| Tunnelling


ensuring safe and efficient excavation. Beyond the mechanical complexity, challenges often emerge from unpredictable geological conditions. Dr.-Ing. Karin Bäppler, Head of Business Development at Herrenknecht, explained: “For tunnels, exploratory drilling is done during the planning phase, but unforeseen ground conditions can still arise. In such cases, we stabilize the TBM’s path by injecting special materials into the rock.” These cutting-edge solutions enable Herrenknecht


to deliver on projects even in the toughest terrains. The Snowy 2.0 hydropower project in Australia is another example of Herrenknecht’s ingenuity. For this initiative, the back-up platforms of the TBM were specially designed to tilt, ensuring stability and functionality while constructing an inclined pressure shaft. Unpredictable geology is an ever-present challenge in tunnelling. Fault zones – areas where rock formations have undergone structural changes – can pose serious risks. However, Herrenknecht’s team employs advanced injection techniques to stabilize problematic geology. These innovations reflect the company’s commitment to ensuring both safety and project success. “Such a steep incline of a 42-degree slope poses


extreme challenges for the machine and therefore the whole team,” Wiedemer reiterated. His statement underscores the intricate interplay of engineering and teamwork that defines these ambitious hydropower projects.


Hydropower: a green energy


mainstay Ambitious hydropower projects like Limberg 3 underscore the global urgency to expand renewable energy sources. Herrenknecht’s work on hydropower projects is nothing new. In Ecuador, the Coca Codo Sinclair waterworks, operational since 2016, provides 30% of the nation’s electricity. This massive facility features two 9.11m diameter Double Shield TBMs, which excavated nearly 25km of inlet tunnels. The project’s 1,500MW capacity underscores hydropower’s potential to transform national energy grids. Austria, where Limberg 3 is under construction, is another leading example. The Alpine nation already generates 67% of its electricity from hydropower and is pushing for climate neutrality by 2040. Limberg 3, with its steep pressure shaft and innovative design, represents a significant step toward that goal. Once operational in 2025, it will join the Kaprun power plant group, contributing to grid stability and renewable energy storage. Not every project involves massive infrastructure. In Italy’s Val d’Astico, Herrenknecht’s HDD Trailer Rig installed an 8-inch pipeline for a small hydropower plant, overcoming a 450-meter elevation difference over nearly a kilometer. These diverse projects – from vast tunnels to compact installations – highlight the versatility and importance of hydropower in the global energy transition.


The future: green power banks Hydropower’s appeal lies not just in electricity


generation but also in its potential for energy storage. Pumped storage power plants like Limberg 3 double as green power banks.


In the Kaprun Valley, this concept has been in action for nearly 70 years. Limberg 3’s steep pressure shaft, built with Herrenknecht’s TBM, adds a new dimension to this storied tradition. The plant’s two 240MW turbines will produce electricity for thousands of homes, helping Austria meet its renewable energy targets. Visitors to the Kaprun Valley can experience this engineering marvel firsthand. A thrilling via ferrata climb along the dam wall offers views of turquoise reservoirs and lush alpine landscapes. As they ascend, they witness not just the beauty of nature but the innovative efforts to secure a sustainable energy future.


Ambitious hydropower projects


worldwide Hydropower projects are becoming increasingly ambitious in response to the global push for renewable energy. The European Union, for example, aims to achieve climate neutrality by 2050. Projects like Limberg 3 are part of a broader movement to expand renewable energy infrastructure, driven by the Paris Agreement and the urgent need to combat climate change. From 2009 to 2011, Herrenknecht’s Double Shield


TBM excavated a 12.4km inlet tunnel for the Palomino hydropower station in the Dominican Republic. Operational since 2012, this 80MW facility highlights the global reach of Herrenknecht’s expertise. Meanwhile, the Coca Codo Sinclair project in Ecuador serves as a case study in hydropower’s transformative potential. By producing 30% of Ecuador’s electricity, the facility has reduced the nation’s reliance on fossil fuels and significantly cut greenhouse gas emissions.


Driving the energy transition Hydropower’s role in the global energy transition


cannot be overstated. Projects like Limberg 3 and Coca Codo Sinclair demonstrate the scale and impact of this renewable energy source. From large-scale installations to smaller initiatives like Val d’Astico, Herrenknecht’s technology is enabling countries worldwide to meet ambitious climate targets. Dr. Bäppler’s observation captures the essence of this movement: “We notice that projects are becoming more ambitious because renewable energy sources urgently need to be expanded if the global climate crisis is to at least be mitigated.” As the world moves toward a sustainable future,


hydropower’s ability to provide clean energy and storage solutions will remain essential. With new tunnelling innovation, the possibilities are as vast and varied as the landscapes these projects traverse.


Mooserboden Reservoir


Inlet tunnel


Above: A twin anti-slip system with full redundancy of the gripper levels reliably prevents the Gripper TBM for Limberg from slipping back


Below: With a capacity of 900MW, Nant de Drance is one of the most powerful pumped storage power plants in Europe. It plays an important role in stabilizing the European power grid and ensuring security of supply in Switzerland


Below: Tunnels for Limberg III


Pressure tunnel


Surge tank


Wasserfallboden Reservoir


Pressure shaft


Slide chamber TBM advance


Power cavern


www.waterpowermagazine.com | January 2025 | 21


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