Capital costs of aquifer thermal energy storage (ATES): a review

For a successful global energy transition, more seasonal thermal energy storage (STES) and district heating and cooling systems are needed. Hence, the economic aspects of STES are essential during the decision-making phase of planning a district heating and cooling system. Until now, only a few studies exist on the capital costs of STES and particular aquifer thermal energy storage systems (ATES). Hence, this study aims to identify and analyse the capital costs of 133 existing ATES systems from the Netherlands, Belgium, Denmark and other countries. Our results show a decrease in capital costs per installed heating and cooling capacity with increasing capacity. Capital costs per installed capacity converge to 300 €/kW after 2 MW of installed heating and cooling capacity. Hence, larger ATES systems should be favoured. Compared with other seasonal thermal energy storage (STES) systems, ATES systems have the lowest capital costs per storage volume (<10 €/m3) and the lowest per stored energy (130–1,630 €/MWh). Hence, if the hydrogeological conditions at a site are favourable for ATES systems, they should be carefully considered for STES, in particular, if cooling and heating are required in equal proportions.