Vienna's first deep geothermal energy plant: green water from 3,000 meters!

Vienna's first deep geothermal energy plant: green water from 3,000 meters!

On August 25, 2025, a significant step was taken in Vienna's energy supply: in a deep geothermal energy test, the companies OMV and Wien Energie pumped hot water from a depth of 3,000 meters for the first time. With a temperature of around 100 degrees Celsius, this project offers promising approaches to climate-neutral heat supply.

The deep drilling for Vienna's first geothermal energy plant was successfully completed in July 2023. The water that is now pumped to the surface is used to examine the temperature, chemical composition and flow rate. The production test on the first well takes about a week, while up to 3,400 cubic meters of water will be pumped.

Green heat for the future

The plan is to supply around 20,000 households in Vienna with this green heat by 2028. Funding is provided by various institutions, including the Ministry of Climate Protection, the Climate and Energy Fund and the European Investment Bank. Wien Energie has the ambitious goal of building several deep geothermal energy systems by 2040 and thus supplying up to 200,000 households with climate-friendly district heating.

The planned total output of these systems should be around 200 megawatts. A “loop test” is currently being prepared for the winter of 2025/26 to test the return of the pumped-out water. The results of these test phases, both the funding test and the loop test, are expected in spring 2026—an important data base for future planning.

The project at Seestadtstraße 17 in 1220 Vienna was launched by the joint venture “deep” between Wien Energie and OMV. The investment amount for the entire project is around 90 million euros, and work began in 2017.

Energy rethought

The use of deep geothermal energy could help not only Vienna, but also other cities to have more sustainable energy supply systems. As the Federal Ministry of Research, Technology and Space explains, deep geothermal energy has great potential to deliver climate-neutral energy. It is base load capable, renewable and could significantly reduce dependence on fossil fuels.

Geothermal energy enables the sustainable supply of heat to urban areas and could make a significant contribution to meeting climate goals. However, currently less than 1% of the heat generated from renewable sources in Germany comes from deep geothermal energy. The development of appropriate technology and concepts is therefore essential in order to further expand the advantages of this form of energy.

In Vienna, preparations for the transformative role of deep geothermal energy are well advanced, which is reflected in the ambitious plans and the implementation of the first test funding. Interested citizens can find out more about the project in the information center on the plant site and follow the future development of sustainable heat supply.

Further information about this innovative project can be found in the reports from Vienna.gv.at, World voice and BMFTR.