ANDRITZ has received an order from TIWAG-Tiroler Wasserkraft AG (TIWAG) to supply two motor-generators for the new Kühtai 2 pumped storage plant in Austria.
The scope of supply for ANDRITZ includes two variable-speed motor-generators, each with a rated output of 95 MVA, including auxiliary equipment. The generators will be connected to the grid via full-size converters and enable efficient and optimized operation within the defined head variations. Speed control is used both for controlling output in pumping mode and for extending the operating range in turbine mode.
The Kühtai 2 pumped storage plant is an extension of the existing Sellrain-Silz power plant group in the Längen Valley of the Tyrolean Stubai Alps and will be built completely underground in a cavern. The power plant group serves as a sustainable energy storage facility to cover peak loads and thus contributes significantly toward stabilizing the power grids and increasing security of energy supply.
Kühtai 2 and the new Kühtai reservoir will increase the generating capacity of the entire power plant group by 50%. Commissioning of Kuhtai 2 is scheduled for 2026.
Per the TIWAG website, the Kühtai storage power plant scheme covers the area of the municipalities of Silz, Umhausen, Längenfeld and Neustift im Stubaital. The main installations are located in Kühtai valley in the municipality of Silz. The proposed site of the new reservoir and new pumped storage power plant are at the back of Längental valley.
The new Kühtai reservoir will have an active storage capacity of about 31 million m3 and will be about half the size of the existing Finstertal reservoir. The dam will be an earth core rockfill dam with a height of 113 m (from the original valley floor to the dam crest). The full supply level will be at 2,140 m asl. The rockfill dam will be built of material extracted on site from the future reservoir or excavated waste from tunnelling activities. The downstream face of the dam will be landscaped with structural elements and natural rocks so that it will merge as well as possible with its surroundings.
The Kühtai 2 power plant with its headrace channel (a tunnel with a 5-m diameter) connects the new Kühtai reservoir and the Finstertal reservoir. The powerplant will be located in an underground cavern and is designed for pumped storage operation. The key components of the power plant are two reversible pump-turbines.
Power transmission is achieved by means of a short, underground 220-kV cable which is connected to the grid at the existing Kühtai power plant. A new high-voltage power line in the Inn Valley will not be required.
International technology group ANDRITZ offers a broad portfolio of plants, equipment, systems and services for the pulp and paper industry, the hydropower sector, the metals processing and forming industry, pumps, solid/liquid separation in the municipal and industrial sectors, as well as animal feed and biomass pelleting. ANDRITZ Hydro supplies electromechanical equipment and services for hydropower plants, with over 180 years of experience and an installed fleet of more than 470 GW output.