First UK homes heated with 'poo power' gas from sewage
A UK water company has begun supplying domestic gas produced from human waste to homes.
Severn Trent Water said it is the first company to provide gas for heating and cooking to the National Grid using "poo power".
The biomethane is produced by breaking down sludge from a sewage treatment plant.
Severn Trent said Northumbrian Water and Wessex Water were also preparing to supply homes using the same method.
It expects to produce 750 cubic metres per hour, supplying 4,200 homes annually, from its largest treatment plant in Minworth.
'A little unsavoury'
Human waste is broken down in 16 anaerobic digesters at the Warwickshire site, producing biogas, consisting of methane and carbon dioxide.
Most of the carbon dioxide is then removed to create biomethane, and an odour is added to imitate the smell of household gas.
The firm's renewable energy manager Simon Farris said the source material was "a little unsavoury", but the process was safe.
"There's lots and lots of power locked in poo, and when that's processed it's perfect to generate clean renewable green gas," he said.
Dr Cynthia Carliell-Marquet, a senior Birmingham University lecturer in water and environmental engineering, said anaerobic digestion is a more efficient method of dealing with waste sewage.
She said the process had been around "a long time" and is often used to break down agricultural waste.
"It is the best way of using that energy," she said.
Dr Carliell-Marquet pointed out that Severn Trent will be paid a subsidy for the project as part of the government's Renewables Obligation scheme.
But if the process at Minworth proves successful, she said, it could signal a move towards wider usage.
One of the reasons, she said, could be concerns over the UK's gas security and ensuring a domestic supply.
"The more we can recycle within our own borders, the more secure the supply," she said.