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Hydrogen production by high-temperature water splitting using mixed oxygen ion-electron conducting membranes.

Description: Hydrogen production from water splitting at high temperatures has been studied with novel mixed oxygen ion-electron conducting cermet membranes. Hydrogen production rates were investigated as a function of temperature, water partial pressure, membrane thickness, and oxygen chemical potential gradient across the membranes. The hydrogen production rate increased with both increasing moisture concentration and oxygen chemical potential gradient across the membranes. A maximum hydrogen production rate of 4.4 cm{sup 3}/min-cm{sup 2} (STP) was obtained with a 0.10-mm-thick membrane at 900 C in a gas containing 50 vol.% water vapor in the sweep side. Hydrogen production rate also increased with decreasing membrane thickness, but surface kinetics play an important role as membrane thickness decreases.
Date: April 24, 2002
Creator: Lee, T. H.; Wang, S.; Dorris, S. E. & Balachandran, U.
Partner: UNT Libraries Government Documents Department

Hydrogen Production in Radioactive Solutions in the Defense Waste Processing Facility

Description: In the radioactive slurries and solutions to be processed in the Defense Waste Processing Facility (DWPF), hydrogen will be produced continuously by radiolysis. This production results from alpha, beta, and gamma rays from decay of radionuclides in the slurries and solutions interacting with the water. More than 1000 research reports have published data concerning this radiolytic production. The results of these studies have been reviewed in a comprehensive monograph. Information about radiolytic hydrogen production from the different process tanks is necessary to determine air purge rates necessary to prevent flammable mixtures from accumulating in the vapor spaces above these tanks. Radiolytic hydrogen production rates are usually presented in terms of G values or molecules of hydrogen produced per 100ev of radioactive decay energy absorbed by the slurry or solution. With the G value for hydrogen production, G(H2), for a particular slurry and the concentrations of radioactive species in that slurry, the rate of H2 production for that slurry can be calculated. An earlier investigation estimated that the maximum rate that hydrogen could be produced from the sludge slurry stream to the DWPF is with a G value of 0.45 molecules per 100ev of radioactive decay energy sorbed by the slurry.
Date: May 26, 2004
Creator: CRAWFORD, CHARLES L.
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

Detailed design data package: 1.9a Measure Hydrogen Generation during formating; 1.10a Nitrate Salt Reaction

Description: This data package provides test data on gas generation rates during formating of NCAW (neutralized current acid waste) and on nitrate salt reactions in dried SRAT/SME NCAW feeds. These issues correspond to the HWVP architectural engineer firm, Fluor Daniels, technology data needs, item 1.9a (Hydrogen Generation) and item 1.10a (Nitrate Salt reactions). This work was performed in accordance with the Fiscal Year 1991 Statement of Work for Applied Technology Tasks to be Performed by Pacific Northwest Laboratory in Support of the Hanford Waste Vitrification Plant Project (Kruger 1991).
Date: March 1, 1996
Creator: Wiemers, K.D.; Langowski, M.H. & Powell, M.R.
Partner: UNT Libraries Government Documents Department

Stepped-anneal and total helium/hydrogen measurements in high-energy proton-irradiated tungsten

Description: To provide structural material design data for the Accelerator Production of Tritium (APT) project, a 1 mA, 800 MeV proton beam at the Los Alamos Neutron Science Center (LANSCE) was used to irradiate a large number of metal samples, including a tungsten target similar to that being considered as the neutron source for the tritium production. The maximum proton fluence to the tungsten target was {approximately} 10{sup 21} protons/cm{sup 2}. An unavoidable byproduct of spallation reactions is the formation of large amounts of hydrogen and helium. Postulated accident scenarios for APT involving the use of tungsten rods clad with Alloy 718, raise concerns as to the amount and rate of release of these gases due to temperatures increases from afterheat accumulation, with the major concern being pressurizing and possibly failure of the cladding. To address these issues, portions of the LANSCE tungsten rods were subjected to temperature histories calculated as likely to occur, and the time-dependent evolution of helium and hydrogen gases was measured. Stepped-anneal and total helium/hydrogen measurements were conducted on multiple samples of the tungsten material. Helium measurements were conducted at Pacific Northwest National Laboratory (PNNL) using a high-sensitivity magnetic-sector isotope-dilution helium analysis system. Stepped-anneal measurements were conducted at temperatures from {approximately} 25 C to {approximately} 1,600 C in {approximately} 100 C steps. Total helium measurements were conducted by rapid vaporization after completion of the stepped-anneal process, and are compared with Monte Carlo calculations performed at Los Alamos National Laboratory (LANL) using the LAHET code system. Hydrogen measurements were conducted between {approximately} 750 C and {approximately} 1,200 C using a high-temperature furnace that had been extensively modified for the application. Hydrogen detection was accomplished by periodic sampling of the furnace gas using a separate quadrupole analyzer. Hydrogen measurements are also compared with LANL calculations.
Date: December 31, 1998
Creator: Oliver, B.M.; Hamilton, M.L.; Garner, F.A.; Sommer, W.F.; Maloy, S.A. & Ferguson, P.D.
Partner: UNT Libraries Government Documents Department

