What we do now

About 97% of the energy we produce ourselves is from sewage sludge, a by-product of sewage treatment processes. One part of these processes is the use of bacteria to break down sewage. This digestion process reduces the volume of sludge produced and also creates methane. We use the methane to fuel Combined Heat and Power (CHP) plants.

The heat generated in the CHP plants is used to maintain the temperatures of the digesting process at around 35°C, whilst the electricity generated is used on-site or exported on to the national grid.

We are currently the leading producer of renewable electricity from sewage sludge biogas within the UK water sector. In 2008 we accounted for 45% of the renewable obligation certificates for sewage sludge biogas in the sector, more than double our nearest competitor.

In addition to CHP we also use hydro power at a number of our reservoir sites. This too is a renewable source of power which is either used to pump water for treatment or to generate electricity. Hydro contributes about 3% of the total renewable energy we produce.