The science: biofuels and climate change
Biofuels, so the theory goes, release only the amount of CO2 the crops have absorbed while growing on the field. This would make them carbon-neutral, which means they would effectively reduce climate change.
Unfortunately, the maths aren't quite that simple.
To begin with, the process of growing, manufacturing and transporting biofuels adds CO2 emissions to the balance sheet, meaning biofuels are in effect carbon-positive. At this point, though, they are still a better alternative to fossil fuels.
But add to that the consequences of land use changes, says the Chief Executive of the Royal Society of Chemistry Dr Richard Pike, and you get a different picture altogether.
Even these figures pale in significance, however, when compared to a little-known but much more potent biofuel greenhouse gas.
It is the release of nitrous oxide, or N2O – a by-product of the fertilizer needed to grow crops, and 300 times more harmful to the environment than carbon dioxide – which constitutes the real problem.
“Most people don’t take N2O into account when they talk about biofuels, and those that do usually get the facts wrong”, says Dutch Nobel-prize winning chemist Dr Paul Crutzen. In January, he published an influential study which analysed the N2O emissions for different biofuels.
“For biodiesel derived from rapeseed, for example, our study shows that the global warming caused by N2O is up to 1.7 times larger than the cooling effect due to saved CO2 emissions.”
This is especially bad news for Britain, where large amounts of arable land are used for oilseed rape production. And according to Dr Pike, there is virtually no alternative to the current fertilizing system.
Dr Crutzen thinks the only forward now is the development of more advanced forms of fuel crops that don’t need large amounts of fertilizer, such as grass or algae fuels.
He says something definitely needs to be done, and remains optimistic. “The current method of producing biofuels is bad, but I’m sure there are ways of improving it considerably.”