By Chris Hayhurst
A windmill blade. A bicycle seat post. The fuselage and wings of a commercial airliner. If you want to know what they all have in common, the person to ask is Keith Graham.
“They can all be made with carbon fiber,” says Graham, “and that carbon fiber can be recycled.”
The vice president of business development with South Carolina-based Carbon Conversions, Graham helps lead one of just a few businesses in the United States focused on reclaiming carbon fiber from post-industrial and end-of-life materials. In 2021, he says, the company recycled approximately 1.5 million pounds of carbon fiber it obtained from sources around the world. One of its suppliers, a global bicycle manufacturer, sends the company everything from prototype forks and handlebars to the cracked frames returned from riders who’ve crashed in the Tour de France.
“Once that ‘waste’ comes to us, we take it and process it to turn it into something that same bicycle company can use again,” Graham says. Carbon Conversions is keeping carbon fiber out of landfills, “but we’re also creating recycled carbon fiber products that manufacturers want to use because they’re cost-effective.”
High value, high cost
It’s the cost of carbon fiber, in fact, that has made it the kind of material typically found only in high-end products like $300 soccer shin guards and $10,000 bicycles.
The vast majority of carbon fiber is derived from a rigid thermoplastic material called polyacrylonitrile, or PAN. Through a combination of chemical and mechanical processes, the carbon atoms in PAN are aligned and spun into strands that are then heated to very high temperatures. This heating process, called carbonization, removes most of the non-carbon atoms to leave micron-thin filaments that can be combined with resins and other materials to form extremely strong and lightweight composites.
When Elon Musk drew up plans for his SpaceX Starship, he originally planned to build it out of carbon fiber to take advantage of these well-known properties. He eventually changed his mind, however, when he ran up against the reality of the material’s price.
While carbon fiber can be anywhere from five to 10 times as strong as steel, its raw-material and manufacturing costs also make it much more expensive. Prices are in constant flux, but one recent analysis put the cost of aerospace-grade carbon fiber at more than 40 times that of steel.
For the SpaceX team, the decision to go with cold metal instead of its stronger and lighter space-age alternative in part had to do with dollars and cents.
Despite carbon fiber’s high value, explains Jinwen Zhang, Ph.D., a professor in the School of Mechanical and Materials Engineering at Washington State University (WSU), there’s currently no economical way to make carbon fiber composites from scratch. Similarly, he says, because the manufacturing is energy-intensive, “that adds to the cost as well, and it makes it a significant source of emissions.”
With that in mind, in 2017 Zhang and his colleagues at WSU developed a chemical process for breaking down carbon fiber composites while preserving the carbon fiber within them. Their goal, he says, was to advance carbon fiber recycling—to help the industry make the material more affordable and environmentally sustainable.
Reclaiming and reusing carbon fiber, he says, offers a lot of promise in this regard, but it also faces a number of major challenges.
First and foremost, according to Zhang: The recycler can’t just take a finished carbon fiber composite and melt it down and reform it like other plastics without compromising the material’s structural integrity. Instead, the process typically involves mechanical chopping and shredding of the composite into small particles that are then used as filler in everything from consumer-electronic plastics to concrete. It’s also commonly recycled through a more complicated heating treatment called pyrolysis or through chemical approaches like that applied by his research team.
“Recycling today—you can do it,” he says, “but it takes investment in infrastructure, and the equipment is very specialized.” Likewise, there’s the supply chain issue of product collection from the manufacturer and delivery to the recycling facility. “Who’s going to get that airplane fuselage or wind turbine blade and break it up and handle the transportation?”
A growing number of companies—recyclers and manufacturers alike—have decided they’re ready to tackle such challenges, but Zhang says the industry is only in its infancy. “The day is coming when we’ll see carbon fiber recycling on a much larger scale,” he predicts, “but it’s probably still five or 10 years away.”
Closing the loop
Carbon Conversions, Keith Graham says, may not be big just yet, but they’re expanding quickly to keep up with demand. “We have 50-plus people working in shifts, and we’re running 24 hours a day.” (Among the small but growing number of companies recycling carbon fiber worldwide are two located on the Front Range of Colorado: Vartega and Mallinda.)
The work of recycling, Graham notes, takes place in a 50,000-square-foot industrial facility in Lake City, South Carolina. Relying on proprietary technology, they chemically extract the carbon fiber from scrap material before selling it back to manufacturers in various forms.
The manufacturers save money in part by avoiding steep landfill disposal costs, and the recycled carbon fiber products they buy back from Carbon Conversions—including bulk chopped fiber and non-woven mat—cost less than they would pay for virgin carbon fiber.
“We like to say we’re ‘closing the loop'” in the carbon fiber lifecycle, Graham explains. Instead of losing carbon fiber (and money) to waste, “the manufacturers are bringing it back into their supply chain and reusing it in their processes.”
Carbon Conversions estimates that, after recycling, the fibers in their recycled products are 95-97% as strong as the originals. Meanwhile, the project global market for carbon fiber in 2031 is $8.9 billion, up from $3/7 billion in 2020, according to a recent report.
As he looks to the future, Graham says, he sees the market for recycled carbon fiber increasing for years to come. “As carbon fiber manufacturers increase their capacity, that just means more waste in the supply chain and more opportunity for us to grow.”
Graham adds that Carbon Conversions will likely have more competitors as time goes on and carbon fiber recycling picks up, but that doesn’t worry him at all. “In this business,” he says, “the sky’s the limit.”
Lead image courtesy of Carbon Conversions