Tongbai Pumped Storage Power Station

The Tongbai Pumped Storage Power Station is a pumped-storage hydroelectric power station located 6 km north of Tiantai city in Tiantai County of Zhejiang Province, China. Construction on the power station began in May 2000 and the first unit was commissioned in December 2005. The remaining three were operational by December 2006. The entire project cost US$904.10 million, of which US$320 million was provided by the World Bank. The power station operates by shifting water between an upper and lower reservoir to generate electricity. The lower reservoir was formed with the creation of the Tongbai Lower Dam on the Baizhang River. The Tongbai Upper Reservoir, which already existed before construction began, is in an adjacent valley above the east side of the lower reservoir on Tongbai Creek. During periods of low energy demand, such as at night, water is pumped from Tongbai Lower Reservoir up to the upper reservoir. When energy demand is high, the water is released back down to the lower reservoir but the pump turbines that pumped the water up now reverse mode and serve as generators to produce electricity. The process is repeated as necessary and the plant serves as a peaking power plant. The power station is operated by Shenergy Company.

The lower reservoir is created by a 68 m tall and 420 m long concrete-face rock-fill dam on the Baizhang River. It can hold up to 12897000 m3 of water of which 967860 m3 can be used for power generation. The upper reservoir is created by a 37 m tall and 456 m long rock-fill dam on Tonbai Creek. It can hold up to 12316000 m3 of water of which 10627000 m3 can be used for power generation. Water from the upper reservoir is sent to the 1,200 MW underground power station near the lower reservoir through headrace/penstock pipes. The drop in elevation between the upper and lower reservoir affords a hydraulic head (water drop) of 239 m.