In contrast to the conventional internal combustion engines(ICE), fuel cell systems (FCS) have the characteristic that the efficiency does not degrade at part load and in fact can be much higher. This is particularly advantageous in transportation applications because the vehicles are mostly operated at part load conditions; the average demand on standard US drive cycles is less than 20% of the rated power of the engine. A recent study concluded that the fuel economy of hydrogen fuel cell vehicles can be 2.5–3 timesthe fuel economy of the conventional gasoline ICE vehicles[1].