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Carl M Stoots - One of the best experts on this subject based on the ideXlab platform.
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Degradation Issues in Solid Oxide Cells During High Temperature Electrolysis
Journal of Fuel Cell Science and Technology, 2011Co-Authors: M. S. Sohal, Carl M Stoots, James E. O'brien, B. Yildiz, Varun Sharma, A. VirkarAbstract:Idaho National Laboratory (INL) is performing High-Temperature Electrolysis (HTE) research to generate hydrogen using solid oxide Electrolysis cells (SOECs). The project goals are to address the technical and degradation issues associated with the SOECs. This paper provides a summary of ongoing INL and INL-sponsored activities aimed at addressing SOEC degradation. These activities include stack testing, post-test examination, degradation modeling, and issues that need to be addressed in the future. Major degradation issues relating to solid oxide fuel cells (SOFC) are relatively better understood than those for SOECs. Some of the degradation mechanisms in SOFCs include contact problems between adjacent cell components, microstructural deterioration (coarsening) of the porous electrodes, and blocking of the reaction sites within the electrodes. Contact problems include delamination of an electrode from the electrolyte, growth of a poorly (electronically) conducting oxide layer between the metallic interconnect plates and the electrodes, and lack of contact between the interconnect and the electrode. INL’s test results on HTE using solid oxide cells do not provide clear evidence as to whether different events lead to similar or drastically different electrochemical degradation mechanisms. Post-test examination of the SOECs showed that the hydrogen electrode and interconnect get partially oxidized and become nonconductive. This is most likely caused by the hydrogen stream composition and flow rate during cooldown. The oxygen electrode side of the stacks seemed to be responsible for the observed degradation because of large areas of electrode delamination. Based on the oxygen electrode appearance, the degradation of these stacks was largely controlled by the oxygen electrode delamination rate. Virkar et al. [19–22] have developed a SOEC model based on concepts in local thermodynamic equilibrium in systems otherwise in global thermodynamic nonequilibrium. This model is under continued development. It shows that electronic conduction through the electrolyte, however small, must be taken into account for determining local oxygen chemical potential within the electrolyte. The chemical potential within the electrolyte may lie out of bounds in relation to values at the electrodes in the electrolyzer mode. Under certain conditions, high pressures can develop in the electrolyte just under the oxygen electrode (anode)/electrolyte interface, leading to electrode delamination. This theory is being further refined and tested by introducing some electronic conduction in the electrolyte.Copyright © 2010 by ASME
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Status of the INL High-Temperature Electrolysis research program –experimental and modeling
Nuclear Science, 2010Co-Authors: James E. O'brien, Carl M Stoots, Edwin A Harvego, Michael G Mckellar, K. G. Condie, J. S. Herring, G. K. Housley, J. J. HartvigsenAbstract:This paper provides a status update on the High-Temperature Electrolysis (HTE) research and development program at the Idaho National Laboratory (INL), with an overview of recent large-scale system modeling results and the status of the experimental program. System analysis results have been obtained using the commercial code UniSim, augmented with a custom High-Temperature electrolyzer module. The process flow diagrams for the system simulations include an advanced nuclear reactor as a source of High-Temperature process heat, a power cycle and a coupled steam Electrolysis loop. Several reactor types and power cycles have been considered, over a range of reactor coolant outlet temperatures. In terms of experimental research, the INL has recently completed an Integrated Laboratory Scale (ILS) HTE test at the 15 kW level. The initial hydrogen production rate for the ILS test was in excess of 5000 liters per hour. Details of the ILS design and operation will be presented. Current small-scale experimental research is focused on improving the degradation characteristics of the Electrolysis cells and stacks. Small-scale testing ranges from single cells to multiple-cell stacks. The INL is currently in the process of testing several state-of-the-art anode-supported cells and is working to broaden its relationship with industry in order to improve the long-term performance of the cells.
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high temperature Electrolysis for large scale hydrogen and syngas production from nuclear energy summary of system simulation and economic analyses
International Journal of Hydrogen Energy, 2010Co-Authors: James E Obrien, Edwin A Harvego, Michael G Mckellar, Carl M StootsAbstract:A research and development program is under way at the Idaho National Laboratory (INL) to assess the technological and scale-up issues associated with the implementation of solid-oxide Electrolysis cell technology for efficient High-Temperature hydrogen production from steam. This work is supported by the US Department of Energy, Office of Nuclear Energy, under the Nuclear Hydrogen Initiative. This paper will provide an overview of large-scale system modeling results and economic analyses that have been completed to date. System analysis results have been obtained using the commercial code UniSim, augmented with a custom High-Temperature electrolyzer module. Economic analysis results were based on the DOE H2A analysis methodology. The process flow diagrams for the system simulations include an advanced nuclear reactor as a source of High-Temperature process heat, a power cycle and a coupled steam Electrolysis loop. Several reactor types and power cycles have been considered, over a range of reactor outlet temperatures. Pure steam Electrolysis for hydrogen production as well as coElectrolysis for syngas production from steam/carbon dioxide mixtures have both been considered. In addition, the feasibility of coupling the High-Temperature Electrolysis process to biomass and coal-based synthetic fuels production has been considered. These simulations demonstrate that the addition of supplementary nuclear hydrogen to synthetic fuels production from any carbon source minimizes emissions of carbon dioxide during the production process.