Electrokinetic Hydrogen Generation from Liquid WaterMicrojets

Description: We describe a method for generating molecular hydrogen directly from the charge separation effected via rapid flow of liquid water through a metal orifice, wherein the input energy is the hydrostatic pressure times the volume flow rate. Both electrokinetic currents and hydrogen production rates are shown to follow simple equations derived from the overlap of the fluid velocity gradient and the anisotropic charge distribution resulting from selective adsorption of hydroxide ions to the nozzle surface. Pressure-driven fluid flow shears away the charge balancing hydronium ions from the diffuse double layer and carries them out of the aperture. Downstream neutralization of the excess protons at a grounded target electrode produces gaseous hydrogen molecules. The hydrogen production efficiency is currently very low (ca. 10-6) for a single cylindrical jet, but can be improved with design changes.
Date: May 31, 2007
Creator: Duffin, Andrew M. & Saykally, Richard J.
Partner: UNT Libraries Government Documents Department

Hydrogen Production in Radioactive Solutions in the Defense Waste Processing Facility

Description: In the radioactive slurries and solutions to be processed in the Defense Waste Processing Facility (DWPF), hydrogen will be produced continuously by radiolysis. This production results from alpha, beta, and gamma rays from decay of radionuclides in the slurries and solutions interacting with the water. More than 1000 research reports have published data concerning this radiolytic production. The results of these studies have been reviewed in a comprehensive monograph. Information about radiolytic hydrogen production from the different process tanks is necessary to determine air purge rates necessary to prevent flammable mixtures from accumulating in the vapor spaces above these tanks. Radiolytic hydrogen production rates are usually presented in terms of G values or molecules of hydrogen produced per 100ev of radioactive decay energy absorbed by the slurry or solution. With the G value for hydrogen production, G(H2), for a particular slurry and the concentrations of radioactive species in that slurry, the rate of H2 production for that slurry can be calculated. An earlier investigation estimated that the maximum rate that hydrogen could be produced from the sludge slurry stream to the DWPF is with a G value of 0.45 molecules per 100ev of radioactive decay energy sorbed by the slurry.
Date: May 26, 2004
Creator: CRAWFORD, CHARLES L.
Partner: UNT Libraries Government Documents Department

Hydrogen adsorption on and solubility in graphites

Description: The experimental data on sorption and solubility of hydrogen isotopes in graphite in a wide ranges of temperature and pressure are reviewed. The Langmuir type adsorption is proposed for the hydrogen -- graphites interaction with taking into account dangling sp{sup 2}{minus}bonds relaxation. Three kinds of traps are proposed: Carbon interstitial loops with the adsorption enthalpy of {minus}4.4 eV/H{sub 2} (Traps l); carbon network edge atoms with the adsorption enthalpy of {minus}2.3 eV/H{sub 2} (Traps 2): Basal planes adsorption sites with enthalpy of +2.43 eV/H{sub 2} (Traps 3). The sorption capacity of every kind of graphite could be described with its own unique set of traps. The number of potential sites for the ``true solubility`` (Traps 3) we assume as 1E+6 appm, or HC=l, but endothermic character of this solubility leads to negligible amount of inventory in comparison with Traps 1 and Traps 2. The irradiation with neutrons or carbon atoms increases the number of Traps 1 and Traps 2. At damage level of {approximately}1 dpa under room temperature irradiation the number of these traps was increased up to 1500 and 5000 appm respectively. Traps 1 and Traps 2 are stable under high temperature annealing.
Date: December 1, 1995
Creator: Kanashenko, S.L.; Gorodetsky, A.E.; Chernikov, V.N.; Markin, A.V. & Zakharov, A.P.
Partner: UNT Libraries Government Documents Department

