How Whisky Makers Could Soon Be Providing A Superior Biofuel


With any luck, future whisky fans may be able to enjoy their three fingers in the afternoon with the added knowledge they’ve contributed to a climate-friendly energy economy. According to E&E; News, a biochemist in Scotland recently founded a company to piggyback biofuel production off the whisky distillation process.

Distillation produces two byproducts: draff — a residual sludge of barley grains — and pot ale — the leftovers in the vat after the high-grade alcohol has been syphoned off. Collectively, they account for roughly 90 percent of the raw material that goes into whisky-making. The industry currently produces 551,156 tons of draff and 422.7 million gallons of pot ale annually, and sells about half the draff as cattle and pig feed. But the rest is simply disposed as waste, at considerable cost.

Martin Tangney, the founder of Celtic Renewables Ltd., hopes to turn that waste into a feedstock for the production of biobutanol — an alcohol similar to ethanol, the most widely used biofuel. But it packs a considerably larger energy punch on a pound-for-pound basis — almost as much as traditional gasoline — and current combustion engine technology can take biobutanol at virtually any fuel mix. By contrast, most American cars can run on 10 percent ethanol at most. Biobutanol’s also much more amenable to pipeline transportation, an option that isn’t available for ethanol.

Tangney also works at the Biofuel Research Centre at Edinburgh Napier University, which got the project of deriving biobutanol from whisky’s byproducts off the ground back in 2010. They’re using a once widely-employed fermentation process called ABE fermentation (for acetone-butanol-ethanol) to get the job done. Biobutanol’s production process has been considerably less cost-effective than ethanol’s, but a number of projects are working on bringing those costs down. E&E; pointed to several biobutanol plants, from Russia to Shanghai, that are producing the fuel using feedstocks like corn, wood chips, and waste from the logging industry.


A Scottish power plant that burns the byproducts to generate electricity got up and running recently, but Tangney’s project appears to be the one major effort to turn draff and pot ale into a usable liquid fuel.

Besides recycling resources and producing a superior biofuel, Tangney’s process also works off agricultural products that would’ve been grown regardless. Demand for conventional biofuels derived from corn or soybeans drives the conversion of more natural grassland or forest to cropland. That cuts down how much carbon dioxide the land can pull in from the atmosphere, reducing the biofuels’ climate benefits. But a biofuel produced from the waste products of agriculture that would be in operation regardless avoids that problem. It also avoids pumping up demand for crops that double as human food, which in turn raises prices and contributes to food instability, especially for the global poor.

“I wanted to set up a biofuels industry in the U.K. from waste products and not use food crops as a substrate,” Tangney said.

Celtic Renewables is currently carrying out a demonstration project at the Centre for Process Innovation at Redcar, England, using about £750,000 Tangney received in public grants and private investment. Over 7,000 tons of draff and 528,344 gallons of pot ale from the Tullibardine distillery are involved, and the project is aiming for 2,642 gallons of biobutanol. Tangney hopes to create a large-scale Scottish biofuels industry around ABE fermentation, with the ultimate goal of creating a competitive drop-in fuel for the U.K. gasoline market.

E&E; News reported that, if Tangney’s vision is fully realized, it could amount to a £100 million annual business in Scotland alone.