Recycling and recovery of fiber-reinforced polymer composites for end-of-life wind turbine blade management

The 3R (reuse, recycling, and recovery) waste management of wind turbine blades (WTBs) is becoming a popular subject, since it has a great practical significance in the disposal of the large numbers of upcoming end-of-life WTBs. Repurposing or reuse is a priority option, but the disposal of end-of-life WTBs on a large scale is a great challenge. Recycling or recovery is considered a priority for effectively dealing with end-of-life WTBs. This review focuses on the progress and challenges in the recycling and recovery of end-of-life WTBs, which are mainly composed of fiber-reinforced polymer composites. Among the commonly-used recycling methods, one advantage of thermal recycling processes is their tolerance of contaminated material. Thermal recycling processes can also effectively treat various polymer composites on a large scale. In particular, pyrolysis and cement kiln co-processing currently show the highest potential in treating end-of-life WTBs in commercial applications. In addition, chemical recycling processes such as solvolysis are promising methods that can achieve the closed-loop recovery of monomers and high-quality fibers, if green and recyclable solvents as well as mild reaction processes can be developed. Importantly, the life cycle management (LCM) of WTBs ending with solvolysis recycling is identified as the most circular and low-carbon solution. The recycling and recovery of end-of-life WTBs have been developed at an initial stage. Although a number of commercial applications have been achieved, most of these projects are built on extensive methods, focusing on mechanical recycling and cement kiln co-processing. This review will guide researchers to make more effort in the recycling of end-of-life WTBs, covering the reuse of gas and oil products as fuels for sustaining thermal processes and the development of green closed-loop recycling processes. This review highlights the progress and challenges in the mechanical, thermal and chemical recycling and recovery of end-of-life WTBs, which are mainly composed of fiber-reinforced polymer composites.