Urban heat as a resource for shallow geothermal heat recycling

Not unlike in the atmosphere, heat increasingly accumulates in the urban subsurface (including its groundwater (GW)). This is caused among others by underground infrastructure and the urban heat island above ground.

Harnessing the accumulated heat of subsurface urban heat islands (SubSUHI) through shallow geothermal energy systems is an opportunity to reduce the CO2 emissions of local heating markets and cool down the groundwater to a pre-industrial level, reducing adverse effects to environment and nature. Once the accumulated heat has been harnessed, the now increased annual heat input can be utilized for heat supply. The impact of climate change on the suitability of geothermal systems for meeting local heating demands is also quantified for two far-future scenarios from the CMIP6 (SSP245 and SSP585 scenario).

Our analysis is based on GW temperature and GW level measurements in Dresden, Germany, and satellite driven data such as air temperature and land use. Both theoretical and sustainable technical geothermal potential are evaluated in the context of Dresden's heat demand to determine the potential contribution of geothermal systems to the city's heating needs. Because of increasing cooling needs, we further investigate, how much “theoretical cooling potential“ hides in the urban underground when using geothermal systems to their fullest potential. By using Google Earth Engine as a platform, we ensure scalability, preparing to complete our analysis on a larger scale, as the results for Dresden are promising, that geothermal energy use could highly contribute in transforming the energy market sustainably.