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May 15, 2009 (Vol. 29, No. 10)

Forging Isobutanol with Modified Microbes

Gevo Is Developing Microbial Fermentation Methods for Renewable Fuel Production

  • Joint Ventures

    To retrofit existing ethanol facilities to manufacture isobutanol, the company designed Gevo’s Integrated Fermentation Technology (GIFT™). The main alteration at ethanol plants involves the addition of separation equipment to purify butanol from the fermentation broth.

    Gevo is working with ICM, an engineering firm, to retrofit an ethanol facility in St. Joseph, MO, to demonstrate the effectiveness of GIFT to advance isobutanol production. ICM built many of the ethanol plants in the Midwest. By retrofitting ethanol plants, Gevo can lower capital and operating costs.

    “We’re completely open-minded about retrofitting ethanol facilities. We may acquire ethanol plants or partner with someone who wants to make a higher value product,” says Dr. Gruber.

    In February 2009, Gevo teamed up with Cargill and received exclusive rights to integrate Cargill’s microorganisms into GIFT to produce butanols from cellulosic sugars that are derived from corn stover, switchgrass, forest residues, and other sustainable feedstocks.

    The Cargill platform is an industrially proven yeast technology that converts sugars into biofuels. “Cargill’s organisms and its enabling technologies give us a significant leap ahead,” continues Dr. Gruber.

    Gevo also has produced renewable gasoline and jet fuel that meet or exceed specifications set by the American Society for Testing Materials, Dr. Gruber notes. The firm recently partnered with Bye Energy to distribute renewable aviation fuel to small and mid-sized airports. Small propeller planes use aviation fuel, but not commercial jets. “Only two refineries in the world make aviation fuel,” explains Dr. Gruber. Isobutanol, a 4-carbon alcohol, is readily converted into aviation fuel, an 8-carbon hydrocarbon.

    Bye Energy has an extensive network of airport owners and operators who service propeller planes. About one billion gallons of aviation fuel are sold yearly. “It’s a specialty market that we can enter,” says Dr. Gruber. Gevo’s renewable aviation fuel offers business and general aviation operators an alternative to petroleum-based products that substantially reduces their carbon footprint.

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