Scottish Water is working in partnership with Veolia to make its Seafield wastewater treatment works more energy self-sufficient.
Since 2015, the resource management company has extended the plant’s ability to generate its own energy from 55 per cent to around 85 per cent.
It has achieved this by boosting the renewable energy derived from a combination of anaerobic digestion of sludge and biogas fired combined heat and power (CHP) plants.
Veolia said the plant, which is the largest treatment works in the east of Scotland, achieved “full self-sufficiency” at various points during 2017 when Seafield used no electricity from the grid.
A thermal hydrolysis process has further increased biogas production by around 10 per cent, while investment in an additional CHP unit and a further 3 per cent increase in the yield of biogas have also contributed.
Veolia said the Seafield plant has reduced its energy costs by 50 per cent. It treats waste for a population equivalent of approximately 850,000 people from Edinburgh and the surrounding area, which equates to 300 million litres of wastewater every day – enough to fill 121 Olympic sized swimming pools.
John Abraham, chief operating officer for water at Veolia, said: “Recent estimates indicate that the water industry could be self-sustaining for electricity by harnessing the 11 billion litre annual flow of waste water.
“Our application of technology to this process demonstrates how we can help deliver greater sustainability for the industry using waste water to energy systems, and also meet water industry carbon reduction targets.
“In this way we can make a significant contribution towards delivering renewable energy targets, while keeping the lights on and taking pressure from the National Grid.”
Veolia said more advanced technologies now mean biogas from all the available sewage could deliver an estimated 1,697GWh – enough electricity to power more than half a million homes.