Low carbon fuel production from combined solid oxide CO₂ co-electrolysis and Fischer-Tropsch synthesis system: A modelling study

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 to produce more value-added products. 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 is important for understanding and design optimization of the combined fuel-assisted SOEC and F-T synthesis system to achieve economical hydrocarbon generation.