PURPOSE: To remove power from water flowing in a city water tube and to effectively use it by disposing a plurality of pairs of magnets through the tube, and disposing a plurality of pairs of electrodes at both sides of perpendicularly radial directions.

CONSTITUTION: A plurality of magnets 2, 3 are so provided along a city water tube 1 as to be opposed at upper and lower parts at both sides of its radial direction. The magnets 2, 3 are magnetized to N-poles and S-poles of different polarities to form a magnetic field crossing vertically the tube 1. A plurality of electrodes 4a, 4b are so disposed at both sides of radial direction perpendicular to the opposed magnets 2, 3 at both side of the tube 1. If water having conductivity flows in the tube 1, an induced current is generated in a direction perpendicular to a magnetic field and the flow of water, the current is removed by the electrodes 4a, 4b, introduced to a superconducting energy storage unit 5 and sequentially stored.