A novel solar-driven thermal-electrochemical approach for sustainable fuel production: integrating an oxygen-permeable membrane with protonic ceramic cells

The solar-driven decomposition of CO2/H2O for fuel production represents a promising approach for practical applications. Based on the two-step electro-thermochemical cycle (TSEC) principle, the electro-assisted oxygen-permeable membrane (EOPM) primarily utilizes thermal energy and produces CO2/CO mixtures with restricted applications. In this work, a protonic ceramic electrolysis cell (PCEC) primarily driven by electrical energy is coupled with EOPM to upgrade the EOPM product into a higher-value mixture and achieve complementary utilization of solar thermal and electrical energy. The product of EOPM can be further upgraded in PCEC to enable the integrated preparation of CH4/H2/CO, and the proportion can be regulated by controlling parameters. Thermodynamic analysis reveals that the system solar-to-fuel conversion efficiency ranges from 19.87% to 24.86%. Sensitivity analysis shows parameter uncertainty widens the system efficiency range to 13.76%–27.43%. The energy utilization diagram (EUD) is adopted to analyze the exergy loss distribution of the system. With the optimization of heat recovery technology, the irreversible exergy loss ratio is reduced by 7.12%. In contrast to systems that utilize mainly one form of solar energy, this work enables the comprehensive harnessing of solar thermal and electrical power. These findings show a competitive approach for CO2/H2O decomposition by solar-powered thermal-electrochemical coupling conversion.