I'm not sure about that. Biodiesel is essentially vegetable oil, and cheap vegetable oil is less expensive per gallon than diesel.
I haven't studied the economics of it all, but on the surface, it looks like biodiesel is cheaper than petroleum diesel fuel. There are other drawbacks, of course, but I don't think price is one of them.
> Biodiesel is essentially vegetable oil, and cheap
> vegetable oil is less expensive per gallon than diesel.
... particularly food oil or oilseed that would otherwise
be wasted. However, the subsidies tell us that the economics
aren't there, and I understand that we can't produce enough
oilseed (without impairing food supply) to make much of a
contribution to supply, nor make much more than a token
guesture towards Mid-East oil independence.
I'd be happy to run cheap DB in my VW TDI, but not if it's
cheap because my taxes are more-than-equivalently higher
to pay for that "savings".