Exergy Analysis of Photovoltaics Coupled With Electrochemical Energy Storage for Lunar Power Applications

Any inhabited base on the moon would require significant resources and power. Due to the high cost of delivering materials to the lunar surface, care must be taken to optimize energy storage and delivery systems. An exergy-based analysis of power generation systems based on a photovoltaic (PV) array coupled with energy storage is conducted. Exergy destruction rates are calculated through quasi-steady state energy and exergy balances, while exergy efficiencies for systems and subsystems are also quantified. The power system configurations analyzed include a PV array coupled with lithium-ion battery (LIB) energy storage and a PV array coupled with regenerative fuel cell (RFC) energy storage. Influence of parameters such as lunar latitude, size, and transient power demand are discussed. In both cases considered, the PV array dominates exergy performance of the overall system. Compared to the RFC, the LIB exhibits a slightly higher system exergy efficiency. Higher system efficiencies are observed during nighttime operation due to efficient discharge of energy storage. Daytime system efficiencies are reduced significantly by radiative heat loss from the solar array. Both configurations experience slightly better exergy efficiencies at lower lunar latitudes, closer to the equator.