Jinsha

History

In June 1959, an on-site survey was conducted at Qiaojia by a domestic expert group and a Czechoslovak expert group and, consequently, the future site for the Baihetan Power Station was selected. However, the breaking down of relations during the Sino-Soviet split in 1962, resulted in the survey team being withdrawn. The beginning of China's "Cultural Revolution" also saw the construction plans becoming shelved for many years.

Surveying of the dam site was restarted in 1992. In 2008, the original plan for the construction of Baihetan Hydropower Station, was formally started. In December 2008, the Baihetan site began construction. The dam was originally scheduled to be constructed between 2009 and 2018. The Jinsha River became officially closed in November 2014.

Power generation

The facility generates power by utilizing 16 turbines, each with a generating capacity of 1.0 GW, taking the generating capacity to 16,000 MW. In terms of generating capacity, it is the second largest hydroelectric power plant in the world, after the Three Gorges Dam. It is estimated to generate 62.44 terawatt-hours (TWh) annually and will save about 90 million tons of coal per year and consequently reduce annual carbon emissions by 248 million tonnes.

As of 2021, each of the 1,000 MW turbines are the biggest in the world. A turbine/generator assembly is 50 meters high and weighs 7,500 tons, and produces 24 kV.

The dam is supported by a substation in Butuo County which converts the 500 kV AC generated to 800 kV DC for long distance transmission.

Background

Preliminary construction (roads, bridges, tunnels) for the dam began in 2003 and work on main structures officially commenced on 26 December 2005. In November 2007, the Jinsha was successfully diverted around the construction site, allowing the dam to be built. Concrete pouring began in 2008. The reservoir was impounded in May 2013 and the first of 18×770 MW Francis turbine-generators was commissioned on 15 July 2013. The fourteenth generator was commissioned in April 2014. The eighteenth and final generator was commissioned on 30 June 2014.

Design

The Xiluodu is a 285.5 m (937 ft) tall and 700 m (2,300 ft) long double-curvature arch dam. It is the third tallest arch dam in the world and a key component of the Jinsha River Project. It withholds a reservoir of 12,670,000,000 cubic metres (10,270,000 acre⋅ft) of which 6,460,000,000 cubic metres (5,240,000 acre⋅ft) is considered active storage for power generation. The dam contains several spillways to include seven surface outlets, eight mid-level orifices and four spillway tunnels. All spillways afford a maximum discharge of 32,278 m3/s (1,139,900 cu ft/s). The dam's power station is split into two underground power stations, one located behind the right abutment, the second behind the left abutment.

Location

The Xiluodu Dam is located on the Jinsha (Upper Yangtze) River as it exits the mountainous region of the Hengduan Mountains and Yungui Plateau and enters the Sichuan Basin. This part of the Jinsha flows between the Daliang Mountains in Sichuan on the left (northwest) bank, and the Wulian Feng in Yunnan on the right (southeast) bank. The Jinsha falls to an elevation of 400 m (1,300 ft) above sea level here while mountains rise more than 2,000 m (6,600 ft) above the Jinsha on either side.

Design

The Guanyinyan Dam is a 159 m (522 ft) tall and 1,158 m (3,799 ft) long gravity dam. Of the dam's length, 838 m (2,749 ft) is roller-compacted concrete and 320 m (1,050 ft) is rock-fill embankment with this portion having a maximum height of 71 m (233 ft). The crest elevation of the dam will be 1,141 m (3,743 ft) above sea level and contain the power plant at the toe of its body. A spillway and two discharge openings are also included in the design.

Background

The dam section is a transverse valley with a water surface 60 to 150 m wide and low water level of 1048 m. The landforms on both banks are basically symmetrical. There is a measurement of about 50 m wide tableland and about 30 degrees above water surface in the left bank, and the slope in the right bank is about 27 degree and the slope above the elevation of 1500 m is about 48 degree. There is poor sand and soil materials and abundant limestone material satisfied with requirement of quality and reserves within 20 km in the dam area, which is qualified for setting up low dam according to existing geological data.

Environmental impact

This project marked the first time representatives from Chinese environmental groups were invited to participate in the environmental impact assessment for a major hydropower project in China, according to the First Financial Daily. Representatives of the Institute for Public & Environmental Affairs and the Green Earth Volunteers took part in the meeting to conduct technical evaluation on environmental impact assessment for the dam on the Jinsha River on December 29–30, 2008 in Beijing.