Der The newly commissioned large volume buffer storage tank by EnergieWerk Ilg GmbH, boasting a storage capacity of around 313 MWh, serves as a showcase project demonstrating advanced construction techniques and the integration of large-scale heat accumulators within sustainable energy systems.
EnergieWerk Ilg GmbH operates several biomass heating plants in Dornbirn to produce both heat and electricity. The heat is fed into the local heating network operated by VKW Nahwärme Dornbirn. As the network continues to expand, both the heat demand and the requirements for peak load coverage are increasing. The existing heating plants operated by EnergieWerk Ilg GmbH have little remaining capacity, which is why the construction of a new heating plant and a large volume buffer storage tank in Dornbirn-Wallenmahd was planned.
The large-scale heat accumulator has been operational since May 2025 and uses water as its storage medium. With a volume of 5,900 m³, a height of 30 metres and a diameter of 18 metres, new standards have been set in tank construction. The integration of the heat storage system enhances security of supply and minimises the use of fossil fuels for balancing peak loads. Additionally, waste heat from the neighbouring industry can now be utilised. Surplus heat from other plants as well as from the company’s own biomass heating plants is temporarily stored and fed into the network as needed.
In addition to its role as a heat storage system, the tank will also serve as the central pressure maintenance system for the entire local heating network, further enhancing system stability. The project therefore plays a crucial role in advancing a sustainable, circular and efficient heat supply for the region.
Storage system medium: Water
Storage system volume: 5,900 m³
Max. energy capacity: 313,000 kWh
PV surface area: 1,270 m²
PV capacity: 250 kWp
This project is funded by the Climate and Energy Fund under the programmes “Large-scale storage systems” and “Flagship PV projects”.
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