Geothermal district heating in Freiham (Munchen)
Overview
The completion of the geothermal heating plant in Freiham marks a significant milestone in Munich's journey towards renewable energy independence. As part of the city's ambitious goal to become the first major city in Germany to supply its residents exclusively with renewable energy by 2040, the Freiham project embodies innovation, sustainability, and environmental stewardship.
At the heart of the project lies a revolutionary doublet system, comprising two wells that establish a closed thermal water cycle. This ingenious design ensures that no water is extracted from the underground, with only the heat of the thermal water utilized for heating purposes. Through a production well, thermal water is brought to the surface and its thermal energy is seamlessly transferred to the district heating water via a heat exchanger, ready for further use. The cooled water then returns underground via an injection well, completing the cycle with minimal environmental impact.
At the Praxisforum Geothermie Bayern, the plant was awarded as the most efficient geothermal heating system in 2020.
The region
The city of Munich, located in southeastern Germany, boasts a robust local economy and favorable geological conditions conducive to the implementation of geothermal direct-use heating systems. This unique combination, coupled with a growing population and a shift in national energy policy prompted by the nuclear disaster in Japan, has catalyzed the development of numerous successful geothermal projects throughout the region. While Munich experienced a period of geothermal growth between 2004 and 2009, activity saw a significant downturn due to various factors, including the global financial crisis. However, recent completions and planned future endeavors signal a resurgence of momentum, instilling confidence within the city regarding the untapped potential of geothermal energy.
Technical details
With the completion of the geothermal heating plant in Freiham in 2016, the Stadtwerke München (SWM) have realized their third district heating project together with ERDWERK.
Here, Stadtwerke München extracts thermal water at 90°C from a depth of 2,500 meters in a closed-loop system. Through the utilization of heat exchangers, a significant portion of heat is extracted from the thermal water, after which the cooled water is returned to the same underground formation via a secondary borehole. The renewable heat derived from this process is then distributed to the district heating network, serving to warm the Freiham district and adjacent areas in the western region of Munich. Throughout the surveyed period, the system recorded a total of 8,592 operating hours, with 7,616 hours being at full capacity. Operating nearly continuously at 8,760 hours per calendar year, the system has proven its reliability and efficiency.
In Bavaria alone, geothermal energy plants collectively generated over 1.1 terawatt hours (TWh) of heat and 161,000 megawatt hours (MWh) of electricity in the year 2020.
What sets the Freiham project apart is its utilization of a special low-temperature network tailored to the housing development, meeting the latest energy standards. By significantly cooling down the district heating water, the system maximizes the extraction of heat energy from the thermal water, capitalizing on the temperature differential to optimize efficiency. This innovative approach not only enhances energy utilization but also underscores the project's commitment to sustainability.
ERDWERK supported the project from the geological preliminary planning through the approval procedure to the execution of the seismic campaign which included the interpretation of the collected data and the drill path concept design. Further, ERDWERK carried out the implementation planning of the drilling and acted as the site manager for the drilling of the wells.
Policy drivers
The project is part of the vision of the city of Munich to be the first major city in Germany to supply its residents exclusively with renewable energy by 2040. Stadtwerke München is working to achieve this vision, with the majority of renewable energy being from geothermal energy.
During the operation of the plant, operational plans agreed with the relevant authority must be followed. In this respect, a rather technology-friendly licensing practice has evolved especially in southern Bavaria where Freiham district is located.
One of the main policy instruments in Germany is investment grants (existing buildings) and use obligation (new buildings) for the implementation of RES-H. Moreover, regulations include:
Energy Saving Ordinance (EnEV) [2014]
EnEV set minimum requirements for the energy-related quality of the building shell and the system technology for both new and renovations of existing residential and non-residential buildings. These requirements are updated to enhance their stringency.
