I've always wondered why some of the available alternative fuels aren't utilized more in the U.S., although my guess would be that bottom line economics keep market opposition to them from existing fossil fuel suppliers high.

I actually worked with some researchers from U.C. Berkely a few years back on a Biodeisel project. I provided technical support in a deisel engine research facility where they bought time to measure exhaust byproducts of various fuel formulations in the forms of exhaust emissions and particulate matter. The differences I saw were dramatic (especially in particulates), so the claims that biodeisel would be helpful in reducing greenhouse effect byproducts seem accurate to say the least.

I wonder if refilling the tank at Long John Silvers' would make the exhaust smell like fish instead of french fries?