The Jinping-II Dam (), also known as the Jinping-II Hydropower Station, is a

gravity dam A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by using only the weight of the material and its resistance against the foundation to oppose the horizontal pressure of water pushing against it ...

on the Jinping Bend of the

Yalong River The Yalong River ( zh, 雅砻江, p ''Yǎlóngjiāng'', w ''Ya-lung Chiang'', IPA ), or Nyag Chu (Tibetan: , z ''Nyag Qu''), is a major tributary river of the Yangtze River in Southwest China. With a length of , the Y ...

(Yalong Jiang) in

Sichuan Sichuan (; zh, c=, labels=no, ; zh, p=Sìchuān; alternatively romanized as Szechuan or Szechwan; formerly also referred to as "West China" or "Western China" by Protestant missions) is a province in Southwest China occupying most of t ...

, China. Construction on the project began in 2007 and it was complete in 2014. Its

hydroelectric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined an ...

power station has a 4,800 MW installed capacity. While Jinping-I relies on a conventional tall dam and large reservoir to supply water, Jinping-II uses a much smaller dam, located 7.5 km downstream of Jinping-I, to divert water into four 16.6 km long headrace tunnels. These tunnels connect to a downstream point on the same river at a much lower elevation, providing a head of water without flooding a large area of land.

History

Harnessing hydropower on the Jinping Bend of the Yalong River has been in planning for decades. The river makes a

hairpin bend A hairpin turn (also hairpin bend or hairpin corner) is a bend in a road with a very acute inner angle, making it necessary for an oncoming vehicle to turn about 180° to continue on the road. It is named for its resemblance to a bent metal ha ...

150 km long around the

Jinping Mountains The Jinping Mountains or Jinping Shan () are a short north-south mountain range in southwestern Sichuan Province, China. The Jinping are located within Yanyuan and Mianning Counties, both in Liangshan Prefecture. This mountain range is notable ...

, but the downstream part of the river on the opposite side of the mountain is separated by only 16 km. In that distance, there is an elevation drop of 310 m, creating an excellent situation for

hydroelectricity Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined an ...

production. Two projects were planned for the bend, the Jinping I and Jinping II with a combined capacity of 8,400 MW. Planning for the projects began in the 1960s under the former Sichuan and Shanghai design institutes along with the Ministry of Water Resources and Electric Power. They produced the "Reinvestigation Report on The Yalong River bend (Jinping)". In July 1965, the Jinping Hydropower Engineering Headquarters was set up and designs for the Jinping 1 and Jinping 2 would progress with the East China Investigation and Design Institute . Construction on the Jinping-II started on January 30, 2007. The dam's first generator was commissioned in December 2012, the second in January 2013. The fifth generator went online in May 2014 and the seventh in October 2014. Jinping-I was fully commissioned by July 2014 and the eighth and final generator for Jinping-II was commissioned on 26 November 2014.

Characteristics

A 37 m tall, 162 m long

sluice Sluice ( ) is a word for a channel controlled at its head by a movable gate which is called a sluice gate. A sluice gate is traditionally a wood or metal barrier sliding in grooves that are set in the sides of the waterway and can be considered ...

dam on the west-side of the Jinping bend diverts water into four 16.6 km long headrace tunnels towards the power station. At the power station, the water turns eight 600 MW

Francis turbine The Francis turbine is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency. The proc ...

s with a total capacity of 4400 MW before being discharged back into the river. About 30% of the power from the Jinping dams is used locally, and 70% will be sent to eastern China via ±800 kV bipolar

HVDC A high-voltage direct current (HVDC) electric power transmission system (also called a power superhighway or an electrical superhighway) uses direct current (DC) for electric power transmission, in contrast with the more common alternating curre ...

transmission lines. In addition to the four headrace tunnels, two roadway tunnels (A and B) were constructed with a diameter of , and a drainage tunnel in diameter. These were all constructed by

drilling and blasting Drilling and blasting is the controlled use of explosives and other methods, such as gas pressure blasting pyrotechnics, to break rock for excavation. It is practiced most often in mining, quarrying and civil engineering such as dam, tunnel ...

, as were headrace tunnels #2 and #4, with a diameter of . Headrace tunnels #1 and #3, with a diameter of , were excavated by

tunnel boring machine A tunnel boring machine (TBM), also known as a "mole", is a machine used to excavate tunnels with a circular cross section through a variety of soil and rock strata. They may also be used for microtunneling. They can be designed to bore thro ...

References

{{Yalong River dams Hydroelectric power stations in Sichuan Dams completed in 2012 Dams on the Yalong River Dams in China Gravity dams Buildings and structures in Sichuan 2014 establishments in China Energy infrastructure completed in 2014

History

Characteristics

See also

References