The exploratory drilling of the German Research Center for Geosciences in Berlin-Adlershof reached a depth of 300 meters on Monday, December 13. Numerous drill cores have already been obtained since drilling began in mid-November. The aim of the project, which is called “Geothermische Fernwärmeversorgung Berlin” GeoFern (Geothermal District Heating Supply Berlin), is to create the conditions for a climate-friendly district heating supply for Berlin with the help of a seasonal geothermal aquifer heat storage system. To this end, the underground must be examined in detail. Rock samples in the form of drill cores are brought up from the depths through drilling and then geologically characterized. The project partner is BTB Blockheizkraftwerks-Träger- und Betreibergesellschaft mbH Berlin, on whose premises the drilling is taking place.
Porous, deep aquifers have great potential for seasonal heat storage. During the summer months, they can absorb surplus heat from the production of combined heat and power plants or industrial plants, for example, which is pumped down there in the form of hot water.
As part of the project, which is funded by the Federal Ministry for Economic Affairs and Climate Action, the exploratory well will be drilled to a depth of approximately 650 meters in the coming weeks. This exploratory drilling will improve the geological understanding of the structure of Berlin's deeper subsurface, which consists of various sand, clay and limestone layers. This will allow conclusions about the storage capacity of certain geological horizons. Together with the BTB Blockheizkraftwerks-Träger- und Betreibergesellschaft, storage concepts will be developed on this basis in order to integrate seasonal heat storage into the existing district heating supply.
In addition to the suitability of the aquifer, the GFZ is also investigating possible interactions of the porous rock with the environment. Extensive mineralogical-geochemical analyses are being carried out both directly on site and in laboratories.
The project leader Ali Saadat, engineer and scientist from the Geoenergy Section at the GFZ, sees the expansion of geothermal energy as an important contribution to the decarbonization of Berlin's energy supply and says: "This exploratory drilling is an important step for the future of a climate-neutral heat supply for the city. The geothermal utilization potential must be significantly expanded to play a greater role in the energy mix." He continues "We need a concept for a sustainable heat supply for Berlin in a timely manner. Therefore, we must start now and quickly to systematically explore the subsurface of Berlin in order to be able to use geothermal energy responsibly in the future."
Ingo Sass, head of the GFZ’s Geoenergy Section, adds, "Geothermal exploration using deep drilling, geophysical and other methods must become as normal for everyone living and working here as, for example, the photovoltaic industry's constant search for and evaluation of roof areas and their suitability. Without a wide exploration of the urban subsurface for geothermal uses, it will be almost impossible to achieve the goals of climate protection. I am glad that here in Berlin we are ahead of other metropolitan areas with this activity. However, the overall knowledge of the Berlin-Brandenburg subsurface is still very limited and many more boreholes will be needed in the German capital to close the knowledge and planning gaps. Without geothermal energy, there will be no heat transition within Germany’s energy transition."