Could nuclear bunkers use geothermal energy

Deep geothermal energy Wilhelmsburg


In the sandstone deep under the Elbe Islands, geologists expect a temperature of 130 degrees Celsius. This energy potential is to be harnessed by drilling to a depth of 3,000 to 4,000 meters. The vision: A geothermal power plant could soon supply several thousand apartments and other buildings in Wilhelmsburg with heat - in the best case even with electricity. From the research project of the IBA Hamburg and the GTW Geothermie Wilhelmsburg GmbH co-founded company, valuable information for the use of deep geothermal energy in all of Hamburg is expected.

Environmentally friendly, independent of the weather and emission-free - geothermal energy is an energy source with a future. Thermal water from deep rock layers is to be used for heat and power supply. The warm stratified water is pumped to the surface through a well. A heat exchanger extracts the heat above ground, uses it as district heating for heating purposes and generates electricity from water vapor via a turbine and a generator. The cooled water is returned to the subsurface through an injection hole. Underground, newly heated water is constantly moving to the production well - this closes the cycle.

In order to be able to better estimate this potential, extensive seismic investigations of the rock layers were necessary. The IBA Hamburg commissioned the engineering office GTN Geothermie Neubrandenburg to plan and prepare the seismic explorations and to evaluate the measurement results.

The geophysicists use clever sound for such explorations. With the measurement method used, reflection seismics, the structure of the earth's crust is determined up to a depth of about 4,000 meters. Along pre-determined measurement profiles, vibrator vehicles send sound waves into the earth's crust in sections, which are reflected by the rock layers in the subsurface and sent back to the earth's surface. Sensitive measuring devices record the signals there. A computer uses the stored information to compute a two-dimensional image from which the geologists can read off the position and properties of the rock layers.

The measurement profiles in Wilhelmsburg ran on two streets: the Georg-Wilhelm-Straße in the south to the Spreehafen in the north as well as on the Wollkammereistraße, Bei der Wollkämmerei and the Mengestraße. The explorations lasted about ten days.

In November 2010 the positive result was finally published. "The results of the seismic investigation are gratifying: the main production layer is large enough that it contains sufficient extractable deep water at a depth of 3,500 meters," says IBA managing director Uli Hellweg. The hot deep water in Wilhelmsburg is in the so-called Rhät, a rock layer of the Upper Triassic. The water here reaches a temperature of up to 130 degrees Celsius and moves in the spaces between the rock.

The IBA Hamburg's shares in GTW Geothermie Wilhelmsburg have now been taken over by Hamburg Energie. This would allow Hamburg Energie to further expand its heating networks on the Elbe island with deep geothermal energy and to network it in the future.