Design of an Integrated Laboratory Scale Test for Hydrogen Production via High Temperature Electrolysis

Description: The Idaho National Laboratory (INL) is researching the feasibility of high-temperature steam electrolysis for high-efficiency carbon-free hydrogen production using nuclear energy. Typical temperatures for high-temperature electrolysis (HTE) are between 800º-900ºC, consistent with anticipated coolant outlet temperatures of advanced high-temperature nuclear reactors. An Integrated Laboratory Scale (ILS) test is underway to study issues such as thermal management, multiple-stack electrical configuration, pre-heating of process gases, and heat recuperation that will be crucial in any large-scale implementation of HTE. The current ILS design includes three electrolysis modules in a single hot zone. Of special design significance is preheating of the inlet streams by superheaters to 830°C before entering the hot zone. The ILS system is assembled on a 10’ x 16’ skid that includes electronics, power supplies, air compressor, pumps, superheaters, , hot zone, condensers, and dew-point sensor vessels. The ILS support system consists of three independent, parallel supplies of electrical power, sweep gas streams, and feedstock gas mixtures of hydrogen and steam to the electrolysis modules. Each electrolysis module has its own support and instrumentation system, allowing for independent testing under different operating conditions. The hot zone is an insulated enclosure utilizing electrical heating panels to maintain operating conditions. The target hydrogen production rate for the ILS is 5000 Nl/hr.
Date: June 1, 2007
Creator: Housley, G.K.; Condie, K.G.; O'Brien, J.E. & Stoots, C. M.
Partner: UNT Libraries Government Documents Department

Initial assessment of the operability of the VHTR-HTSE nuclear hydrogen plant.

Description: The generation of hydrogen from nuclear power will need to compete on three fronts: production, operability, and safety to be viable in the energy marketplace of the future. This work addresses the operability of a coupled nuclear and hydrogen-generating plant while referring to other work for progress on production and safety. Operability is a measure of how well a plant can meet time-varying production demands while remaining within equipment limits. It can be characterized in terms of the physical processes that underlie operation of the plant. In this work these include the storage and transport of energy within components as represented by time constants and energy capacitances, the relationship of reactivity to temperature, and the coordination of heat generation and work production for a near-ideal gas working fluid. Criteria for assessing operability are developed and applied to the Very High Temperature Reactor coupled to the High Temperature Steam Electrolysis process, one of two DOE/INL reference plant concepts for hydrogen production. Results of preliminary plant control and stability studies are described. A combination of inventory control in the VHTR plant and flow control in the HTSE plant proved effective for maintaining hot-side temperatures near constant during quasi-static change in hydrogen production rate. Near constant electrolyzer outlet temperature is achieved by varying electrolyzer cell area to control cell joule heating. It was found that rates of temperature change in the HTSE plant for a step change in hydrogen production rate are largely determined by the thermal characteristics of the electrolyzer. It's comparatively large thermal mass and the presence of recuperative heat exchangers result in a tight thermal coupling of HTSE components to the electrolyzer. It was found that thermal transients arising in the chemical plant are strongly damped at the reactor resulting in a stable combined plant. The large Doppler reactivity component, ...
Date: November 1, 2007
Creator: Vilim, R. B.
Partner: UNT Libraries Government Documents Department

