In the US and Europe, biofuels are once more being touted as a partial answer to the twin challenges of global warming and energy security. In 2005, production of hydrocarbon biofuels from commodities such as maize and sugar was equivalent to one per cent of all road transport usage, but the US intends to cut petrol consumption by 20 per cent in ten years through a combination of improved vehicle efficiency and increased use of biofuels. Both there and in the EU, the need to placate a subsidy-hungry agricultural sector makes fuel farming attractive.
There are a number of counter-arguments. Crops for fuel may tend to displace food crops. Indeed, present relatively modest production is said to be one of the reasons for the fastest-rising food prices in 30 years. There are fears that biofuel demand may increase deforestation as trees are cleared to make way for oil crop plantations. But there are also supply chain and logistics problems that do not appear to have been thought through.
In temperate climes, fuel crops will be highly seasonal so expensive processing/refining plant is likely to be idle much of the year. The analogies with beet production for sugar are close. To feed a refinery of any commercial significance will likely take supplies from three or four English counties. A large part of a beet or of any other crop is water, so a lot of road transport will be employed trucking water around, and as we know from the height of sugar beet production some years ago, bringing gridlock to the most remote rural locations. That water then has to be driven off, using a lot more energy.
Biofuels may reduce dependence on overseas sources but the process is spectacularly inefficient in energy terms.
A question also hangs over the grade of fuel to be produced. Typically, biofuel
production involves converting sugars to ethanol, which is then blended with conventional petrol. There are other techniques that could in theory produce fuels more akin to diesel of heavy fuel oil. It may be difficult to ensure consistency of product across relatively small-scale refineries around Europe, which may themselves be using different feedstocks and technologies. And the perils of blending additives in fuels were well illustrated in the UK with the recent ‘silicones in petrol’ fiasco.
The alternative biological approach, also being promoted is of crops for power generation, suggested inputs ranging from coppiced willow to waste barley straw. This approach has a number of advantages, for example with a suitable mix of inputs year-round generation should be possible, and efficiencies can be gained on small-scale plant, thus minimising the environmental impact of long-distance transport of low-density feedstocks.