Replanting a 1933 hydropower plant

Tummel Bridge Power Station Retrofit and Renovation

Perthshire’s iconic Tummel Bridge Power Station opened in 1933 and generated renewable electricity for almost 90 years. Following one of the largest ever investments in its hydro fleet, SSE Renewables (SSER) set out to complete a £50 million refurbishment on the asset. They commissioned our team to investigate replanting and replacing the turbines and generation units.

During the review process, we developed a deep understanding of the powerhouse structure—a Category A listed building with special architectural or historical interest. By creating a 3D model of the substructure, we could analyze the turbines’ arrangement, interface with the rock, and how the hydraulic thrust could be restrained without disturbing more of the site than was strictly necessary. We considered multiple options and arrangements at the technical concept level and integrated input from both SSER and the supply chain, including a turbine supplier.

The final design included contract specifications that split the replanting works into two phases. It also incorporated the placement of concrete within the power station as a thrust block. This enabled the foundations to support the full load from the turbines and reduce reliance on the original 1930s steel penstocks.

Construction started in 2022 and included replacing the station’s two original ‘Camel Back’ twin-runner, horizontal Francis hydro turbines with new modern runner technology.

Retrofitting these existing energy assets with modern, highly efficient equipment, rather than rebuilding them, added value for SSER and the communities they serve, both in terms of project costs and carbon reduction. An important part of its local history, culture, and Scottish innovation, Tummel now operates at an increased installed capacity of 40 megawatts (up from 34) in optimum conditions. By extending the station’s operational life, the preserved structure will continue contribute to Scotland’s net zero targets and support the local community with reliable hydropower for at least another four decades.