This being from a drunken conversation last night, about renewable energy.
There are 300 million people in America, 10% of these people have been designated as America's Greatest Renewal Resource (TM), and their patriotic duty is to be rendered into biodiesel to fuel our tanks, SUVs, and snow machines.
For parsimony, assume the average American weights 100 kg. This gives us 3*10^9 kg of raw material. Most of this is water, bone, other things that do not react, so assume 20% total reaction efficiency, we wind up with 6*10^8 kg of biodiesel.
This sounds like a lot, but in fact, it's only 7*10^8 liters of fuel, or 3.4*10^6 barrels of biodiesel. Less than one gulf oil spill. A mere drop in ocean.
Well, back to the drawing board.