Disclosed is an installation for using geothermal energy, comprising a main pipe (20) in a borehole (10) of a well. The main pipe (20) has several through-holes (23) to the surroundings and is subdivided into a top and a bottom section by means of a transverse closure (21) that has an opening in which a device or a part of a device (22) generating and/or promoting a flow is disposed. At least one heat-utilizing device (30) is arranged within the main pipe (20) which is surrounded at least in the region of the through-holes (23), preferably everywhere, by a porous bed (11) filing at least some of the remaining hollow space of the borehole (10) around the main pipe (20). The porous bed (11) is hydraulically interrupted within the main pipe (20) by a sealing material (12) at the level of the transverse closure (21). Said installation is used for delivering or dissipating heat, decontaminating especially groundwater, and/or generating power.