Insights into environmental sustainability of microwave assisted chemical recycling of CFRP waste using life cycle assessment

Abstract

With the rapid development of fiber/matrix-based composites in the wind and aerospace industries, minimizing the environmental impact of composite waste has become a critical concern. This study compares pyrolysis and chemical recycling using nitric acid with the microwave assisted chemical recycling (MACR) process for carbon fiber reinforced polymer (CFRP) composite waste. The Life Cycle Assessment (LCA) tool in OpenLCA2.1® software evaluated three recycling scenarios, assuming recovered carbon fibers (RCFs) could be used for new composites. An inventory model was developed for virgin carbon fiber (VCF) production, CFRP manufacturing, and the three recycling processes, with environmental indicators identifying key variables. The results show that the MACR process has the lowest global warming potential (0.64 kg CO₂ eq.) and ozone depletion potential (0.46 × 10⁻⁸ kg CFC-11 eq.) compared to other methods. VCF production is energy-intensive, but if RCFs exhibit similar mechanical properties, they could replace VCFs in new composites. The MACR process also demonstrated higher Recycling System Credits (RSC), lower environmental impacts, and reduced energy consumption. Through comprehensive analysis of the results obtained in this study, the MACR process demonstrates significant benefits by reducing VCFs production burdens and pollution emissions, making it a promising solution for managing composite waste.