Hohhot Pumped Storage Power Station

The Hohhot Pumped Storage Power Station, also known by Huhehaote, is located 20 km north of Hohhot in Inner Mongolia, China. It uses the pumped-storage hydroelectric method to generate electricity. The plant has an installed capacity of 1224 MW. Construction began in 2005 and the first generator was commissioned on 20 November 2014. The second generator was commissioned on 26 December 2014 and the final two were commissioned in June 2015.

Design and operation
When energy demand is high, water from the upper reservoir supplies the power station with four 306 MW reversible Francis pump turbine-generators to generate electricity. After the power is generated, the water is discharged into a lower reservoir in the valley. When energy demand is low and the upper reservoir needs to be replenished, the water can be pumped back up when the pump-generators reverse into pumps. The upper reservoir is situated at an elevation of 1940 m and was formed by the construction of a 62.5 m tall concrete-face rock-fill dam. It has a storage capacity of 6660000 m3, of which 6290000 m3 can be used for power generation. The lower reservoir is formed by two gravity dams constructed of roller-compacted concrete. The upstream dam at a height of 57 m and serves to trap sediment in the river which is the source of water for the power plant. The second gravity dam, located downstream, is 69 m tall and withholds the lower reservoir with a capacity of 7170000 m3 of which 6360000 m3 can be used for pumped-storage. The lower reservoir is located at an altitude of 1400 m. The difference in elevation between the two reservoirs affords a hydraulic head (drop in water) of 521 m. It is estimated that the plant will generate 2.007 billion kWh annually but consume 2.677 billion kWh pumping. Because pumping occurs during periods of low energy demand when there is a surplus and electricity is cheap, the plant is economical.