In China, the world’s largest compressed-air energy storage facility has begun operating. The two units have a combined capacity of 700 MW, comparable to a large power plant.
This is especially important for solar and wind energy: they depend on weather and time of day. The sun does not shine around the clock, and the wind can die down — so surplus electricity needs to be stored somewhere and returned to the grid when generation drops or demand rises.
The principle is almost fantastical: electricity is used to compress air to 130 atmospheres and inject it into salt caverns about a kilometer below ground. Later, the air drives turbines. The heat from compression is also stored. A well can pass up to 2.16 million cubic meters of air per hour — roughly 864 Olympic swimming pools.
