Comparison of pressurized vs. atmospheric pressure fuel cell systems.
Typical hydrogen fueled “commercial” systems (3 atm) operate with approximately 20 % parasitic power losses, primarily due to the compressor.
Straight-Across Comparisons:
- An ambient pressure system with 5 % parasitic power losses operating 0.7 V/cell provides the same efficiency as a 3 atm 20 % parasitic power system operating in 0.83 V/cell (based on LHV of hydrogen).
- The net stack power density for an the atmospheric stack operating at 300 mA/cm2 and 0.7 V/cell is the same as a the 3 atm. system at 450 mA/cm2 and 0.83 V assuming 1/3 of the pressurized stack volume is used for cooling and humidification plates.