Energy Agility for Space Vehicle Applications Enabled by Bipropellant Consuming Solid Oxide Fuel Cells

Abstract

The difficulty and cost of deploying space assets coupled with the variety of operations a space vehicle may be tasked to perform, the range of challenges a space vehicle may face, and the extended duration a space vehicle is often expected to operate without servicing make it desirable to create robust space vehicles that are capable of adapting to evolving circumstances or mission requirements. To help realize this vision, a research effort was begun to develop low profile Solid Oxide Fuel Cells (SOFCs) that can be used to generate electricity, on demand, by consuming fuel and oxidizer used in bipropellant thrusters for on-orbit maneuvering and station keeping. Developing a fuel cell to pair with a bipropellant thruster is of interest as such a combination can allow satellite operators to utilize the fuel and oxidizer stowed onboard a spacecraft equipped with a bipropellant thruster to generate electricity if the need arises. Moreover, creating such a fuel cell using solid oxide technology is of interest as the high operating temperature of SOFCs make them less susceptible to poisoning by contaminants which can be found in reactant flows, the nature of SOFCs make them easily customizable to meet specific electrical needs, and the large amount of energy which can be stowed in chemical storage tanks that can be subsequently converted into electricity by SOFCs can enable a spacecraft loaded with bipropellant chemicals to operate without tapping any other sources of energy for extended periods of time. Results from this work indicate that fuel cells assembled using commercial SOFC components designed to run on hydrogen (H2) and oxygen (O2) are often also effective at generating electricity by consuming fuels and oxidizers under consideration as green alternatives to the hazardous hydrazine (N2H4) fuel and nitrogen tetroxide (N2O4) oxidizer pair commonly used in on-orbit bipropellant thrusters. In this presentation, how fuel cells made with commercial components performed when fed different fuel and oxidizer combinations, each suitable for use in bipropellant thrusters, and the implications of these performances on efforts to create space deployable bipropellant driven SOFCs will be detailed.