The potential for groundwater heat pump systems for mitigating urban heat islands: aquifer suitability evaluation in Canada’s major cities

Urban heat islands (UHI) are a growing issue in the context of global warming and pose significant threats to the public’s health and well-being. The heat rejected into the city air from conventional air conditioners is a significant contributor to UHI. Geothermal energy is an alternative for mitigating this issue by redirecting this heat into the subsurface. This study assesses the suitability for open-loop geothermal technology of 10 selected Canadian cities that commonly experience UHI effects during summer, focusing on groundwater heat pump (GWHP) systems. Utilizing six key criteria related to hydrogeology and geochemistry, an evaluation tool in the form of an index is developed to perform a preliminary assessment of aquifer suitability. Results indicate that Vancouver, Winnipeg, and Kitchener/Waterloo/Cambridge are cities with highly favorable conditions for implementing GWHP systems. The other evaluated cities (Toronto, Montreal, Calgary, Edmonton, Ottawa/Gatineau, Quebec City, and Saskatoon) show moderate potential. While these results are contingent on the hydrogeological data available for these major cities, which are often limited, this study, nonetheless, yields promising results for several Canadian cities and has allowed to verify the usefulness of the developed index for conducting systematic preliminary assessments of site suitability.