There are currently 24 operational anaerobic digester (AD) plants situated on farms in the UK, however there is planning permission to install a further 40-50 as farmers catch on to the financial incentives that can help them secure an extra income from generating energy from waste.
Anaerobic digestion is the process of the breaking down of organic matter (food waste or slurry) without oxygen at a steady temperature of 400C, to form a biogas. This process takes place in a large digester tank where the biogas can be siphoned off and combusted to produce electricity and heat. The digestate residue is also valuable as a fertiliser, replacing petro-chemical fertilisers which are created using a highly carbon intensive process. Anaerobic digestion saves green house gases in three ways. It harnesses the methane that would be given off into the atmosphere if waste and slurry are allowed to biodegrade naturally, which is a large saving as Methane is 21 times more potent than CO2 as a greenhouse gas. It saves greenhouse gases by displacing grid electricity which is largely produced by the combustion of fossil fuels and the digestate replaces the carbon intensive petro-chemical fertilisers. All this adds up to huge greenhouse gas savings for the environment and with the revenue from the feed-in-tariff for electricity generated and Renewable heat incentive for heat created, it is expected that more farmers across the UK will be signing up to turn their slurry into savings!