GoKawiilKentucky’s bourbon industry produces vast quantities of waste grain that is costly to transport and process. Researchers have now found a way to turn that by-product into high-performance energy-storage materials with potential applications in electric vehicles and large-scale grid storage.
More than 95 percent of all bourbon whiskey is made in Kentucky. For each barrel of bourbon, the industry also produces between six and 10 times as much “stillage”—a slurry of spent grain and water. This is normally sold to farmers as a livestock feed or soil additive, but it needs to be dried out first to reduce the weight and make it easier to process.
This is a major burden on distilleries, says Josiel Barrios Cossio, a graduate student in the University of Kentucky’s chemistry department. It either requires a lot of time and space to dry the stillage out via evaporation, or an expensive heating process. He and his colleagues have demonstrated that they can instead directly convert the wet stillage into useful carbon materials that can be used to make electrodes for batteries and supercapacitors.
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In research presented at the spring meeting of the American Chemical Society in Atlanta today, Barrios Cossio showed that the carbon materials could be used to create supercapacitors that match or exceed the energy density of commercial devices, and hybrid lithium-ion supercapacitors that can store up to 25 times as much energy as conventional designs. While the work is just a proof-of-concept, Barrios Cossio says, it could ultimately allow distilleries to turn a waste stream into a source of profit.
“And it’s a win-win scenario, because we can potentially have a more renewable and abundant biomass source, or feedstock, to produce these materials that are every day more in demand from the car industry and renewable energy applications,” he says.
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Barrios Cossio first conceived of the idea while taking part in a research traineeship run by the U.S. National Science Foundation aimed at finding solutions to problems related to water, energy, and food systems. After visiting several distilleries and seeing the scale of the waste produced, as well as the challenges these businesses face in disposing of it, he began thinking of ways to put the stillage to more productive use.
He discovered a group at the Friedrich Schiller University Jena, in Jena, Germany, that had developed a process for converting waste grain from beer breweries into electrode materials for energy-storage devices. Barrios Cossio then spent a summer internship at the lab to learn about their techniques.
After returning to the United States, Barrios Cossio contacted several distilleries to source some stillage to experiment with and soon got a response from the Wilderness Trail Distillery in Danville, Kentucky. “I asked them, ‘Can I take a gallon of stillage?’” he says. “They replied to me some days later saying, ‘Yeah, you are welcome to take it. I would prefer that you take 10,000 gallons and get rid of the stillage from that day.’”
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