TIWAG expects to complete its €1.13bn Kühtai 2 pumped storage project in Tyrol, Austria, in summer 2027, with commissioning underway at the underground powerhouse and trial impoundment progressing at the new Kühtai reservoir.
The 190MW project is being developed as an expansion of TIWAG’s Sellrain-Silz hydropower complex. Around five million cubic metres of water has already been impounded in the new reservoir, which will have a usable storage volume of 31 million cubic metres.
According to TIWAG, the additional reservoir will increase the complex’s total storage capacity by approximately 50%.
“With our expansion project in Kühtai, we are increasing Tyrol’s energy independence and creating additional storage capacity. The project is one of the most important energy infrastructure projects in our state,” said TIWAG Managing Director Alexander Speckle.
Additional water transferred to Kühtai through a diversion tunnel is expected to support the generation of around 216GWh of renewable electricity annually.
Trial impoundment began in mid-June 2026 and is being undertaken in 20m stages. Each stage is followed by a stabilisation period of around six weeks, during which the reservoir level is held constant and monitoring data is assessed before the next stage begins.
The dam, foundation and reservoir will be closely monitored throughout the 18-month trial impoundment programme.
“The results so far meet our expectations. The impoundment programme is proceeding according to plan and confirms the high quality of the construction work carried out,” said TIWAG Project Manager Klaus Feistmantl.
The project’s diversion tunnel was completed in April 2026, while construction of its six water intakes was completed during the summer. Commissioning of the three intakes in the Sulz Valley is underway, with the three Stubai Valley intakes scheduled to enter operation by the end of September.
TIWAG said water withdrawals would be limited to environmentally sustainable levels, with no abstraction during winter.
The Kühtai 2 powerhouse has been constructed entirely underground in a rock cavern and contains two reversible pump-turbine units with a combined installed capacity of 190MW. The units will generate electricity in turbine mode and return water to the higher Finstertal reservoir when operating in pumping mode.
“This technology enables particularly flexible and efficient operation and is an important component for integrating renewable energies from wind and photovoltaics into the electricity grid,” Feistmantl said.
Testing under operating conditions has identified an irregularity in one of the units that damaged generator components. TIWAG and the specialist contractors involved are conducting a root-cause investigation.
Feistmantl said the necessary repairs were not currently expected to affect the planned summer 2027 completion date. Work on the second unit has been brought forward and is progressing to schedule.
