Assessing the circularity of onshore wind turbines: Using material flow analysis for improving end-of-life resource management

•Mass- and energy-weighted circularity of wind turbine materials are estimated for the first time.•Strategies are explored to increase the circularity of wind turbine material flows.•Scenarios based on assumptions are developed to quantify potential circularity improvements. Around 1,600 wind turbines are expected to be decommissioned annually in Germany after 2026. To reduce the amount of material going to landfills and minimise energy use, improving the circularity of decommissioned and new wind turbines is essential. However, there is currently limited understanding regarding wind turbine circularity and end-of-life component utilisation. To address this, this study examines the material flows of three 2-megawatt (MW) turbines in Germany and estimates their circularity using the Circularity Index proposed by Cullen (2017). This study finds low circularity in wind turbine material flows and suggests opportunities for improving resource management for a circular economy transition via enhanced component reuse and recycling. The authors also discuss options for using the Circularity Index and visualisations to monitor and enhance the circularity of renewable energy technologies and to identify opportunities for better resource management.