NOVELTY - The fuel supply device comprises a first storage tank (4) for a carrier agent such as liquid organic hydrogen enriched with the hydrogen, and a second storage tank (6) for a dehydrated carrier agent, where the first and second storage tanks are connected by a flow circulation over a feed line (3) and a drain line (5) for the carrier agent, in which a heat exchanger such as a countercurrent heat exchanger is integrated at a pressure- and temperature-fixed reactor vessel. The reactor vessel has separator function to provide the hydrogen for a consumer.    USE - The fuel supply device is useful for supplying a burning fuel in a combustion chamber such as an internal combustion engine or fuel cells of a motor vehicle with hydrogen.    ADVANTAGE - The fuel supply device ensures economical supply of fuel in the combustion chamber fuel without toxicity in an environmental friendly manner.    DETAILED DESCRIPTION - The fuel supply device comprises a first storage tank (4) for a carrier agent such as liquid organic hydrogen enriched with the hydrogen, and a second storage tank (6) for a dehydrated carrier agent, where the first and second storage tanks are connected by a flow circulation over a feed line (3) and a drain line (5) for the carrier agent, in which a heat exchanger such as a countercurrent heat exchanger is integrated at a pressure- and temperature-fixed reactor vessel. The reactor vessel has separator function to provide the hydrogen for a consumer by dehydrogenation of the enriched carrier agent. The reactor vessel is connected with the combustion chamber of the consumer by a connection line (7). The heat exchanger is connected between the feed line and the drain line. An isolating device such as multi-port-valve is provided for the feed and drain lines, by which the heat exchanger is connected to the reactor by its own connection lines. The heat exchanger is connected by a heat transfer medium such as cooling water or exhaust gases that guides the pipeline with the internal combustion engine or the fuel cell. A shut-off element such as an overflow- or a pressure holding-valve is incorporated into the pipeline that releases an inflow of gas such as hydrogen gas to the internal combustion engine depending on a gas pressure or a mass flow of the gas. A switching state of the isolating device is controlled by a control device such as an electrically or mechanically operated control unit, a condition sensor such as a gas pressure sensor or gas mass flow meter in the pipeline, a loading- or filling level sensor such as a photo diode or a tube capacitor, and both mechanically and electrically or electronically operated control- and/or sensor pipelines. An another control device such as an electro-mechanically actuated control valve or an adjustable flow restrictor that is designed as axially adjustable valve cone insert is incorporated into the pipelines guided by the reactor vessel to the heat exchanger. The isolating device is formed by a valve piston axially guided in a common bore with radial seals, which are conducted as O-rings and are fixed in grooves appropriate on the respective pistons. The valve pistons are performed in the bore within a wall of the vessel. An INDEPENDENT CLAIM is included for a method for supplying fuel.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a fuel supply device.    Feed line (3)    First storage tank (4)    Drain line (5)    Second storage tank (6)    Connection line (7)    Internal combustion engine. (8)