Electric power is produced from flow of water by means of a floating rotor, journalled on a non-rotating shaft, which is moored in place. The rotor is turned by peripheral vanes, which engage the flow. Inside the rotor are mounted energy conversion means which change the energy of rotation into electric or hydraulic power, delivered to a distribution system through the non-rotating shaft.

This invention provides a cogeneration system formed compactly and provided with a plurality of generators, wherein a plurality of miniaturized generators are coupled to a flywheel provided in an engine. In this cogeneration system, a toothed endless belt is meshed with a toothed portion formed on an outer circumference of the flywheel provided in an engine, and electric power is generated by driving a plurality of generators by the toothed endless belt via speedup gears. The electric power generated by the generators is synthesized and then transformed by a transformer, and the resultant electric power is consumed by a load via a rectifying diode and an inverter.