Mapping Hydrogen Evolution and Liquefaction Energy Requirements for Solar System Exploitation

Current mission plans for harvesting lunar resources require further investigation of technological and energy requirements to do so. This paper presents an analysis of the thermodynamics involved in hydrogen (H₂) evolution and liquefaction within this scope. It highlights the use of solar-powered systems for electrolysis and membrane separation as efficient means to produce H₂ on the lunar surface. The study compares energy requirements and logistical considerations of in-situ resource utilization (ISRU) against transporting precursors from Earth, where the energy penalty stands at 540 MJ/kg. It is argued that an ISRU solution stands to present the most energy efficient option, particularly with the use of an active magnetic regenerative refrigeration (AMRR) system for liquefaction. Furthermore, an AMRR system also makes the currently proposed plan of shipping methane (CH₄) from the Earth for H₂ production more favorable than implementing ISRU with the state-of-the-art (SOA) reverse turbo-Brayton cryocoolers (RTBC). This emphasizes the significance of an AMRR system for H₂ production and the need for further research in its development. Additionally, this study underscores the significance of regenerative technologies and advanced life support systems for sustainable off-planet human habitation, particularly in the context of lunar and Martian missions.