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High-Temperature Co-electrolysis of Carbon Dioxide and Steam for the Production of Syngas; Equilibrium Model and Single-Cell Tests

Description: An experimental study has been completed to assess the performance of single solid-oxide electrolysis cells operating over a temperature range of 800 to 850ºC in the coelectrolysis mode, simultaneously electrolyzing steam and carbon dioxide for the direct production of syngas. The experiments were performed over a range of inlet flow rates of steam, carbon dioxide, hydrogen and nitrogen and over a range of current densities (-0.1 to 0.25 A/cm2) using single electrolyte-supported button electrolysis cells. Steam and carbon dioxide consumption rates associated with electrolysis were measured directly using inlet and outlet dewpoint instrumentation and a gas chromatograph, respectively. Cell operating potentials and cell current were varied using a programmable power supply. Measured values of open-cell potential and outlet gas composition are compared to predictions obtained from a chemical equilibrium coelectrolysis model. Model predictions of outlet gas composition based on an effective equilibrium temperature are shown to agree well with measurements. Area-specific resistance values were similar for steam electrolysis and coelectrolysis.
Date: June 1, 2007
Creator: O'Brien, J. E.; Stoots, C. M.; Hawkes, G. L.; Herring, J. S. & Hartvigsen, J. J.
Partner: UNT Libraries Government Documents Department

Documentation of Short Stack and Button Cell Experiments Performed at INL and Ceramatec during FY07

Description: This report provides documentation of experimental research activities performed at the Idaho National Laboratory and at Ceramatec, Inc. during FY07 under the DOE Nuclear Hydrogen Initiative, High Temperature Electrolysis Program. The activities discussed in this report include tests on single (button) cells, short planar stacks and tubular cells. The objectives of these small-scale tests are to evaluate advanced electrode, electrolyte, and interconnect materials, alternate modes of operation (e.g., coelectrolysis), and alternate cell geometries over a broad range of operating conditions, with the aim of identifying the most promising material et, cell and stack geometry, and operating conditions for the high-temperature electrolysis application. Cell performance is characterized in erms of initial area-specific resistance and long-term stability in the electrolysis mode. Some of the tests were run in the coelectrolysis mode. Research into coelectrolysis was funded by Laboratory Directed Research and Development (LDRD). Coelectrolysis simultaneously converts steam to hydrogen and carbon dioxide to carbon monoxide. This process is complicated by the reverse shift reaction. An equilibrium model was developed to predict outlet compositions of steam, hydrogen, carbon dioxide, and carbon monoxide resulting from coelectrolysis. Predicted ompositions were compared to measurements obtained with a precision micro-channel gas chromatograph.
Date: September 1, 2007
Creator: O'Brien, J. E.; Stoots, C. M.; Hartvigsen, J. J. & Herring, J. S.
Partner: UNT Libraries Government Documents Department

High-Temperature Co-electrolysis of Steam and Carbon Dioxide for Direct Production of Syngas; Equilibrium Model and Single-Cell Tests

Description: An experimental study has been completed to assess the performance of single solid-oxide electrolysis cells operating over a temperature range of 800 to 850ºC in the coelectrolysis mode, simultaneously electrolyzing steam and carbon dioxide for the direct production of syngas. The experiments were performed over a range of inlet flow rates of steam, carbon dioxide, hydrogen and nitrogen and over a range of current densities (-0.1 to 0.25 A/cm2) using single electrolyte-supported button electrolysis cells. Steam and carbon dioxide consumption rates associated with electrolysis were measured directly using inlet and outlet dewpoint instrumentation and a gas chromatograph, respectively. Cell operating potentials and cell current were varied using a programmable power supply. Measured values of open-cell potential and outlet gas composition are compared to predictions obtained from a chemical equilibrium coelectrolysis model. Model predictions of outlet gas composition based on an effective equilibrium temperature are shown to agree well with measurements. Cell area-specific resistance values were similar for steam electrolysis and coelectrolysis.
Date: July 1, 2007
Creator: O'Brien, J. E.; Stoots, C. M.; Herring, J. S. & Hartvigsen, J. J.
Partner: UNT Libraries Government Documents Department

