The Chinese authorities have turned on two of the world’s first one-gigawatt turbines at the country’s new mega dam.

The Baihetan Dam is still under construction on the Jinsha River on the border of Sichuan and Yunnan provinces in south-western China.

It will be the world’s fourth-largest dam by volume and it marks the end of an era for mega-dam building in the country.

It is the last large hydropower project in China to be completed and will be the second-largest hydroelectric power plant in the world, in terms of generating capacity, after the Three Gorges Dam, also in China.

Upon completion, it will be the third-largest dam in China and the fourth in the world, in terms of dam volume.

After an eight-year delay, construction started in 2017, and the reservoir started filling in April this year.

The engineers working on the project hope the dam will be fully operational in July next year, meaning the construction period will have lasted a mere four years in contrast to the originally envisaged nine-year construction period.

The dam is a double-curvature arch dam measuring 277 metres (909 feet) in height, 13 metres (43 feet) in crest width (crest) and 72 metres (236 feet) in base width.

The cost of the project has been calculated at USD 6.3 billion (GBP 4.5 billion).

The 16 turbines at the dam will generate a total of 16,000 megawatts, with an annual generation of 60.24 terawatt-hours.

This is around 16 times the energy of the Hoover Dam on the border between the US states of Nevada and Arizona.

The Baihetan Dam marks the end of mega-dam building in China, as the use of solar, wind and coal-fire rises due to falling costs.

After a three-day trial, two of the huge Baihetan station’s 16 one-gigawatt generators started full operation on Monday.

President Xi Jinping called the achievement a breakthrough for the country’s high-end manufacturing output.