Engineering:
Cellulosic Biofuels—Got Gasoline?
John R. Regalbuto
Most people think of ethanol as the only liquid biofuel, and that the major advances in biofuels will revolve around enzymatic conversion of cellulosic or woody biomass (including nonfood stems and stalks of corn stover or switch-grass, and wood chips) into simple fermentable sugars (1). However, in just a few years the commercial scale production of liquid hydrocarbons from biomass will be possible. Hydrocarbons can be made (see the figure) from the sugars of woody biomass through microbial fermentation or liquid-phase catalysis, or directly from woody biomass through pyrolysis or gasification (2). Finally, lipids from nonfood crops as well as algae (3) can be converted to hydrocarbons. The resulting hydrocarbon biofuels will be drop-in replacements for gasoline, diesel, and jet fuel; will give much higher gas mileage than ethanol; and will work in existing engines and distribution networks.
Program Director, Catalysis and Biocatalysis, National Science Foundation, Arlington, VA 22230, USA.
E-mail: jregalbu{at}nsf.gov
