqueous amine solvent technology by improving the solvent to reduce volatility, demonstrating long-term continuous operation at lab- (0.5 liters solvent) and bench-scale (~120 liters solvent), showing low reboiler heat duty measured during bench-scale testing, evaluating degradation products, building a rate-based process model, and evaluating the techno-economic performance of the process. The project team (RTI, SINTEF, Linde Engineering) and the technology performed well in each area of advancement. The modifications incorporated throughout the project enabled the attainment of target absorber and regenerator conditions for the process. Reboiler duties below 2,000 kJ t /kg CO 2 were observed in a bench-scale test unit operated at RTI.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2017

Minimize Solvent Oxidation with NO X Pre-Scrubbing

A novel method to remove nitrogen dioxide (NO 2 ) from the flue gas of coal-fired power plants with CO 2 capture was further developed for commercial implementation. The technology leverages the equipment and chemistry in an existing (sulfur dioxide) SO 2 polishing scrubber upstream of the main CO 2 capture unit to remove the NO 2 , preventing degradation of the CO 2 capture solvent and formation of nitrosamines (environmental hazards). The research in this report focuses on further evaluation of the chemical additives and operating conditions associated with the NO 2 removal process to define conditions for commercial scale testing and deployment. Experimental work systematically evaluated a series of potential additives to minimize the oxidation of sulfite in a representative SO 2 pre-scrubber solution (sulfite, in turn, absorbs NO 2 ). The additive combinations and concentrations were varied alongside important process conditions such as temperature, oxygen concentration, and metals present in solution to mimic the conditions expected in a commercial system. Important results of the parametric experimental work include identifying a new, potent sulfite oxidation inhibitor, revealing the importance of combining inhibitors with metal chelating agents, validation of a low-cost additive process, and development of a new semi-empirical model to represent mechanisms associated with sulfite oxidation. In addition, the experimental work reveled the impact of operating at higher temperatures (representative of a field test unit), which will guide the selection and concertation of additives as well. Engineering analysis found that waste solutions from the pre-scrubber with NO 2 additives may potentially be integrated with existing processes on site (e.g., flue gas desulfurization unit). In addition, techno-economic analysis identified potential net savings as large as $1.30/tonne CO 2 captured and quantified the potential benefit of low cost additive options actively being pursued by the development team. Finally, the experimental results and engineering analysis supported the development of a detailed field testing plan and protocol to evaluate the technology at near-commercial scale. The field test preparation included development of procedures to introduce chemical additives to an existing SO 2 polishing unit and identification of representative flue gas conditions based on a review of existing plants. These activities will have direct bearing on operation and design of commercial units.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2017

The Distributed Geothermal Market Demand Model (dGeo): Documentation

The National Renewable Energy Laboratory (NREL) developed the Distributed Geothermal Market Demand Model (dGeo) as a tool to explore the potential role of geothermal distributed energy resources (DERs) in meeting thermal energy demands in the United States. The dGeo model simulates the potential for deployment of geothermal DERs in the residential and commercial sectors of the continental United States for two specific technologies: ground-source heat pumps (GHP) and geothermal direct use (DU) for district heating. To quantify the opportunity space for these technologies, dGeo leverages a highly resolved geospatial database and robust bottom-up, agent-based modeling framework. This design is consistent with others in the family of Distributed Generation Market Demand models (dGen; Sigrin et al. 2016), including the Distributed Solar Market Demand (dSolar) and Distributed Wind Market Demand (dWind) models. dGeo is intended to serve as a long-term scenario-modeling tool. It has the capability to simulate the technical potential, economic potential, market potential, and technology deployment of GHP and DU through the year 2050 under a variety of user-defined input scenarios. Through these capabilities, dGeo can provide substantial analytical value to various stakeholders interested in exploring the effects of various techno-economic, macroeconomic, financial, and policy factors related to the opportunity for GHP and DU in the United States. This report documents the dGeo modeling design, methodology, assumptions, and capabilities.

