The need for long-duration energy storage, which helps to fill the longest gaps when wind and solar are not producing enough electricity to meet demand, is as clear as ever. Several technologies could help to meet this need. But which approaches could be viable on a commercial scale? Toronto-based Hydrostor is one of the businesses developing long-duration energy storage that has moved beyond lab scale and is now focusing on building big things.
When it’s time to discharge energy, the system releases water into the cavern, forcing the air to the surface. The air then mixes with heat that the plant stored when the air was compressing, and this hot, dense air passes through a turbine to make electricity. The long-term viability of the technology will be closely tied to how its cost compares to other types of long-duration storage. The California plant has a projected cost of about $1.