Groundwater heat pumps diffusion in the Turin City urban area: modelling for the thermally affected zone analysis of an open-loop geothermal system

In urban areas with favourable geological and hydrogeological conditions, Groundwater Heat Pumps (GWHPs) offer an efficient solution for reducing emissions in heating and cooling systems. Turin City’s alluvial shallow aquifer serves as a valuable resource for harnessing low-enthalpy geothermal energy. However, a site assessment to evaluate the consequences of the technical solutions when promoting GWHPs is essential. Despite their proven potential in terms of energy efficiency, the environmental impact is a factor that can limit their development. This study reconstructs the impact of 44 open-loop geothermal systems in Turin’s area: an urbanscale numerical model was set up, and two simulation scenarios have been performed. The impacts simulated around the university buildings of the Politecnico di Torino are described. Findings from the average flow rate scenario demonstrated the absence of relevant hydraulic and thermal disturbances. The aquifer shows a positive response over three years, even in the maximum flow rate (Qmax) scenario with cooling/heating operating seasons for six months/ year. However, due to changes in natural groundwater temperature connected to the Qmax scenario, downstream systems could experience adverse effects due to thermal interference. Precision in designing the construction of a new geothermal structure is crucial, particularly in areas with complex extraction systems.