Maize grown specifically for Anaerobic Digesters to produce “biogas” is an increasingly common crop in England, especially in the South West. The area under Biogas Maize increased by 55% in 2016 compared to 2015, to 52000ha. The National Farmers Union set a target of 200,000ha of land under biogas Maize back in 2011, so they are 25% of the way to their target.
Maize is a very environmentally damaging crop, probably the most environmentally damaging crop grown in the UK. Why then is so much of it being grown? Because the Government pays not one, but two subsidies for it to be grown – the generous single payment (now over £200 per hectare annually) for anyone who owns farmland; and on top of this there are a range of payments including the Renewable Heat Incentive and the Renewables Obligation, depending on how big your Digester is, and when it was built. The really ridiculous thing is that producing gas from Maize produces practically no saving in Greenhouse Gas emissions compared with natural gas, because of all the emissions created in its production.
The Government, belatedly, decided to look again at whether all this money for environmental destruction in the name of climate action could really be justified – and held a consultation earlier this year. The results are finally out – and they have decided (at least on paper) to reduce the subsidy for biogas maize by 50%. Although they should have abandoned subsidy for this crop altogether, this is a step in the right direction. It will remain to be seen whether it has the desired effect in a years time when the 2017 planting area statistics are revealed. Given that this reduction only applies to new plants, it will do nothing to reduce the area already covered.
Richard Lowes, renewable energy researcher at Exeter University, points out that if the Government goes ahead with its preferred option, more than 50% of the gas generated from any new AD plant will need to be produced from waste, not crops. As there is a limited (and contracting) supply of organic waste, this should mean that far fewer new plants will be built.
Grass to Gas?
One energy company is proposing to use grass to run biogas plants, instead of Maize. Ecotricity, normally known for its wind turbines (and vegan Football Club) has plans to grow herbal leys (these are mixtures of grasses and other plants) as catch crops between arable crops like wheat or barley. These herbal leys will then be cut, twice or three times a year, and the mowings used to power the AD plants. This sounds great in theory – in practice though to produce enough gas to replace fossil fuel gas would take up all the agricultural land in the country (including upland grassland which is impossible to harvest). Mark Avery has already poured cold water on the idea, and Biofuelwatch recently produced a fairly comprehensive critique. Both actually overestimated how much gas Ecotricity would produce using their system, as herbal leys which don’t receive fertiliser (other than the digestate from the AD plants) will produce much less energy than a standard rye-grass silage crop (on which all the figures for grass to gas are based.) Benefits for wildlife are also likely to be minimal as the areas where the herbal leys are grown will be rotated around different farms. A few farmland birds might benefit.
The sad truth is that biogas from crops, alongside so many other approaches to bioenergy production, deliver very little apart from the opportunity to harvest large subsidies from the public purse, which as we know is rather empty at the moment. If we really wanted to do something about reducing carbon emissions, there are probably better ways of using the money – like a massive national housing insulation project.
After all, what’s the point of producing gas with a slightly lower carbon footprint, if it’s just going to be used to heat air which disappears out of draughty houses?