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Like ethanol, butanol is an alcohol compound, but with four carbon atoms instead of two. DuPont officials said the different chemical structure of butanol gives it several advantages over ethanol, including tolerance to water contamination, facilitating transportation via pipeline.

The U.S. fuel market has been constrained by the fact that ethanol, which attracts water molecules and therefore tends to corrode pipelines, must be transported on trucks, trains and bargest in relatively small batches to storage terminals where it is then blended with gasoline.

Another advantage of biobutanol, officials said, is that it can be blended into gasoline at higher concentrations than ethanol without the need to retrofit vehicles, and it offers better fuel economy than gasoline-ethanol blends.