REHAU has installed its high pressure RAUGEO ground source energy probe at a reported record breaking depth of 800m as part of an innovative project for Energy SüdWest AG in Landau in der Pfalz, Germany.
In the area of medium depth geothermal energy between 400 and 1000m, the temperature levels are considerably higher than they are closer to the surface which means that, in some cases, direct heating is possible without any requirement for an intermediate heat pump.

In this installation, the heat is being used directly by a nearby car dealership for its underfloor heating system and, with output estimated at 80kW and the return temperature at 40ºC, the annual heating costs are expected to be less than €500 per year.

This is the first time that Energy SüdWest AG has allowed this type of deep energy probe but it has proved more efficient than a shallower depth probe field, as well as requiring considerably less space.

Part of the reason for the success is the use of REHAU's steel-reinforced RAUGEO high pressure deep probe which has been designed to withstand the pressures that occur at the 800m depth as well as the ground temperatures which can be up to 80ºC. The probe consists of three layers. The inner pipe is high pressure, cross linked PE-Xa which demonstrates temperature stability at up to 95ºC. This is braided with a stainless steel reinforcement wire which can absorb the internal pressure, and protecting this is an outer jacket made from tough PE100. All of the connections are compression and pressure tested in the plant to ensure long term performance.

The installation costs on the project were reduced by the fact that Energie SüdWest were able to use a borehole which has previously been used for gas exploration. However, the overall success of the unusual installation and the valuable support which REHAU provided on the planning and implementation means that follow-up projects are already being planned.