Efforts to improve vehicle efficiency have long focused on reducing weight without compromising safety or performance. Lightweight materials such as carbon fiber offer exceptional strength-to-weight ratios, yet their high production costs have kept them largely confined to niche applications like high-end sports cars, aerospace components, and specialized sporting goods. Researchers at MIT, in collaboration with Western Research Institute and Oak Ridge National Laboratory, have developed a method to produce high-quality carbon fibers from petroleum pitch—a low-value byproduct of oil refining—potentially transforming the economics of lightweight vehicle manufacturing.
Petroleum pitch, described by MIT research scientist Nicola Ferralis as “the bottom of the barrel,” is a viscous residue composed of heavy hydrocarbons. Traditionally, it has been used for asphalt or discarded as waste due to its low inherent value and unsuitability as a clean fuel. Coal pitch, a similar byproduct from coking coal for steel production, also represents an abundant and underutilized resource. Both materials are chemically complex, which, according to Ferralis, “makes it a fascinating material to start with” because of the exploitable chemistry embedded in its heterogeneous molecular structure.
The Department of Energy initiated the research roughly four years ago, seeking affordable, lightweight structural materials to reduce vehicle mass and thereby improve fuel efficiency. Ferralis notes that “the weight of cars has increased more than 15 percent within the same category” over the past three decades, driving demand for innovations that could reverse this trend. Lighter vehicles require smaller engines, less robust braking systems, and fewer heavy components, creating a cascading effect of weight reduction across the design.
Conventional automotive-grade carbon fibers cost at least $10 to $12 per pound, with aerospace-grade fibers reaching hundreds of dollars per pound. Steel, by contrast, costs around 75 cents per pound, and aluminum about $2 per pound, though prices fluctuate. These disparities have prevented widespread adoption of carbon fiber in mass-market vehicles, as replacing steel with carbon fiber could double the manufacturing cost of a pickup truck.
Current carbon fiber production relies on refined polymers such as polyacrylonitrile, requiring costly polymerization steps that account for more than 60 percent of the final material’s price. The MIT-led approach bypasses these steps by using raw petroleum pitch directly, dramatically reducing processing complexity and energy requirements. “The process that you need to actually make a carbon fiber [from pitch] is actually extremely minimal,” Ferralis explains.
Graduate student Asmita Jana tackled the challenge of consistency in such a chemically diverse feedstock. Pitch’s molecular variety means that changes in shape or size can drastically alter material properties. By modeling the formation and crosslinking of bonds between constituent molecules, Jana developed predictive tools to forecast fiber characteristics under specific processing conditions. “We were able to reproduce the results with such startling accuracy,” she says, enabling companies to anticipate properties like density and elastic modulus from the model’s outputs.
These predictive capabilities allowed the team to tailor fibers not only for high tensile strength, typical of carbon fiber, but also for compressive strength—an uncommon trait in the material. This opens possibilities for load-bearing applications, potentially eliminating the need for complex fiber layups designed to compensate for compression weaknesses. As Ferralis points out, “It’s a matter of engineering to overcome the deficiencies of the material, but with the new process all that extra complexity would not be needed.”
The DOE’s target was to reduce the cost of lightweight materials below $5 per pound. The team’s estimates suggest their method could achieve around $3 per pound, though a full economic analysis is pending. Such a price point could make carbon fiber competitive with metals for mainstream automotive use, while also enabling applications beyond vehicles.
The collaborative effort drew on Oak Ridge National Laboratory’s expertise in scaling carbon fiber production from laboratory experiments to pilot-plant operations. Researchers Taishan Zhu and Yanming Wang at MIT, Jeramie Adams at Western Research Institute, and Logan Kearney and Amit Naskar at Oak Ridge contributed to the work, which was supported by the U.S. Department of Energy.