Modeling and optimization of a novel power-to-methanol system based on SOEC CO2/H2O co-electrolysis

Power-to-liquid (PtL) by high temperature co-electrolysis technology has emerged as a promising avenue for the transformation and utilization of renewable energy. In this study, a novel process of the Power-to-Methanol (PtM) energy conversion system was developed by integrating the advanced CO2 capture process, CO2/H2O co-electrolysis process by solid oxide electrolysis cell (SOEC) and Fischer-Tropsch synthesis process in turn, in which SOEC mechanism model for co-electrolysis was established and validated. As amult-process system with high-temperature, endothermic and exothermic processes, from the perspective of maximizing energy utilization, the heat exchange network of the process flow is optimized, eliminating thermodynamic isolation effects between subsystems. Compared to the subsystems operated independently, the heat and cold demand of the improved system decreased by 34.8 % and 54.8 % respectively, and the energy efficiency of the holistic system increased from 56.2 % to 65.8 %. The results of the exergy analysis show that the overall exergy efficiency of the improved system has increased from 75.3 % to 79.2 %. Through systematic optimization, the proposed system achieves decent thermodynamic performance, exhibiting advantages in consumption of renewable energy.