Efficient Methanol Electrolyzer for Hydrogen Generation

While methanol has many properties that make it a potentially excellent fuel for portable fuel cells, the large over potential required for oxidization and its tendency to transport through most electrolytes limits the actual energy densities that can be achieved to a small fraction of its potential. A potential low temperature approach to reducing system complexity and eliminating the problems of cross-over is to electrochemically convert the methanol to hydrogen for use in a hydrogen/air fuel cell. Crossover that occurs at the electrolyzer is returned to the anode feed without needing to be consumed. This allows operation at high methanol concentrations without loss of fuel utilization or energy density. Operation with high fuel concentrations also eliminates the need for a complex product water recovery system. The hydrogen stream is produced efficiently without need of high temperature components and no residual CO. While a conventional DMFC typically operates on dilute methanol, 3M or less, with an electrolyzer included in the system methanol can be supplied as an equimolar mixture of methanol and water. Reforming methanol to hydrogen in a PEM electrolyzer will produce a methanol fuel cell that realizes a much larger portion of the energy potential in methanol.