Scottish Water Horizons, a commercial subsidiary of Scottish Water, is driving the transition to a low-carbon economy by identifying and implementing innovative renewable energy projects across Scottish Water’s estate.
As part of Scottish Water’s strategic ambition to go ‘Beyond Net Zero’ by 2040, the company has been actively exploring new ways to generate clean energy. One of its latest groundbreaking projects has been the development of a hydropower scheme at Hamilton Waste Water Treatment Works (WwTW), an initiative that marks a pioneering step in the use of hydro technology within waste water treatment processes.
Neil Beaumont, Senior Development Project Manager at Scottish Water Horizons, highlights the significance of this project: “This is a truly innovative approach to hydropower generation within a waste water treatment environment. It not only optimises renewable energy potential but also showcases the possibilities for similar installations across the industry.”
A first of its kind for waste water hydropower
The Hamilton WwTW project is the UK’s first mid-process waste water hydropower installation, optimising energy potential from waste water flows. Unlike traditional hydropower projects that focus on raw or clean water sources, this scheme demonstrates that renewable generation opportunities exist even in less conventional areas of water treatment.
Additionally, it is Scotland’s first containerised hydropower installation, reducing construction emissions, cost and time while offering a scalable model for future installations across other waste water sites and even in industries such as petrochemicals.
Ian Piggott, Senior Delivery Project Manager at Scottish Water Horizons, said: “This is the first time a hydropower system has been installed mid-process in a waste water treatment works in the UK. It’s a significant milestone in demonstrating how we can recover renewable energy from waste water flows in a way that hasn’t been done before.”
Technical overview of the Hamilton Hydropower Scheme
Located in South Lanarkshire, near Glasgow, Hamilton WwTW serves approximately 57,000 people. The site features waste water treatment processes such as screening, grit removal, primary settlement, aeration, and final settlement before effluent returns to the River Clyde. The aeration tanks, which are relatively new, sit elevated above the rest of the site, offering a unique opportunity to capture energy from falling waste water.
The Hamilton hydropower project captures energy from waste water as it flows from the aeration tanks to the final settlement stage. A hydro turbine was installed at a location offering a head of 10 metres, extended to 11.5 metres with a draft tube, and an average annual flow of 432 litres per second.
The system generates 48kW of renewable electricity, which powers treatment processes on-site, reducing reliance on grid electricity and lowering carbon emissions.
Overcoming challenges and engineering success
Installing a mid-process turbine required careful integration to avoid disruption to site operations. To ensure seamless functionality, several safeguards were implemented:
- A level sensor was installed in the aeration tanks to ensure that water levels remained stable, preventing overflow or depletion.
- A bypass valve was introduced to allow flows exceeding turbine capacity to be redirected safely, ensuring seamless treatment operations.
- An automatic fail-safe mechanism was implemented so that if any mechanical issues arise, the bypass valve would immediately open, allowing uninterrupted flow to the settlement tanks.
Beaumont continued: “One of the biggest challenges was ensuring that the turbine integrated smoothly within the existing waste water treatment process.
By designing the system with built-in safeguards, we’ve ensured that it won’t impact site operations, even in variable flow conditions.”
An additional benefit of the project was the aeration effect created as waste water passes through the turbine. This process naturally oxygenates the effluent, reducing the amount of air needed in the aeration tanks, thereby further decreasing the energy demand of the treatment process.
Selecting the right turbine technology
Given the variable flow rates at Hamilton WwTW, which fluctuate between 300 and 1,200 litres per second due to weather and waste water loads, selecting the right turbine was critical. After careful evaluation, a Crossflow turbine from CINK Hydro-Energy was chosen for its ability to maintain efficiency across a wide range of flow conditions. The turbine is well-suited to waste water applications as it features a self-cleaning mechanism that reduces the risk of clogging from fine particles in the effluent.
A bleed valve was integrated at the pipework inlet to divert excess flow, ensuring continuous power generation even during exceptionally high flow conditions.
Beaumont said: “The Crossflow was the ideal choice because of its resilience in waste water environments and its ability to handle fluctuating flow rates efficiently. As the turbine has only three moving parts, it is an incredibly robust technology that ensures long term reliability with minimal maintenance.”
The turbine harnesses energy from waste water after it has undergone several treatment stages, including screening, grit removal, and aeration. At this point, the effluent contains reactivated sludge, which is denser than fully treated effluent and may enhance turbine power output.
To mitigate potential impacts from fine particles, turbine selection and design modifications were implemented.
Construction and installation process
The construction phase began in April 2023, with the removal of the existing flume in May. A temporary flume was installed to allow effluent to bypass the work area, minimising risks to workers. Following this, concrete sub-structures and tail-race works were completed to accommodate the turbine housing.
The existing pipework was retrofitted with a custom-designed ‘Y’ section, incorporating bypass and bleed valves to optimise flow management. A level sensor installed at the aeration tank outlet communicates with the turbine control system, adjusting the valves and turbine guide vanes to match flow conditions.
A key innovation in the project was the use of a pre-fabricated, containerised turbine house. Assembled off-site by CINK Hydro-Energy, this approach significantly reduced carbon emissions associated with construction and minimised time on-site. Once delivered, the container was crane-lifted into position, pipework was connected, and testing commenced. The turbine control system was calibrated to adjust automatically to varying flow conditions, ensuring optimal performance. The system was connected to the grid in November 2023 and has been generating renewable electricity since.
The future of small-scale hydropower in Scotland
The Hamilton hydropower project is estimated to generate 420,000 kWh of renewable electricity annually, offsetting approximately 14% of the site’s energy demand and saving around 64 tonnes of carbon emissions each year. This success underscores the potential for further hydropower opportunities across Scottish Water’s extensive network.
Beaumont added: “This project has proven that small-scale hydropower can be a valuable addition to waste water treatment sites. We’re now looking at how we can replicate this model at other locations to further support Scottish Water’s sustainability goals.”
The success of the containerised approach at Hamilton provides a blueprint for rapid deployment, reducing both capital expenditure and environmental impact. There is also scope to extend this concept beyond waste water assets, exploring applications in raw water treatment, industrial effluent management, and other sectors where significant water flows are present.
A collaborative effort
The success of the Hamilton hydropower scheme was made possible through close collaboration between Scottish Water Horizons and its supply chain partners. Key contributors included:
- FES Support Services Ltd – Design and project delivery
- Glen Hydro – Specialist hydro consultant
- Calforth Construction Ltd – Civil works
- Dustacco Engineering Ltd – Mechanical installation
- CINK Hydro-Energy k.s. – Turbine supplier
- Glenfield Invicta – Valve supplier
Conclusion
From initial concept to site commencement, the Hamilton hydropower project took approximately 21 months to deliver. This demonstrates the efficiency of the containerised approach, paving the way for faster delivery of future similar projects.
Piggott said: “We’re incredibly proud of what we’ve achieved at Hamilton. This project showcases what can be done when innovation and collaboration come together to deliver real, tangible benefits for sustainability.”
The project stands as a testament to Scottish Water Horizons’ commitment to decarbonising waste water treatment operations. As the company continues to explore and implement renewable energy solutions, the lessons learned from Hamilton will inform future projects, ensuring Scotland remains at the forefront of water industry decarbonisation.
Article by:
Neil Beaumont – Senior Project Manager; Ian Piggott – Senior Project Manager; Stuart Clark – Project Manager; and Steven Brasher – Specialist Graduate
