Staff members walk into a wind and solar energy storage and transmission power station of State Grid Corporation of China, in Zhangjiakou of Hebei province, China, in this March 18, 2016 file picture. REUTERS/Jason Lee/Files

BEIJING (Reuters) - China’s State Grid Corp [STGRD.UL] will invest 38.7 billion yuan ($5.66 billion) to build five pumped hydro storage plants across the country, in an effort to ease the stranded power system amid Beijing’s push to boost clean energy consumption.

Pumped hydro storage plants could be used as reservoirs when demand is low and as hydro power stations to generate electricity when consumption picks up.

The five plants, located in the provinces of Jilin, Hebei, Shandong and Zhejiang, and far west region of Xinjiang, will have a combined capacity of 6 gigawatts (GW) and are expected to be launched by 2026, the State Grid Corp said in a statement on Wednesday.

The state-backed company currently has 19.23 GW of pumped hydro storage capacity and 30.15 GW under construction.

The investment came as China has vowed to boost large-scale energy storage capacity over the next decade and launch at least 40 GW of pumped hydro storage plants by 2020.

Energy storage facilities, including pumped hydro storage plants, compressed air energy storage and bulk storage with batteries, could help prevent renewable power from being wasted when there is not enough transmission capacity to absorb the electricity.

Wind waste rates stood at 8.7 percent in China in the first half of 2018, while solar waste reached 3.6 percent, according to data from the National Energy Administration.

Regions in the western and northeastern part of China, including Xinjiang and Jilin, are identified with the highest rate of renewable energy wastage.

($1 = 6.8349 Chinese yuan)