The amount of renewable energy we generated from our Combined Heat and Power (CHP) units increased by 30 per cent to 44 million kilowatt-hours (kWh).

Our 13 operational units have the capacity to generate up to 13 per cent of the electricity we use from renewable and sustainable sources.

The CHP units produce renewable energy by capturing bio-gas created during the sludge treatment process. The gas is used to provide power and heat the works, with any surplus exported to the National Grid.

Work started during the year to build a CHP unit at our new wastewater treatment works at Peacehaven in East Sussex. The unit will have the capacity to generate a further 8.65 million kWh each year – enough to supply a quarter of the site’s energy.

During 2010-11, we carried out a feasibility study into generating power from hydro turbines in sea outfalls, through which millions of litres of cleaned water are recycled out to sea. Turbines would allow us to recover energy already used to pump the water and are free from emissions.

We started feasibility studies at a number of our sites into injecting surplus methane gas produced at our sludge treatment centres directly into the gas grid network under a Renewable Heat Incentive (RHI). The RHI, which was launched by the Government, encourages businesses to switch from using fossil fuels to renewable forms of heat.