BP, London, U.K., and DuPont, Wilmington, Del., have been working together since 2003 in this area and are now poised to commercialize their first jointly developed product. “Biobutanol” will be introduced as a gasoline blendstock in the U.K. in 2007. Current European regulations allow up to 10% by volume of the alcohol in gasoline.
The biobutanol will be produced from sugar beets by British Sugar, a subsidiary of Associated British Foods (ABF), at a 30,000-metric-ton/yr plant currently under construction at Wissington, Norfolk, U.K. That plant, originally designed to make ethanol, will require some tweaking of fermentation and distillation to produce biobutanol.
Biobutanol is an attractive component for gasoline, say the firms. It has a low vapor pressure and so can easily be added to gasoline. In addition, it can be used at higher concentrations than bioethanol in conventional engines — potentially up to 16% by volume. Moreover, its energy content is closer to that of gasoline; so it poses less of a compromise in fuel economy. Initial indications are that, on the same feedstock basis, biobutanol provides emissions reductions at least equal to those of ethanol.
The companies also say that biobutanol is less susceptible to separation in the presence of water than ethanol/gasoline blends. So, it can be handled by the existing distribution infrastructure without having to modify blending facilities, storage tanks or gas-station pumps. In addition, unlike existing biofuels, it may suit pipeline transport.
Biobutanol also can potentially extend the use of ethanol/gasoline blends, by reducing ethanol’s impact on vapor pressure — one of the issues, note the firms, that hampers wider use of ethanol in existing distribution channels.