Imaichi Pumped Storage Power Station
The Imaichi Pumped Storage Power Station is a large pumped-storage hydroelectric power station in Tochigi Prefecture, Japan.
With a total installed capacity of, it is one of the largest pumped-storage power stations in Japan.
The facility is run by the Tokyo Electric Power Company.
The power plant started operation in July 1988 with a capacity of 350 MW.
The other two units entered operation in December 1991.
The plant is one of the many large scale pure pumped-storage plants built in Japan since the 1970s to compensate for the increased penetration of base-load nuclear power and peak load from cooling and air-conditioning.
Like most pumped-storage facilities, the power station uses two reservoirs, releasing and pumping as the demand rises and falls.
The upper reservoir is contained by the Imaichi Dam, a concrete gravity dam, at an altitude of 512 m. The reservoir is fed by the Togawa river.
The lower reservoir is contained by the Kuriyama Dam, a rock-fill embankment dam at an altitude of 1054 m.
The reservoirs can store of water.
Of that storage volume, can be used for power generation.
This is enough for about 7 hours of operation at full generation capacity, giving a total energy storage capacity of about 7.35 GWh.
The power plant is housed in a large cavern 400 m underground and includes three 350 MW Francis reversible pump-turbines.
The cavern dimensions are 33.5 m width, 51 m height, and 160 m length.
The power station work on a daily or weekly storage cycle.
The plant is connected to the high voltage transmission system with a 500 kV power line.
These power lines constituted the world's first practical applications of 500 kV XLPE cables, together with the power connection at the Shimogo Pumped Storage Power Station.