On December 31, 2024, the last of 12 power units of the Fengning pumped storage power plant, located in the county of the same name in China, came into operation. This is the largest facility of its kind in the world, accumulating excess renewable energy by pumping water into an artificial reservoir located on a hill. The total capacity of the power plant is 3.6 GW, and the stored water is enough to operate for 10.8 hours.
Image source: State Grid Corporation of China
The Fengning pumped storage power plant took 11 years to build, and its implementation cost $2.6 billion (19.24 billion yuan). The volume of the upper reservoir, which serves as a battery, reaches 45.04 million m³, and the lower one – 71.56 million m³. At full power, the power plant can operate for 10.8 hours, accumulating almost 40 GWh of electricity. Excess energy for raising water to a height comes from wind and solar power plants in the neighboring county. The pumped storage power plant’s power grid is connected to the same segment and smooths out generation peaks by supplying energy at night and during periods of calm.
The power plant’s equipment room is also amazing, especially considering that it is completely hidden underground. Its length is 414 m, height – 54.5 m, width – 25 m. Supporting infrastructure includes 190 tunnels with a total length of 50 km.
Water pumping and energy generation are provided by 12 reversible turbines, each with a capacity of 300 MW. Two of them are distinguished by variable rotation speed, which is necessary for more flexible generation and frequency stabilization. To pump the full volume of water into the upper reservoir, 8.71 TWh of electricity per year is required. The net output from water release is 6.61 TWh per year, which means a loss of about 2 TWh. These losses are a payment for the use of renewable resources.
The pumped storage power plant project was developed by State Grid Xinyuan Group, a subsidiary of the State Grid Corporation of China. This is far from the only pumped storage power plant in the country. By the end of 2024, the State Grid Corporation of China operated a total of 40.56 GW of pumped storage capacity, with a further 53.48 GW under construction. Taking into account the active creation of power plants using renewable energy sources, China needs storage and pumped storage capacity to form a sustainable energy system.