Engineers in north Lancashire are turning to human waste to help power their water treatment works and cut energy bills.
A special engine uses the methane which is given off as the waste breaks down to power lights and even provide steam to heat water.
Any extra power which is not used is then sent to the national grid.
The work at the Lancaster United Utilities treatment site is part of a programme to boost water quality.
The unusual power source comes from a new 500kW combined heat and power engine installed at the Stodday plant, a couple of miles outside of Lancaster city centre.
Site process controller Phil Smith said: "We get 1,000 cubic metres of sludge a day into our works which produces 40,000 cubic metres of gas a week.
"By the time we process it, we can get a cubic metre of gas for every kilogramme of sludge we get coming through Lancaster.
"That's enough fuel to make us self sufficient and at the same time we're killing more nasty bugs than ever and meeting tough new regulations."
By using the waste, the treatment works is saving around £60,000 on its power bills.
As well as treating sewage from the 100,000 people who live in Lancaster and Heysham, the plant also handles waste from Windermere and Kendal in Cumbria.
After the treated sewage sludge has broken down what is left is used as a natural nitrogen-rich organic fertiliser on farms.
"There is no shortage of outlets. The farmers love it.
"It's free, full of nutrients and we even deliver it and spread it for nothing," Mr Smith said.
The project at Lancaster is part of United Utilities' £3.6bn investment programme to boost water quality and the environment by 2015.
The firm said the sludge processing scheme will be brought to other treatment sites, including Davyhulme in Greater Manchester.