High-efficiency Hydrogen Production Technology - High-temperature Solid Oxide Electrolytic Cell

  High-Temperature Solid Oxide Electrolysis Cell (SOEC)is a highly efficient, rapid, and flexible energy conversion device. By introducing different feedstocks, it can produce various products, enabling the development of multi-functional electrochemical synthesizers. It can be connected to clean power sources, such as wind and photovoltaic power generation. Its most common application is electrolyzing steam to produce hydrogen. Compared to mainstream water electrolysis technologies like Alkaline (ALK) and Proton Exchange Membrane (PEM) electrolysis, SOEC offers several advantages: higher efficiency (up to 85%), reversibility, and the ability to utilize high-grade waste heat from the generated products.The Solid Oxide Electrolysis Cell (SOEC) converts electrical and thermal energy into chemical energy. In principle, SOEC operates as the reverse process of a Solid Oxide Fuel Cell (SOFC). As shown in Figure 1, the SOEC consists of a dense electrolyte layer in the middle, porous electrodes on both sides, and gas channels outside the electrodes for supplying reactant gases and removing product gases, enabling efficient gas transport and distribution. When a direct current (DC) voltage is applied to the electrodes at high temperatures (600–900°C), water vapor (H₂O) molecules are split at the cathode into protons (H⁺) and oxygen ions (O²⁻). The O²⁻ ions migrate through the solid oxide electrolyte layer to the anode, where they release electrons (e⁻) and form oxygen molecules (O₂).

  The electrons are conducted via the interconnect to the cathode, where they combine with H⁺ to form hydrogen molecules (H₂).SOEC hydrogen production, i.e., solid oxide electrolysis cell-based hydrogen production, is a process that utilizes the ionic conductivity of solid oxide electrolyte membranes to split water into hydrogen and oxygen at high temperatures. The products can be widely applied in industries such as steel plants, chemical plants, and aerospace. SOEC can also be thermally integrated with a range of chemical synthesis processes, enabling the recycling of captured carbon dioxide and water into synthetic natural gas, gasoline, methanol, or ammonia.Compared to other water electrolysis technologies, SOEC offers numerous advantages, including high efficiency, low cost, co-electrolysis capability, reversibility, and suitability for diverse scenarios. Operating at high temperatures (600–900°C), SOEC benefits from favorable kinetics, resulting in high electrolysis efficiency. The elevated operating temperature reduces electrical energy consumption, with overall system efficiency for hydrogen production reaching approximately 85%. This is about 1.5 times the system efficiency of PEM electrolysis and twice the total efficiency of alkaline water electrolysis.In terms of applications, the high-temperature operating conditions of SOEC make it highly compatible with scenarios involving significant waste heat, such as coal chemical plants, steel metallurgy, ammonia synthesis, and nuclear power plants. Integrating waste heat into SOEC operation can supplement electrical energy consumption, improving electrical efficiency and reducing operational costs.Furthermore, a distinctive feature of SOEC compared to other technologies is its reversibility—it can flexibly switch between electrolysis mode (SOEC) and fuel cell mode (SOFC).

SOEC can either produce hydrogen or syngas for energy storage in electrolysis mode or convert chemical energy into electricity in fuel cell mode, creating a synergistic system for hydrogen production, storage, and power generation ("electricity-hydrogen-electricity"). This gives it significant potential for renewable energy storage and grid peak shaving, contributing to effective energy utilization and balance.Overall, with continuous technological advancements and gradual market maturation, SOEC hydrogen production is expected to play a vital role in the future energy landscape, contributing to the achievement of global carbon neutrality goals.