Aluminum-Hydrogen Peroxide Fuel Cell Power System for Ocean Bottom Electrical Power

ALUMINUM-HYDROGEN PEROXIDE FUEL CELL POWER SYSTEM FOR OCEAN BOTTOM ELECTRICAL POWER Richard Gorman, PhD, PE TRW Federal Systems Group Box 10400 Fairfax, VA 22031-8000 1-703-734-6036 Energy supply systems used most frequently for submerged vehicles and systems have been primary and secondary cells and fuel cells. Hydrogen-oxygen fuel cells have been limited by the great weight of high pressure gas storage vessels, their relative complexity and unreliability, and the weight and bulk of pressure vessels protecting vacuum-insulated liquid cryogenic storage. Currently used pressure compensated Ag-Zn secondary cells have relatively low energy density, particularly when the flotation required for neutral buoyancy is included in the system. LiSOC12 primary cells are light and simple but require pressure vessels and buoyancy which increase the system size. A system using aluminum-hydrogen peroxide fuel cells operating at ambient hydrostatic pressure and modular for increased reliability, would be more suitable for submerged use. An ambient pressure system that uses an existing modular automotive aluminum-air fuel cell has been synthesized. Oxygen for the cell is supplied by existing mechanisms for catalytic dissociation of hydrogen peroxide. The system can use a 50% to 90% concentration H202*H20 solution as the oxidizer supply. The weight and volume (as well as the neutral buoyancy equivalent dry weight) for each of two alternative high energy density power systems (LiS0Cl2 primary batteries, H2-02 fuel cells) have been derived. The results show that at a 20,000 feet depth, the dry weight of a neutrally buoyant aluminum-hydrogen peroxide system is less than one third that of LiSOC1, primary batteries inside spherical pressure vessels, and less than that of an H2-02 fuel cell using subcritical liquid cryogenic storage inside spherical pressure vessels. In addition, the advantage, other than cost, of the ability to employ "soft" bags for storage of hydrogen peroxide vice pressure vessels is not readily quantifiable but real, as is the greater depth capability, storability and ease of handling of non-cryogenic liquids.