Aerial photo taken on Sept 10, 2021 shows the scenery of the Three Gorges Reservoir in Zigui cuunty of Yichang city, Central China's Hubei province. [Photo/Xinhua]

Total installed capacity of pumped-storage hydroelectricity in China increased 15.6 percent year-on-year to 36.39 million kilowatts by the end of 2021, ranking the top in the world, an industry report said on Friday.

An estimated installed capacity of 9 million kw will be put into operation this year, pushing total installed capacity to about 45 million kw by year end, the report said.

The report, named Development Report of Pumped Storage Industry 2021, was published by China Renewable Energy Engineering Institute on Friday.

Yi Yuechun, deputy director-general of the institute, said pumped storage hydropower can abate the fluctuating output of intermittent energy sources like solar and wind power as well as provide energy reservation, making it essential to new energy's development as China is transitioning to a greener economy.

"Unlike energy from conventional generation sources, energy from renewable sources, such as wind and solar, is uncontrollably variable and can not be stored on a large scale, which can be a problem especially when during peak demand, making pumped storage essential to new energy's development," Yi said.