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.