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high temperature Electrolysis for large scale hydrogen production from nuclear energy experimental investigations
International Journal of Hydrogen Energy, 2010Co-Authors: Carl M Stoots, James E Obrien, Keith G Condie, J. J. HartvigsenAbstract:Abstract The Idaho National Laboratory (INL) is currently assessing the feasibility of using solid-oxide based Electrolysis cell technology for high temperature Electrolysis of steam for large-scale hydrogen production. In parallel, the INL is studying the simultaneous Electrolysis of steam and carbon dioxide for syngas (hydrogen/carbon monoxide mixture) production. When linked to a nuclear power source, this technology provides a carbon neutral means of producing syngas while consuming CO 2 . The scope of experimental investigations at the INL includes single button cell tests, multi-cell stacks, and multi-stack systems. Multi-cell stack testing used 10 cm × 10 cm (8 cm × 8 cm active area) or 20 cm × 20 cm (18 cm × 18 cm active area) planar cells supplied by Ceramatec, Inc (Salt Lake City, Utah, USA). Multi-stack testing encompassed up to 720 10 cm × 10 cm cells and was conducted in a newly developed 15 kW Integrated Laboratory Scale (ILS) test facility. Gas composition, operating voltage, and operating temperature were varied during testing. The tests were heavily instrumented, and outlet gas compositions were monitored with a gas chromatograph. Results to date show the process to be a promising technique for large-scale hydrogen and syngas production.
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high temperature Electrolysis for hydrogen production from nuclear energy technologysummary
2010Co-Authors: James E Obrien, Carl M Stoots, Edwin A Harvego, J. S. Herring, M. S. Sohal, M. G. Mckellar, K. G. CondieAbstract:The Department of Energy, Office of Nuclear Energy, has requested that a Hydrogen Technology Down-Selection be performed to identify the hydrogen production technology that has the best potential for timely commercial demonstration and for ultimate deployment with the Next Generation Nuclear Plant (NGNP). An Independent Review Team has been assembled to execute the down-selection. This report has been prepared to provide the members of the Independent Review Team with detailed background information on the High Temperature Electrolysis (HTE) process, hardware, and state of the art. The Idaho National Laboratory has been serving as the lead lab for HTE research and development under the Nuclear Hydrogen Initiative. The INL HTE program has included small-scale experiments, detailed computational modeling, system modeling, and technology demonstration. Aspects of all of these activities are included in this report. In terms of technology demonstration, the INL successfully completed a 1000-hour test of the HTE Integrated Laboratory Scale (ILS) technology demonstration experiment during the fall of 2008. The HTE ILS achieved a hydrogen production rate in excess of 5.7 Nm3/hr, with a power consumption of 18 kW. This hydrogen production rate is far larger than has been demonstrated by any of the thermochemical or hybrid processes tomore » date.« less
Massimo Santarelli - One of the best experts on this subject based on the ideXlab platform.
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Use of waste vegetable oil for hydrotreated vegetable oil production with High-Temperature Electrolysis as hydrogen source
Fuel, 2020Co-Authors: Guido Lorenzi, Baldassarre Venezia, Carlos A. Silva, Patrícia Baptista, Massimo SantarelliAbstract:Abstract The research of renewable alternatives to decarbonize the transport sector and to reduce the consumption of fossil fuels pushes towards the development of more sustainable solutions for fuel production. Among the diesel substitutes, hydrotreated vegetable oil (HVO) is considered one of the most promising options, since it can be blended with fossil diesel without limitations. In this context, this paper assesses the technical and economic feasibility of producing HVO using waste vegetable oil (WVO) as feedstock, with the help of a simulation model that maximizes the integration of renewable energy sources. The process to synthesize HVO requires a large amount of hydrogen that, in this study, is supplied through an upstream High-Temperature Electrolysis process occurring in solid oxide Electrolysis cells (SOECs), which are fed by low-carbon electricity. The use of waste oils as feedstock eliminates the competition with food crops (e.g. soybean or rapeseed) and promotes the recycling of substances that need to be disposed. The results of the study prove the technical feasibility of a plant with an annual capacity of 100 kt of HVO, having an energy efficiency of 80%. Also, the breakeven point of such investment would be reached before the fourth year of operation, considering a WVO price of 400 €/t, which is assumed as target price. However, the uncertainty on the market prices of WVO, HVO and electricity, as well as on other fixed and variable production costs, can significantly affect the projected results.
