Life Cycle Assessment of Carbon Fiber Production at Laboratory Scale Made from Two Different Polymers: Expanded Polystyrene (EPS) and Organosolv Lignin

Abstract

This study evaluates the environmental performance of laboratory-scale carbon fiber (CF) production using two alternative precursors, expanded polystyrene (EPS) and organosolv lignin fibers, through a comparative life cycle assessment (LCA). The objective is to compare the environmental performance of two alternative carbon fiber precursors, EPS and organosolv lignin, and to identify key process stages for improvement under laboratory-scale production conditions. The LCA was conducted using the IMPACT World+Midpoint V1.05 method in SimaPro, considering 18 impact categories within a cradle-to-gate system boundary. A Monte Carlo simulation (10,000 iterations, 95% confidence interval) was performed to evaluate uncertainty and support statistical comparison. Results indicate that both laboratory-scale production pathways exhibit similar overall environmental profiles; however, the organosolv lignin-based CF system modeled in this study showed lower impacts across most categories. Statistically significant differences were observed in 17 out of 18 impact categories, with water scarcity being the only exception due to high uncertainty (CoV ≥ 282%). For lignin-based CF, the carbonization stage is the dominant contributor (51–84% of total impacts), primarily due to high energy demand. In contrast, EPS-based CF impacts are mainly associated with washing and drying, electrospinning, and sulfonation, with notable contributions to ozone depletion. A simplified analysis excluding energy inputs further supports the environmental advantages of lignin-derived CF. Overall, the results highlight the importance of optimizing energy-intensive stages, particularly carbonization, to improve the sustainability of CF production. The findings demonstrate the potential of EPS and organosolv lignin as alternative precursors and provide guidance for process optimization and future scale-up of more sustainable carbon fiber technologies.