German energy company EnBW hosted a ceremonial tunnel groundbreaking event late last month, signifying the official commencement of tunnel and mining work at the Forbach pumped storage project in Germany. The event, held at the Rudolf-Fettweis Plant, was attended by representatives from state and local governments, as well as the executing companies.

This ambitious project aims to convert and expand the Rudolf-Fettweis-Werk in Forbach, located in the Northern Black Forest, into a pumped storage power plant. This transformation necessitates the removal of many thousands of cubic meters of granite from the mountain to accommodate the modern facilities and enhance the capacity of the extensive water and energy storage facility.

ANDRITZ, a key partner in this project, will deliver and install a 50MW pump turbine along with three Francis turbines (13, 7, and 3MW), with the commissioning set for the summer of 2027.

In July 2023, construction company Porr announced it had secured a major contract to construct the caverns and a tunnel system as part of the Forbach pumped storage project. EnBW Energie Baden-Württemberg AG, the project’s investor, is committing approximately €280 million to the conversion, with Porr awarded Lot 2 “Civil works” valued at €98.3 million.

The run-of-river power plant, protected for its historical significance and dating back to 1914, played a vital role in the electrification of the northern Black Forest. Its conversion into a pumped storage power plant is anticipated to significantly enhance its efficiency. Previously, water from the Schwarzenbach and Murg dams flowed into an equalization basin and then into the Murg after passing through the turbines. The new plan includes constructing an underground sub-basin to act as an indirect power reservoir, allowing water circulation for electricity generation.

Lot 2 includes constructing caverns, water reservoirs, and tunnels using the mining method. Porr will also handle the shell construction of the power plant cavern, the construction of two pressure shafts, and foundation engineering work. Before the new power plant can begin operations in 2027, the Porr team will undertake the challenging task of blasting and excavating significant cavities and tunnels in the rock, yielding an estimated 450,000m³ of rock excavation material.

The tunnel system within the project will have a total length of 5200m, and approximately 510m of shafts will be constructed using the raise-boring method. The underground water reservoirs will have a combined volume of 200 million liters. The main tunnel will stretch 946m in length and have a cross-section of up to 71.72m². Additionally, the project involves constructing six side tunnels, access tunnels, supply tunnels, and tunnels for energy transmission.