Mountain West News Bureau

Want to grow bigger carrots? A coal byproduct could help

Wyoming Public Radio | By Hannah Merzbach

Published October 28, 2026 at 3:55 PM MDT

A man holds up three carrots, in front of a table of carrots and a jar of something that looks like coffee grinds. — Researcher Resham Thapa poses with a table full of carrots. The University of Wyoming School of Energy has been researching novel uses for Wyoming's coal, including in soil.

You could grow bigger carrots and larger yields by adding a coal byproduct to the soil.

That's the finding from ongoing research at the University of Wyoming. The goal is to find alternative uses for coal, which federal data shows has been in decline for nearly two decades.

The Trump administration is trying to revive the industry to meet rising energy demand, but the research shows coal could also have a future in agriculture, growing corn, sugar beets, or carrots.

"The carrots are crunchy and sweet and delicious," said University of Wyoming soil scientist Resham Thapa, who's leading the study at a research plot in Lingle, Wyoming, close to the Nebraska border.

Close-up on two large carrots growing in the ground. Some dirt has been dug up around them to show the thick orange roots. — A large carrot grows out of a plot of soil in Lingle, Wyoming, with coal char.

Thapa said adding coal char to soil helped grow hefty, 9-inch-long carrots, weighing in at about one pound. This char comes from a process called "pyrolysis," where you heat coal without oxygen.

"Coal char is highly rich in organic carbon. So, the organic carbon in soil is always a good factor to improve soil health," Thapa explained. "Its porous structure also helps to retain soil moisture."

Adding coal char to soil could be particularly helpful for agriculture in dry climates where water is limited, Thapa said. The West needs solutions for saving water right now, as drought persists and water resources shrink, especially in the Colorado River system.

Coal char could help non-irrigated land stay healthy if farmers or ranchers decide to let it go fallow to conserve resources. Outside of agriculture, Thapa said the byproduct could also make the land healthier in active or abandoned coal mines.

The economy in Wyoming, the nation's leading coal producer, has historically fluctuated with the boom and bust cycles of the resource.

Thapa said that agriculture could give the coal industry a market outside of the energy sector, where you don't need to burn coal and create emissions.

"It's kind of a carbon sink," Thapa said. "There is no emission, there is no combustion. So the carbon is locked in the soil."

Mining the coal in the first place, however, can create emissions. According to the U.S. Energy Information Administration, in 2021, methane emissions from active and abandoned coal mines accounted for about 7% of total U.S. methane emissions and around 1% of total greenhouse gas emissions in the country. Methane also traps significantly more heat than carbon dioxide.

Coal char is not yet on the market, but could be after more research. The Wyoming team is in its first year of a three-year project, where it's figuring out the optimal amount of coal char to add to the soil.

In addition to carrots, the team has also had success so far growing corn and sugar beets.

This story was produced by the Mountain West News Bureau, a collaboration between Boise State Public Radio, Wyoming Public Media, Nevada Public Radio, KUNR in Nevada, KUNC in Northern Colorado, KANW in New Mexico, Colorado Public Radio, and KJZZ in Arizona as well as NPR, with support from affiliate newsrooms across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting and Eric and Wendy Schmidt.