One thing I have heard from a friend who used biodiesel was that he use to get the 'leftovers' from the deep fryer at his local fast food resurant for nothing (since they usually just throw it away), and use that to blend. That way he was recycleing waste that normally would get tossed, to make his own.
With keeping the above in mind, I would venture that since the product was now used for two purposes, the energy required to manufacture it in the first place was halfed, as opposed to making a seperate lot for use. He also used a 15% blend, thinning the dinos out that much more, though he did say he noticed a little less acceleration full open.
Just throwing out some more info to fuel the fires of discussion, I guess.