OVERFALL POWER GENERATION SYSTEM

PROBLEM TO BE SOLVED: To install a power generation system capable of supplying power by using water power and night power at the time of the peak of power consumption in a city area. SOLUTION: The overfall power generation system has an underground water storage tank 3 mounted to the underground section of a building constructed near a river 1 in a city and a waterway 4 flowing down water in the river 1 into the underground water storage tank 3. A generating set 5 conducting hydroelectric power generation is arranged into the waterway 4, and power is generated by flowing down water into the underground water storage tank 3 from the river 1. Water in the underground water storage tank 3 can be discharged into the river 1 by a lift pump using night power. Accordingly, power can be supplied by flowing down water from the river 1 to the underground water storage tank 3 at the time of the peak of power consumption. Water in the underground water storage tank 3 is pumped up by night power, and can be brought to the state, in which water can be used again. Warm heat and cold heat obtained from water in the underground water storage tank 3 are stored in a heat storage tank 6 mounted under the basement 2b of the building 2, and employed as a heat source for air conditioning.