NOVELTY - An integrated fuel generator/fuel cell system comprises a fuel reformer coupled with a fuel cell, a cooling system for the fuel cell, a source of pressurized air, a mixer, a burner, and an expander. The expander expands a burner exhaust, thus creating a mechanical energy that is captured to improve system efficiency.    USE - As integrated fuel generator/fuel cell system.    ADVANTAGE - The inventive system exhibits improved efficiency.    DETAILED DESCRIPTION - An integrated fuel generator/fuel cell system comprises a fuel reformer (24) coupled with a fuel cell (44), a cooling system for the fuel cell, a source of pressurized air, a mixer (62), a burner (10), and an expander (32). In the mixer, the pressurized air from the source is used to evaporate the heated water, thus creating a pressurized air/steam mixture (12). In the burner, the air/steam mixture is combusted with a fuel (14) to create a steam-containing burner exhaust. The expander expands the burner exhaust, thus creating a mechanical energy that is captured to improve system efficiency.    An INDEPENDENT CLAIM is also included for a method for increasing the efficiency of the fuel reformer/fuel cell system, by using heat generated by the fuel cell to make a pressurized air/steam mixture, optionally in admixture with water, by direct evaporation of cooling water from the fuel cell into pressurized air. The pressurized air/steam mixture is injected as an oxidant into the fuel burner. A steam containing exhaust (16) having an expansion potential is produced from the fuel burner. The expander is then driven using the expansion potential of the steam-containing exhaust, and the mechanical energy from the expander is recovered.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of the reformer/fuel cell system.    Burner (10)    Air/steam mixture (12)    Fuel (14)    Steam containing exhaust (16)    Fuel reformer (24)    Heat exchangers (26, 34, 46, 56)    Expander (32)    Fuel cell (44)    Carbon monoxide removal system (52)    Mixer (62)    Radiator (66)