Bourbon Waste to Energy: Kentucky Chemists Turn Stillage into Supercapacitors

Researchers at the University of Kentucky have developed a method to convert stillage, a byproduct of bourbon production, into electrodes for supercapacitors, achieving energy storage capacity comparable to existing commercial devices. The findings were presented at a meeting of the American Chemical Society (ACS) in Atlanta, Georgia, this week.

Bourbon whiskey, almost entirely crafted in Kentucky, generates substantial waste grain during its production process, known as stillage. For every barrel of bourbon produced, distillers generate six to ten times that volume in stillage, a watery mash traditionally sold as livestock feed or soil additive. However, transporting the wet stillage is costly, and drying it for easier handling adds further expense, prompting researchers to explore alternative uses.

Josiel Barrios Cossio, a chemistry graduate student at the University of Kentucky, and his advisor, Marcelo Guzman, focused on transforming the stillage into valuable carbon materials. They employed hydrothermal carbonization, a high-intensity pressure cooking technique, to convert the watery waste into a usable form. “We could take the stillage as it is, in a dispersion with a lot of water,” Barrios Cossio explained, “and use that disadvantage as an advantage.”

The resulting carbon materials proved effective as electrodes in supercapacitors, a type of energy storage device. These supercapacitors demonstrated energy storage capabilities on par with commercially available alternatives. The research team’s presentation was part of the ACS Spring 2026 meeting, which featured nearly 11,000 presentations across a range of scientific disciplines.

Kentucky currently produces 95% of the world’s bourbon, according to the American Chemical Society. The bourbon production process requires a mash comprised of at least 51 percent corn, with other grains like rye and barley making up the remainder. After fermentation, the mash is distilled into a clear spirit, “white dog,” and aged in charred new oak barrels for a minimum of two years. The barrels themselves are often repurposed for aging other beverages or even for flavoring products like barbecue sauce.

The James B. Beam Institute for Kentucky Spirits supports research into various aspects of bourbon production, including analysis of corrosion in aging barrels and the complex microbial communities within distilleries. Researchers are also investigating methods to recover liquid lost to evaporation during the maturation process, known as the “angel’s share.”