The energy balance regarding ethanol really depends on what you want for fertilizer input.The studies that said it was negative are pretty much discredited -- they included the input of the sun. One generally accepted "spreadsheet" that produces a 38% net gain in BTUs out over in...of 27,000 BTUs to grow the corn, 12,000 went to Fertlizer, and 7,000 to Irrigation. Only 2,000 to tillage and harvest. I don't know if the irrigation was "worse case" only for places that irrigate, or if it was averaged so it's allocated even to places that don't use it. But that doesn't matter really -- you can easily use a fossil fuel for irrigation. Can you say Windmill? Either direct pump, or too generate electricity. In making alcohol, they use a lot of BTUs in the form of steam. But if you build a plant that is trash-to-energy incinerator, that then uses the steam to make electricity, then the steam they where making anyway goes on to heat the still...how do you account for steam that would've gone unused? Fertilizer you can count a couple ways. One, you could reduce it. So maybe between needing more land and using crop rotations for N, you use 4,000 extra BTUs in the tractor to save 12,000 BTUs in fertilizer...not a bad gain. OTOH, most fertlizer is made from natural gas...most cars burn liquid fuel, not NG. So do you count it as converting the NG to an automobile usable form :) Anyway, we won't replace gasoline with Ethanol. Probably not enough land. But you know, 20% or 30% could make a difference. While some people are real rosy on their numbers, I wouldn't believe the ones who say it takes more energy to make it because they're being just unrealistically conservative in their numbers.
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