RECENT ADVANCES IN HIGH TEMPERATURE ELECTROLYSIS AT IDAHO NATIONAL LABORATORY: STACK TESTS

Description: High temperature steam electrolysis is a promising technology for efficient sustainable large-scale hydrogen production. Solid oxide electrolysis cells (SOECs) are able to utilize high temperature heat and electric power from advanced high-temperature nuclear reactors or renewable sources to generate carbon-free hydrogen at large scale. However, long term durability of SOECs needs to be improved significantly before commercialization of this technology. A degradation rate of 1%/khr or lower is proposed as a threshold value for commercialization of this technology. Solid oxide electrolysis stack tests have been conducted at Idaho National Laboratory to demonstrate recent improvements in long-term durability of SOECs. Electrolytesupported and electrode-supported SOEC stacks were provided by Ceramatec Inc., Materials and Systems Research Inc. (MSRI), and Saint Gobain Advanced Materials (St. Gobain), respectively for these tests. Long-term durability tests were generally operated for a duration of 1000 hours or more. Stack tests based on technology developed at Ceramatec and MSRI have shown significant improvement in durability in the electrolysis mode. Long-term degradation rates of 3.2%/khr and 4.6%/khr were observed for MSRI and Ceramatec stacks, respectively. One recent Ceramatec stack even showed negative degradation (performance improvement) over 1900 hours of operation. A three-cell short stack provided by St. Gobain, however, showed rapid degradation in the electrolysis mode. Improvements on electrode materials, interconnect coatings, and electrolyteelectrode interface microstructures contribute to better durability of SOEC stacks.
Date: July 1, 2012
Creator: X, Zhang; O'Brien, J. E.; O'Brien, R. C.; Hartvigsen, J. J.; Tao, G. & Petigny, N.
Partner: UNT Libraries Government Documents Department

2500-Hour High Temperature Solid-Oxide Electrolyzer Long Duration Test

Description: The Idaho National Laboratory (INL) has been developing the concept of using solid oxide fuel cells as electrolyzers for large-scale, high-temperature (efficient), hydrogen production. This program is sponsored by the U.S. Department of Energy under the Nuclear Hydrogen Initiative. Utilizing a fuel cell as an electrolyzer introduces some inherent differences in cell operating conditions. In particular, the performance of fuel cells operated as electrolyzers degrades with time faster. This issue of electrolyzer cell and stack performance degradation over time has been identified as a major barrier to technology development. Consequently, the INL has been working together with Ceramatec, Inc. (Salt Lake City, Utah) to improve the long-term performance of high temperature electrolyzers. As part of this research partnership, the INL conducted a 2500 hour test of a Ceramatec designed and produced stack operated in the electrolysis mode. This report will provide a summary of experimental results for this long duration test.
Date: November 1, 2009
Creator: Stoots, C. M.; O'Brien, J. E.; Condie, K. G.; Moore-McAteer, L.; Hartvigsen, J. J. & Larsen, D.
Partner: UNT Libraries Government Documents Department

Initial Operation of the High Temperature Electrolysis Integrated Laboratory Scale Experiment at INL

Description: An integrated laboratory scale, 15 kW high-temperature electrolysis facility has been developed at the Idaho National Laboratory under the U.S. Department of Energy Nuclear Hydrogen Initiative. Initial operation of this facility resulted in over 400 hours of operation with an average hydrogen production rate of approximately 0.9 Nm3/hr. The integrated laboratory scale facility is designed to address larger-scale issues such as thermal management (feed-stock heating, high-temperature gas handling), multiple-stack hot-zone design, multiple-stack electrical configurations, and other “integral” issues. This paper documents the initial operation of the ILS, with experimental details about heat-up, initial stack performance, as well as long-term operation and stack degradation.
Date: June 1, 2008
Creator: Stoots, C. M.; O'Brien, J. E.; Condie, K. G.; Herring, J. S. & Hartvigsen, J. J.
Partner: UNT Libraries Government Documents Department

