A concept map of the Wudongde project, located on the upper reaches of the Yangtze River. [Photo: Xinhua]

KUNMING, Dec. 24 -- China on Thursday started construction of its third largest hydropower station on the upper reaches of the Yangtze River.

The Wudongde project, located upstream from two other hydropower stations on the Jinsha River, the upper section of the Yangtze, is the world's 7th largest in operation or under construction, said Lu Chun, chairman of the China Three Gorges Corporation.

The project has a designed capacity of 10.2 gigawatts and will be able to generate 38.9 billion kwh of electricity per year after its 12 generating units start operation, Lu said.

The first unit is expected to start operating in August 2020 and all are expected to be operational by the end of 2021, he said.

The project, which was approved by the State Council on Dec. 16, is estimated to cost more than 100 billion yuan (15.4 billion U.S. dollars), Lu said.

A 270-meter-high dam will be built to block the river to form a reservoir that can store about 7.4 billion cubic meters of water.

The project's construction will require more than 16,000 workers in the next few years.

Meanwhile, about 31,000 residents in 10 counties and districts in the southwestern provinces of Yunnan and Sichuan will be relocated to make room for the project.

Lu said that, as a major project that transfers power from the resource-rich west to the industrial east, it will also help adjust the country's energy mix and reduce pollutant emissions.

China still relies heavily on coal to power its economy and is seeking to increase the clean energy share as it is faced with worsening air pollution.

The project can help reduce coal consumption by 12.2 million tonnes and cut carbon dioxide emissions by 30.5 million tonnes and sulfur dioxide emissions by 104,000 tonnes per year, he said.

Situated between Luquan County in Yunnan and Huidong County in Sichuan, it can help create about 70,000 jobs for locals per year during construction. After it starts operating, it can bring 1.35 billion yuan in revenues for local governments annually.

Authorities have invested more than 900 million yuan in environmental protection in the area, and many precious species of trees have been transplanted, he said.

The other two hydropower stations on Jinsha River are Xiluodu and Xiangjiaba. Both started operating in July 2014.

Xiluodu is the country's second largest, with power-generating capacity of 12.6 gigawatts. It had generated more than 100 billion kwh of electricity as of November.

The Three Gorges hydropower project is the country's largest, with a generating capacity of 22.4 gigawatts in the middle reaches of the Yangtze River.

Baihetan, a fourth hydropower project planned on the Jinsha River, has yet to receive the final government go-ahead.