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Integration of High-Temperature Electrolysis in an HVO production process using waste vegetable oil
Energy Procedia, 2019Co-Authors: Guido Lorenzi, L. Mignini, Baldassarre Venezia, Carlos A. Silva, Massimo SantarelliAbstract:Abstract The production of substitutes for liquid fossil fuels is of utmost importance for the decarbonization of the transport sector. This paper assesses the economic feasibility of producing hydrotreated vegetable oil (HVO) using waste vegetable oils as feedstock. The supply of hydrogen for the upgrading of the oil is obtained through a High-Temperature Electrolysis process, fed by low-carbon electricity. The use of waste materials eliminates the competition with food crops (e.g. soybean or rapeseed) and promotes the recycle of substances that should be treated for disposal. The results of the study show that the production cost of HVO with the considered plant are around 33% higher than that of fossil diesel. Moreover, the variable that has the strongest impact on the production cost of HVO is the price of the waste vegetable oil, which affects the final results more than the electricity price and the cost of the electrolyser.
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Synthetic natural gas via integrated High-Temperature Electrolysis and methanation: Part I-Energy performance
Journal of Energy Storage, 2015Co-Authors: Emanuele Giglio, Andrea Lanzini, Massimo Santarelli, Pierluigi LeoneAbstract:In this two-part paper the production of synthetic natural gas (SNG) through integrated plants featuring high temperature Electrolysis and subsequent syngas methanation is analyzed. Part one focuses on plant configuration and performance evaluation. Part two focuses on cost for an economic assessment.Two different ways to produce SNG have been analyzed: the first option features a plant that integrates steam Electrolysis with methanation (Sabatier reaction); the second one considers co-Electrolysis of water and carbon dioxide coupled with TREMP™ (Topsøe recycle energy-efficient methanation process). In both cases high temperature Electrolysis with solid oxide cells (SOEC) technology has been employed.A power input of 10. MWe was taken as the DC electricity input for both plant SOEC generators, based on power-to-gas plants now under construction in Europe. Sensitivity analyses were used to evaluate the impact of selected operating parameters on the plant performance. Especially the pressurization of the SOEC brings a reduction of the over all electrical input required to run the plant. By operating a pressurized SOEC, post-Electrolysis syngas compression (that would be required otherwise because methanation takes place at ≈33. bar) is partly replaced by liquid water pumping before Electrolysis. Thermal integration based on the pinch analysis methodology was also applied in order to calculate the minimum external (thermal) energy requirement. Notably, most of the heat required for vaporizing and super-heating the Electrolysis water can be recovered from the exothermic methanation section. Hence, a good thermal integration is available between SOEC and syngas upgrade catalytic section. This boosts the electricity-to-SNG efficiency to values as high as 80%.The co-Electrolysis plant shows a LHV efficiency of 81.4% that is more than five percentage points higher than the steam Electrolysis case (76%): notably exothermic in-stack methanation - that occurs in the case of high pressure co-Electrolysis assessment - allows for a reduction of the electricity input to the SOEC for the same amount of syngas produced among the two plants.
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Synthetic natural gas via integrated High-Temperature Electrolysis and methanation: Part I—Energy performance
Journal of Energy Storage, 2015Co-Authors: Emanuele Giglio, Andrea Lanzini, Massimo Santarelli, Pierluigi LeoneAbstract:Abstract In this two-part paper the production of synthetic natural gas (SNG) through integrated plants featuring high temperature Electrolysis and subsequent syngas methanation is analyzed. Part one focuses on plant configuration and performance evaluation. Part two focuses on cost for an economic assessment. Two different ways to produce SNG have been analyzed: the first option features a plant that integrates steam Electrolysis with methanation (Sabatier reaction); the second one considers co-Electrolysis of water and carbon dioxide coupled with TREMP™ (Topsoe recycle energy-efficient methanation process). In both cases high temperature Electrolysis with solid oxide cells (SOEC) technology has been employed. A power input of 10 MWe was taken as the DC electricity input for both plant SOEC generators, based on power-to-gas plants now under construction in Europe. Sensitivity analyses were used to evaluate the impact of selected operating parameters on the plant performance. Especially the pressurization of the SOEC brings a reduction of the over all electrical input required to run the plant. By operating a pressurized SOEC, post-Electrolysis syngas compression (that would be required otherwise because methanation takes place at ≈33 bar) is partly replaced by liquid water pumping before Electrolysis. Thermal integration based on the pinch analysis methodology was also applied in order to calculate the minimum external (thermal) energy requirement. Notably, most of the heat required for vaporizing and super-heating the Electrolysis water can be recovered from the exothermic methanation section. Hence, a good thermal integration is available between SOEC and syngas upgrade catalytic section. This boosts the electricity-to-SNG efficiency to values as high as 80%. The co-Electrolysis plant shows a LHV efficiency of 81.4% that is more than five percentage points higher than the steam Electrolysis case (76%): notably exothermic in-stack methanation – that occurs in the case of high pressure co-Electrolysis assessment – allows for a reduction of the electricity input to the SOEC for the same amount of syngas produced among the two plants.
