Human waste to renewable gas leaves Didcot flushed with success

A sewage works is recycling human waste and using it to heat homes in Oxfordshire. Biomethane gas from Didcot sewage works will produce enough renewable gas to supply up to […]

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By Kelvin Ross

A sewage works is recycling human waste and using it to heat homes in Oxfordshire.

Biomethane gas from Didcot sewage works will produce enough renewable gas to supply up to 200 homes.

The £2.5m initiative, which started this week and has already earned the label ‘poo power’, is a joint venture between Thames Water, British Gas and Scotia Gas Networks and it is hoped it will be the first of many similar projects.

Sludge, the solid part of sewage, is treated in warmed-up vats using anaerobic digestion, a process where bacteria break down biodegradable material, yielding biogas.

Impurities are removed from the biomethane before it is fed into the gas grid. The whole process – from flushing a toilet to gas being piped to people’s homes – takes around 20 days.

Energy secretary Chris Huhne said: “It’s not every day that a Secretary of State can announce that, for the first time ever in the UK, people can cook and heat their homes with gas generated from sewage.

Mr Huhne said the launch of the project was “an historic day”. “I know there are other similar projects across the country that are close to completion, so this is just the start of a new era of renewable energy.”

Thames Water chief executive Martin Baggs said: “We already produce £15m a year of electricity by burning biogas from the 2.8bn litres a day of sewage produced by our 14m customers. Feeding this renewable gas directly into the gas grid is the logical next step in our ‘energy from waste’ business.

“What we have jointly achieved at Didcot is a sign of what is to come, which can be replicated across our network and indeed the whole country. Every sewage works in Britain is a potential source of local renewable gas waiting to be put to use.”

Gearóid Lane, managing director of communities and new energy at British Gas, said: “This renewable gas project is a real milestone in Britain’s energy history, and will help customers and the environment alike. Renewable gas has the potential to make a significant contribution to meeting the UK’s energy needs.Gas from sewage is just one part of a bigger project, which will see us using brewery and food waste and farm slurry to generate gas to heat our British Gas homes.”

The average person produces 30kg of dried-out sewage sludge per year that could be used for producing gas. That means that the UK’s 62.5m people could in theory generate enough renewable gas to meet the annual demand of 200,000 homes, up to 1% of the UK’s population.

British Gas estimates that if all 9,600 sewage treatment facilities in the UK were fitted with this technology, they could provide enough renewable gas for up to 200,000 homes.

Didcot was certainly a talking point at the Renewable Energy Association’s Bioenergy 2010 conference today.

REA chief executive Gaynor Hartnell said: “The Didcot project will prove the technology works, but it is essential that the anticipated financial support follows. It was developed in expectation that the Renewable Heat Incentive will be introduced next year, and we’re waiting for confirmation of this following the Comprehensive Spending Review on 20th October.”

Hartnell added that she was “delighted to hear Oliver Letwin say at the Conservative Party conference that the RHI is a ‘crucial part’ of government’s green energy plans”.

The REA’s biogas adviser David Collins said: “Congratulations to Thames Water, Scotia Gas Networks and Centrica for putting together this milestone project. Now it’s up to government to make sure this technology can be rolled out nationally.”