15 GEOTHERMAL ENERGY↗
DOE OSTI2017

Multi-Scale Ordered Cell Structure for Cost Effective Production of Hydrogen by HTWS

Production of hydrogen using an electrochemical device provides for large scale, high efficiency conversion and storage of electrical energy. When renewable electricity is used for conversion of steam to hydrogen, a low-cost and low emissions pathway to hydrogen production emerges. This project was intended to demonstrate a high efficiency High Temperature Water Splitting (HTWS) stack for the electrochemical production of low cost H2. The innovations investigated address the limitations of the state of the art through the use of a novel architecture that introduces macro-features to provide mechanical support of a thin electrolyte, and micro-features of the electrodes to lower polarization losses. The approach also utilizes a combination of unique sets of fabrication options that are scalable to achieve manufacturing cost objectives. The development of HTWS process and device is guided by techno-economic and life cycle analyses.

08 HYDROGEN↗
DOE OSTI2017

Large Pilot-Scale Carbon Dioxide (CO2) Capture Project Using Aminosilicone Solvent.Final Scientific/Technical Report

GE Global Research has developed, over the last 8 years, a platform of cost effective CO2 capture technologies based on a non-aqueous aminosilicone solvent (GAP-1m). As demonstrated in previous funded DOE projects (DE-FE0007502 and DEFE0013755), the GAP-1m solvent has increased CO2 working capacity, lower volatility and corrosivity than the benchmark aqueous amine technology. Performance of the GAP-1m solvent was recently demonstrated in a 0.5 MWe pilot at National Carbon Capture Center, AL with real flue gas for over 500 hours of operation using a Steam Stripper Column (SSC). The pilot-scale PSTU engineering data were used to (i) update the techno-economic analysis, and EH&S assessment, (ii) perform technology gap analysis, and (iii) conduct the solvent manufacturability and scale-up study.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2018

Fractionation and catalytic upgrading of bio-oil

The goal was to develop a biomass conversion process that optimizes fractionation and conversion to maximize Carbon efficiency and Hydrogen consumption to obtain drop-in fuels. Selective fractionation of raw biomass was obtained via multi-stage thermal fractionation to produce different streams that are enriched in a particular chemical family (acids, furanics or phenolics). These streams were later catalytically upgraded in both liquid and vapor phase to perform C-C bond formation and hydrodeoxygenation. Among various upgrading strategies investigated we have identified an effective path in which cyclopentanone is a crucial intermediate that can be derived from furfural and other furanics obtained in high concentrations from this thermal staged process. Cyclopentanone is a very versatile molecule, which can couple with itself to product high quality jet-fuel, or couple with phenolic or furanics to create long chain molecules. These (mono-oxygenated) compounds in the correct molecular weight fuel range can be hydrotreated to direct drop-in fuels. Interestingly, we have found that the conversion of furfural to cyclopentanone is not affected by the presence of acetic acid, and, more interestingly, it is enhanced by the presence of water. These are very significant findings, since water and acetic acid are always present in all streams from the primary conversion stage. These results have allowed to complete detailed life-cycle assessment and techno-economic analysis that have been back-fed to the experimentalists to refine the catalyst selection and process operations with the objective of maximizing C efficiency at minimum H utilization. These combined investigations have opened the possibility of an economically and technologically effective process that could result in commercial fuels produced from renewable sources at a cost that might be competitive with fossil fuels.

09 BIOMASS FUELS↗
DOE OSTI2018

Development Of Nutrient And Water Recycling Capabilities In Algae Biofuels Production Systems. Final Summary Report

