Yamdrok Hydropower Station

Yamdrok Hydropower Station
Location of Yamdrok Hydropower Station in Tibet
Official name	Chinese: 羊卓雍湖抽水蓄能电厂: Yangzhuoyong Lake Pumped Storage Power Plant
Country	China
Location	Lhoka Prefecture, Tibet Autonomous Region
Coordinates	29°15′51″N 90°36′23″E / 29.2641°N 90.6064°E / 29.2641; 90.6064Coordinates: 29°15′51″N 90°36′23″E / 29.2641°N 90.6064°E / 29.2641; 90.6064
Commission date	1997–98
Pumped-storage power station
Upper reservoir	Yamdrok Lake
Hydraulic head	840 m (2,760 ft)
Generating units	1 x 22.5 MW Francis-type
Pump-generators	4 x 22.5 MW reversible Francis-type
Power generation
Nameplate capacity	112.5 MW

The Yamdrok Hydropower Station (Chinese: 羊卓雍湖抽水蓄能电厂), also known as the Yamdrok Yumtso or Yamzhog Yumcog hydropower station, is a hydroelectric power station just north of Yamdrok Lake, about 16 km (9.9 mi) southwest of Qüxü. The power station is in the Lhoka (Shannan) Prefecture of the Tibet Autonomous Region, China. Opposition to using the lake, considered holy, delayed construction at first. The project ran into difficulties and was two years late, completed in 1998.

Water is taken from the natural lake through long tunnels, without the need for a dam, and the power station discharges it into the Yarlung Tsangpo River. The design is a pumped-storage system, where off-peak power from other generators on the grid is used to pump water back into the lake when power is not needed. However, the river water has high levels of sediment and nitrates compared to the lake, and lower levels of minerals. Pumping may upset the lake's ecosystem, while not pumping may drain it.

Yamdrok Tso is the largest freshwater lake in southern Tibet, with a surface area of 638 square kilometres (246 sq mi) at an elevation of 4,441 metres (14,570 ft). It drains an area of 6,100 square kilometres (2,400 sq mi). Some Tibetans consider that the Yamdrok Yumtso or Scorpion Lake, is holy and contains the spirit of Tibet. The Panchen Lama criticized the project. It was started in 1985, but due to vocal opposition from Tibetans and the intervention of the Panchen Lama the project was halted in 1986.

The project was relaunched after the Panchen Lama died in 1989. In response to the Panchen Lama's concern about the environmental impact of draining the lake, the power station was planned as a pumped storage power station. It would discharge water into the river at peak hours, and pump water from the river up to the lake in off-peak hours, so there would be no overall loss of water volume in the lake. Rather than build a dam, four 6 kilometres (3.7 mi) tunnels were bored through the sides of the lake to carry water down to the power station. Four turbines were supplied by J.M. Voith AG of Germany, as well as pumps and steering systems. An Austrian company provided on-site engineers.