It would be interesting to see the statistics comparing total emissions to total mileage for the various alternative fuels.
I assume somebody has already done this. Nick Hoffman maybe?
A true comparison would take into account all the emissions created in extracting and/or growing the raw material(s), the emissions created in converting to a useable fuel and the emissions created to distribute the fuel to the consumer, divided by the economy of such a fuel. It would be informative to compare this to the actual figures from gasoline, lp and diesel.
Then if we can get whatever our best answer is to grow in the american desert with little water, wa la!!!! We're OK. How about gourds, melons or dates?