Thames Water has plans to install Thermal Hydrolysis process (THP) plants at six of its sewage treatment works as it aims to meet its target of producing 20% of its own power using renewable sources.

The new THP plants are essentially pressure cookers which heat the leftover waste from the treatment process to 160C. the sludge is then fed into digesting units which break it down and produce a biomethane gas which can be burned to create heat and hence energy.

Waste ‘solids’ which are heated using the THP process burn more biogas than those that are not treated helping to generate more energy which will enable Thames Water to meet its target.

The director of capital delivery at Thames Water Lawrence Gibson said:

“We currently produce enough renewable electricity to run a city the size of Oxford, but by the time we install all this new THP we will be producing enough to run Oxford and the whole of Woking, in Surrey, too.

“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 per cent of our annual energy requirements by 2015.”

In 2012 Thames Water saved £15m by generating its own energy.

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