The discussion about using plants for producing fuel is a very controversially one. The discussion about the jatropha plant is one example for that. More information is avaibale on this site.
Fuel made from plants are controversially discussed: Do they help protecting the environment or do they destroy it? A current discussion is held on the jatropha plant: Facts and arguments for and against a use of this plant were now collected by Bread for the World and the United Evangelical Mission.