The geothermal power generation will make a growing contribution to energy supply in 
the future. Very important is the kind of the cycle, which is used for energy 
supply. When the hot thermal water is directly relaxed from a temperature of circa 
200 °C in the turbines, the secondary loop is used under this limit. For this 
purpose the two technologies Kalina Cycle and Organic Rankine Cycle are available. 
For the ORC there is more operational experience, but a higher efficiency of Kalina 
cycle is assumed. Because the choice of the plant for power generation influences 
the economies of geothermal projects, a clarification of the question, which type of 
plant is advantageous for the energy recovery, has an immense importance. GEOCAL® is 
one solution of ORC power plant with various possibilities. Every power plant has 
its own boundary conditions, like temperature of geothermal water, cooling 
conditions and utilization of heat. The most economic is not always the most 
efficient geothermal power plant.

The presentation won’t solve all problems but will give some background information 
and will show some possibilities for a better understanding in ORC technology.

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