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A comparative assessment on hydrogen production from low- and High-Temperature Electrolysis
International Journal of Hydrogen Energy, 2013Co-Authors: Domenico Ferrero, Andrea Lanzini, Massimo Santarelli, Pierluigi LeoneAbstract:Abstract In this work a comparative analysis between low- and High-Temperature Electrolysis for hydrogen generation is assessed. A hydrogen production system based on Solid Oxide Electrolysis Cells ( SOEC ) is designed and modeled and compared to the performance of a more mature system based on PEM technology. The SOEC system mainly consists of an SOEC stack, a heat recovery system and a hydrogen compression section. Experimental data measured in steam Electrolysis tests performed on single solid oxide cells were utilized into the model to characterize the stack performance. The model carries out a thermodynamic analysis in order to calculate the energy efficiency and the exergetic consumption of the system; these performances are subsequently compared with those of a low-temperature hydrogen generation system evaluated from experimental data measured in test sessions performed on a complete BoP integrating a pressurized Proton Exchange Membrane ( PEM ) electrolyser. The comparison is carried out with the two Electrolysis systems generating hydrogen at the same production rate and pressure. The results of this study show that the modeled SOEC hydrogen generation system can compete with the PEM electrolyser, achieving better performance than the low-temperature system at hydrogen production rate higher than 18.3 g h −1 (corresponding to 0.25 A cm −2 ) and showing an energy efficiency up to 14% higher than the PEM system at 1 A cm −2 .
Hyun Seon Hong - One of the best experts on this subject based on the ideXlab platform.
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Characterization of CuO/YSZ High Temperature Electrolysis Cathode Material Fabricated by High Energy Ball-Milling: 900 °C Reduced by Hydrogen Exposure*
Materials Testing, 2014Co-Authors: Sungkyu Lee, Hyun Seon Hong, Mi-jai Lee, Sang-kuk WooAbstract:Abstract As a more economical cathode material than conventional Ni/YSZ cermet for high temperature Electrolysis (HTE) cell, CuO/YSZ composites (40 vol.-% and 60 vol.-% CuO powder with balance YSZ) were successfully fabricated by high energy ball-milling of CuO and YSZ powders, pressing into pellets ( 13 mm × 2 mm) and subjecting them to a subsequent reduction-sintering process at 900 °C under purging with a 5 % H2/Ar gas. The Cu/YSZ cermet material thus fabricated was characterized using various analytical methods such as XRD, SEM, and laser diffraction as well as scattering method. Electrical conductivity of reduction-sintered Cu/YSZ cermet pellets thus fabricated was measured both at room temperature and temperature range between 600 °C and 800 °C by using the 4-probe technique for comparison with those of previously published literature conductivity data of Ni/YSZ and Cu/YSZ cermets produced by the same high-energy ball milling of blended elemental metal with YSZ powders. The effect of composite comp...
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Fabrication and characterization of 900 °C-sintered Ni/Cu/YSZ cermet high temperature Electrolysis cathode material prepared by high-energy ball-milling method
Journal of Alloys and Compounds, 2012Co-Authors: Hyun Seon Hong, Sungkyu LeeAbstract:Abstract Ni/Cu/YSZ cermet (volume ratio of Ni:Cu:YSZ = 40:20:40) is more electronically conductive than the conventional Ni/YSZ cermet for high temperature Electrolysis (HTE) of water vapor and it was successfully fabricated by high-energy ball-milling of nickel, copper, and YSZ powders, pressing into pellets (O 10 mm × 1 mm) and subsequent sintering process at 900 °C under flowing 5%-H2/Ar gas. The Ni/Cu/YSZ composite material thus fabricated was characterized using various analytical tools such as SEM, XRD, and laser diffraction and scattering method. Electrical conductivity of sintered Ni/Cu/YSZ cermet pellets fabricated was measured by using 4-probe technique for comparison with that of conventional Ni/YSZ cermet. The effect of ball-milling time on electrical conductivity and microstructure of Ni/Cu/YSZ cermets for HTE was investigated. The particle size of Ni/Cu/YSZ decreased while electrical conductivity increased with milling time: enhanced electrical conductivity is attributed to well-connected Ni/Cu/YSZ particles rendered by increased ball-milling time.
