Scientists from UK utility Thames Water, in partnership with the University of Surrey, have ‘perfected the art’ of transforming sewage into green electricity at peak times.
The UK uses the most power between 4pm and 7pm, when many families are at home using energy-hungry appliances like ovens, dishwashers and kettles. At this time of day, particularly during the autumn and winter, electricity prices rocket in line with the increased demand.
Thames Water worked with sustainability experts at the University of Surrey on a four-year project to boost the production of biogas from sewage, which can then be used to generate enough green electricity to power its sewage treatment sites during this peak period.
The innovation lies in how sewage sludge is fed into special digesters where anaerobic digestion takes place. Historically, the same amount of sludge was fed in at regular intervals, but specific feeding regimes were designed to increase the biogas production rate between 4pm and 7pm, when the electricity prices are higher than at other times.
Not having to import green power at this time of day means there is more available for everyone else. It also reduces Thames Water’s energy bills.
It is hoped the new science will be adopted industry-wide, contributing to the decarbonisation of the national grid by 2035. Thames Water aims to reach net-zero emissions by 2030 – 20 years before the UK Government target and to be carbon negative by 2040.
“We get all our electricity from renewable sources, but wind and solar can’t always guarantee to produce enough to meet everyone’s demand, especially at peak times,” said Mauro Lafratta, of Thames Water’s energy performance and change team, who led the project while an engineering student.
“Our research proved we can produce more biogas in peak periods to generate electricity when the grid’s prices and carbon emissions peak. This solution can significantly reduce our operating costs, and help the country achieve carbon neutrality. This means better financial and operational resilience, better environmental protection and a better service for our customers.”
The research was trialled at Thames Water’s Beddington sewage works in Croydon and is now standard practice at the site. If rolled out industry-wide, it will help make the UK’s electricity supply cleaner, greener, and more resilient at peak times.