[Fraxinus]

how do the various government agencies collect their per-gallon tribute?

Since biodiesel is cooking oil reprocessed in to an ester, the government is getting its cut from the alcohol that is used to make the esters.

[Bernard]

I'm not sure what that means, but it sounds like you have to add alcohol to used cooking oil to produce biodiesel?

In any event, I'll just hold out until somebody figures out how to turn dog poop into fuel. Then, I'll go back to the shelter and get two more mutts just like the fertilizer factory I already have in the backyard.