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Preparation and characterization of Cu/YSZ cathode for high‐temperature Electrolysis
International Journal of Energy Research, 2009Co-Authors: Jong-min Kim, Kyoung-hoon Kang, Sungkyu Lee, Hyun Seon HongAbstract:The Cu/Y 2 O 3 -stabilized ZrO 2 (YSZ) composite was successfully fabricated by high-energy ball-milling method for possible use as a cathode material in High-Temperature Electrolysis (HTE) cell. Thus, the fabricated Cu/YSZ composite was characterized using various analytical tools such as XRD, SEM, TEM and laser diffraction and scattering method. The Cu/YSZ cermet was observed to consist of crystalline Cu and YSZ in sub-micron scale and evenly distributed without forming aggregates. Electrical conductivity of ball-milled and sintered Cu/YSZ cermet pellet was measured by 4-probe technique and compared with that of conventional Ni/YSZ cermets. The effect of composites composition on the electrical conductivity was also investigated and the marked increase in electrical conductivity for Cu/YSZ over Ni/YSZ was attributed to more open micro-structural morphology of Cu/YSZ and higher electrical conductivity of copper, which explains higher hydrogen production rate for HTE cell with Cu/YSZ cathode compared with HTE cell with Ni/YSZ cathode during actual HTE at 800°C.
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Fabrication and characterization of Cu/YSZ cermet high temperature Electrolysis cathode material prepared by high-energy ball-milling method: II. 700 °C-sintered
Journal of Alloys and Compounds, 2008Co-Authors: Sungkyu Lee, Hyun Seon Hong, Jong-min Kim, Sang-kook WooAbstract:Abstract Cu/YSZ cermet (40 and 60 vol.% Cu powder with balance YSZ) is a more economical cathode material than the conventional Ni/YSZ cermet for high temperature Electrolysis (HTE) of water vapor and it was successfully fabricated by high-energy ball-milling of Cu and YSZ powders, pressing into pellets (∅ 13 mm × 2 mm) and subsequent sintering process at 700 °C under flowing 5%-H2/Ar gas. The Cu/YSZ composite material thus fabricated was characterized using various analytical tools such as XRD, SEM, and laser diffraction and scattering method. Electrical conductivity of sintered Cu/YSZ cermet pellets thus fabricated was measured by using 4-probe technique for comparison with that of conventional Ni/YSZ cermets. The effect of composite composition on the electrical conductivity was investigated and a marked increase in electrical conductivity for copper contents greater than 40 vol.% in the composite was explained by percolation threshold. Also, Cu/YSZ cermet was selected as a candidate for HTE cathode of self-supporting planar unit cell and its electrochemical performance was investigated, paving the way for preliminary correlation of high-energy ball-milling parameters with observed physical and electrochemical performance of Cu/YSZ cermets.
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Performance of Ni/Y2O3-Stabilized ZrO2 Cermet Cathode Prepared by Mechanical Alloying for High-Temperature Electrolysis of Water Vapor
Japanese Journal of Applied Physics, 2008Co-Authors: Sungkyu Lee, Hyun Seon Hong, Kyoung-hoon Kang, Jong-min Kim, Yongseung Yun, Sang-kook WooAbstract:A Ni/Y2O3-stabilized ZrO2 composite cathode was fabricated by high-energy ball milling of Ni and Y2O3-stabilized ZrO2 powders for High-Temperature Electrolysis (HTE) of water vapor. The composite powder composition, time and rotation speed of ball milling were optimized by trial and error for suitable performance with the maximum efficiency of the fabricated cathode in High-Temperature Electrolysis of water vapor (steam) at 800 °C. Thus-synthesized composite powders were characterized using various analytical tools, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and particle size analysis (PSA), and a self-supporting planar unit cell was prepared with a Ni/Y2O3-stabilized ZrO2 composite cathode and a Pt paste anode screen-printed on each side of a Y2O3-stabilized ZrO2 electrolyte disc (30 mm in diameter) and then sintered at 1450 °C for High-Temperature Electrolysis. XRD and PSA results showed that ball milling parameters, such as ball milling time and rotation speed, affect the crystallinity, average particle size, and particle size distribution of ball-milled Ni/Y2O3-stabilized ZrO2 composites. The effects of cathode and Y2O3-stabilized ZrO2 electrolyte thicknesses on the efficiency of hydrogen production were investigated using a self-supporting planar HTE unit cell operating at 800 °C. The engineering significance of high-energy ball milling (HEBM) is evident: HEBM is approximately equivalent to 60 µm screen printing over the Y2O3-stabilized ZrO2 electrolyte and could obviate a tedious and time-consuming screen-printing process in the fabrication of a cathode.
