NOVELTY - The thermal decomposition gas is obtained by thermal decomposition or gasification of solid/liquid fuel. A combustion apparatus (3) generates hot gas supplied to a heating apparatus (4) which heats a working fluid. A flow control valve (6) is set downstream side of the heating apparatus, to regulate flow rate of hot gas such that working fluid is heated in a heater tube (13) by exchange of heat with hot gas.    USE - For generating electric power using gas generated by thermal decomposition of solid, liquid fuel, waste material.    ADVANTAGE - Improves thermal efficiency of the electric power generation system, by operating Stirling engine using thermal decomposition gas as heat source.    DETAILED DESCRIPTION - A reformer modifies thermal decomposition gas obtained by thermal decomposition or gasification of solid or liquid fuel. A fuel gas supply unit supplies gas from the modifier to a combustion portion of the heating apparatus arranged in a Stirling engine (11). A temperature control valve (9) regulates temperature of the hot gas flowing into the heat transfer unit. The working fluid is heated by heat exchanges of working fluid with hot gas. A heat exchanger (5) is arranged downstream side of the heating apparatus to cool hot gas passing to the heating apparatus and to preheat combustion air flowing to the heating apparatus, selectively. AN INDEPENDENT CLAIM is also included for control method of electric-power generation system which involves regulating flow rate and/or temperature of the hot gas obtained by thermal decomposition of the solid or liquid fuel, before supplying to the heat transfer portion. The corrosion component in the thermal decomposition gas is removed before supplying to the combustion portion of the heating apparatus. The working fluid is heated with combustion heat of the thermal decomposition gas or reformed gas.    DESCRIPTION OF DRAWING(S) - The figure shows a flow diagram of the electric power generation system. (Drawing includes non-English language text).    combustion apparatus (3)    heating apparatus (4)    heat exchanger (5)    flow control valve (6)    temperature control valve (9)    Stirling engine (11)    heater tube (13)