Functional Structure from Recycled Wind Turbine Blades

Abstract

This report presents a comprehensive analysis of repurposing recycled wind turbine blades into functional structures, specifically focusing on the creation of a Strandbeest-inspired kinetic structure. Conducted by Group 17 of Delft University of Technology for the Design Synthesis Exercise, the project addresses the growing challenge of wind turbine blade waste, projected to reach 570 million tonnes by 2030. The report identifies the limitations of current recycling methods and explores the potential of repurposing as a sustainable alternative.

The market analysis highlights the intersection of sustainability, functional beach structures, and wind turbine blade recycling, proposing tangible projects like Theo Jansen’s Strandbeest to raise public awareness. Through a detailed trade-off analysis, the team evaluated multiple design concepts, ultimately selecting a hybrid design combining the Strandbeest and Windcar for its superior performance in harsh conditions and material utilization.

Material analysis focused on selecting sustainable alternatives for wind turbine blades, identifying flax-reinforced thermoplastics as a preferable choice due to their recyclability and mechanical properties. Among several natural fibre options, flax was chosen for its consistent mechanical properties, making it the preferred choice for the composite. The chosen composite material balances fibre and thermoplastic matrix influences, enhancing end-of-life performance. Manufacturing techniques and material recovery processes are outlined, emphasizing the potential for producing beams, flat panels, and aerofoil from recycled parts.

The wind turbine design prioritizes vertical axis wind turbines for their sustainability benefits and compatibility with the structure's needs. The design process considered rotor configurations, aerofoil selection, and aspect ratio optimization, ensuring reliable performance under varied wind conditions. The H-rotor configuration was chosen for its manufacturability and space efficiency, and the aerofoil pitch was optimized to account for wind shear effects, ensuring consistent performance.

Kinematic analyses addressed the movement of the structure, incorporating modified Jansen linkages and differential steering for improved navigation. The linkage was designed to improve stability and step height, with the crankshaft and fixed points optimized for a walking robot. Autonomous navigation and obstacle detection systems were integrated using LiDAR sensors and GPS, ensuring the structure can navigate the Dutch coast independently.

Structural analysis was a critical component of the project, divided into body analysis, leg analysis, and evaluation of failure modes. The body analysis involved stability assessments and stress evaluations to determine the optimal width and configuration to prevent tipping and withstand wind turbine forces. The design included springs to dampen vibrations and reduce bending stresses, ensuring the structure's integrity. Leg analysis focused on selecting cross-sections that could handle the stresses without exceeding material limits. This involved a detailed stress analysis and selection of joints to ensure durability.

Power management strategies combined wind turbine and solar panel outputs to meet the system's energy requirements. The final power budget ensured sufficient energy for motion, control, navigation, weather data collection, and other subsystems, balancing the contributions from wind and solar sources.

In conclusion, this report demonstrates a viable method for repurposing wind turbine blades into functional, sustainable structures. By leveraging innovative design, material science, and comprehensive structural analysis, the project addresses significant environmental challenges and showcases the potential for creative reuse of composite materials.