China's highest hydropower plant with a planned total installed capacity of 3 million kilowatts went fully operational on Friday after the last 500,000-kilowatt power generation unit went online.

The annual power generation volume at the Lianghekou station, built at an average altitude of 3,000 meters in southwestern China, is expected to surpass 11 billion kilowatt-hours after it is fully completed by 2023, according to the Yalong River Hydropower Development Co., Ltd.

Construction of the project, with an approved investment of 66.5 billion yuan ($10.5 billion), started in October 2014.

The Lianghekou hydropower plant is located on the Yalong River in the Tibetan Autonomous Prefecture of Garze in Sichuan Province.

The Yalong River basin is one of China's clean energy bases. Officials say the operation of the plant will help ease unbalanced power generation in the province and promote high-quality development of the Yangtze Economic Belt and the Chengdu-Chongqing economic circle.

(With input from Xinhua)

(Video by CGTN's Zheng Songwu)