The G.POT method for the assessment and mapping of the shallow geothermal potential of Borehole Heat Exchangers (BHEs)

Abstract

The technical and economic viability of Ground Source Heat Pumps (GSHPs) strongly depends on the site-specific thermal properties of the ground and on the thermal load profile. These properties influence the shallow geothermal potential, defined as the thermal power that can be exchanged by a Borehole Heat Exchanger (BHE) of a certain depth. We have developed a quantitative method (G.POT), which provides an estimate of the shallow geothermal potential depending on the thermal conductivity and capacity of the ground, on its initial temperature, on the thermal properties of the BHE and on the duration of the sinusoidal thermal load cycle, which reproduces the typical pattern of a thermal load during a heating or a cooling season. G.POT is a simple mathematical tool which can be easily implemented for the large-scale assessment and mapping of the shallow geothermal potential. A case study is shown, in which the G.POT method has been applied to assess the geothermal yield in the Province of Cuneo (Piemonte, NW Italy).