A pumped storage hydropower station in Mudanjiang, Heilongjiang province. (PHOTO: XINHUA)

By WANG Xiaoxia 

China has accelerated the development and utilization of renewable energy, however one problem that kept developers up at night was how to mitigate the influence of weather conditions on wind and photovoltaic power, and how that affected power supply to the grid.

To solve this problem, the simplest way is to store the electricity and then stably discharge it. The new power storage technologies and their application across China, are prime examples of innovation in action.

Innovative power storage tech

Recently, the first unit of a pumped storage hydropower station began operation in Qingyuan, northeast China's Liaoning province. The power station consists of two reservoirs at different elevations. When the power is abundant, the water in the lower reservoir is pumped to the higher one for storage. Acting like a giant battery, it can store hydroenergy and then release it to generate power during peak usage time. Its operation can realize the efficient conversion of energies and stabilize the power supply.  

The other five units of the power station are expected to go live by March 2025. Once completed, it will save 158,000 tons of standard coal and reduce carbon emissions by 375,000 tons per year, which will effectively improve the utilization of renewable energy such as nuclear power, wind power and photovoltaic power in Liaoning and even northeast China and eastern Mongolia.

In addition to conventional pumped storage, innovative methods continue to emerge, such as molten salt energy storage, photothermal energy storage, and electrochemical energy storage. All these are now applied in power bases across China. 

Take the molten salt energy storage as an example, which converts other energies into thermal energy and employs molten salts as a storage method to retain the thermal energy. Recently, the world's first electrically heated molten salt energy storage and steam injection test station was completed and put into operation in China’s Liaohe Oilfield. With a thermal storage capacity of 15 MW, it can produce 48,000 tons of clean steam annually, replacing 3.13 million cubic meters of natural gas and reducing carbon emissions by 6,768 tons.

Smart integration system

With the implementation of energy-storage related policies and plans, and the continuous progress of science and technology, more and more projects are being completed. 

Each power storage project is equivalent to a charging bank, meaning there are more and more "charging banks" of different capacity and different types, hanging on the grid. So, how can these "charging banks" be safely and efficiently coordinated to cooperate with the power grid? 

To solve this problem, "source-grid-load-storage" technology came into being, which coordinates power generation, grid connection, load and energy storage. This smart technology uses energy storage systems to integrate renewable energy into the grid, in order to achieve flexible storage and a supply of energy.

In Ulanqab, Inner Mongolia Autonomous Region, you can see the world’s largest "source-grid-load-storage" demonstration project. With investment and construction by the Three Gorges Group, seven new energy storage technologies are being tested here. The total installed capacity of demonstration project is 3.1 million kW, including 2.8 million kW of wind power, 300,000 kW of photovoltaics, and supporting energy storage facilities of 880,000 kW × 2 hours.

Currently, China has established a complete energy storage industry chain, including batteries, inverters, and energy storage systems. As of the end of September 2023, the total installed capacity of new energy storage projects in China had reached 21.23 million kW, ranking among the top in the world.