Patent ID: 6884528

Claim:
A process comprising: heating a fuel cell stack during cold startup conditions including: pumping a cooling fluid including a liquid to an elevated pressure, transferring thermal energy from the cooling fluid to the fuel cell stack, and repeating the above steps for heating a fuel cell stack during cold startup conditions until the temperature of the fuel cell stack has reached a temperature for operating the fuel cell under post-startup conditions and wherein the operation of the fuel cell stack produces waste heat, and cooling the fuel cell stack during post-startup operations and using waste heat generated by the fuel cell stack to produce shaft work including: pumping the cooling fluid to the fuel cell stack, transferring thermal energy from the fuel cell stack to the cooling fluid to cool the fuel cell stack and to heat the cooling fluid, supplying additional heat to the cooling fluid to change the liquid to a gas, expanding the heated cooling fluid through an expander to produce shaft work, driving an air compressor using the shaft work to compress air and deliver the compressed air to the fuel cell, directing the cooling fluid through a condenser having condenser fans that are turned on to remove heat from the cooling fluid and to change the gas to the liquid, and repeating the above steps for cooling a fuel cell stack during post-startup conditions and using waste heat generated by the fuel cell stack to produce shaft work.