SCC evaluation of candidate container alloys by DCB method

Description: The authors use a solid mechanics approach to investigate hydride formation and cracking in zirconium-niobium alloys used in the pressure tubes of CANDU nuclear reactors. In this approach, the forming hydride is assumed to be purely elastic and its volume dilation is accommodated by elasto-plastic deformation of the surrounding matrix material. The energetics of the hydride formation is revisited and the terminal solid solubility of hydrogen in solution is defined on the basis of the total elasto-plastic work done on the system by the forming hydride and the external loads. Hydrogen diffusion and probabilistic hydride formation coupled with the material deformation are modeled at a blunting crack tip under plane strain loading. A full transient finite element analysis allows for numerical monitoring of the development and expansion of the hydride zone as the externally applied loads increase. Using a Griffith fracture criterion for fracture limitiation, the reduced fracture resistance of the alloy can be predicted and the factors affecting fracture toughness quantified.
Date: September 24, 1999
Creator: Roy, A.K.; Freeman, D.C.; Lum, B.Y. & Spragge, M.K.
Partner: UNT Libraries Government Documents Department

MEASUREMENT AND PREDICTION OF RADIOLYTIC HYDROGEN PRODUCTION IN DEFENSE WASTE PROCESSING SLURRIES AT SAVANNAH RIVER SITE

Description: This paper presents results of measurements and predictions of radiolytic hydrogen production rates from two actual process slurries in the Defense Waste Processing Facility (DWPF) at Savannah River Site (SRS). Hydrogen is a flammable gas and its production in nuclear facilities can be a safety hazard if not mitigated. Measurements were made in the Shielded Cells of Savannah River National Laboratory (SRNL) using a sample of Sludge Batch 3 (SB3) currently being processed by the DWPF. Predictions were made using published values for rates of radiolytic reactions producing H{sub 2} in aqueous solutions and the measured radionuclide and chemical compositions of the two slurries. The agreement between measured and predicted results for nine experiments ranged from complete agreement to 24% difference. This agreement indicates that if the composition of the slurry being processed is known, the rate of radiolytic hydrogen production can be reasonably estimated.
Date: January 10, 2007
Creator: Bibler, N; John Pareizs, J; Terri Fellinger, T & Cj Bannochie, C
Partner: UNT Libraries Government Documents Department

CHARACTERIZATION TESTING AND ANALYSIS OF SINGLE CELL SO2 DEPOLARIZED ELECTROLYZER

Description: This document reports work performed at the Savannah River National Laboratory (SRNL) that further develops the use of a proton exchange membrane or PEM-type electrochemical cell to produce hydrogen via SO{sub 2}-depolarized water electrolysis. This work was begun at SRNL in 2005. This research is valuable in achieving the ultimate goal of an economical hydrogen production process based on the Hybrid Sulfur (HyS) Cycle. The HyS Process is a hybrid thermochemical cycle that may be used in conjunction with advanced nuclear reactors or centralized solar receivers to produce hydrogen by water-splitting. Like all other sulfur-based cycles, HyS utilizes the high temperature thermal decomposition of sulfuric acid to produce oxygen. The unique aspect of HyS is the generation of hydrogen in a water electrolyzer that is operated under conditions where dissolved sulfur dioxide depolarizes the anodic reaction, resulting in substantial voltage reduction. Sulfur dioxide is oxidized at the anode, producing sulfuric acid that is sent to the acid decomposition portion of the cycle. The focus of this work was to conduct single cell electrolyzer tests in order to prove the concept of SO{sub 2}-depolarization and to determine how the results can be used to evaluate the performance of key components of the HyS Process. A test facility for conducting SO{sub 2}-depolarized electrolyzer (SDE) testing was designed, constructed and commissioned. The maximum cell current is 50 amperes, which is equivalent to a hydrogen production rate of approximately 20 liters per hour. Feed to the anode of the electrolyzer is sulfuric acid solutions containing dissolved sulfur dioxide. The partial pressure of sulfur dioxide may be varied in the range of 1 to 6 atm (15 to 90 psia). Temperatures may be controlled in the range from ambient to 80 C. Hydrogen generated at the cathode of the cell is collected for the purpose ...
Date: September 15, 2006
Creator: Steimke, J & Timothy Steeper, T
Partner: UNT Libraries Government Documents Department

