Using sewage for green power

Green energy - power produced and harnessed during the treatment process in some sewage works in the United Kingdom - is helping to run operations within them.

Southern Water's project is proving such a success that the utility company has just announced that it is enlarging the program to start powering more plants.

Six works in Kent and Sussex in south-east England are already using this renewable energy and now another three systems are to be created in works that recycle cleaned wastewater into the environment via rivers and watercourses.

The biogas produced during the treatment works process is made up of 62 per cent methane, 35 per cent carbon dioxide and some trace elements and is recycled into both electricity and heat.

The six sewage works already using this energy are producing 12 million kilowatt-hour (kWh) of electricity a year - enough energy for lighting, cooking and domestic appliances in about 1,700 homes.

If any power is produced above the needs of the treatment works it is now being exported to the national grid to enable more people to take advantage of this green energy.

And in another bonus, the recovered heat from the power plant's engine is treating solid waste removed from the wastewater to be safely recycled as agricultural fertiliser.

Southern Water is hoping to harness more green power in the future and is exploring other ways of using green energy, including hydropower water turbines.