scope:

Abstract:

Space Shuttle Alkaline Fuel Cell Powerplants (FCPs) use O2 and H2 as reactants. These FCPs require higher grade LH2 and LO2 (99.99% and 99.989% purity levels, respectively) than Space Shuttle Main Engines (99.9% LH2 and 99.2% LO2). Proton Exchange Membrane (PEM) FCPs have been developed that can use propellant grade reactants. This means that a common liquid oxygen and liquid hydrogen system could potentially be designed for both propulsion and electrical power generation requirements as well as for Environmental Control and Life Support System (ECLSS). This would simplify cryogenic loading operations by getting rid of extra pad clears and load operations for the FCP Power Reactant Storage and Distribution (PRSD) system and potentially consolidating into one "cryo load." In addition, if propellant grade reactants were used for Lunar or Mars surface lander FCPs, the FCPs could scavenge the residual propellants for use in the FCP (assuming that any pressurant such as Helium could be removed from the propellant tanks.