PROGRESS IN HIGH-TEMPERATURE ELECTROLYSIS FOR HYDROGEN PRODUCTION USING PLANAR SOFC TECHNOLOGY

Description: A research program is under way at the Idaho National Laboratory to assess the performance of solid-oxide cells operating in the steam electrolysis mode for hydrogen production over a temperature range of 800 to 900ºC. The research program includes both experimental and modeling activities. Selected results from both activities are presented in this paper. Experimental results were obtained from a ten-cell planar electrolysis stack, fabricated by Ceramatec , Inc. The electrolysis cells are electrolyte-supported, with scandia-stabilized zirconia electrolytes (~140 µm thick), nickel-cermet steam/hydrogen electrodes, and manganite air-side electrodes. The metallic interconnect plates are fabricated from ferritic stainless steel. The experiments were performed over a range of steam inlet mole fractions (0.1 - 0.6), gas flow rates (1000 - 4000 sccm), and current densities (0 to 0.38 A/cm2). Hydrogen production rates up to 90 Normal liters per hour were demonstrated. Stack performance is shown to be dependent on inlet steam flow rate. A three-dimensional computational fluid dynamics (CFD) model was also created to model high-temperature steam electrolysis in a planar solid oxide electrolysis cell (SOEC). The model represents a single cell as it would exist in the experimental electrolysis stack. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT1. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified for this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Mean model results are shown to compare favorably with the experimental results obtained from the ten-cell stack tested at INL.
Date: April 1, 2005
Creator: O'Brien, J. E.; Herring, J. S.; Stoots, C. M.; Hawkes, G. L.; Hartvigsen, J., J. & Shahnam, Mehrdad
Partner: UNT Libraries Government Documents Department

Status of the INL high-temperature electrolysis research program –experimental and modeling

Description: 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.
Date: April 1, 2009
Creator: O'Brien, J. E.; Stoots, C. M.; McKellar, M. G.; Harvego, E. A.; Condie, K. G.; Housley, G. K. et al.
Partner: UNT Libraries Government Documents Department

Critical Causes of Degradation in Integrated Laboratory Scale Cells during High Temperature Electrolysis

Description: An ongoing project at Idaho National Laboratory involves generating hydrogen from steam using solid oxide electrolysis cells (SOEC). This report describes background information about SOECs, the Integrated Laboratory Scale (ILS) testing of solid-oxide electrolysis stacks, ILS performance degradation, and post-test examination of SOECs by various researchers. The ILS test was a 720- cell, three-module test comprised of 12 stacks of 60 cells each. A peak H2 production rate of 5.7 Nm3/hr was achieved. Initially, the module area-specific resistance ranged from 1.25 Ocm2 to just over 2 Ocm2. Total H2 production rate decreased from 5.7 Nm3/hr to a steady state value of 0.7 Nm3/hr. The decrease was primarily due to cell degradation. Post test examination by Ceramatec showed that the hydrogen electrode appeared to be in good condition. The oxygen evolution electrode does show delamination in operation and an apparent foreign layer deposited at the electrolyte interface. Post test examination by Argonne National Laboratory showed that the O2-electrode delaminated from the electrolyte near the edge. One possible reason for this delamination is excessive pressure buildup with high O2 flow in the over-sintered region. According to post test examination at the Massachusetts Institute of Technology, the electrochemical reactions have been recognized as one of the prevalent causes of their degradation. Specifically, two important degradation mechanisms were examined: (1) transport of Crcontaining species from steel interconnects into the oxygen electrode and LSC bond layers in SOECs, and (2) cation segregation and phase separation in the bond layer. INL conducted a workshop October 27, 2008 to discuss possible causes of degradation in a SOEC stack. Generally, it was agreed that the following are major degradation issues relating to SOECs: • Delamination of the O2-electrode and bond layer on the steam/O2-electrode side • Contaminants (Ni, Cr, Si, etc.) on reaction sites (triple phase boundary) • ...
Date: May 1, 2009
Creator: Sohal, M.S.; O'Brien, J.E.; Stoots, C.M.; Hartvigsen, J. J.; Larsen, D.; Elangovan, S. et al.
Partner: UNT Libraries Government Documents Department