The objective of this project was to develop and demonstrate methods of recycling of water and nutrients for algal biofuels production. Recycling was accomplished both internal to the system and, in a broader sense, through import and reuse of municipal wastewater. Such an integrated system with wastewater input had not been demonstrated previously, and the performance was unknown, particularly in terms of influence of recycling on algal productivity and the practical extent of nutrient recovery from biomass residuals. Through long-term laboratory and pilot research, the project resulted in the following: 1. Bench-scale pretreatment of algal biomass did not sufficiently increase methane yield of nutrient solubilization during anaerobic digestion to warrant incorporation of pre-treatment into the pilot plant. The trial pretreatments were high-pressure orifice homogenization, sonication, and two types of heat treatment. 2. Solubilization of biomass particulate nutrients by lab anaerobic digesters ranged from 20% to nearly 60% for N and 40-65% for P. Subsequent aerobic degradation of the anaerobically digested biomass simulated raceways receiving whole digestate and resulted in an additional 20-55% N solubilization and additional 20% P solubilization. 3. Comparisons of laboratory and pilot digesters showed that laboratory units were reasonable proxies for pilot-scale. 4. Pilot-scale anaerobic digesters were designed, installed, and operated to digest algal biomass. Nutrient re-solubilization by the digesters was monitored and whole digestate was successfully used as a fertilizer in pilot algae raceways. 5. Unheated, unmixed digesters achieved greater methane yield and nutrient solubilization than heated, mixed digesters, presumably due to longer the solids residence times in unmixed digesters. The unmixed, unheated pilot digesters yielded 0.16 L CH4 /g volatile solids (VS) introduced with 0.15 g VS/L-d organic loading and 16oC average temperature. A conventional heated mixed lab digester yielded 0.22 L CH4 /g VS with 0.25 g VS/L-d and 30oC. The highest yield (0.30 L CH4 /g VS) was achieved by the unmixed lab digesters operated at a constant 20oC. All digesters were operated with a 40-d hydraulic residence time. 6. In general, 50-75% of initial particulate N and P could be solubilized during anaerobic digestion and available for subsequent rounds of algae cultivation. 7. Bench-scale experiments showed the recovery from hydrothermal liquefaction (HTL) wastewater of carbon via anaerobic digestion and of nutrients to grow algae. To satisfy the nitrogen demand of algae cultivation, HTL wastewater would be diluted 400-fold, which was found to eliminate inhibition of algae growth by HTL wastewater. 8. Anaerobic digestion methane yield was lower for algal biomass containing coagulants such as would be used to aid harvesting or dewatering. Depending on doses, starch-based coagulant decreased yield by 10-14% and aluminum chlorohydrate decreased it by 14-26%. The lowest yield was 0.28 L CH 4 /g volatile solids introduced to the digesters. 9. Algae harvested from raceways operated on recycled water had methane yields 13% higher than algae from raceways operated on both recycled water and nutrients provided by algae digestate. The slightly lower yield was expected due to the presence of previously digested biomass from the digestate fertilizer. 10. Defined media was replenished with nutrients and recycled repeatedly in sequential batch growth of Chlorella sorokiniana (DOE 1412). This laboratory study tested for inhibition and accumulation of inhibiting compounds (allelopathic or auto-inhibitory substances), information that would help estimate the blowdown ratio needed for an integrated system. In laboratory experiments in which water was recycled a total of five times, each successive round of reuse resulted in an average 4±3% reduction in log-phase specific growth rates. However, linear-phase growth inhibition was only observed in the final fifth round of reuse. 11. No decline in productivity was detected after 15 rounds of water recycling with nutrients provided by whole digestate in lab cultivation. Lab tests allowed for steady light and temperature, increasing the ability to detect inhibition. 12. In initial pilot inhibition studies, wastewater growth media was reused once while productivity was monitored. Media reuse was accomplished with triplicate sets of 33-m2 raceways operated in series. First-round gross productivity (based on effluent biomass flow) averaged 23 g/m 2 -day annually while second-round gross productivity averaged 19 g/m 2 -day annually. In terms of net productivity (based on raceway effluent biomass minus influent biomass), the first-round productivity averaged 15 g/m2-d and second round averaged 13 g/m 2 -d during June-September operation. The higher productivity in the first-round ponds was likely due to heterotrophic/mixotrophic growth on the wastewater organic matter. 13. In a culminating pilot experiment, coagulant was used to decrease the carry-over of unsettled algae into subsequent rounds of growth. Over nearly 8 months, 93% of the media (the equivalent of 14 rounds of water reuse) was recycled without significant productivity loss compared to controls. Ponds receiving both recycled water and nutrients had net productivities of 14-24 g/m 2 -d during fall and mid-summer, respectively. 14. Techno-economic analysis of the proposed facility found minimum fuel selling price to range from $7.01/gallon gasoline equivalent without revenue other than fuel to $3.85/GGE with revenue from wastewater treatment fees and LCFS and RIN (Low Carbon Fuel Standard and Renewable Identification Numbers) credits. 15. Life cycle assessment indicated GHG emissions of 40.7 g CO 2 /MJ fuel and a net energy ratio (energy required/energy produced) of 0.37.

