Cradle-to-Gate life cycle assessment of recycling processes for carbon fibers: A case study of ex-ante life cycle assessment for commercially feasible pyrolysis and solvolysis approaches

Abstract

Waste that derives from manufacturing processes and end-of-life products of the transportation industry is a cause of increasing concern globally. Therefore, systems must be developed to manage such waste and to mitigate greenhouse gas (GHG) emissions. In this study, the carbon fiber reinforced polymer (CFRP) recycle process was analyzed to assess its environmental friendliness. The recycling processes at the Carbon Fiber Recycling Co., i.e., pyrolysis, and Hitachi Chemical, i.e., solvolysis, both of which are currently in production scale, were analyzed. The scaling effect was employed to assess the environmental impacts of the production scale. The results showed that either recycling method offers promising results for reducing environmental impacts, as compared with producing virgin carbon fibers (vCFs). GHG emissions from the Carbon Fiber Recycling Co. pyrolysis were 1.52 kg-CO2 eq/kg while that of Hitachi Chemical solvolysis was 1.92 kg-CO2 eq/kg. GHG emissions resulting from both methods were below the GHG emissions produced by vCFs (24.00 kg-CO2eq/kg). By factoring the GHG credits created from the by-products of these processes, the GHG emissions from the Carbon Fiber Recycling Co. pyrolysis were 0.57 kg-CO2 eq/kg and that from Hitachi Chemical solvolysis was −0.54 kg-CO2 eq/kg. Additionally, the results of this study were consistent with other GHG studies, suggesting credibility.