Thermal energy storage (TES) underground

Scheme of how energy is stored in the ground and can be transported from and to the nearby buildings © Aardwarmte Den Haag

Thermal Energy Storage (TES) is a method to store energy in the form of heat or cold in the soil at a depth of 20 to 120 meters. In the summer, buildings are cooled by extracting coolness from the groundwater via a heat exchanger and a heat pump; the groundwater gets warmer. In the winter the heat is extracted from the groundwater to heat the buildings. The groundwater then becomes cooler again