NOVELTY - A fuel cell electric power generation system comprises electric power generation, fuel processing, oxidant processing, water circulation, and temperature control sub-systems.    USE - For converting fuel fluid streams, e.g. natural gas or propane, and oxidant fluid streams, e.g. oxygen or air, into electrical power, heat, and reaction products, e.g. water and carbon dioxide.    ADVANTAGE - The system is more integrated, more efficient, more reliable, and less expensive to manufacture than conventional fuel cell electric power generation systems.    DETAILED DESCRIPTION - A fuel cell electric power generation system comprises electric power generation, fuel processing, oxidant processing, water circulation, and temperature control sub-systems. The electric power generation sub-system comprises at least one fuel cell with a cathode, an anode, and an ion exchange membrane. The anode has a catalyst for producing electrons and protons from a hydrogen-rich fuel stream. The cathode has a catalyst for promoting the reaction of oxygen with the protons and electrons to form water and heat. The fuel processing sub-system generates hydrogen-rich fuel stream. It comprises desulfurizer, furnace, fuel processor, and fuel feed passage. The desulfurizer receives an inlet fuel stream and produces a desulfurized fuel stream by removing sulfur from the inlet fuel stream. The furnace comprises burner, reformer and at least one heat exchanger assembly. The burner produces a hot burner gas for providing heat, and is fluidly isolated from the inlet fuel stream, the desulfurized fuel stream and a reformate fuel stream. The reformer converts catalytically the desulfurized fuel stream into the reformate fuel stream, which comprises hydrogen, carbon monoxide carbon dioxide, and water vapor. The heat exchanger assembly transfers heat from the hot burner gas to the inlet fuel stream upstream of the desulfurizer. The fuel processor processes the reformate fuel stream to reduce the concentration of carbon monoxide to produce the hydrogen-rich fuel stream. The fuel feed passage directs hydrogen-rich stream from the fuel processing subsystem to the anode. The oxidant sub-system pressurizes an inlet oxidant stream and directs a pressurized oxidant stream to the cathode. The water circulation subsystem circulates and recovers water within the fuel cell electric power generation system for humidification of the desulfurized fuel stream and pressurized oxidant stream and for cooling. The temperature control sub-system circulated a temperature control fluid for controlling the temperature within the system.    An INDEPENDENT CLAIM is also included for a method of operating the above system.