System mass optimization of hydrogen/oxygen based regenerative fuel cells for geosynchronous space missions

Abstract A major disadvantage of conventional battery systems is the strong coupling between their capacity and rated power determined by the energy storage per unit area of the electrodes. For regenerative fuel cell systems these parameters are decoupled, since their capacity is directly related to the fuel storage, while the rated power depends on the electrode area. This intrinsic advantage of the RFC system permits design optimization by varying the current density of both elements, the electrolyzer and the fuel cell stack, and evaluating the masses of the two subsystems. Mass optimization has been carried out considering a dedicated electrolyzer and fuel cell system, together with the masses of a photovoltaic array, a radiator and the required storage. The energy storage capacity has been designed for the limiting conditions of a geosynchronous earth orbit (GEO) mission and a mean power requirement of 25 kW.