Modeling of a combined CH4-assisted solid oxide co-electrolysis and Fischer-Tropsch synthesis system for low-carbon fuel production

Abstract

CH4-assisted solid oxide electrolyzer cells (SOECs) can co-electrolyze H2O and CO2 effectively for simultaneous energy storage and CO2 utilization. Compared with conventional SOECs, CH4-assisted SOECs consume less electricity because CH4 in the anode provides part of the energy for electrolysis. As syngas (CO and H2 mixture) is generated from the co-electrolysis process, it is necessary to study its utilization through the subsequent processes, such as Fischer-Tropsch (F-T) synthesis. An F-T reactor can convert syngas into hydrocarbons, and thus it is very suitable for the utilization of syngas. In this paper, the combined CH4-assisted SOEC and F-T synthesis system is numerically studied. Validated 2D models for CH4-assisted SOEC and F-T processes are adopted for parametric studies. It is found that the cathode inlet H2O/ CO2 ratio in the SOEC significantly affects the production components through the F-T process. Other operating parameters such as the operating temperature and applied voltage of the SOEC are found to greatly affect the productions of the system. This model can be used for understanding and design optimization of the combined fuel-assisted SOEC and F-T synthesis system to achieve economical hydrocarbon generation.