How do underground thermal energy storage systems work?

Underground thermal energy storage (UTES) systems store energy by pumping heat into an underground space. There are three typical underground locations in which thermal energy is stored: boreholes, aquifers, and caverns or pits. The storage medium typically used for this method of thermal energy storage is water.

Why is the underground a good place to store thermal energy?

The underground is suitable for thermal energy storage because it has high thermal inertia, i.e. if undisturbed below 10-15 m depth, the ground temperature is weakly affected by local above ground climate variations and maintains a stable temperature [76, 77, 78].

What is underground gravity energy storage (Uges)?

The proposed technology, called Underground Gravity Energy Storage (UGES), can discharge electricity by lowering large volumes of sand into an underground mine through the mine shaft.

How can electricity be stored?

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. If there are generators connected to its wheels, they can create electricity as the train rolls downhill.

What are the limitations of underground thermal energy storage systems?

However, as reported by Lanahan and Tabares-Velasco (2017), limitations of underground thermal energy storage systems applied with elements such as energy piles include the comparatively large amount of heat loss compared to insulated water tank or gravel tank systems (Schmidt and Mangold, 2006; Rad and Fung, 2016).

What is underground thermal energy storage (SHS)?

SHS can be developed at a small-scale (<10 MW) above surface technology or at a large-scale system in the subsurface. Underground Thermal Energy Storage (UTES) is a form of energy storage that provides large-scale seasonal storage of cold and heat in underground reservoirs [74, 75, 76, 77].