Assessment of recycling and recovery options of end-of-life wind turbine blades

With the global growth of wind energy investments, decommissioned wind turbines are becoming an environmental concern. Upon reaching their average lifespan of 25–30 years, they require waste management strategies. While approximately 85% of wind energy systems are recyclable, the remaining 15% mainly consists of turbine blades. These blades are composed of glass fiber, thermoset resins, balsa wood, adhesives, and coatings. Although the complex structure and non-biodegradability of these blades pose challenges for waste management, various solutions are available for reuse, recycling, and recovery. Recycling and recovery methods are generally classified into three categories: mechanical, chemical, and thermal processes. Among these methods, pyrolysis is particularly significant as it enables the production of syngas, pyrolysis oil, and char. This study was conducted using a real turbine blade sample. The primary focus was on the combustion profile and characteristics, as well as the pyrolysis profile and characteristics. The results obtained will provide significant contributions to both economic and sustainability aspects of waste turbine blade recycling and recovery. Additionally, this study aligns with the United Nations Sustainable Development Goals (SDGs), specifically Goal 7 – Affordable and Clean Energy, Goal 9 – Industry, Innovation, and Infrastructure, Goal 12 – Responsible Consumption and Production, and Goal 13 – Climate Action. In this thesis, a turbine blade, ground into powder, was first subjected to a characterization process. This characterization involved elemental analysis, ash content determination, calorific value measurement, and structural analysis of the waste turbine blade. Subsequently, pyrolysis was performed using both thermogravimetric analysis and a tube furnace to determine the pyrolysis profile and characteristics. Characteristic pyrolysis temperatures, conversion rates, and product characterization were separately examined. The combustion profile and characteristics were also determined using thermogravimetric analysis, and the structural properties of the ash formed after combustion were analyzed. Various analyses were conducted in this study, and the findings were discussed in detail. The average higher heating value (HHV) of the waste turbine blade samples was found to be 11.95 MJ/kg, meeting the minimum requirement for use as an alternative raw material or supplementary fuel in cement factories. The pyrolysis oil primarily contained bisphenol A and its derivatives, with small amounts of esters and benzoates. The average char yield was 61.73%. The combustion profile of the waste turbine blade exhibited three stages, with the highest mass loss occurring between 200°C and 400°C. The recovery of end-of-life wind turbine blades, or in other words, waste wind turbine blades, remains an open research topic that requires a holistic approach and must be managed with sustainability in mind. This study will serve as a reference for many future studies. Additionally, since the management of waste turbine blades has not yet been fully defined in our country, further research in this field is necessary.