PURPOSE: To enable the output of an available turbine to be suitable for electricity need without affecting the running of a reciprocating piston internal combustion engine by arranging adjusting and cut-off valves controlled in common in a secondary line and an inflow line.

CONSTITUTION: Exhaust gas which is not necessary for the running of a supercharger turbine 5 is possible to be supplied to an available turbine 15 through an exhaust manifold 8 branched from a combining line 4 between an internal combustion engine 1 and the supercharger turbine 5. A dynamo 20 of which input is varied is driven by the available turbine 15. An adjusting and cut-off valve 9, 10 is arranged each in a secondary line 16 communicating with an exhaust outlet branched from the exhaust manifold 8 and an inflow line 13 to the available turbine 15. The adjusting and cut-off valves 9, 10 are controlled in common to enable the sum of the parts of exhaust gas flow mass flowing through the secondary line 16 and the inflow line 13 to be constant whatever the adjusting position is, and equal to the unnecessary exhaust flow for the supercharger turbine 5.