Thames Water is investing £250 million for a scheme to help the firm generate 20% of its energy from sewage.
The water company will install thermal hydrolysis process (THP) plants at six of its sewage treatment facilities (pictured). The plants act as “pressure cookers” which condition sludge – the leftover solids from wastewater treatment – by heating it up to around 160 degrees. The sludge is then transferred into existing anaerobic digesters to be broken down, producing biomethane gas that is then burned to create heat and generate renewable electricity.
Thames Water claims it currently produces enough renewable energy to “run a city the size of Oxford” but by installing the new THP plants, it aims to produce enough electricity to run Oxford and Woking too.
Lawrence Gosden, Director of Capital Delivery said: “This investment is good for the environment, our business and our customers. For as well as being environmentally friendly, generating energy from waste also reduces our running costs by protecting us from the price fluctuations of the mainstream, non-renewable energy markets, bringing savings that help to keep customers’ bills down. This investment will also help us to achieve our target to renewably self-generate 20% of our annual energy requirements by 2015.”
The water company claims it saved around £15 million off its power bills by generating 14% of its annual energy usage from sewage last year. It will be installing the new THP plants at Beckton and Riverside sewage works in Essex, Crossness in Thamesmead, Longreach in Barking, Oxford and Crawley by 2015.