Human waste transformed into renewable gas to power homes

A COMPANY in Britain has begun transforming human waste into renewable gas that powers homes for the first time.

Centrica began feeding biomethane gas from sewage into Britain’s natural gas network yesterday, as the country’s biggest energy supplier seeks to trim carbon emissions.

The project will supply enough gas for 200 homes using anaerobic digestion to treat waste from Thames Water customers, Centrica said. The biogas produced is then cleaned to remove any odour and fed directly into the gas network.

Biomethane could account for about 15% of the British domestic gas market by 2020, Centrica said.

Britons consumed 86.5 billion cubic meters of natural gas in 2009. Over 50% of the country’s gas is imported from Norway, Qatar and mainland Europe.

“Biogas has exactly the same emissions as regular gas, but it’s renewable so we’re not depleting fossil fuel resources and we’re not taking the gas from other countries,” said Martin Orrill, project manager at the Didcot Renewable Gas Project.

The waste is stored for 18 days and then turned into domestic gas which will supply about 200 homes with power.

Sewage arrives at the Didcot works for treatment, and then sludge – the solid part of the waste – is further treated to break down the biodegradable material and create gas.

The gas is cleaned and fed into the gas grid in a process which takes around 20 days from lavatory flush.

The average person produces about 30 kilograms (66 pounds) a year of waste suitable for producing biomethane.

This means Britain’s 62.5 million people could generate enough renewable gas to meet the annual demand of about 200,000 homes, Centrica said. The Windsor-based utility and its partners spent six months and about €2.5 million developing the Didcot project.

Britain’s energy and climate change 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.

“This is a historic day for the companies involved, for energy from waste technologies, and for progress to increase the amount of renewable energy in the UK.”