Solute and heat transport in groundwater similarity: Model application of a high capacity open-loop heat pump

•Great heat pump that uses groundwater (low enthalpy geothermal energy) in Milan city (Italy).•Prediction of the effects on groundwater withdrawal and recharge through numerical model that exploits the similarity between the heat migration and the solutes transport.•Conflicting use of groundwater (potable, geothermal) in the urban environment.

The use of renewable resources has increased in Europe so that A2A Calore & Servizi, a leading company in the field of district heating in Milan (Italy) and the surrounding province, has built two co-generation power plants in order to produce heat from both conventional sources (combustion of natural gas in boilers, cogenerative engines and turbines) and through the exploitation of the geothermal potential of groundwater by a large heat pump (15 MWt). Geothermal exploitation is limited to the shallow aquifer; the temperature of which, below the first few metres, remains roughly constant throughout the year.Groundwater flow and heat transfer within the subsurface can be simulated using a numerical model to identify the pumping and recharge well layout that maximizes the efficiency of geothermal exploitation and groundwater protection.Starting with the similarity between solutes and heat transport within aquifers, different scenarios of heat pump operation in the Canavese power station, which has a maximum water withdrawal of 0.3 m3/s, have been developed.