Strategies towards a sustainable thermal use of the shallow subsurface

Abstract

The thermal use of the shallow subsurface has constantly increased over the last years. Frequently applied techniques that are nowadays used to heat or cool entire residential neighborhoods or industrial facilities include borehole heat exchangers and aquifer thermal energy storage. Despite the capabilities to reduce CO2-emissions several concerns arise from the intensive thermal use of the subsurface. Potential effects include depletion of groundwater quality with resulting reduction of groundwater ecosystem services and over-exploitation of the thermal potential with resulting reduction of system efficiency. Heat and mass transport by groundwater dispersion and convection may lead to a carryover of effects into groundwater dependent ecosystems. Conflicts between thermal energy use and groundwater protection as well as conflicts between thermal energy users are expected to arise. Therefore, an emerging demand exists to assess potential effects and to develop strategies towards a sustainable thermal use of the shallow subsurface