As you may have already seen, along with WWF, the RSPB, Friends of the Earth and enoughsenough.org, we've placed an advert in several of today's papers warning the government about the environmental risks of biofuels as an alternative to petrol and diesel. Hang on, I imagine some of you are saying right now, aren't they supposed to be clean and green with the power to save us from the tyranny of fossil fuels? Well, yes... and no.