Renewable Energies Heating Act (EEWärmeG) [2009]
The Act mandates use of renewable energy sources to provide heating and cooling in both residential and non-residential buildings, whether new or existing. EEWarmeG imposes the use of renewable energies, including solar heating systems and heat pumps, in the construction of new buildings (so-called obligation to use). The government supports the act through capital grants for smaller systems and low interest loans or redemption grants for larger systems.
Incentive Programme for Promotion of the Use of Renewable Energies (MAP) [2000]
Promotes renewable energy systems that provide space heating, hot water, cooling and process heat through investment grants or repayment grants for low-interest loans. Funding is provided for both residential and non-residential buildings. It has a section for smaller buildings administered by the Federal Office of Economics and Export Control (BAFA), and one for large buildings and commercial uses, the latter being a premium component of the KfW Banking Group renewable energies program. Several geothermal technologies can be supported by the MAP; it subsidizes the installation of efficient heat pump systems in residential buildings with a repayment bonus, depending on the installation size. Funding is also provided for setting up heat networks and heat storage units. More than 1.8 million systems have already been funded via the MAP since 2000.
The expansion
SWM is tasked with providing various utilities throughout the city, including electricity, heating, internet, and water services. In 2008, SWM embarked on a journey to diversify its energy portfolio, with a particular focus on expanding renewable energy sources. As an early advocate for geothermal energy in the region, SWM recognized its immense potential for Munich. To date, SWM has spearheaded numerous key and notably successful projects in Sauerlach, Riem, and Freiham.
With six operational geothermal plants in and around Munich, SWM announced the construction of its seventh facility, slated to commence in 2024 on the premises of the Michaelibad swimming pools in the southeast of Munich. Upon completion, the plant is expected to supply sufficient heat for approximately 75,000 Munich residents.
A significant milestone has been achieved in the project's approval process, with the local building commission issuing its preliminary decision greenlighting the construction of the geothermal plant. The rationale behind this decision underscores the distinct public interest in transitioning Munich's district heating system to one that is climate-neutral. The approval comes with stipulations, including provisions for noise abatement and tree preservation, underscoring the project's commitment to environmental considerations.
Environmental protection
The HAS Innova Rig, utilized for drilling boreholes for the Freiham district heating network, is a collaborative creation involving Herrenknecht Vertical and the German Research Centre for Geosciences (GFZ) Potsdam. Specifically designed for urban geothermal projects, this rig adheres to the highest standards, particularly in environmental protection. With optimized noise protection and advanced safety measures, this modern equipment sets new benchmarks in drilling quality and occupational safety.
Notably, the rig's design prioritizes noise reduction, achieved through innovative features such as hydraulic mechanisms and the absence of a monkey board, resulting in significantly reduced noise levels, particularly during high-altitude operations. Additionally, its compact footprint makes it ideal for constrained urban sites, requiring less space than conventional drilling rigs.
Despite its impressive pulling capacity of 410 metric tons, the rig remains highly maneuverable, ensuring efficient operations and minimal downtime. This versatility not only enhances productivity but also reduces both manpower requirements and operating costs, as emphasized by Uwe Schindler, CEO of H. Anger’s Söhne.
Furthermore, the implementation of the Freiham district heating system is projected to yield substantial environmental benefits, including an estimated annual reduction of up to 22,500 tons of carbon dioxide emissions.
Furthermore, it is estimated that Freiham district heating saves up to 22,500 tons of carbon dioxide annually.
Summary
Depth of drilling: production well: 2518m TVD, Injection well: 2,557 m TVD
Geothermal power: 13 MWTh
Temperature of the water drawn: 92⁰C
CO2 emissions avoided: up to 22,500 tons annually
Sources:
SWM: Weiterer Meilenstein zum Gelingen der Wärmewende: Geothermieanlage am Michaelibad
IEA Geothermal | Germany - International Energy Agency geothermal (iea-gia.org)
Opportunities geothermal energy in Germany | Global law firm | Norton Rose Fulbright ~
Energy Transition in Germany: Phasing Out Nuclear and Coal For Local Geothermal Energy (eavor.com)