Geothermal ORC-power - GEOCAL®

GEOCAL®-„geological caloric" describes our organic rankine cycle product line for the use of geothermal energy. The name GEOCAL® stands for power plants that offer the technological solution to raise vast geothermal potentials based on the organic rankine cycle process. By help of this process it is made possible, to tap reservoirs of geothermal energy in temperature ranges from approx. 85°C up to 250°C (185°F up to 482°F) for the generation of electricity which are unable to be developed with the water steam cycle.

In competition with other thermodynamic cycle processes GEOCAL®-geothermal -organic rankine cycle-modules achieved the highest theoretical electrical efficiency in temperature ranges typical for the geological formations in middle Europe because of their sophisticated construction properties and data of chemical media.

GEOCAL® geothermal ORC-power

  • ORC-geothermal power

  • Thermal waters (1) in a temperature range from 100 °C up to 250 °C (212°F- 482°F) that rise to the surface from hot water aquifers (aquifer = ground or mineral water containing layer of earth) or after the Hot-Dry-Rock principle flow through an evaporator (2). This evaporator has to be made from special, salt resistant metal alloys because of the high content of salt and solute gases in the thermal water. The water is cooled down to approximately 80 °C (176°F) and then is reinjected into the drill hole (3). The residual heat can be used for heating purposes

  • In the evaporator (1) the heat energy of the thermal water is transferred to an organic working medium. In the secondary cycle of the evaporator (1) the geothermal heat is absorbed by a specific organic fluid that GMK holds a patent on. Because of its physical properties it expands when charged with the energetic thermal water and flows over the fresh steam pipe (2) to the ORC-turbo-generator(3&4) where it performs expansion work.

  • Having done the expansion work in the turbine (3) the now decompressed steam moves on to the recuperator (5) where its residual heat is taken up by the liquified substance. Afterwards it is liquefied again in a condenser (6) which is cooled by either a wet or an air cooling tower. In the condenser the liquefied working medium is collected in a hotwell. From there it is taken by the feed pump (7). This pump picks it up and feeds it back to the pre-heater-evaporator over the recuperator (5) to close and continue the cycle.

  • The electrical energy produced with the generator is fed into the power grid. In Germany this electricity is supplied to the power grid under privileged conditions according to the Renewable Energies Act (EEG).

Key figures geothermal ORC power plants
Electrical power output: 0.05 - 15.0 MW
Thermal power output: 0.5 - 120.0 MW
Operating period: 8,400 h p.a.
Manpower requirements: 0.1 - 4.0 employees