What is aquifer thermal energy storage (ATES)?
Aquifer thermal energy storage (ATES), in Dutch “warmte-koudeopslag” (WKO), is a form of ground source energy in which heat and cold are stored seasonally in water-bearing layers underground (aquifers). In winter the stored heat is used via a heat pump to heat the building; in summer the stored cold is used for cooling. The Netherlands is one of the countries where ATES is most widely used.
How does an open system work?
- At least two wells are drilled: a warm well and a cold well, both in the same water-bearing sand layer.
- Summer: cool groundwater from the cold well cools the building, and the warmed water is returned to the warm well.
- Winter: water from the warm well supplies heat via a heat pump, and the cooled water goes back to the cold well, ready for the next summer.
- The groundwater is circulated, not consumed.
Open and closed systems
- Open system (ATES): pumps groundwater. Mainly for larger buildings and district schemes.
- Closed system: a fluid circulates through vertical boreholes (ground heat exchangers) without abstracting groundwater. Common for individual homes with a ground source heat pump.
Points to watch
- Balance: over the years the ground should receive back roughly as much heat as cold, or a well becomes depleted. Summer cooling helps recharge the heat for winter.
- Permits: open systems abstract groundwater and usually require a permit from the water authority; closed boreholes may also need notification. Check local rules before starting.
- Ground conditions: a suitable aquifer is not present everywhere, and drilling may be restricted in groundwater protection zones.
- Emitters: works best with low-temperature heating such as underfloor or wall heating.
Related terms
- Ground source energy
- Aquifer
- Ground heat exchanger
- Underfloor heating
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