Compact Intermediate-Temperature Fuel Cells

"Fuel cell membrane electrode assemblies (MEA's) operating between 250 and 400 C will be optimized to utilize hydrogen (H2) fuel contaminated with methanol reforming side products. At this operating temperature, H2/CO equilibrium mixtures can be made byreforming liquid fuels, such as methanol-water mixtures. The proposed MEA structures are based on a proprietary hybrid electrolyte system that consists entirely of inorganic components. This novel electrolyte design offers very low fuel crossover andimproved mechanical properties. In addition, because of the high temperature of operation, the fuel cell has high CO tolerance and enhanced catalyst activity. The focus of the Phase I research effort is to test and optimize performance and durability ofthese inorganic components. Preliminary stability and lifetime studies will also be conducted in Phase I. Because the system is CO tolerant, its performance characteristics under dynamic load should be superior to those of PEM fuel cells coupled toexternal reformers. NuVant's hybrid electrolyte design should solve several of the outstanding problems of polymer electrolyte membrane (PEM) fuel cells: low catalyst activity, poor tolerance to CO, high cost of catalysts and membranes, poor thermalintegration of fuel reformers, and poor response to transient power loads. Development of these fuel cells in Phase I and Phase II will allow NuVant to commercialize fuel cells for both military and civilian applications. The early market insertion pointis in the 10 W - 500 W system range, where the cost per watt is not a figure of merit. In this power range, internal reforming of methanol and conventional balance-of-plant components are viable options. The primary military application in this power rangeis for recharging units for portable secondary batteries, and the target civilian application is high reliability backup power. As the technology develops, NuVant plans to adapt the system to external reforming of lower cost hydrocarbon fuels for largerscale (10 kW to megawatts) backup power systems and stat