World's largest pumped storage power plant in full operation in China

The world's largest pumped storage power plant, Fengning Pumped Storage Power Station, began full operation on December 31 with the commissioning of the last variable speed unit. Located in Fengning County, Hebei Province, near Beijing and Tianjin, the plant is an important part of China's renewable energy infrastructure, supporting a 10 GW wind and solar site near Zhangjiakou.

Source From: Hydropower

The project is being developed by State Grid Xinyuan Group Co Ltd, a subsidiary of China's State Grid Corporation, with a total investment of 19.24 billion yuan (US$2.6 billion). Construction of the project began in May 2013 and took more than 11 years to complete. The plant has 12 reversible pump turbine units with a capacity of 300 megawatts (MW) each, including two variable speed units, for a total installed capacity of 3.6 gigawatts (GW). It is designed to generate 6.61 TWh of electricity per year, with a pumping consumption of 8.71 TWh, and is connected to the North China power grid via four 500 kV transmission lines.

Fengning Reservoir is advanced in design, with an upper reservoir capacity of 45.04 million cubic meters and a lower reservoir capacity of 71.56 million cubic meters. At full power, the upper reservoir can store enough energy to run the supply station at full capacity for 10.8 hours, which is equivalent to nearly 40 gwh. This makes Fengning the most important pumped storage facility in North China in terms of balancing renewable energy output.

One of the plant's most striking features is its underground power plant, which is the largest underground power plant in the world. The facility is 414 meters long, 54.5 meters high and 25 meters wide. In addition, the supporting infrastructure includes 190 underground tunnels that are more than 50 kilometers long.

The plant utilizes state-of-the-art variable-speed pump-turbine technology, which allows for flexible load adjustment and faster frequency response during pumping operations. These advances enhance the plant's ability to manage the intermittency of renewable energy sources such as wind and solar. According to the developer, the station combines its output with a flexible direct current (DC) grid and supports multiple energy sources to complement each other, reducing the impact of fluctuating renewable energy supplies on the wider grid.

China has become a global leader in pumped storage technology, which is the most proven solution for large-scale, long-term energy storage. By the end of 2024, China's State Grid Corporation had 40.56 gigawatts (GW) of operational pumped storage capacity and 53.48 GW of pumped storage capacity under construction. As China continues to expand its renewable energy capacity, pumped storage projects like Fengning are expected to play a key role in stabilizing the grid and maximizing the use of clean energy.