The potential of geothermal energy increases the further down a project goes, allowing it to access hotter resources.
According to the International Energy Agency in its ‘The Future of Geothermal Energy’, the technical potential for geothermal electricity at depths of less than 5,000 m is an estimated 42TW of power capacity over 20 years of generation, while potential at 5,000-8,000 m exceeds 550TW.
Beyond the greater output potential, it should also be noted that there are few countries with favourable geothermal conditions to effectively harness high-temperature heat for electricity generation at a depth of 2,000 m. However, the IEA noted, the conditions for geothermal electricity generation typically become more widely plentiful at greater depths. Almost every region has technically suitable resources beyond 7,000 m.
It is, therefore, imperative that the sector seeks to unlock the true power of geothermal by accessing sources only found in the depth of the earth. In Vienna, a project is being currently undertaken to do just that.
A pioneering project in Vienna
Drilling has begun for the first deep geothermal plant in the city for a project expected to supply 20,000 Viennese households with sustainable heat. This goal has been set by deeep, a joint venture between OMV and Wien Energie, and will see drilling at a depth of more than 3,000 m in order to tap a natural hot water reservoir, the ‘Aderklaaer Konglomerat’. This water formation is located in a water-bearing rock layer and has a temperature of around 100 degrees Celsius.
Now begun at Aspern (Vienna-Donaustadt), the project is regarded as an important milestone on the way to a climate-neutral heat supply for Vienna. The plant in Vienna’s 22nd district will feed into the city’s district heating network and is being delivered off the back of a planned investment of approximately EU€90mn. Three wells will be drilled for the pilot plant in Aspern and are planned to be completed in mid-2025 before final completion of the plant in 2028. These include a pilot well for exploration, maintenance and protection, a production well and an injection well for the return of the cooled water.
“Vienna is particularly fortunate because it sits on top of a large heat reservoir – and after years of research and planning, we are now going derive its benefit,” explained Wien Energie Managing Directors Michael Strebl and Karl Gruber. “With the first deeep geothermal plant for Vienna, we will generate even more climate-neutral district heating. As we will be less dependent on gas imports, this will contribute to security of supply and price stability.”
OMV, which published a press release when drilling began in December, explained that deep geothermal can play an important role in the city’s carbon-neutral heat supply (targeted for 2040). This plant will serve as the basis for further expansion.
“Just like the mountain spring water pipeline or the Danube regulation were in their times, the development of deep geothermal energy is a project of the future that will contribute to the quality of life in our city for well over a hundred years,” remarked Peter Hanke, City Councillor for Economic and Financial Affairs and Wiener Stadtwerke. “This deep geothermal plant is a forward-looking project that sets an example for our city. We are not only generating energy, but also strengthening our supply independence and our economic position.”