Although the physical principles behind power generation from fuel cells were discovered in 1839 by the British scientist Sir William Grove, successful research, development, and use of the cells occurred only recently, in the context of the U.S. space program. Fuel cells were first used to supply electric power for spacecraft during the Gemini-Titan V mission in 1965, and their use has continued through the Apollo and space shuttle programs to the present. Subsequent improvements have resulted in a more than 50-percent reduction in fuel cell size and weight and a twofold increase in power output. Fuel cells are employed in the space program because they produce the highest amount of energy for a given weight and volume. In addition, because liquid hydrogen and oxygen are used as rocket fuel, the same combination can be used to generate electric power.
Fuel cells can even provide drinking water for the crew.
Commercial success with a broader use of fuel cells in vehicles, where ambient air is used instead of oxygen to eliminate the need for extra onboard storage tanks, has been handicapped by a number of problems that include cell size, weight, durability, and cost. For example, some existing PEM fuel cells, which are composed of channeled carbon plates that serve as electrodes and flow path manifolds, have suffered from uneven air distribution that can result in inefficient operation. The Institute goal is to address these problems by investigating alternatives and developing new cell architectures. Approach Several prototype PEM fuel cells using novel cylindrical designs have been assembled and tested at SwRI, based on the hypothesis that cylindrical cells can overcome some of the weaknesses caused by the flat-plate geometry of existing PEM fuel cell designs. Other important characteristics that can affect cell efficiency, including electrical and thermal resistance, reactant pressures, temperature, catalyst loading, and surface area, are being studied to evaluate their effects on the mass and energy balances in the cell.