James E. O'brien - One of the best experts on this subject based on the ideXlab platform.
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A 25 kW high temperature Electrolysis facility for flexible hydrogen production and system integration studies
International Journal of Hydrogen Energy, 2020Co-Authors: James E. O'brien, J. J. Hartvigsen, R.d. Boardman, D. Larsen, S. ElangovanAbstract:Abstract A 25 kW High-Temperature Electrolysis (HTE) flexible test facility has been developed at Idaho National Laboratory (INL) for performance evaluation of solid-oxide Electrolysis cell (SOEC) stacks operating independently or in thermal integration with co-located systems. This facility is aimed at advancing the state of the art of HTE technology while demonstrating dynamic grid and thermal energy integration and operational characteristics. The 25 kW HTE flexible test station will provide a test bed for state-of-the-art HTE stack technologies from multiple industry partners. The test station will ultimately be integrated with a co-located thermal energy distribution and storage system within the INL Systems Integration Laboratory. The HTE test station will also be designed to communicate with co-located digital real-time simulators for dynamic performance evaluation and hardware-in-the-loop simulations in a dynamic microgrid environment. Operation of the 25 kW HTE system will be followed by deployment of a test skid with infrastructure support for up to 250 kW HTE turnkey systems. A detailed description of the 25 kW HTE system is provided along with results obtained from initial stack testing at the 5 kW scale.
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RECENT ADVANCES IN HIGH TEMPERATURE Electrolysis AT IDAHO NATIONAL LABORATORY: SINGLE CELL TESTS
ASME 2012 10th International Conference on Fuel Cell Science Engineering and Technology, 2012Co-Authors: Xiaoyu Zhang, James E. O'brien, Robert C. O'brienAbstract:An experimental investigation on the performance and durability of single solid oxide Electrolysis cells (SOECs) is under way at the Idaho National Laboratory. In order to understand and mitigate the degradation issues in high temperature Electrolysis, single SOECs with different configurations from several manufacturers have been evaluated for initial performance and long-term durability. A new test apparatus has been developed for single cell and small stack tests from different vendors. Single cells from Ceramatec Inc. show improved durability compared to our previous stack tests. Single cells from Materials and Systems Research Inc. (MSRI) demonstrate low degradation both in fuel cell and Electrolysis modes. Single cells from Saint Gobain Advanced Materials (St. Gobain) show stable performance in fuel cell mode, but rapid degradation in the Electrolysis mode. Electrolyte-electrode delamination is found to have significant impact on degradation in some cases. Enhanced bonding between electrolyte and electrode and modification of the microstructure help to mitigate degradation. Polarization scans and AC impedance measurements are performed during the tests to characterize the cell performance and degradation.Copyright © 2012 by ASME
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Degradation Issues in Solid Oxide Cells During High Temperature Electrolysis
Journal of Fuel Cell Science and Technology, 2011Co-Authors: M. S. Sohal, Carl M Stoots, James E. O'brien, B. Yildiz, Varun Sharma, A. VirkarAbstract:Idaho National Laboratory (INL) is performing High-Temperature Electrolysis (HTE) research to generate hydrogen using solid oxide Electrolysis cells (SOECs). The project goals are to address the technical and degradation issues associated with the SOECs. This paper provides a summary of ongoing INL and INL-sponsored activities aimed at addressing SOEC degradation. These activities include stack testing, post-test examination, degradation modeling, and issues that need to be addressed in the future. Major degradation issues relating to solid oxide fuel cells (SOFC) are relatively better understood than those for SOECs. Some of the degradation mechanisms in SOFCs include contact problems between adjacent cell components, microstructural deterioration (coarsening) of the porous electrodes, and blocking of the reaction sites within the electrodes. Contact problems include delamination of an electrode from the electrolyte, growth of a poorly (electronically) conducting oxide layer between the metallic interconnect plates and the electrodes, and lack of contact between the interconnect and the electrode. INL’s test results on HTE using solid oxide cells do not provide clear evidence as to whether different events lead to similar or drastically different electrochemical degradation mechanisms. Post-test examination of the SOECs showed that the hydrogen electrode and interconnect get partially oxidized and become nonconductive. This is most likely caused by the hydrogen stream composition and flow rate during cooldown. The oxygen electrode side of the stacks seemed to be responsible for the observed degradation because of large areas of electrode