Karlsruhe/Bruchsal. In the presence of numerous guests, the foundations will be laid today in Bruchsal for the first geothermal power plant in Baden-Württemberg. The joint pilot project between EnBW Energie Baden-Württemberg AG and Energie- und Wasserversorgung Bruchsal GmbH (ewb) is supposed to demonstrate that it is technically possible to open up the geothermal potential in Baden-Württemberg and the fact that geothermal power plants can be operated economically in the long term. With an output of 550 kilowatts, the geothermal power plant should be able to supply around 1000 households with CO2-free electricity as early as the autumn of 2008.
Dr. Hans-Josef Zimmer, EnBW’s Chief Technical Officer, emphasised the following in his speech: ‘With our commitment in Bruchsal, we are pursuing the aim of gaining experience in the construction and operation of geothermal power plants. We want to demonstrate in Bruchsal that geothermal power is feasible here in Baden-Württemberg and that it can become affordable through additional research and development. During this process, we will be faced with challenges which we are as yet unaware of as the operator of traditional power plants and with which Germany has not yet had much experience.’
The Mayor of Bruchsal and Chairman of the Supervisory Board of ewb, Bernd Doll: ‘This groundbreaking ceremony is an important day for Bruchsal, because our vision of environmentally friendly energy generation from local resources has now become a reality.’
With great commitment and many years of pioneering work, the city of Bruchsal has opened up a rich source of thermal water in the depth of its boundaries. While drilling at a depth of 1,900 and 2,500 metres, they came across a so-called hydrothermal spring with large volumes of thermal water with a temperature of about 130°C. Another reason why this really is pioneering work is the fact that such hydrothermal systems only make up about 4 percent of the geothermal potential in Germany.
In contrast to other geothermal systems, when it comes to hydrothermal systems, it is possible to make use of any groundwater already present on the site in question. One of the main technical challenges in Bruchsal is dealing with the thermal water with its high mineral and salt content, because only pure water circulates in the conventional water circuits. Special attention should therefore be paid to the water chemistry and the interaction of the thermal water with the materials used.
New technical ground will also be broken in the area of power plant technology: as a result of the thermal water temperatures in Bruchsal, a particularly efficient power plant technology will be used which currently only a few plants in the world use: the Kalina process. Whereas steam circuits in traditional power plants work with temperatures of up to 600 °C, the Bruchsal thermal water is available at the power plant at a temperature of 118°C. Water is not suitable as a medium for a process with much lower temperatures. In the Kalina process, a mixture of ammonia and water circulates as a working medium and minimises the heat transfer losses of thermal water during the power plant process, which improves the efficiency of the power plant.
The Bruchsal geothermal project with total investments amounting to about 17 million euros was launched in 1983 as part of a community project by the European Union, the German Federal Government, the Federal State of Baden-Württemberg and Energie- und Wasserversorgung Bruchsal GmbH (ewb). The first drilling on the site took place in 1983 and was followed by the second one in 1984/85. The project was then put on hold for a while. With the promotion from the Renewable Energy Sources Act, geothermal energy was given positive, new economic prospects and the project was continued in 2001. As a partner of the municipalities and the federal state, EnBW had decided in 2005 to support the Bruchsal geothermal project, thereby also actively promoting the geothermal initiative of the Federal State of Baden-Württemberg. EnBW will invest a total of around 6.5 million euros in the Bruchsal geothermal project.