The T-I-GER method: A graphical alternative to support the design and management of shallow geothermal energy exploitations at the metropolitan scale

Abstract

The number of shallow geothermal exploitations is growing without a widespread technical framework for this energy resource to be sustainably allocated between users. The thermal impacts that are produced by neighboring exploitations can deplete the resource if they are not properly distributed. Therefore, we present an accessible and simple methodology to define the maximum potential that can be extracted and the position of the exploitations with the objective of limiting the thermal impacts to the available space. The proposed method, named T-I-GER, takes into account the hydraulic and thermal properties of the subsurface as well as the size and orientation of the owner's plot. All this information is integrated in two different graphs: the thermal characteristic curve and the thermal plume graph. Therefore, the installer is able to graphically define the maximum potential and to check that thermal influences are restricted to the plot area. We show with a hypothetical application in Azul city, Argentina, that the maximum extraction potential from similar plots can vary depending on the orientation of the plots with respect to groundwater flow. In the plots where the major dimension is parallel to groundwater flow, the maximum potential can be approximately twice the potential of the perpendicular plots.