The main criticism is with ethanol. It takes a large amount of heat to distill it to a pure enough form to use as fuel. In other words it takes about 3 gallons of ethanol to make four gallons. Biodiesel is different, it takes about one gallon of biodiesel to produce 10 gallons. Although alternative heat sources (solar, geothermal,nuclear) could be used to distill it that energy could be used for other things.

Another problem with biofuels is acrolein emissions. Acrolein emissions are notably higher when using biofuels in engines when compared to petroleum based fuels. Acrolein is also a by product of distillation although it can be controlled in a production process. In short, we will not all be able to use biofuels due to the increase in acrolien emissions, however that doesn't mean that some of us can't.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

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