• Transactions of the Korean hydrogen and new energy society
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• v.31 no.6
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• pp.596-604
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• 2020

Solid oxide electrolysis cell (SOEC) attracts much attention because of its high energy efficiency among many water-electrolysis technologies. SOEC operates at temperatures above 700℃, so that the water required for water-electrolysis must be supplied in the form of steam. When the steam to be supplied to the SOEC is generated by the SOEC system itself, an enormous amount of latent heat is required to vaporize the water, so additional energy must be supplied to the SOEC system. On the other hand, if the steam can be supplied from the outside, a small amount of energy is required to raise the temperature of the low temperature steam, so that the SOEC system can be operated without additional energy supply from outside, which enables efficient water-electrolysis. In this study, we figure out the size of heat exchanger for various steam temperature and effectiveness of heat exchanger, and propose the energy efficiency of the system.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.6
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• pp.707-714
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• 2022

Hydrogen production using solid oxide electrolysis cells (SOEC) is a promising technology because of its efficiency, cleanness, and scalability. Especially, high-power SOEC system has received a lot of attention from researchers. This study compared and analyzed the low-power and high-power SOEC system in term of economic. By using revenue requirement method, levelized cost of hydrogen (LCOH) was calculated for comparison. In addition, the sensitivity analysis was performed to determine the dependence of hydrogen cost on input variables. The results indicated that high-power SOEC system is superior to a low-power SOEC system. In the capital cost, the stack cost is dominant in both systems, but the electricity cost is the most contributed factor to the hydrogen cost. If the high-power SOEC system combines with a nuclear power plant, the hydrogen cost can reach 3.65 $/kg when the electricity cost is 3.28 ¢/kWh and the stack cost is assumed to be 574 $/kW.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.2
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• pp.169-176
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• 2020

There is a growing interest in hydrogen energy utilization since an alternative energy development has been demanded due to the depletion of fossil fuels. Hydrogen is produced by the reforming reaction of natural gas and biogas, and the electrolysis of water. An solid oxide electrolyte cell (SOEC) is reversible system that generates hydrogen by electrolyzing the superheated steam or producing the electricity from a fuel cell by hydrogen. If the water can be converted into steam by waste heat from other processes it is more efficient for high-temperature electrolysis to convert steam directly. The reasons are based upon the more favorable thermodynamic and electrochemical kinetic conditions for the reaction. In the present study, steam at over 180℃ and 3.4 bars generated from a boiler were converted into superheated steam at over 700℃ and 3 bars using a cylindrical steam superheater as well as the waste heat of the exhaust gas at 900℃ from a solid refuse fuel combustor. Superheated steam at over 700℃ was then supplied to a high-temperature SOEC to increase the hydrogen production efficiency of water electrolysis. Computational fluid dynamics (CFD) analysis was conducted on the effects of the number of 90° elbow connector for piping, insulation types and insulation layers of pipe on the exit temperature using a commercial Fluent simulator. For two pre-heater injection method of steam inlet and ceramic wool insulation of 100 mm thickness, the highest inlet temperature of SOEC was 744℃ at 5.9 bar.

• Journal of Energy Engineering
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• v.29 no.2
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• pp.1-9
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• 2020

In recent days, fuel cell has received attention from the world as an alternative power source to hydrocarbon used in automobile engines. With the industrial advances of fuel cell, There have been a lot of researches actively conducted to find a way of generating hydrogen. Among many hydrogen production methods, Solid Oxide Electrolysis Cell(SOEC) is not only a basic way but also environment-friendly method to produce hydrogen gas. Solid Oxide Electrolysis Cell has lower electrical energy demands and high thermal efficiency since it is possible to operate under high temperature and high pressure conditions. For these reasons, experimental researches as well as studies on numerical modeling for Solid Oxide Electrolysis Cell have been under way. However, studies on numerical modeling are relatively less enough than experimental accomplishments and have limited performance prediction, which mostly is considered as a result from inadequate effects of electrochemical properties by temperature and pressure. In this study, various experimental studies of commercial Membrane Electrode Assembly (MEA) composed of Ni-YSZ (40wt%, Ni-60 wt% YSZ)/8-YSZ (TOSOH, TZ8Y)/LSM (La_0.9Sr_0.1MnO₃) was utilized for improving effectiveness of SOEC model. After numerically analyzing effects of electrochemical properties according to operating temperature, causing the largest deviation between experiments and simulation are that Charge Transfer Coefficient (CTC), exchange current density, diffusion coefficient, electrical conductivity in SOEC. Analyzing temperature effect on parameter used in overpotential model is conducted for modeling of SOEC. cross-validation method is adopted for application of various MEA and evaluating feasibility of model. As a result, the study confirm that the numerical model of SOEC based on structured process of effectiveness evaluation makes performance prediction better.

