Achieving carbon neutrality is a measure for mitigating climate change. As a result, development of zero net buildings and houses is accelerating in Japan. In this connection, ground source heat pump (GSHP) systems are being promoted as a potential energy saving cooling and heating technology. The aquifer thermal energy storage (ATES) system is an GSHP system that has been attracting attention for its low initial cost and high operation efficiency compared to other GSHP systems such as closed-loop systems. However, successful implementation strongly depends on the hydrogeological conditions of the host area. ATES systems require an adequate groundwater supply to meet the thermal demand of buildings. To increase ATES adoption in Japan, research to evaluate areas that are appropriate for ATES, including the hydrogeological environment, have been actively carried out in the last decade. Existing literature on the thermal use of groundwater in Japan and studies related to ATES from the 1970s to the present are reviewed and analyzed. Then, the latest findings on the ATES potential map and/or suitability evaluation for Osaka city and Yamagata basin are presented. Both findings imply that geological conditions might impact the suitability of implementing an ATES system. Finally, challenges surrounding development of a technique to assess the applicability and potential of ATES at different locations in Japan are discussed. The safe and effective installation and operation of an ATES system requires an understanding of prevailing hydrogeological conditions.
