Carbon Fibers Waste Recovery via Pyro-Gasification: Semi-Industrial Pilot Plant Testing and LCA

ABSTRACT

Carbon-fiber-reinforced polymers (CFRPs) are increasingly used in a variety of applications demanding a unique combination of mechanical properties and lightweight characteristics such as automotive and aerospace, wind turbines, and sport and leisure equipment. This growing use, however, has not yet been accompanied by the setting of an adequate recycling industry, with landfilling still being the main management route for related waste and end-of-life products. Considering the fossil-based nature of carbon fibers, the development of recovery and recycling technologies is hence prioritized to address the environmental sustainability challenges in a bid to approach mitigating the climate emergency and achieving circularity in materials’ life cycles. To this aim, we scaled up and tested a novel semi-industrial pilot plant to pyrolysis and subsequent oxidation of uncured prepreg offcuts and cured waste of CFRPs manufacturing. The environmental performance of the process proposed has been evaluated by means of a life cycle assessment to estimate the associated carbon footprint and cumulative energy demand according to three scenarios. The scale-up of the process has been performed by investigating the influence of the main parameters to improve the quality of the recovered fibers and the setting of preferable operating conditions. The pyro-gasification process attested to a reduction of 40 kgCO2eq per kg of recycled CFs, compared to virgin CFs. If the pyro-gasification process was implemented in the current manufacturing of CFRPs, the estimated reduction of the carbon footprint, depending on the composite breakdown, would result in 12% and 15%. This reduction may theoretically increase up to 59–73% when cutting and trimming waste-optimized remanufacturing is combined with circular economy strategies based on the ideal recycling of CFRPs at end-of-life.