A novel efficient solar-gas assisted hydrogen-electricity cogeneration system based on photo-thermal energy cascade conversion: modeling and performance analysis

In this study, an efficient solar-gas assisted hydrogen-electricity cogeneration system is proposed. It constructs from thermos-photovoltaics (TPV), supercritical carbon dioxide Brayton cycle (SCO₂-BC) and Cu-Cl chemical cycle according to photo-thermal energy cascade conversion. A system thermophysical analysis model is established and the effect of parameters on the electricity/hydrogen production efficiency and irreversible loss are investigated based on second law. The design concept is proposed that using by-product oxygen from hydrogen generation to assist combustion for system stable running. Besides, the superiority of the novel system is discussed by comparing with different configurations. The results show that the concentration ratio, TPV area, and turbine inlet temperature can be used to adjust the ratio of electricity/hydrogen production. In actual applications, the system can keep continuous and efficient by appropriately increasing the oxygen ratio when solar energy input is insufficient. The second law analysis shows the exergy destruction factor of TPV module is the largest (about 30 %), followed by receiver module (11.68 %). The system energy efficiency can reach 61.26 % for electricity/hydrogen cogeneration, and the equivalent electrical efficiency can reach 52.98 %, which has obvious advantages compared with other different system configurations. This work provides guidance for the development of solar high-efficiency hydrogen/electricity cogeneration technology.