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Fig. 1: The first Kalina system for electricity generation in the EU commenced operation in Unterhaching. The geothermal power station building also contains the production pump for the thermal water and the above ground system with plate heat exchangers for the heating network.
© Geothermie Unterhaching
First Kalina system in the EU
Projektinfo 10/2009
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Geothermal electricity generation combined with a heating network

The region between the Swabian and Franconian mountains and the Northern Alps, also known as the South German Molasse Basin, has large geothermal resources. Hot water at depths of 1,500 to 5,000 m has given rise to health resorts with thermal baths over the last few decades. In recent years, some communities have also begun to integrate geothermal energy into their local district heating systems.

The Unterhaching community, located south of Munich, has been using these geothermal resources in a communal heating network since 2007. The very first geothermal power station in South Germany commenced operation here early in 2009. The community initiated their own energy concept ten years earlier, establishing a heating atlas as the first step. This resulted in the development of a plan to cover at least 50% of the local energy requirements with more efficient systems by 2015. In 2001 the community council decided to construct a geothermal plant. Two wells in Unterhaching resulted in copious hot water reserves at temperatures above 120 °C. The original usage concept gave a primary role to electricity generation with district heating for municipal buildings assuming a secondary role.


The greatly increased prices for fossil fuels and the unexpectedly high temperature and volume of water resulted in a change of project priority, with the main focus becoming the supply of district heating for the community. This resulted in a new district heating network that already covers 25% of the local requirements and is still being expanded. Only the excess heat is channelled into a power station that has been specially designed for low temperature heat. For the first time in the EU, the power station uses a mixture of water and ammonia as the working fluid (Kalina process).
Sample project management solutions were also created, e.g. in the areas of geological risk insurance, drilling contracts and end-customer tariff structures, which should assist similar projects elsewhere. The geological analyses and testing of a Kalina plant were subsidised by the German Federal Ministry for the Environment (BMU).

Projektinfo 10/2009:
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