Modeling of Multi-Physics Phenomena for High-Temperature Co-Electrolysis

Abstract

Solid Oxide Electrolysis Cells (SOEC) are on the rise and can usher in the energy transition. Storage of renewably supplied energy using P2X technologies enables on-demand retrieval of energy but also supply to various sectors. High temperature co-electrolysis of H2O and CO2 is a process capable of de-fossilizing the production of syngas, which can be integrated in future renewable P2X-scenarios. To describe the fundamentals of the co-electrolysis process, a theoretical model considering thermodynamics, kinetics, heat transfer, chemistry, and diffusion processes occurring together at the same time in the cell as well as the material properties of the respective layers, was developed. The boundaries are set with only steam and only CO2 electrolysis where the model is verified by matching calculated IV-characteristics with experimental ones. Comparing with experimental data, the activation loss is not dominating at low current densities. The reaction system is kept simple in order to account for the most probable rate-limiting step.