A fuel cell power plant has a fuel cell (38) receiving hydrogen (37) from a fuel processing system (12) which employs a vaporizer (19) to vaporize clean gasoline from a source (13). A conventional start burner (22) and startup heat exchanger (28) are utilized to convert water (31) from the fuel processing system (12) and fuel cell (38) into steam (32); but during sub-zero startup, an aqueous antifreeze solution (46) is provided to the heat exchanger (28) to produce the steam (32) for starting the vaporization of gasoline in the vaporizer (19).