Energy and environmental impact of groundwater heat pumps in urban areas.

Heat pumps are expected to play a major role in future energy scenarios. Proliferation of these systems in urban areas may cause issues related to environmental impact on water basins and interactions between installations. Both issues are associated with the thermal plume produced by the heat pump during operation and are particularly evident in the case of groundwater flow, because of the advective term of heat transfer. In this paper, the impact of heat pump installations is calculated through a thermo-fluid dynamic model of the subsurface which considers fluid flow in the saturated unit and heat transfer both in the saturated and unsaturated units. This model is coupled with the thermal request of the user and the heat pump performances through appropriate boundary conditions imposed at the wells. Various scenarios corresponding to different annual heating/cooling request, groundwater velocity, groundwater temperature variation are considered.