• Journal of the Korean Ceramic Society
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• v.47 no.1
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• pp.1-7
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• 2010

Solid oxide fuel cells (SOFCs) have been under development for a variety of power generation applications. Power system sizes considered range from small watt-size units (e.g., 50-W portable devices) to very large multi-megawatt systems (e.g., 500-MW base load power plants). Because of the reversibility of its operation, the SOFC has also been developed to operate under reverse or electrolysis mode for hydrogen production from steam (In this case, the cell is referred to as solid oxide electrolysis cell or SOEC.). Potential applications for the SOEC include on-site and large-scale hydrogen production. One critical requirement for practical uses of these systems is long-term performance stability under specified operating conditions. Intrinsic material properties and operating environments can have significant effects on cell performance stability, thus performance degradation rate. This paper discusses potential applications of the SOFC/SOEC, technological status and current research and development (R&D) direction, and certain aspects of long-term performance degradation in the operation of SOFCs/SOECs for power generation/hydrogen production.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.5
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• pp.416-423
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• 2009

High-temperature steam electrolysis (HTSE) using solid oxide cell is a challenging method for highly efficient large-scale hydrogen production as a reversible process of solid oxide fuel cell (SOFC). The overall efficiency of the HTSE hydrogen and synthesis gas production system was analyzed thermo-electrochemically. A thermo-electrochemical model for the hydrogen and synthesis gas production system with solid oxide electrolysis cell (SOEC) and very high temperature gas-cooled reactor (VHTR) was established. Sensitivity analyses with regard to the system were performed to investigate the quantitative effects of key parameters on the overall efficiency of the production system. The overall efficiency with SOEC and VHTR was expected to reach a maximum of 58% for the hydrogen production system and to 62% for synthesis gas production system by improving electrical efficiency, steam utilization rate, waste heat recovery rate, electrolysis efficiency, and thermal efficiency. Therefore, overall efficiency of the synthesis production system has higher efficiency than that of the hydrogen production system.

• 한국전기화학회:학술대회논문집
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• 2004.04a
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• pp.68-68
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• 2004

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.2
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• pp.162-167
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• 2024

Fossil fuels have been main energy source to people. However, enormous amount of CO₂ was emitted over the world , resulting in global climate crisis today. Recently, solid oxide electrolyzer cell (SOEC) is getting attention as an effective way for producing H₂, a clean energy resource for the future. Also, SOEC could be applicable to reverse water-gas shift reaction process due to its high-temperature operating condition. Here, SOEC system was utilized for both H₂ production and CO₂ reduction process, allowing product gas composition change by controlling operating conditions.

• 한국전기화학회:학술대회논문집
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• 2001.06a
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• pp.255-258
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• 2001

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.6
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• pp.470-476
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• 2021

In the near future, with the urgent requirement of environmental protection, hydrogen based energy system is essential. However, at the present time, most of the hydrogen is produced by reforming, which still produces carbon dioxide. This study proposes a high-power electrolytic hydrogen production system based on solid oxide electrolysis cell with no harmful emissions to the environment. Besides that, the parametric study and optimization are also carried to examine the effect of individual parameter and their combination on system efficiency. The result shows that the increase in steam conversion rate and hydrogen molar fraction in incoming stream reduces system efficiency because of the fuel heater power increase. Besides, the higher Faraday efficiency does not always result a higher system efficiency.