Steady state operation of a 10 kW SOEC module under pressurized conditions of up to 20 barg

Kurzfassung

The integration of solid oxide electrolysis cell reactors (SOECs) with downstream processes, such as hydrogen storage, methanisation, ammonia production, and Fischer–Tropsch synthesis, can benefit from elevated pressure operation. Pressurisation reduces the need for intermediate gas compression and can thus be economically favourable. However, conventional SOEC systems are not typically designed for such conditions. In particular, increased heat losses, altered flow field dynamics, and the risk of high differential pressures between the fuel and air sides or between the system and the environment must be taken into account. These conditions affect SOEC performance due to changes in area-specific resistance (ASR), temperature, and voltage distribution. To analyse the characteristics of an SOEC modules between 8 and 25 barg, the test environment e-XPlore was developed by DLR. This involved a systematic approach combining advanced pre-simulations (thermo¬dynamic design calculations, computational fluid dynamics [CFD], finite element method [FEM]) and hardware adaptations. A commercial electrolyte-supported SOEC module with a rated power input of 10 kWel was modified to operate under pressures of 8–25 barg in a pressure vessel, optimised for higher external temperatures and equipped with detailed sensor technology. An experimental characterisation was carried out under isothermal conditions to assess the influence of pressure. Dynamic current–voltage (iV) sweeps were performed to determine ASR, and energy balances. Key design aspects, including safety measures, hotbox and reactor configurations, and differential pressure control strategies, were implemented to ensure stable operation. The e-XPlore test environment has been successfully commissioned and was operated in the German-funded flagship project H2Mare under maritime. This work presents results from the test campaign at pressures between 8 and 20 barg, including: (1) ASR analyses under pressure, (2) heat loss analyses, (3) validation of temperature and voltage distributions against simulations, and (4) insights into design challenges. The adapted SOEC module demonstrates compatibility with pressurised environments. The analyses provide data for a deeper understanding of SOEC performance under elevated pressure and thus the interplay between pressurisation, process compatibility and system performance.