United Utilities engineers at Davyhulme wastewater treatment works have taken delivery of a fleet of electric vehicles which will run on power generated by the plant itself.
It’s all part of a drive by the water company to cut carbon emissions at the Manchester treatment works – one of the biggest sewage plants in the UK.
The new electric ‘Polaris’ vehicles are replacements for five diesel vans. Each vehicle will be able to charge up at its own docking station at Davyhulme’s award-winning sludge recycling plant.
Davyhulme area business manager, Keith Haslett, explained: “Davyhulme is a vast site and our engineers need transport to get around. By taking the diesel vans off the road we’ll save around five tonnes of carbon a year.
“What’s more, with a top speed of 15 mph the electric cars mean we have to stick to the site speed limit, helping improve health and safety.”
Davyhulme wastewater treatment works is United Utilities’ biggest plant and will be energy neutral by 2018, thanks to the electricity generated on site from the biogas produced by the sludge digestion process.
The biogas is used in five combined heat and power engines to generate renewable electricity – up to 80GWh per year. Purchased at current electricity prices, that volume of electricity would have cost over £6 million – the equivalent of the needs of 25,000 homes.
The electricity is retained on site and used to power the entire Davyhulme wastewater treatment works process – one of the largest works in the UK – and it means the site is now nearly energy neutral. The sheer amount of renewable energy being generated by the process has helped United Utilities to reduce its overall carbon footprint by 19 per cent since 2005/06.
Keith added: “We’re always looking at ways to maximise the value we can get from sewage sludge.
“It might have been considered a waste stream at one time, but now we call sludge ‘black gold’. Already we use our digestion gas to generate around £6 million of our own electricity a year – enough to power the entire works. It makes perfect sense to use this to power our transport as well.”