09 BIOMASS FUELS↗
DOE OSTI2018

A Microalgae-Based Platform for the Beneficial Re-use of Carbon Dioxide Emissions from Power Plants

This project sought to address the technical and economic barriers to carbon dioxide capture and utilization using microalgae. Operating data were collected in 2016 and 2017 during cultivation of Scenedesmus acutus at Duke Energy’s East Bend Station – a coal-fired power plant located in northern Kentucky – using flue gas as the CO 2 source. Algae were grown in a 1200 L “cyclic flow” photobioreactor (PBR) designed by the University of Kentucky. A key finding was that the harvested algae contained only very low concentrations of heavy metals (As, Cd, Hg, Se), consistent with heavy metals incorporation from the supplied nutrients. This indicates that algal biomass produced from coal-derived flue gas would be suitable for a variety of applications, including the production of bioplastics, use as fertilizer, etc. A lifecycle assessment showed that the UK-designed PBR employed in this work qualifies as a net CO 2 capture technology. Indeed, over a 30-year period, net CO 2 capture would equate to 43% of the targeted amount, i.e., the amount captured from the supplied flue gas. A techno-economic analysis indicated that the minimum production cost of Scenedesmus acutus biomass in the US is in the order of 875 USD/ton, excluding the cost of capital. While this figure is not too dissimilar to values reported for open raceway ponds in similar scenarios, it emphasizes that for current cultivation technology any pathway to economic viability will require applications for which algal boimass can be sold at prices in excess of 1,000 USD/ton. Currently, such applications represent relatively small markets, such as pigments (e.g., astaxanthin) and nutraceuticals (ω-3 unsaturated fatty acids), as well as nutritional supplements (whole algae) for human consumption and for use in pet food. Consequently, the commercialization of large-scale algae-based CO 2 capture and utilization will require the development of new technologies to reduce the cost of algae production and/or the development of new, high-value applications for algal biomass. One of the more promising applications for algal biomass is in the production of bioplastics. In this work, the potential for the algae grown in the East Bend PBR for the production of bioplastic with adequate mechanical properties was clearly shown. Positive features of the produced biomass included a high protein content and a composition that was generally more homogeneous than biomass grown in open ponds (in which many species may be present). The best candidate for further review, after incorporation into ethylene-vinyl acetate, was a lipid and sugar extracted material, which showed the highest extension values with comparable load values to other UK-derived samples. It also demonstrated extension benefits against the Algix Bloom product (currently offered commercially), even though it contained agglomerates which generally exert a negative effect on mechanical properties. This leads to speculation that with enhanced milling that exists on the commercial scale, the sugar and fat extracted product may be even more competitive. This, in turn, points to the need for additional work in order to assess the properties of such optimized algae-based plastics and the price point they can command.

09 BIOMASS FUELS↗
DOE OSTI2017

An Advanced Catalytic Solvent for Lower Cost Post-Combustion CO 2 Capture in a Coal-Fired Power Plant

