We can't just write off biofuels, but we can't accept them blindly either. My view is that there are only three solutions to the coming energy crisis: reduce, reduce and reduce. (Yes I know it's an old one) Once we have minimised our fuel use, where do we get the remainder from?
In some circumstances biofuels are economically viable, but in some cases they are not. US farmers are heavily subsidised to grow crops for bio-ethanol, but it is very doubtful that the energy in the bio-fuel exceeds the energy needed to plough the fields, fertilise the crop, irrigate it, spray it against diseases and pests (and produce and deliver the fertilisers and insecticides to the farm), harvest it, process it and deliver it to the refinery and then refine it. It's good business for US farmers, but it's pushed up the world price of wheat which is affecting UK pig farmers and third-world countries trying to buy food.
Have you seen this month's Ecologist magazine? An article talks about how Colombia is becoming a major producer of African oil palm, a biofuel plant. This development is supported by the US and the EU, and on the face of it, it's attractive. It provides a source of green fuel (plant growth is more effective in warmer Colombia) and it can displace some of the drug barons' coca crops. The drug barons see an opportunity too. They are taking over the land, if necessary driving out the local farmers at gunpoint, and planting the oil palms. The government plans to cover an area twice the size of Belgium with the trees. If necessary they cut down the rain forest. Mono culture is rarely viable, and before long the land is exhausted and turned to scrubland. The rain forest has been destroyed, the ecosystems have been destroyed, the livelihood of the local people has been destroyed and the possibility of growing more biofuel crops on that land has been destroyed - and for what? To allow Westerners to continue to drive highly inefficient vehicles!
Our fatal assumption is that we will be able to continue with our present lifestyle and continue to enjoy the same access to energy, but just get it from different sources. There is a serious risk that if we don't wake up to reality, and if chase solutions without thinking through their consequences, we will destroy the planet faster than ever before!