Britain's maize boom brings biofuel future closer
The increased farming of maize in Britain may contribute to a faster adoption of biofuel. Hectares dedicated to growing the crop rose from fewer than 25,000 to almost 200,000 between 1985 and 2016. A quarter of all maize grown is transformed through anaerobic digestion to create methane for electricity generation. However, there are concerns that the crop could cause environmental damage, and that the fuel may be inefficient. The UK government has said that new biogas facilities will only gain subsidies if at least 50% of the gas generated was made from waste materials.
IN A field on the outskirts of Norwich, Innes McEwan, head of farming at Future Biogas, explains the benefits of maize. It is full of starchy energy, responds well to organic fertilisers, has a short growing season and can be cultivated in a range of soil types, including the sandy stuff found in parts of East Anglia. It is also, he notes wryly, “a physically domineering crop”—something that is made clear as he plunges through a densely packed plot.

Although little of the British countryside could be confused with Iowa or Mato Grosso, where maize has long been big business, the plant’s tall green shoots are an increasingly common sight. In 1985 less than 25,000 hectares were devoted to the crop. By 2016 nearly 200,000 were. It is especially common in the south-west, where cattle farming is concentrated.

The growth came in two spurts. First, in the 1990s dairy farmers began to use maize as a high-energy feed for cows, says Richard King of Andersons, an agricultural consultancy. As herds were moved into barns, and thus away from grass, more and more munched maize. Then, beginning a decade or so ago, the plant began to be used as a form of green energy. When Mr McEwan’s crop is harvested next week, it will be transported to a nearby anaerobic-digestion facility, whose methane belches will power a generator that feeds electricity into the national grid.

A quarter of maize grown in Britain now goes into such digesters, up from a hundredth just seven or eight years ago, says John Morgan of the Maize Growers Association. The result is that maize is increasingly sprouting in parts of the country with few dairy herds. Future Biogas has anaerobic-digestion plants along the east coast, for instance, so that the energy produced can run straight into the grid coming from the North Sea.

The spread of maize bothers some. The Soil Association, a charity, frets that the tall crops leave the earth exposed. Maize is often harvested late in the year when the soil is wet, allowing pesticides to run off the ground and increasing the risk of floods. Some farmers have taken steps to tackle this. New varieties of maize, tailored for the British climate, can be harvested earlier. Planting another crop beneath the maize may help stop soil erosion.

A more damaging criticism is that maize makes an inefficient fuel. Anaerobic digesters do most to reduce carbon emissions when they convert waste products to energy. The growth of maize, by contrast, requires considerable energy inputs, from petrol for tractors to fertiliser. It also means that food crops have to be grown elsewhere, increasing farm emissions, notes Rob Bailey, an energy analyst at Chatham House, a think-tank.

Such displacement will be less common in future, though. The trend in dairy farming “is to go back to what everyone assumes happens already,” says Peter Melchett of the Soil Association: “that cows graze grass.” Meanwhile, at the end of last year the government announced that new biogas facilities would receive subsidies only if they generated at least 50% of their gas from waste. More stringent conditions mean the outlook for maize is no longer so sunny.