Paper Waste Spurs Testing of Low-Cost Carbon Fiber for Products

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By Adam Allington

When you think about the materials that go into making cars, you don’t generally consider the plants growing in your backyard. But that’s the direction industry is headed.

At the American Chemical Society’s national meeting in Washington, D.C., on Aug. 24, researchers from Washington State University presented a method for converting biomaterial, such as paper and pulp wastes, into lower-cost carbon fiber. And that fiber would be strong enough to manufacture high-performance components for aircraft, cars, and wind turbines.

Demand for carbon fiber has increased significantly in recent years—especially in aviation and the auto industry—where reducing the weight of a vehicle is critical to increasing fuel efficiency and bringing products like electric cars into the mainstream. Ford Motor Co. and Hyundai have invested in Washington State University’s research.

Cheap and Abundant

The source for this potential materials revolution is among the most common raw materials. It’s called “lignin,” and after cellulose, it’s the second-most abundant molecule in the world. Present in the cell walls of land-based vascular plants, lignin is an organic polymer that gives plants and trees their sturdy structure.

It also amounts to a whole lot of waste—about 40 to 50 million tons created each year as a byproduct of the U.S. paper and pulp industry. The figure jumps up by another 100 to 200 million tons when counting waste produced by biorefineries for the production of cellulosic ethanol, according to research published in Green Chemistry, the journal of the Royal Society of Chemistry.

“The interesting value proposition here is that we have all these residues and some have no real use” yet, said Birgitte Ahring, the principal investigator on the Washington State research team. “What we are proposing is to take a really low-value product and turn it into a high-value, sustainable product.”

Because lignin already falls under existing guidelines for industrial use of biomass, Ahring said there shouldn’t be any specific regulatory hurdles to clear. “Overall, we are not dealing with anything that is harmful,” Ahring said.

Ahring told Bloomberg BNA that most lignin byproduct is either burned to make steam in biorefineries—which is very inefficient—or sent to landfills. That is because, despite lignen’s widespread availability, scientists have yet to develop a cost-effective way of breaking it down into its individual components so it can be combined with other polymers to make products.

But Ahring said the research community is close to cracking that nut. “I think we could be able to start development of test materials this fall,” she said. “I think we’re probably five years out from entering the market.”

The ‘Holy Grail’ of Manufacturing?

Advanced carbon fibers have strength-to-weight ratios that are ten times better than steel. Light weight vehicles are therefore more fuel efficient and better able to meet emissions reductions targets.

The carbon fiber found in most modern cars and aircraft is made from Polyacrylonitrile (PAN), an expensive, non-renewable polymer made from oil or coal. In contrast, Ahring’s lab has been able to blend small amounts of lignin with PAN at high temperatures and then spin the polymer melt to form new fibers.

Initial tests found that PAN fiber consisting of 20 to 30 percent lignin produced fibers with the same properties as low to medium-strength carbon fiber.

Debbie Mielewski leads the sustainable materials division at Ford Motor Company. “People have been working for 20 years to make carbon fibers out of lignin, it’s a really tricky problem to solve,” Mielewski said.

“Carbon fiber is the ‘Holy Grail’ of manufacturing. It’s very high performance, but carries a very high price tag,” she said.

Carbon fiber is already widely used in everything from sporting goods and furniture to military and medical equipment. If lignin can be incorporated into carbon fiber, even in small amounts, it could lower costs as much as 37 to 49 percent of the final production cost of carbon fiber, according to Washington State University.

In addition to carbon fiber, automakers also are looking into other biomaterials as a way to “lightweight” car parts.

Much of the interest in fuel-efficiency is focused on the power-train. But Mielewski said the typical vehicle carries about 400 pounds worth of plastic, most of which is mixed with large quantities of glass or talc, which are quite heavy.

To address this issue, Mielewski’s department has developed biomaterial applications in everything from soy foam in seat cushions to wheat straw in storage bins and cellulose in arm rests.

Regulatory Questions

Since the lignin-PAN carbon fiber under development does not yet involve the use of carbon nanofibers, Washington State University’s Ahring said the product will not require clearance under the Toxic Substances Control Act (TSCA).

But some worry that the enthusiasm supporting the rapid commercialization of biobased chemicals has gotten out in front of potential regulatory questions.

“It is entirely possible a carbon fiber with a lignin may require notification under TSCA,” said Lynn Bergeson, a managing partner with the Washington, DC-based law firm Bergeson & Campbell, which advises chemical companies about regulatory compliance.

“There are currently three types of lignin listed on the TSCA Inventory,” Bergeson said. “The details of the material will dictate its TSCA status. Anything made from different forms of lignin are not fungible for regulatory purposes.”

Scalability

Federal government backing for biobased products is codified in legislation, executive orders, and procurement policies, all with the intent of boosting national support for such innovations and spurring their development.

Despite the federal support—as well as recent breakthroughs in lignin-PAN research—the timeline toward commercialization remains murky. In an email to Bloomberg BNA, Alper Kiziltas, research scientist with Ford’s sustainable materials team, described current projects involving bio-based carbon fiber as “making good progress, but still far away from commercialization.”

Likewise, others suggest the quantities of biomass necessary to support large-scale use of carbon fiber in the transportation sector may be hard to deliver through the existing supply chain.

When corn started being used for fuel it affected the marketplace, according to Donald Collins, CEO of the Western Research Institute, a technology development center serving private clients, industry, and government.

“We saw problems arise with food supply/prices when a big push occurred to use corn to produce ethanol.”

“Absent government subsidies that interfere with normal market pricing, one should expect that the price of a resource will increase when it experiences a large increase in demand,” he said.

Collins also pointed to the current price of carbon fiber—$12 to $15 per pound—as another barrier to widespread adoption by manufacturers.

The magic number for getting carbon fiber into mainstream automotive applications is closer to $5 per pound, according to Collins. Even if lignin-PAN methods do ultimately prove out in terms of strength and weight, “that likely won’t be enough to get costs down to that level.”

To contact the reporter on this story: Adam Allington in Washington at aallington@bna.com

To contact the editor responsible for this story: Rachael Daigle at rdaigle@bna.com

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