delamination. Based on the oxygen electrode appearance, the degradation of these stacks was largely controlled by the oxygen electrode delamination rate. Virkar et al. [19–22] have developed a SOEC model based on concepts in local thermodynamic equilibrium in systems otherwise in global thermodynamic nonequilibrium. This model is under continued development. It shows that electronic conduction through the electrolyte, however small, must be taken into account for determining local oxygen chemical potential within the electrolyte. The chemical potential within the electrolyte may lie out of bounds in relation to values at the electrodes in the electrolyzer mode. Under certain conditions, high pressures can develop in the electrolyte just under the oxygen electrode (anode)/electrolyte interface, leading to electrode delamination. This theory is being further refined and tested by introducing some electronic conduction in the electrolyte.Copyright © 2010 by ASME
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Status of the INL High-Temperature Electrolysis research program –experimental and modeling
Nuclear Science, 2010Co-Authors: James E. O'brien, Carl M Stoots, Edwin A Harvego, Michael G Mckellar, K. G. Condie, J. S. Herring, G. K. Housley, J. J. HartvigsenAbstract:This paper provides a status update on the High-Temperature Electrolysis (HTE) research and development program at the Idaho National Laboratory (INL), with an overview of recent large-scale system modeling results and the status of the experimental program. System analysis results have been obtained using the commercial code UniSim, augmented with a custom High-Temperature electrolyzer module. The process flow diagrams for the system simulations include an advanced nuclear reactor as a source of High-Temperature process heat, a power cycle and a coupled steam Electrolysis loop. Several reactor types and power cycles have been considered, over a range of reactor coolant outlet temperatures. In terms of experimental research, the INL has recently completed an Integrated Laboratory Scale (ILS) HTE test at the 15 kW level. The initial hydrogen production rate for the ILS test was in excess of 5000 liters per hour. Details of the ILS design and operation will be presented. Current small-scale experimental research is focused on improving the degradation characteristics of the Electrolysis cells and stacks. Small-scale testing ranges from single cells to multiple-cell stacks. The INL is currently in the process of testing several state-of-the-art anode-supported cells and is working to broaden its relationship with industry in order to improve the long-term performance of the cells.
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Analysis of Improved Reference Design for a Nuclear-Driven High Temperature Electrolysis Hydrogen Production Plant
2010Co-Authors: Edwin A Harvego, James E. O'brien, Michael G MckellarAbstract:The use of High Temperature Electrolysis (HTE) for the efficient production of hydrogen without the greenhouse gas emissions associated with conventional fossil-fuel hydrogen production techniques has been under investigation at the Idaho National Engineering Laboratory (INL) for the last several years. The activities at the INL have included the development, testing and analysis of large numbers of solid oxide Electrolysis cells, and the analyses of potential plant designs for large scale production of hydrogen using an advanced Very-High Temperature Reactor (VHTR) to provide the process heat and electricity to drive the Electrolysis process. The results of these system analyses, using the UniSim process analysis software, have shown that the HTE process, when coupled to a VHTR capable of operating at reactor outlet temperatures of 800 °C to 950 °C, has the potential to produce the large quantities of hydrogen needed to meet future energy and transportation needs with hydrogen production efficiencies in excess of 50%. In addition, economic analyses performed on the INL reference plant design, optimized to maximize the hydrogen production rate for a 600 MWt VHTR, have shown that a large nuclear-driven HTE hydrogen production plant can to be economically competitive with conventional hydrogen production processes, particularly whenmore » the penalties associated with greenhouse gas emissions are considered. The results of this research led to the selection in 2009 of HTE as the preferred concept in the U.S. Department of Energy (DOE) hydrogen technology down-selection process. However, the down-selection process, along with continued technical assessments at the INL, has resulted in a number of proposed modifications and refinements to improve the original INL reference HTE design. These modifications include changes in plant configuration, operating conditions and individual component designs. This paper describes the resulting new INL reference design and presents results of system analyses performed to optimize the design and to determine required plant performance and operating conditions.« less
Junichiro Mizusaki - One of the best experts on this subject based on the ideXlab platform.
