http://www.theguardian.com/environment/georgemonbiot/2014/mar/14/uk-ban-maize-biogas
"It was also a brilliant idea to turn waste chip fat into biodiesel. But the incentives to produce biodiesel, often justified by the claim that they would make use of waste, have created multiple ecological disasters. They have encouraged farmers to feed cars rather than people and financed the conversion of rainforests in Indonesia, Malaysia and West Africa into oil palm plantations, driving orangutans and many other species to the brink of extinction. In most cases, biodiesel, as a result of the changes in land use, has much higher greenhouse gas emissions than the fossil fuel it replaces.....
Biogas is now going the same way. Provide the money to do the right thing and if you're not careful it will be used to do the wrong thing....Economic modelling commissioned by the government tested eight different mixes with which farmers could feed an anaerobic digester, to try to work out which were profitable. All of them included grass, wheat, maize or potatoes, and in some cases the models specified a higher tonnage of these specially grown crops than the waste the digesters are supposed to process. As maize has both a high yield per hectare and a high yield of biogas per tonne, it has become what the farming press calls the biogas "core crop". There could scarcely be a better formula for subverting everything biogas is supposed to achieve....The first and most obvious problem is that it means taking land out of food production. According to Farmers' Guardian, a biogas plant with a capacity of one megawatt, "requires 20,000-25,000 tonnes [of maize] a year, accounting for 450-500 hectares of land"....It reports that the area of maize being grown for biogas in the UK has trebled to 15,000 hectares in the past two years alone, and is likely to rise to 25,000 hectares next year. This is an astonishing rate of growth. If, as the National Farmers Union (NFU) advocates, 1,000 medium-sized biogas plants are built by 2020, and maize supplements the slurry and manure they process, that will mean the use of between 100,000 and 125,000 hectares...."
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