Two south west London wastewater treatment sites converting sewage into electricity

Thames Water has announced two more of its wastewater treatment sites in south west London have been utilising technology to turn sewage sludge into electricity.

Hogsmill and Beddington sewage treatment works have been exporting enough electricity to supply over 2,000 homes and businesses for over six months now by converting sewage sludge into biomethane.

A byproduct of the sewage treatment process is sewage sludge of which a solid material in the sludge is separated from the liquid and treated in heated tanks, known as digesters, to kill bacteria. By heating the sludge, a bio gas is created known as biomethane, which can be used to power engines which are connected to electricity generators.

The so-called “poo power” generated is used at the Thames Water site first, to offset the amount of energy it has used, the leftover energy is then used by the grid to power homes and businesses.

To make the conversion possible, Thames Water has worked with UK Power Networks to upgrade electricity network capacity for the project. At this local level, this has increased the export limit meaning the converted wastewater is able to be used as an energy source for thousands of homes and businesses.

Thames Water’s work at Hogsmill and Beddington sewage treatment works follows its successful gas-to-grid project at Mogden sewage treatment works in Hounslow.

Thames Water currently collects 4.6bn litres of wastewater daily from 16M customers and predicts there will be a growing demand for biomethane, resulting in high use and a cost-effective way of using energy. The company says that, having cut emissions by almost 70% since 1990, it has also self-generated 536GW/h of renewable energy in 2022/23, covering 27% of its own energy needs, which will provide a better environmental outcome for customers and help protect the water cycle for future generations.

Thames Water head of waste water treatment in south London Ian Ruffell said: “We are thrilled to introduce poo power as a source of energy from two sites in south west London as we look to play a role in the future of renewable energy.

“The successful use of biomethane conversion at Hogsmill and Beddington shows the dedication of our teams to delivering this project and our own commitment towards reducing our carbon footprint.”

UK Power Networks major connections manager Steve Carlow said: “It was great to work with Thames Water on these projects and be part of their journey to net zero.

“We look forward to working with Thames Water on future projects to further assist their transition to a low carbon future.”

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