Evolution of characteristic components from retired wind turbine blades in multiple thermal atmospheres: thermal decomposition characterization and kinetic behavior

Abstract

The lack of adequate data and in-depth insights into the thermal decomposition kinetics of retired wind turbine blades (RFTBs) critically impede its thermal recycling and upgrade. This study explores the non-isothermal pyrolysis of RFTBs under inert N₂ atmosphere and reactive air and CO₂ atmospheres at heating rates of 10–30 K/min. The PET component (C1) and full RFTBs component (C3) exhibited two pyrolysis stages (Py1 and Py2) in N₂, whereas the glass fiber reinforced polymer (C2) revealed only one pyrolysis stage. Higher heating rates shifted peaks of heat weight loss rate upward due to thermal hysteresis. Under air and CO₂ atmospheres, all feedstocks developed an additional gasification stage (Gs, >400 °C), originating from products undergoing partial oxidation reactions in air and interactions in CO₂. Both pathways release heat that accelerates pyrolysis through localized thermal enhancement, effectively reducing heat transfer limitations via short-distance energy redistribution. Apparent activation energies for C3 obtained via Model-free fitting method were 148.43/181.34 kJ/mol (Py1/Py2, N₂), 151.07/151.57/136.62 kJ/mol (Py1/Py2/Gs, air), and 67.76/87.79/78.85 kJ/mol (Py1/Py2/Gs, CO₂), demonstrating that autothermal pyrolysis in air and CO₂ gasification are more active and energy-saving than traditional pyrolysis in N₂. Model-fitting method revealed optimal mechanisms involving random nucleation and nuclei growth (A_n, n = 4 for Py1, n = 2/3 for Py2 and Gs), accurately describing CO₂ gasification of full RFTBs component, and these were validated through kinetic compensation effect analysis. This study provides accurate and critical guidance for the design, optimization and scale-up of RFTBs pyrolysis procedures and reactors.