Powered by poo
22 Nov 2010 by Evoluted New Media
I’m all for recycling, but the news that residents in Didcot are using their own poo to heat their homes just sounds a bit too disgusting to imagine.
I’m all for recycling, but the news that residents in Didcot are using their own poo to heat their homes just sounds a bit too disgusting to imagine.
When put in those simple terms it does sound a little bit gross, but in reality, the residents just flush away their waste as normal and three weeks later it’s been converted into gas which they can use for cooking and heating. It sounds like a very environmentally-friendly idea and the venture – between Thames Water, British Gas and Scotia Gas Networks – will supply 200 homes with clean gas derived from their own waste
So how does it work? Human waste is transferred to a sewage processing plant where it is collected in settlement tanks and separated into clean water and sludge. This sludge undergoes anaerobic digestion where carefully managed bacteria turn the waste into methane gas and solids for fertilisers.
So far, this isn’t really anything new – the practice of converting faeces into power is already well established across the country, and Thames Water have been generating electricity by burning waste for decades. In 2008/2009, they claimed to have saved £15m by burning sewage sludge or methane derived from it, generating 14% of its power needs.
The next step in the process is new and required British Gas to install an additional plant at the Thames Water sewage treatment works to clean up the spare biogas. Impurities are removed and an odorant is added to make the gas smell like gas. It is transferred to the National Grid where it is pumped back into homes and used in gas central heating and household hobs. From flush to finish takes about 20 days.
"When put in those simple terms it does sound a little bit gross, but in reality, the residents just flush away their waste as normal and three weeks later it’s been converted into gas which they can use for cooking and heating” |
“The gas that we are transporting from Didcot doesn’t arrive from the North Sea or abroad, but comes from the very homes we are delivering the gas to,” said John Morea, chief executive of Scotia Gas, “That’s has to be recycling at its very best.”
The project took six months to complete and cost £2.5 million and the trio aim to roll the process out across the UK as part of their commitment to helping the UK reach the target of producing 15% of energy from renewable sources by 2020.
“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,” said Martin Baggs, chief executive of Thames Water, “Every sewage works in Britain is a potential source of local renewable gas waiting to be put to use.”
Generating gas from sewage is just one part of a wider project – the collaboration hope to develop technology to use brewery waste and farm slurry to generate gas. And they’re not the only one’s hoping to tap into this renewable resource – energy firms including United Utilities and Ecotricity have also announced plans to inject biomethane into the National Grid. In a £4.3m project, United Utilities hope to cater for 500 homes in Manchester by next year.
On the face of it, it sounds quite disgusting – using poo to cook and heat your home just seems wrong, but burning animal dung was widespread among our ancestors, and in some parts of the world it’s still practiced today. Even in the UK, chicken faeces has been used to generate electricity, so why should using our own excrement be any different. It is an important and necessary step if we are to maintain the level of living that we have come to expect – our traditional gas supplies are from a finite resource so we have to look at alternatives. If our own waste is the way forward then that’s some powerful poo!
