Solar underground thermal storage design

What is underground thermal energy storage?

Rajandrea Sethi, in Encyclopedia of Energy Storage, 2022 The expression Underground Thermal Energy Storage (UTES) identifies shallow geothermal systems where heat from external sources (solar thermal collectors, industrial processes, combined heat and power systems) is stored seasonally into the ground to be used during periods of higher demand.

Are solar energy storage systems underground?

The experience of USTES applications worldwide in recent years shows that most of the solar energy seasonal storage projects have significant economic, social and environmental benefits. However, the key part of solar energy storage system is underground.

What are the different technologies for underground thermal energy storage (Utes)?

Different technologies for underground thermal energy storage (UTES) exist. ATES (Aquifer Thermal Energy Storage), BTES (Borehole Thermal Energy Storage), PTES (Pit thermal Energy Storage), TTES (Tank Thermal Energy Storage) and MTES (Mine Thermal Energy Storage).

What is a thermal energy storage unit?

During the daytime, a part of the thermal energy collected in the solar field is supplied to the thermal energy storage unit. The red color line indicates the storage of thermal energy. During the endothermic reaction, metal hydride stores thermal energy equivalent to reaction enthalpy.

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 ].

How does thermal energy storage work?

In a sensible thermal energy storage system, the heat is stored/released by increasing/decreasing the temperature of the storage medium, while LTES stores/releases energy by undergoing the phase change process. The TCES stores/releases energy in the form of the enthalpy of the corresponding chemical reaction.