Researchers at UMass Amherst have come up with a way to make gasoline out of cellulose (i.e. plant material).
Currently the process is about 50% efficient and the researchers say if they can get close to 100% efficient the cost will be about a buck a gallon.
Don’t start chopping down plants and showing them into your gas tank yet – commercialization of the technology will probably take another 5 to 10 years.
(more at popularmechanics)