Energy Recovery from a
Waste Water Treatment Works

Containerised hydro-electric plant proposed for a waste water treatment facility in Scotland

As featured in the British Hydro Association magazine, July 2022

Scottish Water, Scotland’s publicly owned water utility, has pledged to reach net zero operational emissions by 2030. As Scotland’s biggest user of energy that’s no mean feat.

More than a billion litres of fresh water are delivered to homes and businesses, with another billion litres of treated waste water released into the environment each day. The distribution of these vital services require energy – and lots of it.

In a bid to further reduce the carbon impact of its operational activities, Scottish Water is taking the unusual step of installing a hydro turbine within one of its waste water treatment facilities.

The company has already made tremendous strides in decarbonising its asset base through smart and innovative technologies. Its subsidiary, Scottish Water Horizons, is spear-heading renewables and low carbon initiatives which include facilitating the UK’s first heat from waste water scheme in the Scottish
Borders.

Containerised hydro plant at the ‘mid-process’ stage

Horizons’ latest low carbon innovation is to install a containerised hydro-electric plant ‘mid-process’ at a waste water treatment facility.

Neil Beaumont, Horizons Hydro Energy Team Lead, said: “Scottish Water has a vast array of land, property and operational assets that offer enormous potential when it comes to renewables. To achieve our green energy ambitions we need to be open to fresh ideas and be bold in our delivery.

“We believe it will be the first containerised hydro scheme to be installed ‘mid process’ in such a facility in the UK”

Neil Beaumont, Horizons Hydro Team Leader

“That’s why we’re taking the novel approach of installing a hydro-electric generator within the pipeline of a waste water treatment plant. Up until recently all previous hydro efforts have concentrated on the water side of the business. With 33,000 miles of sewer pipes operating across Scotland 24 hours a day, there is massive opportunity to harness energy potential.

“Our upcoming hydro-electric project is a culmination of months of research. We’re looking at a containerised solution as well as traditional site construction. We believe it will be the first containerised hydro scheme to be installed ‘mid process’ in such a facility in the UK. Our approach has been very much based on the lean principles of ‘minimum viable product’ which includes minimising capital and carbon expenditure whilst maximising energy recovery.

Innovative scheme to be installed in Hamilton

“The innovative scheme which will be located in Hamilton, South Lanarkshire is expected to come on-stream in 2023. It is projected to generate 0.28GWh of green electricity each year and offset 10 per cent of the treatment works annual electricity demand. In addition to aiding the treatment process, it is also
expected to cut carbon emissions by around 55 tonnes each year.

Neil continues: “To further support our programme’s ethos we are being carbon conscious when constructing assets, reusing and repurposing where possible. In the case of the Hamilton site, we will reduce construction emissions by selecting a prefabricated solution that can be manufactured off-site and shipped pre-commissioned. This will enable the turbine to be installed within an existing decommissioned primary settlement tank on site.

The hydro-electric turbine is supplied from the flow to final settlement pipework located towards the south west of the works, within Scottish Water owned grounds. The turbine house will be largely screened from view by vegetation and layout of the site.

Neil adds: “This project has generated lots of interest from internal and external stakeholders with many acknowledging this as a novel approach. As we progress on our journey towards net zero emissions, we expect more opportunities to present themselves on waste water assets so that we can realise even
greater potential.”

The scheme will be delivered by local contractor FES and will join a portfolio of almost 80 water and waste water treatment works which are now either self-sufficient or partly sufficient in generating their own power requirements