To maximize the contribution of variable renewable energy sources, long duration storage is critical, since variable sources, notably wind and solar, often generate excess power at off-peak times. The successful Yingcheng compressed air energy storage project in China is presently the world’s largest, and the first of its kind to operate without the use of supplemental fuels. With a five-hour discharge at full capacity of 300 MW, the project is a breakthrough for long-duration storage technology at such scale.
