| Spotlight
approach. At first it seemed like a setback, but in the end, it helped us refine the project to make it more commercially viable. By slightly reducing the turbine size, we were able to accelerate the project timeline while maintaining strong energy generation potential.”
The siphon-fed hydro system At its core is a 199kW Ossberger Crossflow turbine,
housed in a powerhouse at the base of the dam. Water is drawn through a submerged intake, lifted over the dam via the siphon system, and then directed through the turbine - generating clean electricity before flowing into the Hungry Snout Pumping Station. Beyond energy generation, the siphon system enhances reservoir compliance by increasing drawdown capacity – a critical requirement under SEPA (Scottish Environment Protection Agency) regulations. This eliminates the need for a separate multi-million-pound infrastructure project, making it a cost-effective solution. Clark adds: “This is a completely new way of implementing hydropower on an operational reservoir. Traditionally, increasing reservoir drawdown capacity would require a separate capital project, often costing millions. By integrating smart controls with the siphon system, we’ve created a solution that not only ensures compliance with reservoir regulations but also maximises renewable energy generation.”
A sustainable solution Beyond financial savings, the scheme will also deliver
substantial environmental benefits. The hydro turbine is expected to generate 820,000 kWh of renewable electricity per year, offsetting 30% of the Hungry Snout Pumping Station’s energy demand and reducing carbon emissions by 111 tonnes of CO2
annually. Alan Mearns, Delivery Project Manager with Scottish
Water Horizons, says: “This project is about much more than just generating renewable electricity. It’s about delivering a solution that makes economic sense, enhances infrastructure resilience, and supports long- term sustainability goals. By optimising how we use our existing assets, we’re not only reducing costs but also making a significant progress towards Scottish Water’s commitment to net zero.”
Construction & commissioning Construction at Whiteadder Reservoir began in August
2023, starting with site access, temporary tracks, and key infrastructure installation. A major engineering challenge was laying the
penstock pipeline up the dam face, requiring precise excavation and installation on steep terrain. A specialist diver team was brought in to carry out the work under carefully controlled conditions, ensuring safe installation of the submerged intake without impacting water quality. With the pipeline in place, the Ossberger Crossflow turbine was delivered and installed by Emtec Energy, working in partnership with Dulas and Ossberger GmbH. Commissioning followed a rigorous process, including pipework pressure testing, valve function checks, and both electrical and mechanical commissioning of the turbine system. The project also underwent grid accreditation (G99 compliance) and a 14-day reliability testing period, ensuring seamless integration into Scottish Water’s infrastructure. Following successful commissioning, the system
was transferred to Scottish Water for long-term operation and maintenance. “From concept to completion in just over three years, this project demonstrates how complex hydro schemes can be delivered at pace,” Mearns reflects on the project’s success. “What’s even more exciting is that it’s a replicable model - one that could unlock further hydropower opportunities across Scotland.”
Shaping the future of renewable energy The Whiteadder Reservoir hydro project marks a major
milestone for Scottish Water, proving that siphon-fed hydro systems can be successfully integrated into an operational reservoir without disrupting the public water supply. Now fully operational, the scheme is set to deliver long-term benefits including reduced energy costs, lower carbon emissions and enhanced infrastructure resilience.
Building on this success, Scottish Water Horizons
is already exploring other hydropower opportunities across its asset base, using Whiteadder as a model for future projects. As Clark sums up: “We are constantly looking for
ways to use our assets to generate renewable energy. The Whiteadder project is just the beginning - we are fully committed to developing innovative solutions that contribute to Scottish Water’s and Scotland’s sustainability goals.” By combining smart technology with innovative engineering, Scottish Water Horizons has demonstrated a scalable and cost-effective approach to integrating hydropower into critical infrastructure. As the UK accelerates toward net-zero, projects like this highlight the untapped potential of existing assets – proving that even long-established infrastructure can be reimagined for a greener future.
Key innovations of the siphon-fed hydro system
Siphon-fed design - eliminates the need for major civil works on the dam, reducing environmental and financial impact.
Smart-controlled turbine - maintains reservoir levels while optimising energy generation.
Europe-first approach - demonstrates a pioneering method for integrating hydropower into operational reservoirs.
Above: Siphon and priming unit
Above: Aerial view of the turbine house
Below: Inside the turbine house
www.waterpowermagazine.com | May 2025 | 11
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