Characterization Testing of H20-SO2 Electrolyzer at Ambient Pressure

Description: This document reports work performed at the Savannah River National Laboratory (SRNL) that resulted in a major accomplishment by demonstrating the proof-of-concept of the use of a proton exchange membrane or PEM-type electrochemical cell to produce hydrogen via SO{sub 2}-depolarized water electrolysis. For the first time sulfur dioxide dissolved in liquid sulfuric acid was used to depolarize water electrolysis in a modern PEM cell. The use of such a cell represents a major step in achieving the ultimate goal of an economical hydrogen production process based on the Hybrid Sulfur (HyS) Cycle. The HyS Process is a hybrid thermochemical cycle that may be used in conjunction with advanced nuclear reactors or centralized solar receivers to produce hydrogen by water-splitting. Like all other sulfur-based cycles, HyS utilizes the high temperature thermal decomposition of sulfuric acid to produce oxygen. The unique aspect of HyS is the generation of hydrogen in a water electrolyzer that is operated under conditions where dissolved sulfur dioxide depolarizes the anodic reaction, resulting in substantial voltage reduction. Sulfur dioxide is oxidized at the anode, producing sulfuric acid, that is sent to the acid decomposition portion of the cycle. The focus of this work was to conduct single cell electrolyzer tests in order to prove the concept of SO{sub 2}-depolarization and to determine how the results can be used to evaluate the performance of key components of the HyS Process. A test facility for conducting SO{sub 2}-depolarized electrolyzer (SDE) testing was designed, constructed and commissioned. The maximum cell current is 50 amperes, which is equivalent to a hydrogen production rate of approximately 20 liters per hour. The test facility was designed for operation at room temperature with pressures up to 2 bar. Feed to the anode of the electrolyzer can be water, sulfuric acid of various concentrations, or sulfuric ...
Date: July 29, 2005
Creator: Steimke, J
Partner: UNT Libraries Government Documents Department

ANALYSIS OF A HIGH TEMPERATURE GAS-COOLED REACTOR POWERED HIGH TEMPERATURE ELECTROLYSIS HYDROGEN PLANT

Description: An updated reference design for a commercial-scale high-temperature electrolysis (HTE) plant for hydrogen production has been developed. The HTE plant is powered by a high-temperature gas-cooled reactor (HTGR) whose configuration and operating conditions are based on the latest design parameters planned for the Next Generation Nuclear Plant (NGNP). The current HTGR reference design specifies a reactor power of 600 MWt, with a primary system pressure of 7.0 MPa, and reactor inlet and outlet fluid temperatures of 322°C and 750°C, respectively. The reactor heat is used to produce heat and electric power to the HTE plant. A Rankine steam cycle with a power conversion efficiency of 44.4% was used to provide the electric power. The electrolysis unit used to produce hydrogen includes 1.1 million cells with a per-cell active area of 225 cm2. The reference hydrogen production plant operates at a system pressure of 5.0 MPa, and utilizes a steam-sweep system to remove the excess oxygen that is evolved on the anode (oxygen) side of the electrolyzer. The overall system thermal-to-hydrogen production efficiency (based on the higher heating value of the produced hydrogen) is 42.8% at a hydrogen production rate of 1.85 kg/s (66 million SCFD) and an oxygen production rate of 14.6 kg/s (33 million SCFD). An economic analysis of this plant was performed with realistic financial and cost estimating The results of the economic analysis demonstrated that the HTE hydrogen production plant driven by a high-temperature helium-cooled nuclear power plant can deliver hydrogen at a competitive cost. A cost of $3.03/kg of hydrogen was calculated assuming an internal rate of return of 10% and a debt to equity ratio of 80%/20% for a reactor cost of $2000/kWt and $2.41/kg of hydrogen for a reactor cost of $1400/kWt.
Date: November 1, 2010
Creator: McKellar, M. G.; Harvego, E. A. & Gandrik, A. M.
Partner: UNT Libraries Government Documents Department

A short analysis of new nuclear data evaluations and their impact on nuclear responses in fusion structural materials

