Energy and environmental analysis of an open-loop ground-water heat pump system in an urban area

Abstract

In this paper a multidisciplinary methodology for analyzing the opportunities for exploitation of open-loop groundwater heat pump is proposed. The approach starts from a model for calculation of a time profile of thermal requirements (heat and domestic hot water). This curve is then coupled with a model of the control system in order to determine the heat pump operation, which includes its energy performances (primary energy consumption) as well as profiles of water discharge to the aquifer in terms of mass flow rate and temperature. Then the thermo-fluid dynamics of the aquifer is performed in order to determine the system impact on the environment as on possible other systems. The application to a case study in the Piedmont region, in Italy, is proposed. Energy analysis of the system shows that ground-water heat pumps constitute an interesting option in areas with small housing density, where there is not district heating. In comparison with typical heating/cooling systems, environmental benefits are related with reduction in global emissions. These benefits may be significantly enhanced using renewables as the primary energy source to produce electricity. The analysis also shows that possible issues related with the extension of the subsurface thermal plume may arise in the case of massive utilization of this technology.