A 2017 story in the United Kingdom daily The Guardian titled “Carbon fiber: The wonder material with a dirty secret” explains the blessings of this increasingly popular
structural material for planes, cars, and wind turbine blades, making them not just lighter but also more efficient and more robust. So far so good, but times are changing.
The article neglected the growing use of carbon in boatbuilding, not just for extreme racing yachts but also in less demanding recreational uses—foils and foil masts for surfboards, parts for small boats, and other applications perfectly suitable for prepregs that have exceeded their official expiration date, rendering them invalid for aerospace or military applications (see “Adapt and Adjust,” Professional BoatBuilder No. 201, page 8). As good as the material might be for weight reduction, it also has “a dirty secret,” The Guardian wrote: “….wasteful to produce and difficult to recycle.” In other words: when it’s done, it’s headed to a landfill. But that too is changing.
The challenges are well known. Carbon fiber production is petroleum intensive; it remains expensive to produce; and it devours a lot of energy during manufacture and in processing. So, managing and minimizing waste during production are important to make it friendlier to the atmosphere and to buttress a builder’s bottom line. Better still isrecycling or, more correctly, downcycling it for another use. However, what was built to be light and strong from carbon fibers and polymer resins cured at elevated temperature and/or pressure is not easy to break apart. The polymers must be burned off or chemically dissolved to reclaim the fibers, which must stay intact to retain enough useful strength for reintroduction to the supply chain. Several startups have entered the game, but one U.K. firm has been at it for more than a decade.
“Segregated waste material is cut to make handling easier and to make the thermal processes more effective,” explained Mark Hitchmough, managing director at Gen 2 Carbon, the company known as ELG Carbon Fibre before a management buyout in 2021. “The next step is pyrolysis, which removes the resins and any paper or plastic contamination, to leave clean fibers. These may be chopped again to get the correct length [2.36″–3.94″/60mm–100mm] for the nonwoven matting.”
At the 2022 JEC World in Paris, Gen 2 Carbon introduced a lightweight (60 g/m2 or 1.77 oz/sq yd) recycled carbon fiber (rCF) nonwoven fabric. It is marketed under the G-Tex TM brand to OEMs and suppliers in the automotive, aerospace, renewable energy, marine, and electronics sectors. It can be processed in different ways, including prepreg, resin film, and liquid resin compression molding. The company also manufactures G-Tex TM, a comingled rCF/polymer mat for direct pressing.
IMOCA teams make liberal use of carbon fiber to build their 60′ (18.3m) foiling racing yachts, while simultaneously promoting steps to lessen the giant carbon footprints of the boats. The U.S. team of 11th Hour Racing compiled Life Cycle Assessment (LCA) data that shows the emissions generated by the build of a modern foiling IMOCA 60 racing yacht increased by approximately two-thirds compared to an IMOCA 60 a decade ago, to 550 tons carbon dioxide equivalent (see also “Measuring Impact with Life Cycle Assessment,” PBB No. 197, page 46). The team compared it to “105 midsize American cars” and added that “80% of these emissions were associated with composite construction.” Also, 11th Hour Racing said it is sending 10 tons of carbon fiber waste to Gen 2 for processing. It is a laudable initiative but only a drop in the bucket. Most (90%) of the recyclate currently coming to Gen 2 is waste from the aerospace and automotive industries, while end-of-life product currently makes up less than 1%.
“Environmental impact is far less than virgin fiber and other alternative materials such as glass fiber, magnesium, and aluminum,” Hitchmough said about G-Tex, citing Gen 2’s own impact data suggesting reduction of CO2 emissions in the recycling process over the past few years, coupled with less embodied energy and sharply reduced water consumption compared to virgin carbon fiber and other materials. However, a detailed LCA of recyclate is difficult to establish due to the absence of data from suppliers showing material impacts.
G-Tex matting prices vary with weight, ranging from 60g/m2 to 700 g/m2 (1.77 oz/sq yd to 20.65 oz/sq yd) and was quoted at £28/kg ($15.72/lb) before volume discount.
Among the benefits customers can expect from G-Tex matting made of recycled carbon fibers, Hitchmough listed higher loft (meaning greater thickness), electric conductivity, low weight, greater affordability, improved drapability, and “good surface finish,” meaning there is no print-through—qualities that make it a useful first layer in an infusion laminate.
The most promising applications for rCF at this point are in the electronics industry, in nacelles of wind turbines, and automotive panels. “We are also involved in a program to put recycled-carbon-fiber mat into aerospace interiors, [for example] at the Boeing ecoDemonstrator,” Hitchmough said. Scaling up the modular processing operation, he added, is mostly a matter of investing in equipment and decentralizing production by locating the processing plant closer to the waste sources.
Giving new life to old carbon fibers is a work in progress driven by larger and more innovative industries than boatbuilding. Recycling or downcycling carbon composites is inching closer to the scenario The Guardian laid out: “The good news is that carbon fiber products last a long time: the current generation of wind turbine blades and electric vehicles won’t be heading to the wrecking yard for at least another decade. Perhaps by [that time], we will have somewhere better to put…precious carbon fibers than a hole in the ground.”
Gen 2 Carbon, Cannon Business Park, Darkhouse Ln., Coseley, West Midlands, U.K., WV14 8XR, tel. +44 (0) 1902406010