As part of the ATES Vienna project, Wien Energie investigated the potential of aquifer storage systems for integration into Vienna’s district heating network. This innovative technology makes use of thermal water reservoirs located at depths of 600 to 3,000 metres, which are unsuitable for use as drinking water.
Similar to geothermal systems, ATES systems consist of one or more production and injection wells. The key requirement is an underground layer of water-bearing rock or sediment, which serves as a heat accumulator. These aquifers are located over a 1,000 metres below ground in the Vienna region and remain completely isolated from both the surface and groundwater.
Closed-loop system
To store the heat, the thermal water is brought to the surface through a production well and heated there using a heat exchanger. Through another well, known as the injection well, the heated water is returned underground and stored. This creates a closed loop, which operates in reverse during the cold season: when heat demand is higher in winter, the heated water is pumped back to the surface. At the surface, the thermal energy can be extracted and fed into the district heating network, while the cooled water is returned underground.
Within the ATES Vienna1 project, the groundwork for developing a high-temperature aquifer heat storage system was established, alongside an exploration of opportunities to integrate these storage solutions into Austria’s district heating sector.
Technologies for urban living spaces
Due to their minimal surface footprint, this storage system solution is particularly attractive for cities where available open space is limited. Alongside specific geological conditions, the presence of suitable energy sources for storage systems and a matching heat demand in the local area are vital. A district heating network or manufacturing companies would be ideal consumers. In contrast to deep geothermal energy, this technology remains largely underutilised today. Although ATES storage systems have been implemented in select international cases, the Austrian project takes a leading role in advancing research on this innovative concept.
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1 Project partners: Wien Energie (project management), GeoSphere Austria, Geo5, Heinemann Oil, AEE INTEC, AIT Austrian Institute of Technology
The ATES project is part of the Green Energy Lab innovation network.
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