by Ann M. Thayer (Chemical and Engineering News) Scottish startup to make biobased chemicals from the leftovers of whisky production
The process for making Scotch whisky uses three ingredients: water, yeast, and a grain, primarily barley. About 10% of the output is spirits, and the rest is by-products.
Those spirits can’t be called Scotch whisky until they age in oak casks—in Scotland—for at least three years. The by-products are residual solids called draff and a yeasty, copper-contaminated liquid known as pot ale. They are usually spread on agricultural fields, turned into low-grade animal feed, or discharged into the sea.
The Scottish start-up Celtic Renewables is looking to take draff, pot ale, and its own microbe to produce acetone, 1-butanol, and ethanol. Along the way, the small company hopes to revitalize the once widely used ABE fermentation process, so-named after the three chemicals it makes.
Draff and pot ale “have no commercial value, and in the modern context they represent a disposal issue,” says Martin Tangney, founder, president, and chief scientific officer of the Edinburgh-based firm. Looking to address local Scottish and other U.K. targets for waste reduction and increased biofuel use, he sees an opportunity to “use what you have in abundance.”
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The ABE process was once one of the largest industrial-scale fermentations practiced. Renowned scientist and Israeli statesman Chaim Weizmann discovered how to use anaerobic Clostridium acetobutylicum to convert molasses and other sugars into chemicals needed during World War I. But by the 1960s, the process had largely died out, unable to compete with advancing petrochemical production, according to Ronald F. Cascone, a principal with the consulting firm Nexant.
… Besides the three chemicals, the ABE process yields protein-containing solids that can be turned into a high-grade animal feed.
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To help fund the scale-up, Celtic Renewables has obtained about $1.3 million from the U.K. Department of Energy & Climate Change and $660,000 in private equity. Raw material will come from Tullibardine Distillery, which spends $400,000 per year to discard up to 6,500 metric tons of draff and 2 million L of pot ale.
“We’ll be working at 1,000-fold where we were before, so it’s a huge jump,” Tangney says. If successful at the larger scale, Celtic Renewables’ next step will be to draw up plans for a commercial facility in Scotland and seek help from a $40 million U.K. Department for Transport biofuels plant development fund.
Celtic Renewables isn’t the only company targeting biobutanol, which is attractive as a biofuel and in chemical markets. Butanol has 25% more energy per unit volume than ethanol and can be burned in unmodified engines at higher levels. It can be blended into gasoline and diesel in existing facilities. And, when burned, it boasts very low greenhouse gas emissions.
Competitors include Gevo and Butamax, a BP-DuPont joint venture, but both make isobutyl alcohol, not the 1-butanol that comes from the ABE process. More direct competition comes from Green Biologics and Cobalt Technologies, which both use Clostridium-based approaches. In 2011, Eastman Chemical acquired similarly focused TetraVitae Bioscience, but little has happened since, according to Nexant’s Cascone.
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For example, the remote western Scottish island of Islay houses several distilleries. “It’s difficult getting fuel on and off the island, and the winters can be harsh,” Tangney says. “We’re talking to the Islay Energy Trust about locating a plant there at some point in time to take locally generated residues and convert them to fuel that can be used on the island.” READ MORE