Numerical simulations of a borehole heat exchanger leakage in drinking water catchment areas

Abstract

Given the necessity to provide a substantial contribution to the climate protection goals borehole heat exchangers (BHE) and thermal energy storages (BTES) provide an efficient way to produce and store heat, especially in urban areas, but are for reasons of preventive groundwater protection usually rarely approved in areas of drinking water production. Numerical simulations of a BHE leakage in an aquifer used for drinking water production show that even at a distance of only 100 m between the BHE and the drinking water production well concentrations for most components used in commercially available heat transfer fluids do not exceed the limit values due to microbial degradation and dilution. Considering these results and in view of the ambition to reduce fossil primary energy sources by 80–95% by 2050 general distance requirements (currently >1000 m) therefore seem worthy of discussion, at least with regard to the drinking water pollution caused by leakages of BHE.