Actually a weed called "switch grass" that will grow even in crappy soil nets more fuel than corn. Unfortunately it would take 120 million acres of sawgrass at the current yield to make a dent in gas imports. There are 30 million acres of land not farmed as part of the old government set aside program where they paid farmers not to farm. They hope to reduce the number of acres of switch grass needed to equal that 30 million acres of unused land through technological advances in the conversion process.
There are even more acres of abandoned farm land in addition to the 30 million acres of set aside land. The problem is we have lost farmers. Generations of farming has been broken and the next generation of farmers moved to the burbs and got jobs because farming was not profitable. All the old farming equipment was sold off or scrapped.
I believe we have the land, knowledge and wherewithal to grow biofuels the problem is who is going to do it? Is Bobby Joe going to quit his job as the Service manager at the Toyota dealership to go back to the family farm, buy new equipment, put in irrigation, and start growing switch grass?