Vienna's First Deep Geothermal Project Tests Exceed Expectations, Heating Capacity Raised to 25,000 Households

en.Wedoany.com Reported - On September 17, Wien Energie disclosed the latest progress of the Aspern deep geothermal project, which it is advancing through the joint venture deeep with OMV. The project has completed capacity testing and closed-loop reinjection testing of a geothermal well approximately 3,000 meters deep, with results exceeding earlier design expectations. The project is expected to provide district heating for up to approximately 25,000 Vienna households, an increase of 5,000 households compared with the original plan of approximately 20,000.

The Aspern project is located in eastern Vienna and is the city's first deep geothermal heating facility. The target formation for project development is the Aderklaaer Conglomerate aquifer, located approximately 2,800–3,500 meters underground, with formation water temperature close to 100°C. The project transports high-temperature formation water to the surface through production wells, extracts heat through a heat exchange system, and then sends the water back underground through reinjection wells, achieving closed-loop operation.

Since the fall of 2025, the project began extracting formation water from a depth of approximately 3,000 meters for the first time and carried out closed-loop testing. During the testing phase, approximately 3,400 cubic meters of formation water were extracted in total to test temperature, chemical composition, flow rate, and long-term stability, and to verify the continuous circulation capacity between the production well and the reinjection well. Results published by Wien Energie in June showed that reservoir capacity and stability were significantly better than previous model predictions.

The project was previously planned for a maximum thermal output of approximately 20 MW. Based on the latest reservoir test results, Wien Energie has increased the number of households that can be served from approximately 20,000 to up to 25,000. The geothermal facility will subsequently be connected to Vienna's existing district heating network and operate as a baseload heat source for the city. The project is scheduled to enter operation in 2028.

The Aspern project is being developed by deeep, a joint venture established by OMV and Wien Energie, with OMV focusing on underground geology, drilling, and reservoir development, and Wien Energie responsible for surface heating facilities and connection to the city heating network. Drilling of three deep geothermal wells began in December 2024, and the main drilling work was completed in July 2025.

The Aspern project is also a demonstration project for Vienna's subsequent large-scale development of deep geothermal energy. Wien Energie plans to build up to 7 deep geothermal facilities in the urban area by 2040, which by then could provide geothermal heating for up to approximately 200,000 households. The company also plans to invest approximately 1 billion euros over the next 5 years to expand and decarbonize the district heating network, with geothermal energy, large-scale heat pumps, industrial waste heat, and waste incineration waste heat all included in the future heat source system.