Description: Current emphasis in the design of fusion reactor systems entails meeting the objective of having radiation resistant materials with low-activation characteristics. Therefore, the reactors will have a long usable lifetime and, once they are decommissioned, these facilities will not present serious waste-disposal problems due to the presence of long-lived radioactive byproducts generated in the high-neutron-intensity environments encountered during their operation. A reliable estimation of the performance of a fusion reactor in this context requires accurate knowledge of half lives and neutron-reaction cross sections. A large number of materials, reactions, and radioactive byproducts must be considered. For the most part, the half lives of the radioactive species involved are reasonably well known. Therefore, the main emphasis in improving of the data base needs to be in the area of cross sections. This paper focuses on only two nuclear data issues concerning recent evaluations of cross sections: hydrogen production in vanadium from the {sup 51}V(n,p){sup 51}Ti and {sup 51}V(n,np+d){sup 50}Ti reactions and the production of 7.4 e + 05 y {sup 26}Al (a major waste-disposal concern). Al-26 can be generated mainly by the {sup 27}Al(n,2n){sup 26}Al, and {sup 28}Si(n,np+d){sup 27}Al(n,2n){sup 26}Al reaction processes. The current status and quality of the evaluated cross sections related to these nuclear-reaction processes is examined and the impact on generation of hydrogen gas and {sup 26}Al radioactive in fusion reactors is assessed in the present study.
Date: August 1, 1998
Creator: Gomes, I.C.; Smith, D.L. & Cheng, E.T.
Partner: UNT Libraries Government Documents Department

Nuclear fuel elements made from nanophase materials

Description: A nuclear reactor core fuel element is composed of nanophase high temperature materials. An array of the fuel elements in rod form are joined in an open geometry fuel cell that preferably also uses such nanophase materials for the cell structures. The particular high temperature nanophase fuel element material must have the appropriate mechanical characteristics to avoid strain-related failure even at high temperatures, in the order of about 3,000 F. Preferably, the reactor type is a pressurized or boiling water reactor and the nanophase material is a high temperature ceramic or ceramic composite. Nanophase metals, or nanophase metals with nanophase ceramics in a composite mixture, also have desirable characteristics, although their temperature capability is not as great as with all ceramic nanophase material. Combinations of conventional or nanophase metals and conventional or nanophase ceramics can be employed as long as there is at least one nanophase material in the composite. The nuclear reactor so constructed has a number of high strength fuel particles, a nanophase structural material for supporting a fuel rod at high temperature, a configuration to allow passive cooling in the event of a primary cooling system failure, an ability to retain a coolable geometry even at high temperatures, an ability to resist generation of hydrogen gas, and a configuration having good nuclear, corrosion and mechanical characteristics.
Date: December 1, 1997
Creator: Heubeck, Norman B.
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

Performance of Single Electrode-Supported Cells Operating in the Electrolysis Mode

Description: An experimental study is under way to assess the performance of electrode-supported solid-oxide cells operating in the steam electrolysis mode for hydrogen production over a temperature range of 800 to 900ºC. Results presented in this paper were obtained from single cells, with an active area of 16 cm2 per cell. The electrolysis cells are electrode-supported, with yttria-stabilized zirconia (YSZ) electrolytes (~10 µm thick), nickel-YSZ steam/hydrogen electrodes (~1400 µm thick), and manganite (LSM) air-side electrodes. The experiments were performed over a range of steam inlet mole fractions (0.1 – 0.6), gas flow rates, and current densities (0 to 0.6 A/cm2). Steam consumption rates associated with electrolysis were measured directly using inlet and outlet dewpoint instrumentation. On a molar basis, the steam consumption rate is equal to the hydrogen production rate. Cell performance was evaluated by performing DC potential sweeps at 800, 850, and 900°C. The voltage-current characteristics are presented, along with values of area-specific resistance as a function of current density. Long-term cell performance is also assessed to evaluate cell degradation. Details of the custom single-cell test apparatus developed for these experiments are also presented.
Date: November 1, 2009
Creator: O'Brien, J. E.; Housley, G. K. & Milobar, D. G.
Partner: UNT Libraries Government Documents Department

High Temperature Electrolysis for Hydrogen Production from Nuclear Energy – TechnologySummary

Description: 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 to date.
Date: February 1, 2010
Creator: O'Brien, J. E.; Stoots, C. M.; Herring, J. S.; McKellar, M. G.; Harvego, E. A.; Sohal, M. S. et al.
Partner: UNT Libraries Government Documents Department

Economic Analysis of a Nuclear Reactor Powered High-Temperature Electrolysis Hydrogen Production Plant

