On the application of fuel cell technology to electric propulsion

The origin of fuel cell technology has a notable connection to the history of spaceflight, having been used in remarkable programs such as Gemini, Apollo and the Space Shuttle. With the constant growth of the electric propulsion technology in the last years, one natural application for fuel cells to be considered would be the electrical feeding of those thrusters for different mission profiles. In this article we explore in details this possibility, showing what would the necessary characteristics of such a device be in order to improve mission parameters, as payload ratio and thrust, among others. In the first section, a brief review of the applications of fuel cells in the space industry is shown, and the classical analytical modeling of these devices is presented. In the second part, two case studies illustrating most of the possible ways to use fuel cells in conjunction with electric propulsion systems are shown , and the possible advantages and limitations of the applications are demonstrated analytically. The result of the analysis shows that, in the case where the fuel cell reaction products are disposed of and the propulsion has its own feed system, the application of fuel cell technology would bring no advantages for most kinds of missions. On the other hand, when the case where the fuel cell exhaust is used as a propellant is considered, it is shown that it is possible to improve mission parameters, such as thrust and specific impulse, if certain conditions are met.