Biofuel -- really techie!

Propeller head warning! There has been discussion here in the past year about using ethanol and biodiesel for fuel in our boats. I've been skeptical of these alternative fuels, wondering just how much of a net gain we get after paying for the fertilizer and fuel (and other environmental costs) of producing this stuff. I just came across a research paper that addresses this. I have not studied it with a critical eye, but the summary shows that biodiesel is a clear winner over ethanol. Biodiesel reportedly produces 93% more energy than it takes to produce, compared with just 25% for ethanol. Here's the citation with a link to the whole paper (there's a fee for the paper): http://www.pnas.org/cgi/content/abstract/0604600103v1 Alfred Poor 1969 Cal 29 #132, "Pentaquod"