Butanol, or butyl alcohol is a more complex alcohol that can be utilized as a direct gasoline replacement without modification. It can be burned alone, or mixed with gasoline without ill effects. It has 10% less energy than gasoline, but a 25% higher octane rating, meaning that with higher compression it should be possible to get more energy out of it, making it potentially ideal as a racing fuel. Most butanol is currently made from fossil fuels but it can also be made by a bacterium, Clostridium acetobutylicum - first used to make TNT in 1916.
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