I've seen a number of articles in publications such as New Scientist and on the BBC web site discussing the fact that the processing of newly grown agricultural products into biodiesel and ethanol is actually worse for the environment that using dino diesel.

Now this report from the OECD no less discussing the same thing.

http://www.reportonbusiness.com/servlet/story/RTGAM.20070914.wibreguly14/BNStory/robColumnsBlogs/home

This does not criticize the conversion of waste products such as food or wood waste into bio fuels, as the Germans do, or WVO use, but it certainly criticizes the trend to grow corn and canola for fuel production.

If this is all true then I may as well stick with the cheaper dino diesel