Alkaline versus Polymer Electrolyte Membrane Fuel Cells for Space-Based Regenerative Fuel Cell Systems
- Paper number
IAC-08.C3.2.7
- Author
Mr. Zachary Adam, University of Washington, United States
- Coauthor
Mr. Sanjoy Som, University of Washington, United States
- Coauthor
Dr. Steven Vance, University of Washington, United States
- Year
2008
- Abstract
The hydrogen/oxygen regenerative fuel cell system (RFCS) is the most promising near-term technology to serve as a secondary electrical power supply for robotic and manned missions. It has a high specific energy, and the primary system reactant (water) can be scavenged from planetary bodies (i.e., Mars, Enceladus, or Europa) to compensate for operating losses. NASA Glenn Research Center has been developing a polymer electrolyte membrane (PEM) RFCS, with possible applications for exploring the Moon and Mars. However, a circulating alkaline fuel cell may be more robust than PEMs for autonomous power storage in the planetary space environment. Circulating alkaline fuel cells can be designed to withstand higher acceleration forces, offer higher operating efficiency, and enable easier thermal management compared to PEM fuel cells. Alkaline fuel cells are not as sensitive to the water vapor content of the fuel and exhaust streams and the dissolved alkali can act as a chemical buffer against some contaminants within the water scavenged to replenish fuel cell water operating losses. Finally, alkaline fuel cells are more robust than PEMs when stored in a safe mode (such as would be required during interplanetary transfer maneuvers) which greatly reduces H2 gas losses, electrode deterioration, and parasitic currents during periods of low or no power production. We propose an innovative hybrid power system combining a primary Radioisotope Thermoelectric Generator (RTG) or solar panel system with a secondary alkaline fuel cell. This combination provides the opportunity to utilize more effectively the energy produced by the primary power system, to produce and store O2 and H2 via electrolysis of melted ice, and use this obtained O2 and H2 for applications ranging from planetary rovers and deep-space probes to human habitats.
- Abstract document
- Manuscript document
(absent)