China builds world's largest clean energy corridor

Photo shows the Three Gorges Dam in Yichang, central China's Hubei province. (People's Daily Online/Wang Geng)

As the longest river in China, the Yangtze River amasses a number of tributaries and winds through many deep gorges, offering rich hydropower resources, abundant shipping routes and huge freshwater reserves.

Six mega hydropower stations along the mainstem of the Yangtze River -- Wudongde, Baihetan, Xiluodu, Xiangjiaba, Three Gorges Dam, and Gezhouba Dam -- form the world's largest clean energy corridor, which spans over 1, 800 kilometers with a water level drop exceeding 900 meters. A total of 110 hydroelectric generators operate in tandem along the corridor, consistently generating green electricity.

Recently, all the six cascade hydropower stations have been connected to an industrial internet platform, which marked the completion of an "industrial brain" of the world's largest clean energy corridor. This is expected to significantly boost the corridor's operational efficiency and reliability.

It is reported that these six cascade hydropower stations have generated over 3.5 trillion kilowatt-hours of electricity, equivalent to saving over 1 billion tons of standard coal and reducing carbon dioxide emissions by more than 2.8 billion tons. Besides, the coordination among these cascade reservoirs has also ensured unimpeded shipping, sufficient water supply, and ecological conservation.

The Baihetan hydropower station has 16 hydro-generating units with a total installed capacity of 16 million kilowatts. These units are powered by water plunging over 200 meters from above, with each rotation producing around 150 kilowatt-hours of electricity.

"Our staff work round the clock. With the installation of sensors to collect data in real time, any abnormalities will trigger automatic alerts within the system, " said Wang Bin, deputy director of the operations department of the Baihetan hydropower station run by China Yangtze Power Co., Ltd. (CYPC).

Photo shows the Baihetan hydropower station. (People's Daily Online/Yan Keren)

In December 2022, all units of the Baihetan hydropower station went fully operational, which marked the completion of the world's largest clean energy corridor, a witness to the breakthroughs made by China in hydropower engineering.

For instance, the Gezhouba Dam, completed in the 1980s, has a single-unit capacity of 170 megawatts. Besides, the Three Gorges Dam, the world's largest hydropower project, is equipped with power-generating units each with a capacity of 700 megawatts.

China's capability to produce million-kilowatt power-generating units couldn't have been obtained without new techniques, materials, and industrial upgrades.

Li Haijun, deputy director of the electromechanical technology center of China Three Gorges Corporation (CTG), said that million-kilowatt units undergo significantly higher water pressure impact, rotational speeds and stresses compared to smaller units.

In response to this challenge, CTG has taken the lead in collaborating with major steelmakers to develop 800 MPa high-strength steel plates specifically designed for spiral casings. Such breakthrough has effectively put an end to the long-term reliance on imported steel plates, Li explained.

Scheduling these giant hydropower stations involves multiple aspects across vast spatiotemporal scales, regions, and grids. To handle peak and base loads, higher safety and stability standards are demanded, " explained Tang Zhengyang, deputy director of CYPC's Water Resources Research Center.

Yangtze finless porpoises swim downstream the Gezhouba Dam in Yichang, central China's Hubei province. (People's Daily Online/Wang Gang)

The industrial internet platform enables the hydropower stations to cope with all-business scenarios, including intelligent operations, maintenance, repairs, dispatching, and decision-making, which comprehensively strengthens smart operations and propels digitalization.

Apart from supplying electricity, the clean energy corridor has also formed a 768-kilometer deep waterway that steadily improves the navigation conditions of the Yangtze River. Previously unnavigable sections have been turned into wide passages, and small ports along the corridor have grown stronger and bigger. For example, along the section in southwest China's Chongqing municipality, multiple 5,000-ton deep water berths have emerged, which amplify the advantages of water transportation along the Yangtze River, known for its low energy consumption, high capacity and cost-effectiveness.

As a strategic freshwater source of China, the Yangtze River basin commands 995.9 billion cubic meters of water resources annually, accounting for about 36 percent of China's total. The clean energy corridor alone forms a cascade reservoir cluster with 91.9 billion cubic meters of storage, which serves as a vital strategic freshwater reserve.

Fish populations serve as a crucial indicator of a river's ecological health. Systematically increasing water discharges from the reservoirs to gradually raise river levels can help create favorable conditions for natural fish spawning and reproduction. Relevant authorities have conducted multiple ecological scheduling experiments with an increasi ngly broad scope.

According to an official with the Changjiang Water Resources Commission of the Ministry of Water Resources, current scheduling objectives have expanded beyond facilitating fish propagation. They now encompass layered water withdrawal for temperature regulation, prevention and control of algal blooms, sediment sluicing and silt reduction in reservoirs, and curbing excessive growth of submerged aquatic vegetation.

These efforts are contributing to the conservation and restoration of the aquatic ecosystem across the Yangtze River basin. As a result, the world's largest clean energy corridor has evolved into a corridor of ecological conservation.