Assessment of Pressure Effects on High Temperature Steam Electrolysis Based on Solid Oxide Technology

Abstract

To manage the grid with renewable electrical sources, hydrogen chains have to be considered. However, hydrogen must be pressurized before being used or stored. Why not performing the High Temperature Steam Electrolysis (HTSE) step directly under pressure? An experimental and modelling approach has been adopted in order to better understand the basic underlying mechanisms of pressurized steam electrolysis operation. Experiments were carried on two different single commercial cathode-supported Solid Oxide Electrolysis Cells (SOEC) at 800°C in the pressure range of 1 to 10 bars. According to the i-V curves, the Open Cell Voltage increases with increasing the pressure. Nevertheless, the limiting current density increases because of a better gas diffusion in through the thick porous cermet support, meaning that the hydrogen production can be improved depending on the voltage. The model, which has been calibrated on the experimental i-V curves recorded at the atmospheric conditions, has been validated for the pressurized operation.