Development of proton exchange membrane fuel cells for underwater applications

A 20 kW proton exchange membrane (PEM) fuel cell power plant developed for application in unmanned underwater vehicles (UUVs) is described. The power plant is based on a simple system concept requiring no circulation of gases for thermal and water management-enhancing reliability, durability and maximizing energy density and vehicle range. The power plant is part of an energy storage system designed to replace the silver-zinc battery system currently used to supply power in the 44-inch UUV developed by the United States Advanced Research Projects Agency. The power plant may be operated with hydrogen and oxygen supplied from a variety of alternative sources. Hydrogen generation from methanol by reforming is discussed. Specifically, a method demonstrated for reducing the carbon-monoxide content of reformate to levels compatible with the long endurance of the PEM fuel cell is presented. Data showing compatibility with hydrogen supplied from a regenerable metal hydride bed is also presented