Regenerative Fuel Cell System Testbed Program for Government and Commercial Applications

High power density fuel cell.

NASA Lewis Research Center's Electrochemical Technology Branch has led a multiagency effort to design, fabricate, and operate a regenerative fuel cell (RFC) system testbed. Key objectives of this program are to evaluate, characterize, and demonstrate fully integrated RFC's for space, military, and commercial applications. The Lewis-led team is implementing the program through a unique international coalition that encompasses both Government and industry participants. Construction of the 25-kW RFC testbed at the NASA facility at Edwards Air Force Base was completed in January 1995, and the system has been operational since that time.

RFC systems can provide efficient, environmentally benign, highly reliable, renewable energy conversion for a variety of applications. These systems consist of the following subsystems: fuel cells, electrolyzers, photovoltaic arrays, reactant storage, thermal management, and electrical power management. Fuel cells consume hydrogen and oxygen (or air) to produce electricity, water, and heat. The product water is stored and later dissociated into its hydrogen and oxygen constituents by a solar-powered electrolyzer. The hydrogen and oxygen are then stored for subsequent fuel cell consumption, and the fuel cell waste heat can be utilized in many different ways. If the fuel cell is designed to consume air rather than pure oxygen, then the oxygen from water electrolysis is available for other uses, such as in biological waste purification. For many years, individual RFC subsystem components have been under development for nonregenerative applications. The objectives of the Lewis testbed program are to design, test, and evaluate RFC's to characterize system life, performance, and integration issues for candidate RFC system technologies. The testbed is generic in the sense that it can be used to evaluate the different technologies that are specific to space, military, and commercial needs.