The discussion/decision about what should be the source vegetation for biodiesel in the US repeats a familiar theme. The Europeans- lead by Germany decided long ago that for their climate and infrastructure Rapeseed (Canola) oil is the best from a cost benefit perspective. When the US got it's collective feet held to the fire on the same subject, the lawmakers in their infinite stupidity, decided that WE could do better!
Nevermind that the Germans have been doing some pretty good engineering over the years (they DO build Mercedes after all). They are also darn fine chemical engineers. If they have figured out that Rapeseed oil is the way to go we had better have some pretty good evidence to NOT go that route. All the information to date points out that we DON'T HAVE that evidence!
Not to say that soy (Soy Methyl Ester - SME - Soyate) can't work or that biodiesel made from WVO isn't a good thing; on a large scale its just not the best thing "energywise".
The flap over ethanol for fuel in the US is a classic study in lobbyists/subsidies ending up with exactly the Wrong conclusion. Large subsidies which ADM and other monopolistic conglomerates lobbied for and got, high import duties against Brazilian ethanol, mandated ethanol use before the energy balance results are in. Large fundamental changes in the way our food agriculture system works without sufficient consideration of the consequences. We'll be paying for this bad goverment for a LONG time!