In this report, CAER addresses DOE’s objectives for improvements on post-combustion CO 2 capture through a three-fold approach including 1) advanced solvent, 2) homogeneous catalyst and 3) membrane carbon enrichment system. CAER-B3 solvent was formulated to improve the overall thermodynamics with the addition of a proton receiver while maintaining faster kinetics with the addition of thermally robust primary amine. The EH&S study indicates that CAER-B3 solvent poses little human toxicological or ecological risk in its raw material form. Generation of significant quantities of nitrosamines was deemed unlikely when using B3 solvent for CO 2 capture from coal-derived flue gas. The catalytic solvent caused a 21% reduction in energy demand, achievable via decreasing the liquid flowrate. Cyclic capacity nearly doubled due to the slower flowrate, and therefore, reduced the sensible heat required to remove CO 2 in the stripper. The increased rich loadings achieved by either pre-concentrating membrane or dewatering membrane prior to stripper, in addition to improved cyclic capacity, will lower downstream compression costs, while reducing the energy consumption per unit of CO 2 produced. Moreover, the CAER-B3 solvent demonstrated a greater thermal stability, lessening the rate of amine loss, caused by solvent degradation and emissions, by 50-70%. The CAER developed catalysts with a second order rate constant of 7.5 x 10 4 – 10 5 M -1 s -1 , far beyond those reported to date. The catalyst was designed to be a mimic of the enzyme carbonic anhydrase and increase the rate of CO 2 hydration to produce bicarbonate. As such, a 10-25% improvement in absorption rate was observed over the MEA base case. Enhancements can be imparted to the full scale system to reduce packing height of the absorber column, resulting in significant capital cost savings. Furthermore, the family of CAER catalysts showed less than 10% decomposition over 100 hours at 100 °C, suggesting that these catalysts will be stable in the harsh oxidative and thermal process conditions of an industrial carbon capture unit. Flue gas contaminants, such as NO x and SO x , also did not impact catalytic activity. A method for synthetic production of 500 g/batch was designed, verified, and well-documented, with scaling capabilities up to 500 kg. Two types of membranes were designed and tested for the purpose of increasing the solvent carbon loading prior to entering the stripper column. 500 hour and 100 hour verification studies were completed for the pre-concentrating membrane and zeolite dewatering membrane, respectively. Results demonstrated that a membrane-based CO 2 enrichment step using a commercial CO 2 membrane, or a zeolite dewatering membrane, or both, should be implemented in the carbon capture process to increase the CO 2 partial pressure by 16%, resulting in a stripping energy reduction of 35% relative to DOE Case 12 MEA solvent. Experimental data showed a carbon loading enrichment of 18-40% in comparison to the configuration without the pre-concentrating gas membrane. During the timespan of this project, challenges were identified and addressed so that enhanced performance may be realized long-term. Mitigation implementations included re-configuration of the bench unit with a solvent recovery column and a knock-out drum, as well as an increase in stripper pressure set point. Both changes resulted in a considerable reduction in the rate of solvent loss. Additionally, the membrane synthesis procedure was modified and validated to address zeolite dissolution concerns along with a new separation module. The techno-economic analysis conducted by WorleyParsons indicated the CAER-adCCS hybrid approach may outperform NETL Case 12 with regards to net plant HHV efficiency and cost of electricity.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2018

