China crisis: Fear of the May earthquake has reduced production at the world’s No. 2 and No. 3 hydroelectric plants by 30%

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Production figures published without explanation this week by China’s state-owned, citing London, operator of the Three Gorges Dam – at 22.6 gigawatts, the world’s largest power plant – renewed fears that earthquakes would continue to cripple power at one of the world’s most powerful power plants tremor-prone areas.

Current speculation about one or more earthquakes along the centers of China’s longest rivers is not on the Three Gorges Dam, but instead on two sister stations upstream operated by the same owner, the China Yangtze Power Company (CYPC).

Electricity production during the second quarter of 2021 fell by 31.8% and 27.3%, respectively, at the Xiluodu and Xiangjiaba mega plants, the operator told investors in London this week, without explanation.

CYPC operators blamed the collapse of the water flows, but did not offer any other explanation. CYPC reported that flows through the Xiluodu Reservoir decreased by 44.68% to 13.061 billion cubic metres. The reservoir is the source of all afflicted plants.

Both dams are located about 50 miles upstream of the Yangtze River, in Yunnan Province in southwest China.

The pairs are respectively rated at 13.86 GW and 6.45 GW, and represent half and a quarter of the Three Gorges complex’s capacity. Giving context, the world’s most powerful nuclear plant, Japan’s Kashiwazaki-Kariwa, is rated at 8.2 gigawatts.

The longest river in Asia at 3,915 miles or 6,300 kilometers, the Yangtze River originates in Yunnan Province in the far southwest of China, near Tibet. Its upper regions are known as Jinsha, whose basin, the meeting point of the Eurasian and Indian tectonic plates, is said to be the most geologically unstable region of China, and among the most dangerous in the world.

On May 25 this year, the city of Dali near Tibet suffered a 6.1-magnitude earthquake, 270 miles upstream and southwest of the two stricken hydrological stations. Geologists have placed the epicenter at a depth of up to 10 kilometers below the surface. And the Chinese authorities officially recorded three deaths from the earthquake, but 12,882 properties were damaged.

Seismologists and ecologists have long argued that the uniquely unstable geology of the upper Yangtze River has been weakened by dam construction. An August 2014 interview with an independent geologist from the Hengduan Mountain Research Institute claimed that the 6.5-magnitude earthquake earlier that year was related to the filling of the reservoir. The earthquake reportedly killed 600 people and displaced 300,000 others.

At least three earthquakes in the region over the past 18 months included one in April 2014 in Yongshan, just seven kilometers from the Xiluodu Reservoir. The expert said that all the earthquakes coincided with the filling of the reservoir.

A research paper published in Nature in September 2014 revealed the Xiluodu Reservoir straddling an important tectonic fault in the Jinsha Basin. “There are serious concerns of deadly earthquakes in the future,” Hu Xianming, a geophysicist with the Sichuan Earthquake Administration, was quoted as saying on a third-party website.

CYPC operates four giant dams on the Yangtze River. Five hundred miles from the Xiluodu Reservoir, the Three Gorges Hydro Station, the world’s largest, has experienced a water flow drop of just 6.67% in the past quarter. Its generation output was virtually unchanged, totaling 22,291 GWh, and Gezhouba, CYPC’s fourth hydraulic project, saw production rise 6.9% to 5,074 GWh.

It took ten years to build the Xiluodu Dam, which is surrounded by 2,000-meter mountains. Its height is 285 meters, its reservoir capacity is 12.7 billion meters, a little more than half of it is considered active energy storage. All eighteen of the plant’s turbines were commissioned within twelve months after December 2013.

The construction of the Xiangjiaba hydro dam began in 2006. Its first turbine was installed after six years, and the last turbine of eight was commissioned in July 2014.

Adding to the water problems in the Yangtze, shrinking meltwater flowing from the Himalayas, known to climatologists as the “third pole of the world.” Up to 16% of the Himalayan’s meltwater has been lost since the 1980s, according to a paper published in Nature Climate Change last month.

Energyst asked China Yangtze Power Company why the flows at the two dams were down 44% and the resulting 30% drop in generation. We also sought to find out what steps you could take in relation to earthquakes. At the time of publication the company did not respond.

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