Reply #1: (aside) Comparison of biofuel efficiency - corn/sugar cane (Nat'l Geographic)

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http://magma.nationalgeographic.com/ngm/2007-10/biofuels/biofuels-p4.html

Green Dreams
By Joel K. Bourne, Jr.

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Growers in the emerald desert can get seven harvests from their fields before replanting, and the distilleries recycle their wastewater into fertilizer. Like most of Brazil's usinas, São Martinho consumes no fossil fuel or electricity from the grid; for heat and power it burns cane waste, known as bagasse, typically generating a slight surplus of power. Even the cane trucks and agricultural machinery burn a blend of diesel and ethanol, while the favorite crop duster, a hot little plane called the Ipanema, is the first fixed-wing aircraft built to burn pure alcohol. "We're obsessed with efficiency," says plant director Agenor Cunha Pavan.

While corn ethanol's energy ratio hovers around breakeven, "we get eight units of ethanol for every one unit of fossil fuel," says Isaias Macedo, one of Brazil's leading sugarcane researchers. Experts estimate that producing and burning cane ethanol generates anywhere from 55 to 90 percent less carbon dioxide than gasoline. And Macedo envisions even greater efficiencies. "We can do the same thing with two-thirds or half of the bagasse, better manage tractors in the field, and approach levels of 12 or 13."