Final Report UCLA-Thermochemical Storage with Anhydrous Ammonia

In ammonia-based thermochemical energy storage (TCES), ammonia is dissociated endothermically as it absorbs solar energy during the daytime. When energy is required, the reverse reaction releases energy to heat a working fluid such as steam, to produce electricity. Ammonia-based TCES has great advantages of simplicity, low cost reactants, and a strong industrial base in the conventional ammonia industry. The concept has been demonstrated over three decades of research at Australian National University, achieving a 24-hour demonstration of a complete system. At the start of this project, three challenges were identified that would have to be addressed to show that the system is technically and economically viable for incorporation into a CSP plant with an advanced, high temperature power block. All three of these challenges have now been addressed: 1. The ammonia synthesis reaction had not, to our knowledge, been carried out at temperatures consistent with modern power blocks (i.e., ~650°C). The technical feasibility of operating a reactor under high-temperature, near-equilibrium conditions was an unknown, and was therefore a technical risk. The project has successfully demonstrated steam heating to 650°C and energy recovery to steam at the 5 kWt level. 2. The ammonia system has a relatively low enthalpy of reaction combined with gas phase reactants. This is not a direct disadvantage since the reactants themselves are low cost. The challenge lies in storing the required volume of reactants cost effectively. Therefore, a second key goal was to show, through techno-economic analysis, that underground storage technologies can be used to store the energy-rich gas at a cost that is consistent with the SunShot cost goal. We have identified two promising technologies for gas storage: storage in salt caverns has an estimated cost of 1(USD)/kWht and storage in drilled shafts could be on the order of 7(USD)/kWht. Together these two options answer the technical challenge associated with storage of gas phase components. 3. While this project is primarily concerned with high-temperature heat recovery and methods to store the gaseous components, it is also important to consider the feasibility of the entire system. Consequently, an additional goal was to perform analysis to show the feasibility of integrating endothermic reactors within a tower receiver. A conceptual design of an ammonia dissociation receiver/reactor has been developed that fits into the same size cylindrical envelope as the molten salt receiver in SAM, and has the same design thermal capacity. The calculated thermal efficiency of this receiver is 94.6%. Thus, this investigation has established the technical feasibility of a surround field tower system using ammonia dissociation. With these challenges addressed, we proceeded to design a full-scale synthesis and heat recovery system. A model was developed and validated by comparison with our experimental data. A parametric study showed, among other things, the importance of using small tube diameters and spacing to enhance heat transfer. Multi-parameter optimization was used to find a design that minimizes the wall material volume. Finally, cost estimation shows that the ammonia system has good prospects of meeting the Sunshot 15(USD)/kWht target: estimated costs of the entire synthesis system for the 220 MWt plant with 6 hours of storage are 13(USD)/kWht using salt cavern storage and 18(USD)/kWht using shaft drilling. Costs per kWht are even lower with more hours of storage. With the established technology of ammonia synthesis as a starting point, the successes of the project have mitigated technical risks associated with high-temperature synthesis reaction, underground storage, and tower receiver design. Estimated costs are less than 15(USD)/kWht with salt cavern storage. It is now possible to map a time line to commercial deployment that is likely to be shorter and less risky than other thermochemical cycles under active investigation. UCLA has filed a patent that protects the new ideas developed during this project. Discussions are ongoing with potential investors with the aim of partnering for further work. As well as immediate improvements and extra work with the existing experimental system, a key goal is to extend it to a small solar-driven project at an early opportunity.

14 SOLAR ENERGY↗
DOE OSTI2018

SunShot Innovator in Residence Final Report.

This report describes the development of Radical-Ion Flow Battery (RIFB) technology for electrochemical grid storage, and solar thermochemical cycles for conversion of concentrated solar energy to stored chemical energy. The Radical-Ion Flow Battery stores energy via electrolysis of a molten salt electrolyte such as NaNO2 into an alkali metal and nitrogen dioxide, both of which can be stored as liquids in non-pressurized tanks. The use of extremely facile ion-radical single electron transfer reactions at both electrodes that entail no breaking of covalent bonds is directed towards minimizing thermodynamic irreversibility in the charge/discharge cycle, and eliminating the need for catalytically active electrode materials. Both kinetics and mass transport are also facilitated by the absence of diluent species; the battery electrolyte and active chemical ingredient are one and the same. Our underlying strategy for low-cost scalability is the use of only earth abundant starting materials (NaCl, N2, O2, and steel). The underlying strategy for avoiding the problem of capacity fade over 10,000 charge/discharge cycles is the use of extremely simple chemistry. It is argued that operation at elevated temperature is highly advantageous for very large-scale batteries from the standpoint of battery heat-sinking, access to ultrahigh conductivity electrolytes, and increased electrochemical kinetic rate constants. Numerous practical considerations, such as seals, insulators, and electrical feedthroughs are examined in detail, as are questions related to low-cost mass production and battery techno-economic analysis.

25 ENERGY STORAGE↗
DOE OSTI2018

Indirect Liquefaction of Coal-Biomass Mixture for Production of Jet Fuel with High Productivity and Selectivity

