The world's growing energy needs are still predominantly met by fossil energies (coal and oil) and by nuclear power (uranium). Given the finite nature of fossil energy resources and the issues of nuclear waste disposal and climate change (greenhouse gas emisions), one of the greatest challenges of the 21st century will be to organize energy supplies in such a way that the energy itself (electricity and heat) can be made available in an efficient, safe and sustainable way.

Geothermics

The use of the heat from the interior of our planet (geothermics) will play an important role in supplying the world's population with energy in the future. 99 percent of our planet is hotter than 1,000 degrees centigrade. This would seem to represent an almost inexhaustible supply of energy. In central Europe the temperature in the upper area of the earth's crust increases by around three degrees centigrade every hundred meters. So below us there is a dormant source of energy available to us 24 hours a day, 365 days a year. The question is, how can we economically utilize the heat from the depths of the earth?

Hydrothermal geothermics

One promising way of utilizing the heat from the depths of the earth is to develop hydrothermal deposits. Hot deepwater is brought up to the surface by means of deep drilling, and there it is used for generating electricity and providing heat. In Germany there are three regions which are suitable for using geothermics in this way: the North German Basin, the Upper Rhine Rift and the North Alpine Molasse Basin.

Geothermal power plants in Germany

Positive experience has already been made in Germany with using heat from the depths of the earth to provide heat. However, generating electricity from geothermal heat represents a far greater challenge. Because of the comparatively low temperature gradients in central Europe, technically demanding processes have to be applied to produce electricity, e.g. the organic ranking cycle (ORC) or the Kalina cycle. Deep drilling to over 3,000 meters is needed in order to provide the minimum required temperature of 120 degrees centigrade. HOCHTIEF Energy Europe, HOCHTIEF Construction's competence center for the construction of power plants in Europe, is heavily involved in building geothermal plants.

Each geothermal energy project comprises two phases. The first phase includes location development, borehole drilling and ascertainment of the borehole's properties. If these properties are satisfactory, SGG in a second step sells the borehole to an investor, for instance a municipal authority. The buyer then commissions SGG to construct and operate the power plant. The company draws on HOCHTIEF's wide-ranging experience in the areas of planning, construction and operation of complex infrastructure projects. For instance, HOCHTIEF PPP Solutions, an infrastructure service provider, is involved and so is power plant construction expert HOCHTIEF Construction Energy Europe. The HOCHTIEF subsidiary Streif Baulogistik has already procured a future-oriented deep boring plant for the projects. It is possible that once the power plants are completed, HOCHTIEF Facility Management could take over their operation. With this closely interlinked range of services, HOCHTIEF is developing another fast-growing business segment.