While the share of renewables in the power generation sector steadily increases, less attention is paid to the decarbonisation of the heating and cooling sector. Since most industrial nations are located within the moderate climate zone, the global heating and cooling supply is less a matter of energy shortage than a matter of seasonal storage. Aquifer Thermal Energy Storage (ATES) is considered to bridge this seasonal gap between times of highest energy demand and times of highest energy supply. With more than 2,800 ATES in operation, 90 % of all systems are operating in the Netherlands and Scandinavia. At the same time, more than 99 % of all ATES system are low temperature (LT) systems storing temperatures below 30 °C. In contrast, there are currently only two high temperature (HT) ATES (>50 °C) in operation worldwide. As early HT-ATES projects had to be abandoned due to significant geochemical problems, several research projects in Central Europe and North America strive to demonstrate technical feasibility. This talk provides an overview of ongoing HT-ATES projects in Germany, Switzerland, the Netherlands and the US.