The paper presents a concept of coupling a Solid Oxide Electrolysis Cell with a Molten Carbonate Fuel Cell for co–electrolysis of H2O with CO2 for generating synthetic fuel (methane based) for an electricity storage application on a larger scale. The concept is focused on coal/natural gas fired power plants for upgrade as peak energy storage. MCFC anode and SOEC cathode are exposed to the same flow, SOEC produces hydrogen for MCFC and MCFC delivers CO2 for methanation processes. Both electrodes have compatible polarity, thus they can be directly connected by the current collector and there is no need to apply bipolar plates. On the other side, SOEC will release oxygen to the flue gases and MCFC will capture oxygen and carbon monoxide, thus at the outlet will be a flow with increased oxygen content and decreased carbon dioxide concentration. The concept requires detailed electrochemical, chemical, and thermal simulations.