Aquifer thermal energy storage (ATES) is a sustainable method used to store energy in the soil, in the form of heat or cold. The system uses the excess heat generated in the summer to warm building during winter. The excess cold stored over the winter is used to cool buildings during the summer.

Storage and recovery of thermal energy is achieved by extraction and injection of groundwater from aquifers using groundwater wells.The groundwater that is extracted in summer, is used for cooling by transferring heat from the building to the groundwater by a means of a heta exchanger. Subsequently, the heated groundwater is injected back into the aquifer, which creates a storage of heated groundwater. In winter, the flow direction is reversed such that the heated groundwater is extracted and can be used for heating.