Scientists are working on a project to use biogas from sewage to meet peak electricity demand in London, in an approach that could be adopted across the water industry.

The UK uses the most power between 4pm and 7pm, when many people are at home using high-energy appliances like ovens, dishwashers and kettles. At this time of day, especially during autumn and winter, electricity prices rocket in line with the increased demand.

Now Thames Water is working 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. Not having to import green power at this time of day means there’s more for everyone else and Thames Water’s own energy bills are reduced - savings that can benefit customers.

The research was successfully trialled at Thames Water’s Beddington sewage works in Croydon and is now standard practice at the site.

If rolled out industry-wide, it would contribute to the decarbonisation of the national grid by 2035. It would also help make the UK’s electricity supply cleaner, greener, and more resilient at peak times, when customers need it most. It also makes the water industry more resilient to energy price rises.

“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 innovation lies in how sewage sludge is fed into special digesters, where the biogas-producing process of 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 – the period when the price of electricity is much higher.