Optimising solid oxide cells for co-electrolysis operation: parameter interactions and efficiency gains at industrial scale

Solid Oxide Electrolysis (SOE) is a promising technology for the production of hydrogen and syngas through the co-electrolysis of steam and CO2, offering a potential route to clean and sustainable energy production. To optimise the performance of SOE systems, particularly at industrial scale, it is essential to fully understand the effects of various operating parameters. This study uses a Design of Experiments (DoE) approach to investigate the performance of an industrial-scale electrolyte-supported SOE stack during co-electrolysis. Key parameters, including current density, temperature, inlet gas composition and flow rate, are systematically varied to assess their effects on stack efficiency and behaviour. Advanced techniques such as electrochemical impedance spectroscopy (EIS), distribution of relaxation times (DRT) and spatial temperature profiling are used to investigate internal processes such as diffusion and polarisation losses. The results show that the current density has a significant effect on the stack voltage, which is temperature dependent. However, it was found to have a minimal effect on the composition of the product gases. By optimising the operating conditions, we were able to reduce the electrical power requirement by more than 7 % without compromising the product gas composition or production rate. These findings provide valuable insights into optimising SOE stack performance and have important implications for scaling up this technology for large-scale applications in clean hydrogen and syngas production, potentially improving energy efficiency and reducing operating costs in industrial settings.