Other use of the subsoil
With the exception of salt extraction, it is largely the same types of layers in the subsoil which can be used for these various purposes. It is necessary to prioritize use of the subsoil for different purposes, as the storage of CO2 will for example permanently prevent the layers from being used for other purposes.
In connection with geothermal heat production, the storage of natural gas and CO2, subsoil porous and permeable sandstone layers at depths of 1,500 m to 2,500 m can be used in many areas in Denmark. The capture and storage of CO2 and gas storage require the porous sandstone layers used for capture/storage to be part of a geological structure that permits the gases injected to be trapped in the porous layers. Above the porous layers, there must be a seal or cap consisting of tight clay layers which are impermeable to the injected gases. On the other hand, the use of porous sandstone layers for geothermal heat production does not require a subsoil structure. Porous sandstone layers which contain hot water are sufficient to enable the production of geothermal heat.