Read this and thought some people here might be interested in it.
Bio diesel is a renewable energy source that can be setup to run on any diesel based vehicle with minimum modifications. To supply all of the US with enough diesel to power their transportation needs yearly, they'd need to produce around 140 billion gallons of Bio diesel annually. To produce this much Bio diesel, they'd need roughly 15 000 square miles of desert land. Just to give you an idea of how much land this is, the sorona desert, a perfect climate for producing biodiesel, is roughly 120,000 square miles.
Now cost of setup and maintence. To setup the farms it would take about 80,000 per hectare, which works out to around 308 billion dollars to setup. Ongoing costs like labour and such would run about 46.2 billion dollars a year. Compare that to the $100-150 billion they spend annually, then the farms should pay for themselves within 3 years approximately.
Minimum modifactions to the vehicle, would involve..changing the fuel lines and other rubber that may contact the feul to ensure no chemical reactions. Sadly, they didn't go into environmental benifits of running diesel.. but im sure google can answer those questions.
parts of my write up were quoted from the article...its just really long, and I dunno how many people wanna sit through that.