Quantifying the technical geothermal potential from shallow borehole heat exchangers at regional scale

The extraction of shallow geothermal energy using borehole heat exchangers (BHEs) is a promising approach for decarbonisation of the heating sector. However, a dense deployment of BHEs may lead to thermal interference between neighboring boreholes and thereby to over-exploitation of the heat capacit...

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Bibliographic Details
Published in:Renewable energy 2021-03, Vol.165, p.369-380
Main Authors: Walch, Alina, Mohajeri, Nahid, Gudmundsson, Agust, Scartezzini, Jean-Louis
Format: Article
Language:English
Subjects:
Borehole heat exchangers
Geographic information systems
Numerical modelling
Potential estimation
Shallow geothermal energy
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Summary:The extraction of shallow geothermal energy using borehole heat exchangers (BHEs) is a promising approach for decarbonisation of the heating sector. However, a dense deployment of BHEs may lead to thermal interference between neighboring boreholes and thereby to over-exploitation of the heat capacity of the ground. Here we propose a novel method to estimate the technical potential of BHEs which takes into account potential thermal interference as well as the available area for BHE installations. The method combines simulation of the long-term heat extraction through BHEs for a range of borehole spacings and depths and includes an optimisation step to maximise the heat extraction. Application of the method to a case study in western Switzerland, from an available area of 284km2, yields an annual technical potential of 4.65TWh and a maximum energy density of 15.5kWh/m2. The results also suggest that, for a minimum borehole spacing of 5m and a maximum borehole depth of 200m, the cumulative installed borehole depth should not exceed 2km/ha. The estimated technical potential can be used by urban planners for the techno-economic analysis of BHE systems and by policy makers to develop strategies that encourage the use of shallow geothermal energy. [Display omitted] •Technical potential for densely deployed vertical borehole heat exchangers (BHEs).•Estimation of the potentially available area for the installation of BHEs.•Model of thermal interference between BHEs for various borehole spacings and depths.•Trade-off between optimal operation and minimal interference of neighboring BHEs.•Case study in Western Switzerland: potential of 4.65 TWh on 284 km2 available area.
ISSN:0960-1481
1879-0682
DOI:10.1016/j.renene.2020.11.019