PURPOSE: To provide a power source which allows a large reduction of fuel cost and a lower installation cost and is stable by a method wherein the waste heat generated by the secondary resistance inserted into a main shaft driven induction generator is utilized as a heat source for a feed water heater of an exhaust-gas turbo mechanism.

CONSTITUTION: The waste heat generated by the secondary resistance 2 inserted into the main shaft driven induction generator 1 is utilized as the heat source for the feed water heater 7 of the exhaust-gas turbo driven synchronous generator 3. The heat generated at the secondary resistance 2 heats the water fed from a feed water tank 8 into an auxiliary boiler 10 by a feed water pump 9, thereby recovering the power loss. The warm water heated by the feed water heater 7 is further heated to a higher temperature and evaporated by an exhaust-gas boiler 12 connected to the main engine 11, drives a turbine 13 to drive the exhaust-gas turbo driven synchronous generator 3 to rotate. The steam coming out of the turbine 13 is returned to the feed water tank 8 via a condenser 14 and a condensate pump 15.