After the boom: Evaluation of Dutch ates-systems for energy efficiency

Aquifer thermal energy storage (ATES) is a technology to sustainably provide space heating and cooling. Particularly in The Netherlands the number of ATES systems has grown rapidly in the past decade, often with the (re)development of urban areas. To meet objectives for greenhouse gas emission reduction the number of ATES systems is expected and required to further rise in future both in The Netherlands and elsewhere. To evaluate the lessons learned and the role of practical aspects in the Dutch development of ATES systems, in this study the geohydrological conditions and well characteristics for 331 (~15% of total) Dutch ATES systems are evaluated with respect to optimal well design for maximal thermal energy recovery. The study shows that well design of most (70%) ATES systems is suboptimal. The well design criteria that have been used thus far in practice, focus on allowing maximum flow/capacity, disregarding the effect of groundwater flow on efficiency and the effect of well design on subsurface space use. Instead, well design should be based on a more representative value for the storage volume that takes into account . Based on monitoring data and analysis of variations and uncertainties of the actual storage volume, a guideline is defined to reflect these in the storage volume used for design. Also a guideline for well design is introduced that accounts for both conduction and dispersion losses as well as advection losses in case of high ambient groundwater flow.