Germany's most powerful geothermal plants to provide green district heating in future

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Picture (from left):Tilo Wachter (CEO of Süddeutsche Geothermie-Projekte GmbH and geothermal expert at BayWa r.e.) and Thomas Hoppenz (CEO of Energieversorgung Ottobrunn) recently signed a long term heat supply contract.

From 2019, numerous households in the Ottobrunn, Hohenbrunn, Neubiberg and Höhenkirchen-Siegertsbrunn areas will be supplied with environmentally responsible district heating from the Kirchstockach and Dürrnhaar geothermal power plants.

This is what the long term heat supply contract recently signed by Energieversorgung Ottobrunn GmbH and Süddeutsche Geothermie-Projekte GmbH & Co. KG (SGG) has provided for. These two facilities, commissioned in late 2012 and early 2013 respectively, are currently Germany's most powerful geothermal power plants, each being capable of some 45 MW of thermal output and up to 7 MW of electric power. So far, plant operator SGG, a joint venture from BayWa r.e. renewable energy GmbH and Hochtief PPP Solutions GmbH, has only produced electricity for the national grid. In order to use the geothermal potential to produce heat in future as well, and to supply even more households with environmentally responsible district heating, Energieversorgung Ottobrunn hopes to greatly expand its district heating network over the coming years.

Tilo Wachter, CEO of SGG and geothermal expert at BayWa r.e., stated: "Geothermal is 100 percent renewable and is capable of covering the base load. It does not depend on the weather, the climate or the time of day and is always available. The reservoir for geothermal energy is particularly large in the region just south of Munich. A strong partnership with Energieversorgung Ottobrunn will enable us to take full advantage of this potential to provide heat in the future."

Thomas Hoppenz, CEO of Energieversorgung Ottobrunn, explained: "This heat supply agreement and the upcoming network expansion will allow us to make an important contribution to the energy transition through our supplying of heat to the Munich region. For our customers this means that they will continue to be reliably supplied with electricity and heat – but as of 2019 they will also be able to save on heating oil, reduce their carbon dioxide emissions and so protect our climate."

A treasure trove of energy: Why geothermal is particularly worthwhile around Munich

Deep beneath the Earth's surface lies hot, thermal water stored in layers of limestone. We can extract this to take advantage of its geothermal energy. The closer the rock layer is to the Earth's core, the higher the temperature – an average of three degrees Celsius per 100 metres. Thanks to its location in the Bavarian Molasse Basin, the Munich region has a particularly large geothermal potential. Few other regions in Germany (including the Upper Rhine Graben) are as privileged. Hot, thermal water (approximately 135 degrees Celsius) lies beneath the two geothermal power plants in Kirchstockach and Dürrnhaar at a depth of around 4000 metres. To compare: North-east of Munich – in Straubing, for example – this thermal water is not nearly as deep, which is why its temperature is only 35 degrees Celsius.

During the drilling phase, two deep bore holes were drilled at each of the plants to connect to the thermal water there. One of the bore holes allows the warm water to be extracted, whilst the other serves to reinject the cooled water into the subsoil. Energy is extracted via a heat exchanger in the above-ground facility, which can then be used to generate electricity or produce heat. When operating at full capacity, nearly 4 billion litres of water is transported annually through the pipelines at the two plants.

Expansion of the district heating network in the region

Energieversorgung Ottobrunn wants to invest 15 million euros in expanding the district heating network in the coming years. The first step is to link up the adjacent areas with the geothermal power plant in Kirchstockach by 2019 through an approximately six-kilometre district heating pipe. The second step is to connect its sister plant, Dürrnhaar, by 2022, using a seven-kilometre pipe that leads through the Höhenkirchen-Siegertsbrunn and Hohenbrunn areas. There are also plans to connect to the local organic waste fermentation plant. Its lost heat is currently being emitted into the environment, where it goes to waste. This measure could even see the current total capacity of both plants increase from 90 MW (thermal) to 100 MW (thermal).

The support from the local political sphere is just as great: The mayors of all four municipalities, Ursula Mayer (Höhenkirchen-Siegertsbrunn), Thomas Loderer (Ottobrunn), Günter Heyland (Neubiberg) and Dr Stefan Straßmair (Hohenbrunn), support the project and hope to see it driving forward the energy transition on the Munich heating market.



HOCHTIEF is one of the most international construction groups worldwide. The company delivers complex infrastructure projects, in some cases on the basis of concession models. The Group operates in the transportation infrastructure, energy infrastructure and social/urban infrastructure segments as well as in the contract mining business. With around 53,000 employees and a sales volume of more than EUR 22 billion in FY 2014, HOCHTIEF is represented in all the world’s major markets. With its subsidiary CIMIC, the Group is market leader in Australia. In the USA, the biggest construction market in the world, HOCHTIEF is the No. 1 general builder via its subsidiary Turner and, with Group company Flatiron, ranks among the most important players in the field of transportation infrastructure construction. Because of its engagement for sustainability, HOCHTIEF has been listed in the Dow Jones Sustainability Indexes since 2006. 

Energieversorgung Ottobrunn GmbH:

Energieversorgung Ottobrunn is the local energy provider for Ottobrunn and south-east Munich – independent, committed and individual. As a municipal company we are actively engaged in promoting the local energy transition. This includes working towards the exclusive supply of green power, as well as expanding renewable energies and district heating. In doing so, our close relationship with the public is especially important to us. We are involved in the local community. We create jobs and our profits benefit the region

BayWa r.e. renewable energy GmbH (BayWa r.e.): 

BayWa r.e. renewable energy GmbH, a wholly owned subsidiary of BayWa AG, draws together the Group's activities in the fields of solar energy, wind power, bioenergy and geothermal energy. With its registered offices in Munich, BayWa r.e. is active in its core markets of Europe and the USA. The company acts as a full service partner and employs around 870 staff. It is able to draw on over 20 years of experience in this market where it develops, realises, consults and supports BayWa r.e. projects in the renewable energies sector. In addition, the company manages the operation and maintenance of plants. Further business activities include trading in PV components, as well as the purchase and sale of energy from renewable sources.Parent company, BayWa AG, is an international trading company and service provider whose core business sectors include agriculture, energy and construction.

Felix Gmelin Communications Manager BayWa r.e. renewable energy GmbH
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