And if soy and corn prices keep going up to "meet demand" (artificially created), more and more people will realize that there's a cheap weed that grows practically everywhere, needs no pesticides, can provide oil as well as livestock feed, fiber for clothes and paper, as well as a wide variety of medicines: HEMP.

Most households don't turn out enough in the way of mass for the stuff. One of the auto shows on Pike did a bit on one of those home brewers. You put in (for example) 15 gallons of cooking oil and get something less tha 15 gallons out of it, with filtration and whatnot. Plus the chem treatments aren't all that cheap. Even assuming you get the basic components for free because you've got a restaurant willing to give you a steady supply of use cooking oil from their fryer, (Which as Alex points out, can be problematic, and I think will be increasingly so) the costs for the mixing treatment chems will end up running on the order of a buck a gallon. Of course the still/mixer ends up running a few thousand.

Sorry, I don't see it.

One imagines that you’re going to see more of this as gas prices continue to rise–both the thefts of grease to sell on the market, as well as more biodiesel “moonshiners” making fuel on the cheap by avoiding regulation.

I'd be interested to see estimates of how much biofuel could be produced from the biomass produce by an average household. Maybe homebrew kits could be economically viable for some people.

We're going to have to face the fact that if biofuels are to be a big part of our energy future it will be from crops grown expressly for the purpose.