Anaerobic Digestion for Gas – not Fracking
We need to give installation of Anaerobic Digestion (AD) plant our strong support as the counter-balance to our opposition of fracking. Both produce methane gas that can be injected to the gas grid to heat homes and businesses as well as generating electricity in quick start up power plant that can be used to balance intermittent renewables. Obviously biogas from AD is preferable.
British Gas estimate 50% of UK gas needs could be met from waste and there is a lot plant being installed at the moment such as this http://www.nextgenmedia.co.uk/news/1373-4-5m-anaerobic-plant-plans-for-malt-supplier
No one seems to have calculated how much could be produced from farm integrated AD plant but perhaps it could produce the other 50%. The big one at Poundbury (info: here) produces up to 80% of West Dorset’s gas needs from just six farms growing grass and maize on a 4 year crop rotation between cereal crops.
The solid digestate looks and smells similar to horse plop and is used for the cereal crops as an alternative to inorganic fertilisers. It is slow release and an excellent soil improver. On livestock farms, part of the motivation to install AD is to process the animal waste to produce a high quality digestate to spread on the land as a replacement to the raw animal dung which can pollute nearby water courses in some weather conditions. AD plant should be seen as an integral part of efficient British agriculture making it more sustainable, more organic, more productive.
Grass grows exceptionally well in the damp UK climate and is the ideal feedstock for AD. Rather than leave cuttings on the ground. we could divert cuttings from road verges, sports fields, parks and any area where a less fertile soil is the aim (so that wild flowers compete better with the grass)to AD plant.
We should not forget that renewable gas is almost as important as renewable electricity.
Biomethane is great and Poundbury has been a success, helping 20 projects that are being built this year.
But realistic max Biomethane is 20 TWh/Annum…..total gas consumption is 700 TWh so we need to import lots of gas
Qatar LNG is very high GHG and forecast to cost £10 billion/Annum in 2025….that’s a lot of money, if we can produce this gas in UK we will have £7 billion tax…..to fund renewables and insulation
Thanks John for joining the debate on these pages. You are very welcome.
I agree quantification is the best way to reach an idea of what is possible. Looking at the statistics from DECC 700 TWh is a reasonable estimate of 2014/2015 UK gas demand. However, we must take into account ongoing reduction in gas demand from electricity generation as more and more renewable electricity generation comes on line. It was a modest 1% reduction in 2013 but our present government, with its destabilising influence on renewable electricity due to wild changes in tariff levels and licensing costs and ease (or not) of gaining planning consent, is holding back installation of renewables. With proper stable backing, renewables, let of the leash, could rocket. So let’s hope for a diminished Conservative influence in the next government.
Poundbury produces 0.004 Twhy which would mean 86,000 Pounbury sized plants in the UK (or 1000 per UK county) to meet the 344 TWhy domestic gas consumption. I agree this is probably not realistic but think your estimate of 20 TWhy ceiling (or 5,000 Poundbury sized AD plant) for the UK is also not accurate.
I still maintain that with falling gas demand due to better insulated and better constructed houses following the 2016 improvement to building regulations, roll out of solar thermal and wood heat and much reduced demand to generate electricity, AD could meet a much higher proportion of UK gas demand than anyone is currently predicting. I admit I can’t quantify the potential accurately yet because AD to gas grid is at the first stage of development.
However, I believe continued use of slowly declining extraction of North Sea gas along with rapid expansion of AD gas, big improvements in energy efficiency and renewable electricity generation can see us through without the need for fracked gas. Like nuclear power, fracking carries low probability but high impact risks that are just not worth taking.
Keith Wheaton-Green