Benchmarking and Simulation of Solid-Oxide Steam Electrolysis for Propellant Production in a Vacuum Chamber-Simulated Lunar Environment

Federal space agencies across the globe have prioritized development of in-situ resource utilization (ISRU) technology, such as propellants from lunar ice, to support space activities. High-temperature, solid oxide electrolysis cell (SOEC) systems integrated with an efficient balance-of-plant (BOP) have the potential to produce H 2 and O 2 at specific energy (kWh elec /kg H2 ) lower than conventional liquid-phase alkaline and PEM electrolysis systems, due to lower voltages for steam electrolysis (vs. liquid H 2 O). This NASA-sponsored collaboration explored the feasibility of achieving such low specific energy in a high-temperature SOEC system operating in a cryo-vacuum characteristic of permanently shadowed craters on the lunar surface where H 2 O ice can be found. A lab-scale »2.5-kW elec SOEC stack and BOP achieved a specific energy < 50 kWh elec /kg H2 at a production rate of > 0.075 kg H2 /h operating in a cryo-vacuum chamber. System-level simulation models of the lab-scale SOEC stack were benchmarked with experimental tests and used to explore scaling of a system for lunar deployment. The lab-scale tests and scale-up modeling suggest a pathway to a MW-scale SOEC system that can achieve < 46 kWh elec /kg H2 with relatively low specific mass (kg system /(kg H2 /h)).