Northumbrian Water Creates Fuel from Flatulence

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Industry Tags: Energy, Sewage, Sewage Treatment

Northumbrian Water creates fuel from flatulence next stage in revolutionary 'power from poo' work

Three years after Northumbrian Water first used its sewage sludge to generate electricity a new £8m project is set to inject the vapours from a £35m ‘anaerobic digester’ on Tyneside direct into the national gas grid.

Process engineer Tony Rutherford, who has worked on the project to harness the wondrous wind, said it would bring a new extra efficient source of renewable energy to to region.

He explained: “Using the gas to drive turbines and generate electricity is only around 40% efficient, as you lose a lot of energy as heat, but this new system is 90 to 95% efficient,” By the time the plant is fully online, which Mr Rutherford said could be by the end of June, it will be capable of creating enough energy to power more than half the homes in Alnwick or Ponteland, or all the houses in Corbridge, Acomb and Ovingham combined.

Richard Warneford, Northumbrian Water’s wastewater director, said: “More than 20% of our total power use is now from renewable energy sources including hydro power at our treatment works and reservoirs like Kielder Water.

“We are leading the industry in pushing the bounds of technology, and our customers can be reassured that we are doing all we can to use the waste they flush down the toilet as a fuel and turn it into electricity and gas to add to the national grids which people use to light their homes and cook their meals.”

Northumbria Water believes it is the only water company in the UK to reuse all of the sludge left over after sewage treatment to produce renewable power.

The process currently sees around 300,000 tonnes of wet sludge a year taken from treatment works all over the North East to plants at Howdon in Wallsend and Bran Sands in Middlesbrough, where it is placed in what are effectively giant pressure cookers, at 165C and six bars of pressure.

That destroys any pathogens and breaks down the cell structure, making it easier for the billions of bacteria in giant digester tanks to set to work breaking it down further.

The resulting bio-gas that is released by the bacteria is collected in 11-metre diameter storage bags before being burned in gas engines capable of producing the equivalent of about 35 million kWh per year. And any leftover, post digestion sludge makes a good agricultural fertiliser.

However, having to heat the sludge before feeding it to the micro-beasties remains tremendously inefficient, with almost half a KWh of electricity being needed to treat just one cubic metre of water.

That was why in 2013 scientists from Newcastle University announced they were working with Northumbrian Water to try and find a better solution - one that “could put the North East on the map in a similar way to the railway.”

Biological engineering expert Professor Tom Curtis and his colleagues, including professor of electrochemical engineering Keith Scott and Dr Elizabeth Heidrich proposed that by placing a “cassette” containing a positively charged rod and a negatively charged rod on the opposite side of a permeable membrane – a process known as electrolysis – into waste water it would be possible to create both electricity and hydrogen gas.

And to prove it they successfully ran a 100-litre “poo reactor” at Howdon for 422 consecutive days – showing that such a process if scaled-up could make water treatment at the very least energy neutral, if not energy generating.

Source: Chronicle Live

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