Coal to liquids (CTL) and coal-biomass to liquids (CBTL) processes were advanced by testing and demonstrating Southern Research’s sulfur tolerant nickel-based reforming catalyst and Chevron’s highly selective and active cobalt-zeolite hybrid Fischer-Tropsch (FT) catalyst to clean, upgrade and convert syngas predominantly to jet fuel range hydrocarbon liquids, thereby minimizing expensive cleanup and wax upgrading operations. The National Carbon Capture Center (NCCC) operated by Southern Company (SC) at Wilsonville, Alabama served as the host site for the gasifier slip-stream and simulated syngas testing/demonstration. Reformer testing was performed to (1) reform tar and light hydrocarbons, (2) decompose ammonia in the presence H2S, and (3) deliver the required H2 to CO ratio for FT synthesis. FT Testing was performed to produce a product primarily containing C5-C20 liquid hydrocarbons and no C21+ waxy hydrocarbons with productivity greater than 0.7 gC5+/g catalyst/h, and at least 70% diesel and jet fuel range (C8-C20) hydrocarbon selectivity in the liquid product. A novel heat-exchange reactor system was employed to enable the use of the highly active FT catalyst and larger diameter reactors that results in cost reduction for commercial systems. Following laboratory development and testing, SR’s laboratory reformer was modified to operate in a Class 1 Div. 2 environment, installed at NCCC, and successfully tested for 125 hours using raw syngas. The catalyst demonstrated near equilibrium reforming (~90%) of methane and complete reforming/decomposition of tar and ammonia in the presence of up to 380 ppm H2S. For FT synthesis, SR modified and utilized a bench scale skid mounted FT reactor system (SR-CBTL test rig) that was fully integrated with a slip stream from SC/NCCC’s transport gasifier (TRIG). The test-rig developed in a previous project (DE-FE0010231) was modified to receive up to 7.5 lb/h raw syngas augmented with bottled syngas to adjust the H2/CO molar ratio to 2, clean it to cobalt FT catalyst specifications, and produce liquid FT products at the design capacity of up to 6 L/day. Promising Chevron catalyst candidates in the size range from 70-200 μm were loaded onto SR’s 2-inch ID and 4-inch ID bench-scale reactors utilizing IntraMicron’s micro-fiber entrapped catalyst (MFEC) heat exchange reactor technology. During 2 test campaigns, the FT reactors were successfully demonstrated at NCCC using syngas for ~420 hours. The catalyst did not experience deactivation during the tests. SR’s thermo-syphon heat removal system maintained reactor operating temperature along the axis to within ±4 °C. The experiments gave a steady catalyst productivity of 0.7-0.8 g/g catalyst/h, liquid hydrocarbon selectivity of ~75%, and diesel and jet fuel range hydrocarbon selectivity in the liquid product as high as 85% depending on process conditions. A preliminary techno-economic evaluation showed that the SR technology-based 50,000 bpd plant had a 10 % lower total plant cost compared to a conventional slurry reactor based plant. Furthermore, because of the modular nature of the SR technology, it was shown that the total plant cost advantage increases to >35 % as the plant is scaled down to 1000 bpd.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2018

System Advisor Model (SAM) General Description (Version 2017.9.5)

This document describes the capabilities of the System Advisor Model (SAM) developed and distributed by the U.S. Department of Energy's National Renewable Energy Laboratory. The document is for potential users and others wanting to learn about the model's capabilities. SAM is a techno-economic computer model that calculates performance and financial metrics of renewable energy projects. Project developers, policy makers, equipment manufacturers, and researchers use graphs and tables of SAM results in the process of evaluating financial, technology, and incentive options for renewable energy projects. SAM simulates the performance of photovoltaic, concentrating solar power, solar water heating, wind, geothermal, biomass, and conventional power systems. The financial models are for projects that either buy and sell electricity at retail rates (residential and commercial) or sell electricity at a price determined in a power purchase agreement (PPA). SAM's simulation tools facilitate parametric and sensitivity analyses, Monte Carlo simulation and weather variability (P50/P90) studies. SAM can also read input variables from Microsoft Excel worksheets. For software developers, the SAM software development kit (SDK) makes it possible to use SAM simulation modules in their applications written in C/C plus plus, C sharp, Java, Python, MATLAB, and other languages. NREL provides both SAM and the SDK as free downloads at https://sam.nrel.gov. SAM is an open source project, so its source code is available to the public. Researchers can study the code to understand the model algorithms, and software programmers can contribute their own models and enhancements to the project. Technical support and more information about the software are available on the website.

