Mar 20, 2009

Biobutanol: Better Than Ethanol

A number of agricultural groups and several car manufacturers are promoting ethanol these days, but perhaps they should take a look at another alcohol: biobutanol. According to some experts, butanol has a number of important advantages over ethanol. It has a higher energy value per unit of weight and is more resistant to combining with water (“hydrophobic,” not unlike W.C. Fields), so it can be transported via existing pipelines within the petroleum-based fuel infrastructure. This is a happy result of its chemical makeup -- a longer hydrocarbon chain means it is more similar to gasoline than to ethanol.

Biobutanol is chemically identical to butanol derived from oil (petrobutanol), but it can be produced from a wide variety of biomass. Because it is similar in nature to gasoline, it can also be added to gasoline at a higher percentage without engine modification than ethanol, and it is believed to have applications in both diesel and gasoline blends. With all this going for it, it is surprising that butanol’s light has been hidden under a bushel, but that is changing. SRI Consulting has just published its new Chemical Inputs and By-Products of Biofuels report, providing comprehensive information on the technological and economic aspects of producing biobutanol.

Two new processes show promise in bringing biobutanol into the mainstream. One is a modification of the established Acetone-Butanol-Ethanol (ABE) fermentation developed by the University of Illinois. The second process is based on the production of isobutanol by a proposed solvent-tolerant microorganism with a proprietary recovery process based on conversion of a corn dry mill. Neither process is commercial yet.

“Due to the superior energy density of biobutanol and despite higher capital costs, the relative costs on an energy basis ($/Btu) for biobutanol is equal to or slighter better than ethanol at $2.28/gallon, if the projected performance in the simulation can be met,” Ronald Bray, co-author said.

We’re always worried about meeting projected performance targets, but maybe that’s just us.