NOVELTY - A fuel cell and heat engine hybrid system (1) comprises high-temperature fuel cell (2) with anode compartment (3) to receive fuel from fuel supply path (6) and to output anode exhaust gas, and cathode compartment (4) to receive oxidant gas and to output cathode exhaust gas; a heat engine assembly (30) to receive oxidant gas and further gas comprising anode exhaust gas and/or gas from it, to cause oxidation of further gas and generate output power. The heat engine also generates heat engine exhaust including oxidant gas, which is used as oxidant gas to cathode compartment of fuel cell.    USE - As fuel cell and heat engine hybrid system (claimed).    ADVANTAGE - The system eliminates the need for an oxidant gas supply assembly and for a water supply assembly by using the heat engine exhaust to provide oxidant gas to the cathode and by recycling water in the anode exhaust to the fuel, and effectively recovers heat from the anode and the cathode exhaust gases produced by the fuel cell thus reducing the need for independent heating devices. With the hybrid system, the recovery of waste heat from the fuel cell combined with the oxidation of the anode exhaust gas in the heat engine assembly results in very high system efficiencies. The supplemental air from a blower is combined with the exhaust gas from the expansion section of the gas turbine before it is fed to the cathode section of the fuel cell, and the combined gas ensures a required cathode flow for both the oxidant gas and the removal of waste heat from the fuel cell. The cooled anode exhaust gas containing residual fuel not utilized in the fuel cell is optionally compressed in a gas compressor and flows to combustor or oxidizer forming a part of the heat engine assembly and which also receives heated compressed oxidant gas, where the gas compressor boosts the pressure of the anode exhaust gas helps to bring the pressure of the gas output of the oxidizer up to the inlet pressure of the expansion cycle or section of the gas turbine of the heat engine assembly, and the anode exhaust gas is oxidized in the oxidizer and the output of the oxidizer including heated compressed oxidant gas is supplied to the expansion cycle or section of the gas turbine of the heat engine assembly, which results in a mechanical power output from the expansion section and an exhaust gas comprising oxidant gas which is used as the oxidant gas for the cathode section of the fuel cell.    DETAILED DESCRIPTION - A fuel cell and heat engine hybrid system (1) comprises high-temperature fuel cell (2) with anode compartment (3) to receive fuel from fuel supply path (6) and to output anode exhaust gas, and cathode compartment (4) to receive oxidant gas and to output cathode exhaust gas; a heat engine assembly (30) to receive oxidant gas and further gas comprising anode exhaust gas and/or gas from anode exhaust gas to cause oxidation of further gas and generate output power. The heat engine also generates heat engine exhaust including oxidant gas, which is used to provide oxidant gas to cathode compartment of fuel cell. The system further comprises a water transfer assembly (9) condensing and transferring water from the anode exhaust gas and outputting water-separated anode exhaust gas; and further gas comprises water-separated anode exhaust gas. The system also comprises a compressor compressing the water-separated anode exhaust; and further gas comprises compressed water-separated anode exhaust gas. An INDEPENDENT CLAIM is included for operating the fuel cell and heat engine hybrid system involving operating the high-temperature fuel cell by supplying fuel to anode compartment of the fuel cell and oxidant gas to the cathode compartment of the fuel cell; and allowing oxidant gas and further gas to the heat engine assembly.    DESCRIPTION OF DRAWING(S) - The figure shows a block diagram of the fuel cell and heat engine hybrid system.    System (1)    High-temperature fuel cell (2)    Anode compartment (3)    Cathode compartment (4)    Fuel supply path (6)    Water transfer assembly (9)    Heat recovery unit (15)    Compression cycle or section (16)    Heat exchanger section (17)    Oxidizer (18)    Expansion section or cycle (21)    Heat engine assembly. (30)