Overview of High-Temperature Electrolysis for Hydrogen Production

Description: Over the last five years there has been a growing interest in the use of hydrogen as an energy carrier, particularly to augment transportation fuels and thus reduce our dependence on imported petroleum. Hydrogen is now produced primarily via steam reforming of methane. However, in the long term, methane reforming is not a viable process for the large-scale hydrogen production since such fossil fuel conversion processes consume non-renewable resources and emit greenhouse gases. Nuclear energy can be used to produce hydrogen without consuming fossil fuels and without emitting greenhouse gases through the splitting of water into hydrogen and oxygen. The Nuclear Hydrogen Initiative of the DOE Office of Nuclear Energy is developing three general categories of high temperature processes for hydrogen production: thermochemical, electrolytic and hybrid thermo-electrolytic. This paper introduces the work being done in the development of high temperature electrolysis of steam. High Temperature Electrolysis (HTE) is built on the technology of solid oxide fuel cells (SOFCs), which were invented over a century ago, but which have been most vigorously developed during the last twenty years. SOFCs consume hydrogen and oxygen and produce steam and electricity. Solid Oxide Electrolytic Cells (SOECs) consume electricity and steam and produce hydrogen and oxygen. The purpose of the HTE research is to solve those problems unique to the electrolytic mode of operation, while building further on continuing fuel cell development. ORGANIZATION Experiments have been conducted for the last three years at the Idaho National Laboratory and at Ceramatec, Inc. on the operation of button cells and of progressively larger stacks of planar cells. In addition, the INL has been performing analyses of the cell-scale fluid dynamics and plant-scale flowsheets in order to determine optimum operating conditions and plant configurations. Argonne National Laboratory has been performing experiments for the development of new electrode materials, ...
Date: June 1, 2007
Creator: Herring, J. S.; O'Brien, J. E.; Stoots, C. M.; Hartvigsen, J. J.; Petri, M. C.; Carter, J. D. et al.
Partner: UNT Libraries Government Documents Department

Advanced Cell Development and Degradation Studies

Description: The Idaho National Laboratory (INL) has been researching the application of solid-oxide electrolysis cells for large-scale hydrogen production from steam over a temperature range of 800 to 900ºC. From 2003 – 2009, this work was sponsored by the DOE Nuclear Hydrogen Initiative (NHI). Starting in 2010, the HTE research program has been sponsored by the Next Generation Nuclear Plant (NGNP) program. HTSE research priorities in FY10 are centered on understanding and reducing cell and stack performance degradation to an acceptable level to advance the technology readiness level of HTSE and to justify further large-scale demonstration activities. This report provides a summary of our FY10 experimental program, which has been focused on advanced cell and stack development and degradation studies. Advanced cell and stack development activities are under way at five technology partners: MSRI, Versa Power, Ceramatec, NASA Glenn, and St. Gobain. Performance evaluation of the advanced technology cells and stacks has been performed by the technology partners, by MIT and the University of Connecticut and at the INL HTE Laboratory. Summaries of these development activities and test results are presented.
Date: September 1, 2010
Creator: O'Brien, J. E.; Stoots, C. M.; Herring, J. S.; O'Brien, R. C.; Condie, K. G.; Sohal, M. et al.
Partner: UNT Libraries Government Documents Department