Design Optimization of Highly Efficient SOEC Co-Electrolysis Processes

Abstract

High-temperature co-electrolysis of water and carbon dioxide using solid oxide electrolysis cells (SOECs) has attracted interest as an efficient synthesis gases production method. The SOECs and a fuel synthesis reactor are usually combined to produce hydrocarbon-rich fuel. In this study, we focused on investigating the effects of H2O/CO2 ratio of feed gas to the SOEC fuel electrode and gas and heat recycles on the fuel production efficiency were evaluated by mass and heat balance analysis. The results described that the amount of fuel production depended on the feed gas composition. In the case of increasing CO2 flow rate to the fuel electrode, the maximum amount of methane was produced and the efficiency of fuel production became 93.1% when the feed gas composition was controlled as H2O/CO2 = 4.32. These results indicate that the fuel production efficiency significantly depended on the operation condition of SOEC co-electrolysis and the system design.