Excavation of the new machine cavern at the Forbach hydropower complex in Germany’s Black Forest has been completed, Tractebel has confirmed. Crews removed 48,000 m³ of rock to create a cavern measuring 125m in length, 19m in width, and up to 42m in height.
Concrete work has now begun. A total of 15,000m³ will be poured to support installation of a pump turbine for the Schwarzenbach plant, rated at 53.4MW in turbine mode and 56.7MW in pump mode, as well as three 24.9MW Francis turbines for the Murg plant. All equipment will be located within the new underground hall along with associated auxiliary systems.
Tractebel is leading the planning consortium on behalf of EnBW Energie Baden-Württemberg AG, working with GEOCONSULT and Lahmeyer International. Since early 2025, the engineering teams have provided reinforcement and formwork plans for the cavern. Tractebel has been involved in the project since its launch in 2007.
The modernisation aims to bring the century-old Forbach scheme in line with current technical and grid requirements. Once commissioned in 2027, the upgraded facilities will expand Forbach’s hydropower capacity and add flexible storage and generation capability, supporting grid reliability and contributing to Germany’s broader energy-transition objectives.
