GIS-supported evaluation and mapping of the geo-exchange potential for vertical closed-loop systems in an Alpine valley, the case study of Adige Valley (Italy)

Abstract

In this paper, the aim of the authors is to propose a replicable novel methodology, tailored for an Alpine valley, for the GIS-supported evaluation and mapping of the territorial suitableness, defined as “geo-exchange potential”, to exploit shallow geothermal energy through vertical closed-loop systems. In a first step, climate, geological, hydrogeological and thermophysical data, useful for the elaboration of specific thematic maps, are collected and organized on a provincial scale. Follows a second step in which, by using of GIS spatial analysis tools, the physical parameters that mostly influence both the thermal demand for building air conditioning and the thermal performance of the underground, in terms of heat exchange and storage, are spatially represented. The shallow underground is investigated to the depth of 100m, considering the heat transfer by conduction and by convection (considering the groundwater flow). Finally, to obtain a representation of how the geo-exchange potential for vertical closed-loop systems differs within the study area, the considered properties are combined identifying specific heat extraction rates (W/m), according to the German VDI guideline 4640. In the Province of Trento (Italy), a detailed demonstration study focuses on the Adige Valley, thanks to the availability of a high number of geognostic drillings (358) and hydrogeological measurement points (288), distributed uniformly across the whole area.