Energy storage batteries buried underground

Deep underground energy storage is the use of deep underground spaces for large-scale energy storage, which is an important way to provide a stable supply of clean energy, enable a strategic petroleum reserve, and promote the peak shaving of natural gas.

Batteries can take that excess electricity and store it until such time as it can be put to work. But there are other ways of storing electricity that rely on potential energy. An example of potential energy is a freight train parked at the top of a mountain.

More storage also means more backup power for ever-hotter heat waves, when whole regions flick on their AC units. Companies are figuring out how to store energy underground, too. A company called Hydrostor, based in Toronto, Canada, uses excess renewable energy on the grid to pump compressed air into subterranean caverns filled with water.

Unlike battery energy storage, the energy storage medium of UGES is sand, which means the self-discharge rate of the system is zero, enabling ultra-long energy storage times. Furthermore, the use of sand as storage media alleviates any risk for contaminating underground water resources as opposed to an underground pumped hydro storage alternative.

This paper clarifies the framework of underground energy storage systems, including underground gas storage (UGS), underground oil storage (UOS), underground thermal storage (UTS) and compressed air energy storage (CAES), and the global development of underground energy storage systems in porous media is systematically reviewed.

Based on the analysis of the background, types and status, and the study of the key theoretical and technical problems of deep underground energy storage in China, we make the following conclusions: (1) The use of deep underground spaces for energy storage is an important direction for future energy reserve maintenance.