HPP Jettenbach-Töging: revitalizing a century of hydropower heritage

First hydroelectric power station built on the River Inn

Situated along the River Inn in Upper Bavaria, Germany, the Jettenbach-Töging hydropower scheme has an incredibly rich history. When originally completed in 1924, it was the first hydroelectric power station built on the River Inn, originally purposed to generate electricity for an aluminium plant in Töging. However, to meet the demands of a modern power grid and maximize the river's potential, VERBUND Innkraftwerke GmbH initiated a massive revitalization project.

This complete rebuild involved an investment volume of around €250 million, making it Germany's largest hydropower project in recent years. Litostroj Power was selected as the manufacturer for the massive new turbines.

The challenge: honoring the rast while building the future

Replacing a historic, century-old energy infrastructure is never a simple task. The project encompassed the complete rebuilding of the weir in Jettenbach and the machine house in Töging. Crucially, each of these new structures was built right next to the original listed, heritage-protected structures.
The engineering and delivery teams faced several distinct challenges:

• Several plant expansion options were considered, including adapting the original machine building, but this was rejected because it would have severely limited plant availability for years and caused massive power generation losses.
• The concrete seal of the roughly 20-km diversion channel, originally installed between 1919 and 1924, had to be raised by 70 cm to accommodate the required rise in the reservoir head.
• The transition needed to ensure that the maximum hydro-potential of the canal was utilized, significantly increasing the overall energy output compared to the historic, outdated units.

A modern keyturn evolution

To meet these demands, a comprehensive mechanical solution replaced the 15 original Francis turbines that previously populated the powerhouse.
The core of the delivery focused on advanced Kaplan technology:

• Litostroj engineered and supplied three identically built, vertical Kaplan turbines, designed for a maximum water flow capacity of 136.7 m³/s.
• These turbines feature adjustable runner blades and guide vanes, enabling them to double-regulate.
• This flexibility allows the system to achieve maximum efficiency across a wide range of flow rates, even when dealing with a reduced water supply.
• The new 6-blade impellers were manufactured from high-grade stainless steel to ensure longevity and peak operational performance.

Conclusion

The plant commissioning ceremony was held on September 30, 2022, marking a major milestone in European hydropower modernization. By consolidating the plant's generation into three highly advanced Kaplan units capable of producing roughly 700 GWh annually, the project perfectly showcases how state-of-the-art hydraulic engineering can breathe new life into historic infrastructure.