Geothermal Segments:The Tunnel as Heat Supplier

Quelle/credit: Rehau/Züblin

Installation of the geothermal segments in the Jenbach Tunnel, Lot H8

Quelle/credit: Rehau/Züblin

Tunnel lining with segments for energetic activation

Quelle/credit: Rehau/Züblin

Production of a geothermal segmenet: The absorber pipes (grey) are attached to the reinforcement

Quelle/credit: Rehau/Züblin

Thermal activation of the 54 m long section of the Jenbach Tunnel: absorber circuit between tunnel collector and building yard

Quelle/credit: Rehau/Züblin

Scheme of the heating circulation

Quelle/credit: Rehau/Züblin

Simulation of the extraction rate in permanent and interval operation

Quelle/credit: Rehau/Züblin

Measurement series with Re≈1650, practical operation

Quelle/credit: Rehau/Züblin

Test set-up in Jenbach with cooling unit

Quelle/credit: Rehau/Züblin

Measurement series with cooling unit at Re≈1200, test operation

Quelle/credit: Rehau/Züblin

Measurement series with cooling unit at Re≈2300, test operation

Quelle/credit: Rehau/Züblin

Measurement series with cooling unit at Re≈4200, test operation

Quelle/credit: Rehau/Züblin

Estimated extraction rate from “hot” and “cold” tunnels at a flow temperature of 5 °C

Quelle/credit: Rehau/Züblin

Extraction rate depending on tunnel type and tunnel length

Quelle/credit: Rehau/Züblin

Simple payback of tunnel types

Quelle/credit: Rehau/Züblin

At a time of increased mobility and also with the demand for reduction of CO₂output, regenerative energy sources are gaining significance. In addition to sun and wind, geothermal energy is also an option. Heat in the ground can be exploited by energetically activating structures in contact with the ground, e.g. tunnels. In the course of the upgrading of the railway route from Munich to Verona, a part of a tunnel in the area of Jenbach in the Tyrol has been thermally activated in order to supply geothermal energy to the nearby utility centre.

Thanks to the logging of data from the operation of the Jenbach thermal power plant since 2012, and also from additional tests, it is now possible to make more detailed statements about the energy potential and opportunities of energetic activation. The heat, which in this case is extracted from quite a shallow depth, is used for heating and cooling purposes in buildings and transport structures with a potential extraction rate of 25–40 W/m². It has been demonstrated that the payback period is of the same order as normal geothermal plants.