Description: A reference design for a commercial-scale high-temperature electrolysis (HTE) plant for hydrogen production was developed to provide a basis for comparing the HTE concept with other hydrogen production concepts. The reference plant design is driven by a high-temperature helium-cooled nuclear reactor coupled to a direct Brayton power cycle. The reference design reactor power is 600 MWt, with a primary system pressure of 7.0 MPa, and reactor inlet and outlet fluid temperatures of 540°C and 900°C, respectively. The electrolysis unit used to produce hydrogen includes 4,009,177 cells with a per-cell active area of 225 cm2. The optimized design for the reference hydrogen production plant operates at a system pressure of 5.0 MPa, and utilizes an air-sweep system to remove the excess oxygen that is evolved on the anode (oxygen) side of the electrolyzer. The inlet air for the air-sweep system is compressed to the system operating pressure of 5.0 MPa in a four-stage compressor with intercooling. The alternating-current, AC, to direct-current, DC, conversion efficiency is 96%. The overall system thermal-to-hydrogen production efficiency (based on the lower heating value of the produced hydrogen) is 47.12% at a hydrogen production rate of 2.356 kg/s. An economic analysis of this plant was performed using the standardized H2A Analysis Methodology developed by the Department of Energy (DOE) Hydrogen Program, and using realistic financial and cost estimating assumptions. The results of the economic analysis demonstrated that the HTE hydrogen production plant driven by a high-temperature helium-cooled nuclear power plant can deliver hydrogen at a competitive cost. A cost of $3.23/kg of hydrogen was calculated assuming an internal rate of return of 10%.
Date: August 1, 2008
Creator: Harvego, E. A.; McKellar, M. G.; Sohal, M. S.; O'Brien, J. E. & Herring, J. S.
Partner: UNT Libraries Government Documents Department

Optimized Flow Sheet for a Reference Commercial-Scale Nuclear-Driven High-Temperature Electrolysis Hydrogen Production Plant

Description: This report presents results from the development and optimization of a reference commercialscale high-temperature electrolysis (HTE) plant for hydrogen production. The reference plant design is driven by a high-temperature helium-cooled reactor coupled to a direct Brayton power cycle. The reference design reactor power is 600 MWt, with a primary system pressure of 7.0 MPa, and reactor inlet and outlet fluid temperatures of 540° C and 900°C, respectively. The electrolysis unit used to produce hydrogen consists of 4.176 × 10 6 cells with a per-cell active area of 225 cm2. A nominal cell area-specific resistance, ASR, value of 0.4 Ohm•cm2 with a current density of 0.25 A/cm2 was used, and isothermal boundary conditions were assumed. The optimized design for the reference hydrogen production plant operates at a system pressure of 5.0 MPa, and utilizes an air-sweep system to remove the excess oxygen that is evolved on the anode side of the electrolyzer. The inlet air for the air-sweep system is compressed to the system operating pressure of 5.0 MPa in a four-stage compressor with intercooling. The overall system thermal-to-hydrogen production efficiency (based on the low heating value of the produced hydrogen) is 49.07% at a hydrogen production rate of 2.45 kg/s with the high-temperature helium-cooled reactor concept. The information presented in this report is intended to establish an optimized design for the reference nuclear-driven HTE hydrogen production plant so that parameters can be compared with other hydrogen production methods and power cycles to evaluate relative performance characteristics and plant economics.
Date: November 1, 2007
Creator: McKellar, M. G.; O'Brien, J. E.; Harvego, E. A. & Herring, J. S.
Partner: UNT Libraries Government Documents Department

HIGH-TEMPERATURE ELECTROLYSIS FOR HYDROGEN PRODUCTION FROM NUCLEAR ENERGY

Description: An experimental study is under way 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. Results presented in this paper were obtained from a ten-cell planar electrolysis stack, with an active area of 64 cm2 per cell. 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). Steam consumption rates associated with electrolysis were measured directly using inlet and outlet dewpoint instrumentation. Cell operating potentials and cell current were varied using a programmable power supply. Hydrogen production rates up to 90 Normal liters per hour were demonstrated. Values of area-specific resistance and stack internal temperatures are presented as a function of current density. Stack performance is shown to be dependent on inlet steam flow rate.
Date: October 1, 2005
Creator: O'Brien, James E.; Stoots, Carl M.; Herring, J. Stephen & Hartvigsen, Joseph J.
Partner: UNT Libraries Government Documents Department