High Temperature

In larger depth and at higher temperature the crystalline basement has a large potential for electricity production and simultaneous heat production. In Switzerland the DHM project in Basel is the first one, that uses this energy.
In the next years however surely further projects will develop n order of the electricity production.

If the temperature of the geothermal heat source is over 100°C, then a transformation of the heat into electricity can be profitably. The geothermal fluid ascends in the borehole under high pressure and high temperature, why it consists of a water vapour mixture. The energy content of steam which is at pressure is converted by the use of turbines and generator into electricity, which is then fed into an existing distributed network.

At the exit of the turbine, thus after the transformation of the geothermal energy into electricity, the temperature of the fluid is still high. This permits afterwards a direct utilization of the heat, for example to heat-up buildings.

Until nowadays, geothermal usage was done mainly for heating and cooling usage. The "Enhanced Geothermal System (EGS)" also called the "Stimulated Geothermal System" offers a big step towards the artificial production of heat. Thus the placement of a heat exchanger in the crystalline rocklayer. With this technics, which is still under development, it should become possible to produce "Volume-Energy". That means energy availability at any time. An advantage which can be found rarely with renewable energies. The water injected in drilling-wholes is heated up in the artificially seperated crystalline rocks in a depth of approximately 5 km up to 200 °C. Back at the surface the obtained energy serves a turbine with coupled generator.

Hydrothermal plants in different countries are using deep Aquifers in depths of 1’500 – 2’000 meters and thus are reaching temperatures about 100 – 350 °C.

Scheme about the use of a very deep geothermal reservoir for the production of electricity and heat