How do biofuels save carbon – aren the tailpipe emissions just the same as normal fossil fuels?
Tailpipe emissions are about the same. But the carbon in biofuels is part of today’s carbon cycle – when the wheat or oil-seed rape grows it takes in the carbon dioxide, and when the fuel is burned it releases it. Fossil fuels by contrast have kept their carbon locked in the ground for millions of years.
It is true that the amount of carbon dioxide released by a vehicle is about the same whether it runs on biofuels or fossil fuels. However, the carbon in biofuels has been absorbed recently from the atmosphere – for example when oil-seed rape grows it takes in carbon dioxide and releases oxygen through photosynthesis – and when the fuel is burned it is re-released. In contrast, the carbon that is released when fossil fuels are burned has been locked in the ground for millions of years. Fossil fuels therefore add carbon over and above what was already circulating in the atmosphere. The potential risk in using biofuels is that the cultivation process can be energy intensive, and may actually be predicated on the use of fossil fuels, for instance to power agricultural machinery and to manufacture fertilisers. These processes reduce the actual overall carbon savings available through using biofuels, and in the worst case scenarios may make the carbon emissions of biofuels higher than the eq
