In 2005, total U.S. ethanol production was 3.9 billion gallons, or 2.9% of the total gasoline pool.

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But butane also adds to the total gasoline pool, so that means that gasoline supplies increase in the winter as more butane is added to the mix.

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The percentage of biofuels blended into gasoline is projected to account for 4.3% of the total gasoline pool by volume in 2007, 7.5% in 2012 and 7.6% in 2030.

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If the farmer heats his swimming pool with propane, you are, arguably, consuming that propane when you buy a gasoline-ethanol blend.

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