Southern Water has installed Combined Heat and Power (CHP) systems at nine of its wastewater treatment works in Sussex, Kent and Hampshire.

The CHP systems are fuelled by biogas which is produced during the wastewater treatment process – when the sewage is turned into a fertiliser product.

They then generate renewable electricity which is used to help power the works and any surplus is exported back into the National Grid.

In addition, the heat which is generated is recycled and used to heat the sewage treatment processes.

Southern Water has two more CHP schemes under construction in Hampshire.

When all 11 plants are operational, they should generate about 41 million kWhs of electricity each year – about 10 per cent of the company’s annual consumption.

Southern Water is also investigating other forms of generating renewable energy – including energy recovery from drinking water and wastewater networks using hydro recovery turbines and wind generation.