Hydrogen-Air Fuel Cell for High Altitude Aircraft Use

Unmanned aerial vehicles (UAV¿s), especially High Altitude Long Endurance (HALE) aircraft, offer unique combinations of capabilities for use as observation and relay platforms. They operate closer to the ground and at lower cost than satellites, while being capable of staying over a small area for extended periods and remaining aloft for extended periods. The current generation of vehicles for fixed duration operations are based on conventional turbine or piston technology and have flight times limited to one or two days. There are no potential improvements that could extend this time to a week or longer. Missions of this duration can be achieved by electrically driven craft using liquid hydrogen fuel with a lightweight proton exchange membrane (PEM) fuel cell to generate electricity using ambient air as the oxygen source. Fuel cells have adequate performance for this application without the need for precompression, as used with combustion engines, even when operated at the low pressures present at high altitudes (2 psia at 50,000 ft), but current densities are limited, requiring high active areas. Success requires lighter fuel cell hardware than is currently available. The proposed project will demonstrate a novel fuel cell architecture that substantially reduces the weight of a fuel cell stack.