Human waste to heat thousands of homes in £4m plan to recycle it into gas

By David Derbyshire
Last updated at 1:52 AM on 16th June 2009

Within two years, thousands of people will be preparing their dinner and heating their homes using methane gas extracted from human waste.

The energy company behind the scheme say the 'sewage works gas' will be clean, environmentally friendly and indistinguishable from the North Sea variety.

The pilot biogas conversion plant will be built at Britain's second biggest sewage works in Manchester and could generate enough power for 5,000 homes by 2011.
Other plants are expected to follow - eventually producing sewage gas for hundreds of thousands of people.

The £4.3 million scheme is the brainchild of United Utilities who yesterday got Government funding for the plant at Davyhulme waste water treatment works.

Caroline Ashton, the company's biofuels manager, said: "Sewage treatment is a 24-hour process so there is an endless supply of biogas.
'It is a very valuable resource and it's completely renewable.

'By harnessing this free energy we can reduce our fuel bills and reduce our carbon footprint.'

Methane is produced when microbes break down sewage sludge in a process known as 'anerobic digestion'.

Most sewage plants burn raw methane to generate electricity.  The new plant will clean up the gas by removing moisture, carbon dioxide and the traces of sulphides and other contaminants that give sewage its distinctive aroma.

The pure methane produced by the plant will be clear and almost identical to the gas that comes from the North Sea.

Like raw North Sea gas, it will also be odourless - and will have to be given an artificial 'gas' smell before it is piped into people's homes.
'Currently, the methane from wastewater treatment plants is burnt to generate electricity,' a spokesman for United Utilities said.

'But that's not a particularly efficient way to use the gas.'

Although the gas comes from human waste, it is hygienic to use for cooking, he added.

'It's just the same as drinking water that has been through the water cycle, or eating food that has been grown in soil fertilised with manure,' he said.

'We are talking about a chemical compound - it doesn't matter where it comes from'.

United Utilities plan to use some of the biogas to fuel a fleet of 24 sludge tankers.

Some of the gas will also be used to provide electricity for the sewage works.

Janine Freeman, head of National Grid's Sustainable Gas Group said: 'Biomethane is a fuel for the future. Renewable electricity from sources such as wind power is already available, but this is the first time we will be able to supply renewable gas to consumers. This pilot is an important step in helping deliver a low carbon energy future.

'Not only are we reusing a waste product, but biomethane is a renewable fuel, so we helping to meet the country's target of 15 per cent of all our energy coming from renewable sources by 2020.

'This pilot project should supply gas to about 500 homes and the overall potential of biomethane from a plant like Davyhulme would be to supply a small town of about 5,000 homes.'