Combining climatic and geo-hydrological preconditions as a method to determine world potential for aquifer thermal energy storage.

A heat pump combined with Aquifer Thermal Energy Storage (ATES) is proven technology to economically and sustainably provide space heating and cooling. The two most important preconditions for the applicability of ATES are favorable climatic conditions and the availability of a suitable aquifer. This paper shows how these two preconditions can be combined to identify where in the world ATES potential is present, or will become present as a consequence of climate change. Countries and regions are identified where regulation and stimulation measures may increase application of ATES technologies and thus help reduce CO2-emissions. Two types of data determine ATES suitability, and their combination with a 3rd identifies potential hot-spots in the world: 1) geo-hydrological conditions, 2) current and projected climate classification and 3) urbanization. Our method combines the data into an ATES-suitability score as explained in this paper. On the one hand the results confirm the suitability for ATES where it is already applied and on the other they identify places where the technology is or will become suitable. About 15% of urban population lived in areas with high potential for ATES at the start of the 21st century, but this figure will decrease to about 5% during the 21st century as a consequence of expected climate change. Around 50% of urban population currently lives in areas of medium ATES suitability, a percentage that will remain constant. Demand for ATES is likely to exceed available subsurface space in a significant part of the urban areas.