Credit: Marc Rosenthal

It is now well accepted that for several reasons, corn ethanol will have a rather limited role as a renewable substitute for petroleum-derived liquid transportation fuels. The shortcomings of corn ethanol have sparked interest in the production of other types of fuels--such as higher alcohols, oils, and hydrocarbons--from renewable biomass feedstocks (see "The Price of Biofuels"). While the potential economic, environmental, and security benefits of such cellulosic biofuels are clear, many hurdles need to be cleared before they can begin to make a difference in the overall supply of liquid fuels for transportation.

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