Harmonizing life cycle assessment studies of emerging technologies: The case of virgin and recycled carbon fibers

The use of carbon fibers has expanded beyond aerospace to renewable energy and automotive sectors, driving demand for low-cost, eco-friendly alternatives to energy-intensive PAN-based production. This study Identified 28 Life cycle assessment (LCA) articles, encompassing 56 inventories for virgin and recycled carbon fibers. Following a screening process, 10 inventories representing distinct technologies were harmonized by aligning functional units, system boundaries, and background systems for meaningful comparison. Supercritical hydrolysis, a promising alternative, showed the lowest environmental impact, while energy-autonomous pyrolysis exhibited negative greenhouse gas emissions but produced fibers with 80 % of virgin tensile strength. This study represents the first attempt to harmonize LCAs of emerging technologies, addressing incomparability issues in published research to enable meaningful comparisons. It evaluates the reproducibility of LCA studies and offers recommendations for improvement. Additionally, it provides insights into the environmental impacts of emerging carbon fiber production and recycling technologies.