A cannabis plant grows in the Amsterdam Cannabis College. (Christopher Furlong/Getty Images)
Researchers have developed nano-thin sheets of carbon from hemp fibers, which could be a very cheap replacement for graphene, which is used to make supercapacitors for energy storage applications. David Mitlin is presenting his group’s findings at the American Chemical Society expo this week, as described on the organization’s website:
Mitlin’s team built their supercapacitors using the hemp-derived carbons as electrodes and an ionic liquid as the electrolyte. Fully assembled, the devices performed far better than commercial supercapacitors in both energy density and the range of temperatures over which they can work. The hemp-based devices yielded energy densities as high as 12 Watt-hours per kilogram, two to three times higher than commercial counterparts. They also operate over an impressive temperature range, from freezing to more than 200 degrees Fahrenheit.
“We’re past the proof-of-principle stage for the fully functional supercapacitor,” he says. “Now we’re gearing up for small-scale manufacturing.”
Industrial hemp growth is booming in Canada, where Mitlin conducted his research at the University of Alberta. Growing cannabis with or without high concentrations of the psychoactive substance tetrahydrocannabinol, or THC, has been restricted in the United States under Substance Control Act for more than 60 years. The 2014 Farm Bill (PL 113-79) provides that research institutions and state agricultural programs can grow industrial hemp with less than a 0.3 percent concentration of THC in states where legal under state law, such as North Dakota.