The result is a three-part technology package that Gevo has developed that essentially allows current ethanol producers to leverage existing infrastructure to produce higher value end products. This is accomplished through a minor retrofit that requires a small, one-time capital investment.
Since its inception in 2005, Gevo has attracted an impressive list of investors, including Khosla Ventures, Richard Branson’s Virgin Green Fund, Burrill & Company, and the French oil and gas company Total. “[Total’s] investment really gave us a lot of commercial validation, in our opinion,” Lund says. “They are one of the largest oil and gas companies in the world; they’ve gone out and looked at all the alternative technologies that are out there, and chose to invest in Gevo.”
The Technology
One primary component of Gevo’s technology package is the company’s genetically modified biocatalyst. The biocatalyst is a strain of yeast that has been biologically engineered to produce isobutanol rather than ethanol. According to Lund, Gevo’s researchers essentially shut off the yeast’s ability to produce ethanol and engineered it to produce isobutanol instead.
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The pathway of the biocatalyst, or the way in which the biocatalyst is able to make isobutanol, was licensed by Gevo from the University of California, Los Angeles. The company has also licensed other intellectual property relating to the biocatalyst from CalTech and maintains strong research relationships with both institutions.
Another primary component in Gevo’s technology is the method the company has developed to separate the isobutanol from the biocatalyst as it is produced. Gevo has patented this separation technology known as Gevo Integrated Fermentation Technology.
Historically, there have been two main issues with biobased isobutanol production: intolerance of the biocatalyst to high levels of isobutanol and problems with effectively and economically separating the isobutanol from water. Through the development of GIFT and its proprietary biocatalyst, Gevo has been able to overcome both of these issues.
“The problem with butanol in the past has been that as soon as the biocatalyst starts producing butanol, the butanol becomes toxic … and kills it,” Lund says. “What we’ve done is genetically modified [the biocatalyst] to make it produce a lot of butanol and make it very tolerant so it doesn’t die.
“We’ve also developed [our GIFT technology] to separate the butanol from the organism as it is produced, and that further helps in assisting the organism so it doesn’t die while it’s producing fuel,” Lund continues. That innovation in engineering also negates the issue of water separation. “As the fermentor is producing butanol, we separate it from the fermentation …. in a pure form. So, we are basically pulling it off as it is produced,” he says. “That allows us to avoid having to do very costly water separations.”
Gevo’s technology is feedstock flexible and has been designed to utilize all traditional ethanol feedstocks as well as cellulosic biomass. “We’ve developed our technology to work using corn, sugar and cellulosic biomass,” Lund says. “We don’t actually convert cellulose into sugar, but we have developed our technology to work with mixed sugars from cellulosic biomass.”
The final primary component of Gevo’s technology involves the conversion of isobutanol into a wide variety of end products. “We have developed technology to convert isobutanol into a number of hydrocarbons,” Lund says. “We can turn it into renewable gasoline, renewable diesel or renewable jet fuel.” Isobutanol can also be converted into a number of chemical products, including rubbers, plastics, polymers and fibers.
The end products can be produced in two ways: the conversion component of the technology can be incorporated into the ethanol plant during the retrofit, which would allow the facility to produce renewable gasoline, jet fuel or diesel onsite, or the isobutanol could be shipped to a central location for processing.
Demonstration-Scale Production
The process used to retrofit an existing ethanol plant to utilize Gevo’s technology is relatively simple. “To complete the retrofit, we use all of the existing equipment that is in [the plant],” Lund says. “We also add a few pieces of equipment and bring in our biocatalyst. So, instead of using the yeast that is used to make ethanol, we use ours — which is used to make isobutanol.” Once the retrofit is complete, the plant operates essentially in the same way as a traditional ethanol plant.
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