Intriguing MIT research

Research from MIT working with microbes to produce isobutanol might have a broader impact than what appears on the surface.
By Susanne Retka Schill | August 31, 2012

Research from MIT working with microbes to produce isobutanol might have a broader impact than what appears on the surface. Biology researcher Christopher Brigham and his colleagues at MIT have been working with a soil bacterium which in nature turns fatty acids and other carbon compounds into a polymer. They’ve tweaked the microbe genetically so it produces isobutanol instead – from carbon dioxide. Next up is to see if they can make other alcohols (butanol was mentioned) and other chemicals, as well as use other carbon sources, such as food processing and ag waste, as feedstocks.

Much is made about how only part of a bushel of corn gets turned in ethanol and about one-third is the coproduct DDGS. There’s another coproduct, though, that comprises the rest of the equation – CO2. Just imagine, sometime in the future, today’s corn ethanol plants might produce three fuel streams. There are several cellulosic ethanol technology developers working to create bolt-on cellulosic units at existing corn ethanol plants. It makes sense to utilize existing infrastructure for a second fuel stream. Providing a market for stover would benefit farmers, too, creating a new revenue stream and removing a portion of the crop residue that must be managed when it gets heavy.

Using CO2 for a third fuel stream would be a slick addition. Not long ago, I learned that ethanol plants are prime candidates for CO2 projects because the gas stream is relatively clean. A few existing plants have partnerships with companies to capture and process their CO2. The problem is, of course, that many ethanol plants are not close to end markets. But, they are set up to handle liquid fuels. I understand biobutanol and isobutanol have their own handling challenges, but they are described as “drop-in” fuels.

Another intriguing aspect of this research is the scientists are trying to develop a continuous process, where they’d keep the bacteria happily producing isobutanol while siphoning off the fuel-containing liquid to extract the alcohol. Right now, ethanol plants essentially do batch fermentation and continuous distillation. Plants have several fermentation tanks, timing the batches so that once fermentation is done, the fermenter is emptied and run through the solids separation and distillation processes. By the time one fermentation tank is emptied, the next is ready. I suspect somebody has tried doing a continuous siphoning of ethanol, leaving the yeast behind to continue producing, but there are limiting factors. Perhaps somewhere there are scientists using the new genetic tools to tweak brewer’s yeast to thrive in a continuous production environment, just as these MIT researchers are tweaking R. eutropha. I do recall hearing that some of the cellulosic ethanol technology developers have worked on this as well.

Intriguing possibilities for the MIT research, but it will be a while. When asked, Brigham said it could be five years before the work being done now at lab scale is ready for scale-up.