The biggest problem with bio-fuels is that even if 20% of crops were to be used for biofuel, they would meet less than 5% of current energy needs.

As the price of crops increases, grazing landwill not be used .....instead poor farmers in third word countries will burn/chop down more forests to increase available land.

Land that would largely be unsuitable for farming and using it will result in destruction of the top soil.