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polarization mechanism of high temperature Electrolysis in a ni ysz ysz lsm solid oxide cell by parametric impedance analysis
Solid State Ionics, 2013Co-Authors: Euichol Shin, Jungmo Jo, Ji Haeng Yu, Junichiro MizusakiAbstract:Abstract Comprehensive modeling of the spectra of the state-of-the-art Ni–YSZ/YSZ/LSM solid oxide cells including the instrumental stray impedance allowed the systematic deconvolution of the four major polarization losses ranging over one order of impedance magnitude. The stray impedance can be successfully modeled as an inductor connected in parallel with a parasitic resistor whose resistance was shown proportional to the inductance. From the high frequency the ohmic losses, the ‘charge-transfer’ impedance of the Ni–YSZ electrode, the surface diffusion and reaction co-limited impedance of LSM electrode, and the gas phase transport impedance of Ni–YSZ electrode were successfully distinguished. The latter two were satisfactorily described by the ideal Gerischer impedance with two independent parameters, respectively. The gas-concentration impedance increases with Electrolysis due to the gas density decrease with hydrogen production, while the LSM polarization decreases due to the increased oxygen activity. Compensation of the opposite polarization behavior of Ni–YSZ and LSM electrodes explains the apparently ohmic polarization over a wide Electrolysis range until the upturn where exponentially increasing gas-concentration impedance of Ni–YSZ electrode prevails. Apparently being quite distinct from the fuel cell polarization behavior, the polarization of the high temperature Electrolysis can be consistently explained by the chemical potential variations of the reactants and products, which is suggested to be general characteristic of the gas electrodes of solid oxide cells, co-limited by surface diffusion and reaction process. The finite-length Gerischer model constituted of series resistors, shunt resistors, and shunt capacitors, allows the evaluation of the surface diffusivity (ca. 2 ⋅ 10 − 4 cm 2 s − 1 ), reaction constant (ca. 10 3 s − 1 ), and the utilization length (ca. 5 μm) among the LSM–YSZ composite functional layer of thickness of ca. 10 μm. The strong decrease in LSM polarization with Electrolysis at the humidity of 30% can be contributed by the increase in surface diffusivity, chemical capacitance, and the surface reaction constant in the decreasing order, while the adsorption capacitance increases is mainly responsible for the polarization decreases at higher humidity condition of 50%.
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Polarization mechanism of high temperature Electrolysis in a Ni-YSZ/YSZ/LSM solid oxide cell by parametric impedance analysis
Solid State Ionics, 2013Co-Authors: Euichol Shin, Sun-dong Kim, Sang-kuk Woo, Junichiro Mizusaki, Pyung-an Ahn, Hyun-ho Seo, Jong-sook LeeAbstract:Abstract Comprehensive modeling of the spectra of the state-of-the-art Ni–YSZ/YSZ/LSM solid oxide cells including the instrumental stray impedance allowed the systematic deconvolution of the four major polarization losses ranging over one order of impedance magnitude. The stray impedance can be successfully modeled as an inductor connected in parallel with a parasitic resistor whose resistance was shown proportional to the inductance. From the high frequency the ohmic losses, the ‘charge-transfer’ impedance of the Ni–YSZ electrode, the surface diffusion and reaction co-limited impedance of LSM electrode, and the gas phase transport impedance of Ni–YSZ electrode were successfully distinguished. The latter two were satisfactorily described by the ideal Gerischer impedance with two independent parameters, respectively. The gas-concentration impedance increases with Electrolysis due to the gas density decrease with hydrogen production, while the LSM polarization decreases due to the increased oxygen activity. Compensation of the opposite polarization behavior of Ni–YSZ and LSM electrodes explains the apparently ohmic polarization over a wide Electrolysis range until the upturn where exponentially increasing gas-concentration impedance of Ni–YSZ electrode prevails. Apparently being quite distinct from the fuel cell polarization behavior, the polarization of the high temperature Electrolysis can be consistently explained by the chemical potential variations of the reactants and products, which is suggested to be general characteristic of the gas electrodes of solid oxide cells, co-limited by surface diffusion and reaction process. The finite-length Gerischer model constituted of series resistors, shunt resistors, and shunt capacitors, allows the evaluation of the surface diffusivity (ca. 2 ⋅ 10 − 4 cm 2 s − 1 ), reaction constant (ca. 10 3 s − 1 ), and the utilization length (ca. 5 μm) among the LSM–YSZ composite functional layer of thickness of ca. 10 μm. The strong decrease in LSM polarization with Electrolysis at the humidity of 30% can be contributed by the increase in surface diffusivity, chemical capacitance, and the surface reaction constant in the decreasing order, while the adsorption capacitance increases is mainly responsible for the polarization decreases at higher humidity condition of 50%.