Hydrogen PEFCs active

The additional problem identified recently, of in-situ generation of CO by reduction of CO2 within the PEFC cathode, can be minimized by the use of a PtRu anode catalyst. Low PtRu loading (0.1 mg/cm ) seems to be effective in maintaining the anodic hydrogen oxidation activity while minimizing the rate of CO2 reduction. 

This performance still requires platinum loadings that are almost ten times higher (around 3 to 5 mg/cm ) than needed in high-performance direct hydrogen PEFC. When feeding concentrated methanol directly, the cross-over can be as high as 30 to 50 percent compared with the amount oxidized electrochemically. If the concentration is reduced, the cross-over is reduced but so is the current density (due to reduced activity of the reactants). Obviously, the methanol crossed over is... 

From the Nernst equation with unity reactant activity we can show the theoretical equilibrium potential, which is close to accurate for the SOFC but assumes zero crossover and only accounts for equilibrium effects. From experimental observation of a hydrogen PEFC, Parthasarathy and co-workers [30] found that... 

Recently, the major activity in transportation fuel cell development has focused on the polymer electrolyte fuel cell (PEFC). In 1993, Ballard Power Systems (Burnaby, British Columbia, Canada) demonstrated a 10 m (32 foot) light-duty transit bus with a 120 kW fuel cell system, followed by a 200 kW, 12 meter (40 foot) heavy-duty transit bus in 1995 (26). These buses use no traction batteries. They operate on compressed hydrogen as the on-board fuel. In 1997, Ballard provided 205 kW (275 HP) PEFC units for a small fleet of hydrogen-fueled, full-size transit buses for demonstrations in Chicago, Illinois, and Vancouver, British Columbia. Working... 

Natural gas is the main source of hydrogen. See Barclay (1998) for details of an early ICI large natural gas reform plant, outputting hydrogen and methanol. Balanced marketing of both hydrogen and methanol from such a plant or a modern Canadian equivalent (Methanex Inc. see web site) would be needed. The DMFC is therefore a potentially important, but relatively immature, type of PEFC, and, logically, Ballard and Johnson Matthey are active in that area. 

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