Assessment of energy generation mechanism and daytime-nighttime operation characteristics of lunar base solar-hydrogen complementary energy system

Sustainable lunar base operations, a cornerstone of deep space exploration, face a critical energy bottleneck: the absence of a heat source during long lunar nights. This study proposes an innovative closed Brayton cycle (CBC) system integrated with hydrogen-oxygen combustion and chemical storage, featuring three operational modes to achieve uninterrupted power across the full lunar day-night cycle. A unique electrolysis-storage-combustion chemical pathway is established to transfer surplus daytime solar energy to low or zero solar irradiance conditions via hydrogen, fully aligning with lunar in-situ resource utilization principles. A comprehensive thermodynamic model is developed to simulate the 29.5-Earth-day performance and quantify the impacts of key parameters, including electrolyzer operation duration, power allocation, and working-fluid mass flow rate. Results demonstrate that the system extends stable power generation from ∼14 to the entire lunar cycle, overcoming critical limitations of physical thermal storage such as sintered lunar regolith. Hydrogen-oxygen combustion enables kilowatt-level nighttime power and boosts thermal efficiency to 15.5% during early/late lunar daytime, with an optimal combustion-to-electricity energy return rate exceeding 0.9. By adjusting the operating time of different modes, the system achieves a maximum efficiency of 0.41 for the full-cycle conversion of electrical energy to chemical energy to combustion energy and back to electrical energy. The system also exhibits a favorable power-to-weight ratio of 31.9 W/kg, marginally surpassing a conventional CBC, which indicates the chemical storage path has no additional mass penalty. This work provides a technically viable design for continuous lunar energy supply.