Heat-Cold storage (ATES) is a low-threshold and widely used method of seasonally storing thermal energy from the soil and groundwater. With this stored energy it is possible to heat and cool buildings. Geothermal energy can be used by applying two different systems: open or closed loop geothermal energy systems.
Open loop geothermal energy systems
In open geothermal energy systems, groundwater is pumped up from aquifers. The maximum depth of the pumped water is around 150 metres, with a maximum of 500 metres. Groundwater heated in the summer is pumped up for heating in the winter. Groundwater cooled down in the winter is pumped up in the summer to provide cooling. The exchange of this thermal energy for cooling or heating is done through a heat exchanger.
Closed loop geothermal energy systems
A closed geothermal energy system makes use of the heat-conducting properties of soil material. Thermal energy is exchanged between the liquid circulating in the tube and the soil by means of a long vertical up and down pipe (the vertical soil heat exchanger). In the winter, heat is extracted from the soil and in the summer, heat is returned.