Integrating solar photovoltaic and thermal energies into a fuel cell-heat engine hybrid system to produce solar fuel for improving energy conversion and reducing carbon emission

Coupling advanced fuel cell hybrid systems with carbon dioxide (CO2) capture and CO2-to-liquid fuel conversion offers a promising solution for achieving a global carbon emission peak. Focusing on the molten carbonate fuel cell (MCFC) hybrid system, this study employs a solar photovoltaic-thermal synergistic approach to promote low-carbon and efficient utilization of fuels. In detail, based on the reliable thermodynamic models, a new hybrid system proposed in this study is described and simulated. The energy efficiency of the referenced hybrid system reaches about 62 %, without cutting down this performance, the photovoltaic power-to-methanol efficiency can be expanded in the range of 73 %–90 %, which is at a current leading level. Furthermore, this study studies the effects of electrolysis current density, electrolysis temperature, and CO2 hydrogenation on system performance. The results indicate that the new system realizes energy and exergy efficiency enhancements of 2.0 % and 7.5 % compared to the reference system, respectively. Meanwhile, this peak of exergy efficiency correlates with CO2 sequestration rates of 57 % by using liquid methanol. In addition, a feasible operational strategy utilizing unstable solar energy is investigated. These findings provide theoretical guidance for improving the thermodynamic perfection of the system and utilizing renewable energy to drive emission-to-methanol conversion.