In a bold move toward energy transformation, the City of Vienna is embracing deep geothermal energy as a cornerstone of its climate strategy. At the heart of this initiative lies a joint venture between two of Austria’s most influential energy players: OMV, the international oil, gas, and chemical group headquartered in Vienna, and Wien Energie, the city's primary municipal utility provider. The partnership, named "deeep," is more than just a play on words it reflects a serious commitment to fundamentally rethinking the city’s approach to district heating.
The objective is straightforward yet ambitious: to harness the Earth’s natural heat by drilling thousands of meters underground and using the extracted thermal energy to supply Vienna’s expansive district heating network. Currently, this network is one of the largest in Europe, serving over 400,000 households. Traditionally powered by a combination of natural gas, waste incineration, and biomass, the system is now shifting toward non-combustion-based solutions. Deep geothermal energy—whereby hot water from subsurface reservoirs is extracted and used directly for heating—offers a particularly compelling path forward. Unlike solar or wind, geothermal energy is unaffected by weather or seasonal changes, making it highly reliable as a base-load source of urban heat. By integrating geothermal energy into this infrastructure, the city aims to reduce its dependency on gas and take a significant step toward meeting its climate-neutral targets by 2040.
The first phase of the project focuses on a pilot geothermal plant in Aspern, a rapidly growing district in Vienna's Donaustadt area. Preparations at the site are already underway, and drilling is scheduled to begin in late 2024. The plan includes drilling three wells, each reaching a depth of about 3,000 meters, into a geothermal reservoir expected to deliver water at temperatures near 100 degrees Celsius. This high-temperature water will be brought to the surface and transferred through a heat exchanger system directly into Vienna’s district heating grid.
Once operational, the pilot plant is expected to produce enough thermal energy to heat approximately 20,000 households. If the pilot proves successful, this model could be scaled up across the city. The ultimate goal is to build up to seven geothermal plants, which would together provide heat for around 200,000 households. This would make it one of the largest urban geothermal heating projects in Europe and could serve as a blueprint for other cities aiming to reduce their reliance on imported fossil fuels while significantly lowering CO₂ emissions.
What sets this project apart from earlier geothermal efforts in Austria is not just its scale but its depth and technological sophistication. The site will demonstrate that deep geothermal systems can be deployed safely, efficiently, and economically in densely populated urban areas, even those with aging energy infrastructure. The system incorporates advanced drilling technologies, 3D seismic subsurface modelling, and real-time monitoring to manage reservoir pressure and temperature. Much of this technology has been adapted from the oil and gas industry and repurposed for renewable heating applications.
Vienna’s geothermal expansion is part of a broader European trend. The European Commission has named deep geothermal energy a key element of its REPowerEU plan to reduce reliance on imported gas and accelerate the green energy transition. Austria’s national climate action strategy also supports geothermal development through funding initiatives and streamlined permitting. Locally, the City of Vienna has embedded geothermal expansion into its climate action roadmap, supported by both municipal and federal subsidies and regulatory frameworks.
Internationally, the project has attracted the attention of organizations like the World Economic Forum, which have cited Vienna’s geothermal initiative as a leading example for other European cities. With increasing geopolitical and environmental pressures, geothermal energy is gaining momentum as a reliable and renewable heat source for urban areas. Given its technical ambition, urban setting, and innovative public-private structure, Vienna’s initiative stands as one of the most advanced efforts to scale geothermal energy in Europe.