U Researchers Develop Method to Turn Coal Into Carbon Fiber


The James L. Sorenson Molecular Biotechnology Building, an engineering building at the University of Utah | Chronicle archives.

With the steady rise in preference for natural gas and renewable energy, coal and oil extraction has declined. Workers in the coal industry have taken the fall with layoffs and lower wages. Researchers in the engineering department at the U are working to find another use for coal in order to preserve jobs in the coal industry.

Eric Eddings, associate dean for research in the College of Engineering and professor of chemical engineering, is one of the leaders on a $1.6 million project to convert coal into carbon fiber.

“The utilization of coal as a raw material in the production of carbon fiber has the potential to provide an alternate, more carbon-friendly use for coal,” Eddings said.

The carbon fiber material, called “pitch” by researchers, is intended to be used in anything from skis to automobile and aircraft parts.

“The extent to which coal can be used for this purpose will depend on how big the market for carbon composite materials will become,” Eddings said.

The process of making pitch is complicated, but researchers don’t think that the cost will be a barrier.

“Coal is heated in the absence of oxygen in a process called pyrolysis, whereby the molecular structure of the solid coal is broken down into smaller liquid or gaseous hydrocarbon products,” said Eddings. “These products are then collected and can be processed to form pitch, which is a highly viscous material, not unlike asphalt. The pitch is then spun into carbon fibers that can then be used to make carbon composite materials.”

The process releases some carbon dioxide into the atmosphere, but the quantities are substantially lower than that of coal energy power.  By converting the coal’s carbon into carbon fire, they are essentially isolating the carbon in a different form, rather than turning it to a gaseous state.

Researchers at the U will deliver the pitch to the University of Kentucky’s Center for Applied Energy Research, where they will spin the pitch into fibers.

“They will assess the properties of the carbon fibers in the context of various potential carbon composite applications or products,” Eddings said.  “Our project team will also engage in a market study to explore the market potential of coal pitch-based carbon fiber, based on the information gleaned from our studies on the characteristics of the carbon fiber materials we produce.”

There are already some carbon composite products on the market manufactured by companies like Mitsubishi.  The primary raw material used by these manufacturers isn’t coal, however, but polyacrylonitrile. In comparison, the pitch-based market is significantly smaller.

“I’m confident the research team can take Utah coal and produce carbon fiber,” said Greg Jones, director of the Utah Advanced Materials and Manufacturing Initiative. “The question is can Utah coal have some innate benefit that lends itself to carbon fiber that is somehow better than other coals? Can we find a way to produce carbon fibers more economically so it can be competitive and the market can grow?”

According to Eddings, the carbon composites made from coal would compete with those made from other fibers because “carbon composites derived from coal pitch have unique properties, including very high stiffness, high thermal conductivity, and a very low coefficient of thermal expansion.”

Citing the Utah Geological Survey and the Utah Division of Oil, Gas and Mining, the U’s press release said that in 2014 six Utah coal operators produced 17.9 million tons of coal valued at $600 million, and that there are six active coal mines in Utah as well as sites that produce coal from waste piles in Carbon, Emery, Sevier and Kane counties.

“There’s an abundance of coal and we would like to find an alternative use for it.” Eddings said. “It is a huge natural resource in the US, and we have a whole coal-mining community that is desperate for a new direction.  If we can find an economical way to use coal to produce carbon fibers and have enough useful products so there can be a market for it, then they have that new direction, and it’s more carbon-friendly than just burning coal in a power plant.”

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