Ethanol is not the only alcoholic fuel that can be made from renewable feedstocks through microbial fermentation. Gevo is producing higher-chain alcohols such as isobutanol, which currently come from oil.
“We found a way to produce isobutanol at 50 percent of the cost of petrochemical processes, and it’s 99.5 percent pure,” says Patrick Gruber, Ph.D., Gevo’s CEO. The company’s microbial fermentation method for making isobutanol can be readily adapted, he says, to equipment and infrastructures at existing ethanol plants, where the drop in oil prices has diminished ethanol output.
The microbial method for making isobutanol was developed in the laboratory of James Liao, Ph.D., a professor of chemical and biomolecular engineering at the University of California, Los Angeles. Gevo holds an exclusive license to the technology, which genetically alters E. coli to generate several higher-chain alcohols from glucose, including isobutanol, 1-butanol, 2-methyl-1-butanol, and 2-phenylethanol. Dr. Liao metabolically engineered E. coli’s amino acid biosynthetic pathway to divert its 2-keto acid intermediates for alcohol synthesis.
Bacteria and yeast naturally ferment sugars to ethanol, but isobutanol had never been produced from a renewable source with yields high enough to be a viable alternative to gasoline.
“We use biotechnology to take the variability out of Mother Nature and make pure products selectively,” adds Dr. Gruber.
Gevo started in Pasadena, CA, in 2005, to pursue the conversion of waste methane into methanol, based on technology developed at the California Institute of Technology. Although the project proved commercially impractical, knowledge gained about the molecular biology and energy pathways in microorganisms is now being applied to making 3-, 4-, and 5-carbon alcohols. Gevo moved to the Denver area in February 2007, attracted by skilled workers and lower operating costs, and to be closer to feedstocks and ethanol facilities in the Midwest.