NOVELTY - A raw hydrocarbon (HC) (6) is subjected to thermal catalytic cracking under hydrogen (H2) for dehydrogenation to produce a reformed hydrocarbon (RH) having a degree of unsaturation higher than that of the raw HC and H2. The RH, H2 and unreacted HC are introduced into a pressure-reducing-rising device. The unreacted HC is cracked and liquid gas separation is promoted by reducing and then raising pressure.    USE - For producing reformed hydrocarbon and hydrogen, where the hydrogen is used as a fuel for a fuel cell to generate electricity for an electric controller for a motor or an air conditioner. The hydrocarbon is used as a fuel for a fuel cell-mounting engine (claimed), reciprocating engine, rotary engine, diesel engine or turbine jet engine. The energy station is used for supplying fuel or electric energy to electric automobiles, hybrid automobiles and reciprocating engine-type automobiles.    ADVANTAGE - Reformed hydrocarbon with a high octane number and hydrogen are efficiently produced with the suppression of carbon formation. The fuel cell mounting engine has improved energy efficiency.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) an apparatus for producing reformed hydrocarbon and hydrogen, comprising a reactor (2), a pressure-reducing-rising device and a separator (3) for separating reformed hydrocarbon, hydrogen and unreacted hydrocarbon obtained in the pressure reducing-rising device into gas components (8) comprising hydrogen and liquid components (5) comprising reformed hydrocarbon and unreacted hydrocarbon by a liquid-gas separation;    (2) a fuel cell-mounting engine which comprises a fuel cell (7) which utilizes the gas components from the separator as fuel, and an engine which utilizes the liquid components from the separator as fuel; and    (3) an energy station which comprises a power unit which operates the pressure-reducing-rising device and the electric and thermal energies produced by the power unit is taken out with the pressure-reducing-rising device.    DESCRIPTION OF DRAWING(S) - The figure shows a block diagram of an apparatus for producing reformed hydrocarbon and hydrogen.    Reactor (2)    Separator (3)    Liquid components (5)    Raw hydrocarbon (6)    Fuel cell (7)    Gas components (8)