47 OTHER INSTRUMENTATION↗
DOE OSTI2018

Hybridizing a Geothermal Plant with Solar and Thermal Energy Storage to Enhance Power Generation

The objective of this project is to identify cost-effective thermal storage systems for a geothermal/solar hybrid system in order to increase the plant dispatchability. Furthermore, an optimal quantity of thermal storage will also be determined to achieve the best economics of a geothermal/solar hybrid plant. NREL is working with Hyperlight Energy and Coso Operating Company to develop techno-economic models of such a system.

15 GEOTHERMAL ENERGY↗
DOE OSTI2018

Chefornak Energy Configuration Options: Energy Infrastructure Optimization to Reduce Fuel Cost and Dependence in Chefornak, Alaska

The U.S. Department of Energy is funding, through the Grid Modernization Program, the Alaska Microgrid Partnership (AMP), a multi-stakeholder collaborative comprised of national labs and Alaska based partners. The over-arching goal of AMP is to reduce the use of total imported fuel into communities to secure all energy services by at least 50% in Alaska's remote microgrids without increasing system lifecycle costs, while improving overall system reliability, security, and resilience. One goal of AMP is to investigate if a combination of Energy Efficiency (EE) and high contribution (from Renewable Energy (RE)) power systems can reduce total imported energy usage by 50% while lowering Life Cycle Costs (LCC) and improving reliability and resiliency. A techno-economic analysis was conducted for the community of Chefornak to investigate system architectures that could meet the goal of reducing imported fuel consumption by 50% or more.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2018

Global Value Chain and Manufacturing Analysis on Geothermal Power Plant Turbines

Currently, geothermal project developers customize the size of the power plant to fit the resource being developed. The turbine is designed and sized to optimize efficiency and resource utilization for electricity production; most often, other power plant components are then chosen to complement the turbine design. These custom turbine designs demand one-off manufacturing processes, which result in higher manufacturing setup costs, longer lead-times, and higher capital costs overall in comparison to larger-volume line manufacturing processes. In contrast, turbines produced in standard increments, manufactured in larger volumes, could result in lower costs per turbine. In this study, we developed a manufacturing cost model to identify requirements for equipment, facilities, raw materials, and labor. Then we used discounted cash flow (DCF) analysis to calculate the minimum sustainable price (MSP). We analyzed three different cases 1) 1 MWe geothermal ORC turboexpander 2) 5 MWe ORC turboexpander and 3) 20 MWe geothermal steam turbine, and calculated the cost of manufacturing the major components, such as the impellers/blades, shaft/rotor, nozzles, inlet guide lanes, disks, and casings. The results showed that MSP could highly vary between 893 /kW and 30 /kW based on turbine size, standardization and volume of manufacturing. The analysis also showed that the economy of scale applies both to the size of the turbine and the number manufactured in a single run. As an example, the unit price of a 5 MW standard design turbine could be 150 /W cheaper than the custom design. Sensitivity analysis indicated that these savings come largely from reduced labor costs for design and engineering and manufacturing setup. In addition to manufacturing cost savings, there is a delivery time saving up to 10 months, which could have a positive effect to construction financing operation time. Another advantage of these standard turbines is their adaptability to different geothermal systems by operating at off-design conditions. We also modeled off-design turbine efficiencies within the commercially-favorable operating range of a standard ORC compared to custom-designed ORC equipment. Than we used these performance calculations and power output capacities in a discounted cash flow (DCF) analysis of plant operations and financing, thereby creating representative techno economic models of a total geothermal power plant. I this scope we used NREL's System Advisor model (SAM) and performed DCF analysis of standard and custom design turbines using results from IPSEpro over range of temperatures of interest. In this scope 63 different off-design cases were analyzed. This helped us to answer the question; 'Can today's capital cost savings compensate the future revenue losses due to lower electricity generation?' The results showed that, the net capital cost savings for the modeled 5 MW case study may reach up to plus 1,298,672. Also, the difference between NPV of standard design and custom design turbine could reach up to 733,940. To sum up, when all the things mentioned above are taken into consideration, it can be said that, the standard turbines are competitive over a wide range of temperatures and flow rates and the give positive NPV differences for certain cases near their design point.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