Investigation of off-design characteristics of solid oxide electrolyser (SOE) operating in endothermic conditions

Efficient storage technologies are a key enabling factor in promoting the use of intermittent renewable energy sources. Currently, much attention is focused on Power-to-X (P2X) installations, which convert excess electricity into hydrogen as a final product or substrate for further downstream processes. Produced fuels are treated as energy carriers, which can be easily stored and transported. High temperature electrolysers, based on Solid Oxide Cells (SOC), are considered an interesting option for P2X systems. In the current work, the SOC and stack operated in electrolysis mode. The numerical model of the SOC stack was developed and validated using experimental data. The calibrated model was used to generate stack performance maps. The results obtained were used to determine the behaviour of the tested unit and select the optimal working conditions. Such maps generated with the model are convenient tools that give a wider view of stack parameters in different scenarios. This approach makes analysis of the results more intuitive, providing better understanding and facilitating optimisation of the system. Performance maps might help determine operating parameters for the SOE module in situations when a specific stack is planned to be used in a designed system, without incurring the extra cost of additional experiments.