B - Bioethanol
Bioethanol A mixture of petrol and ethanol. The ethanol is made from natural crops such as sugar beet and cereals.
The ethanol is virtually carbon neutral, because the crops grown to make the fuel absorb carbon dioxide.
However, there is some controversy about it. There are worries that poorer countries will clear land to grow biofuel crops for export instead of growing food, and that we could be growing crops to feed cars, not people.