POWER-TO-METHANE VIA H2O/CO2 CO-ELECTROLYSIS INTEGRATION: A CONCEPTUAL PERFORMANCE ASSESSMENT ON METHANATION OFF-GAS RECIRCULATION USING EXERGY METHODS

Abstract

Electrolytic Power-to-Methane processes have been a motive of interest in the recent years due to the benefit of producing sustainable methane from renewable energy sources like solar and wind. Solid oxide electrolysis cell (SOEC) reactors have emerged as a promising option because of their high electrical efficiency and the potential for direct H2O/CO2 co-electrolysis for syngas production. Co-electrolysis operation is still understudied, for this reason, modelling methods can lead to improvements in process efficiency and overall carbon utilization. This contribution presents a system concept modelling study of a co-electrolysis SOEC reactor coupled with a methanation reactor considering three system configurations. The base case consists of an open system with no recirculation. The other two systems assess the recirculation of product-gas to either the electrolyser or the methanation reactor. The study was performed using an inhouse component-oriented modelling framework written in python which is experimentally supported by the research group’s extensive experimental facilities. This approach ensures smooth implementation and modification of simplified process system configurations, while producing reliable and reproducible fluid and thermodynamic process calculations. The results presented quantify the advantages and disadvantages of the two configurations in terms of yield, and exergy efficiency – upon optimization of key operational variables