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The purpose of this study was to develop a replicable methodology for testing the capabilities and characteristics of a wind turbine blade in a structural re-use application with the specific goal of creating and demonstrating an efficient and commercially viable wind blade pedestrian bridge design. Wind energy experienced a dramatic increase in popularity following the turn of the century and it is now a common source of renewable energy around the world. However, while wind turbines are able to produce clean energy while in service, turbine blades are designed for a fatigue life of only about 20 years. With the difficulty and costs associated with recycling the composite material blades used on the turbines, wind power companies choose to dispose of decommissioned blades in landfills instead. The Re-Wind BladeBridge project aims to promote a more sustainable life cycle for wind power by demonstrating that decommissioned wind turbine blades have the capability to be repurposed as structural elements in bridges. This paper presents an analysis and characterization of a LM 13.4 wind blade from a Nordex N29 turbine, along with a design for a pedestrian bridge using two LM 13.4 wind blades to create a 5-meter span bridge. Software developed by the Re-Wind team called “BladeMachine” was used to generate the engineering properties of the blade at multiple sections along the blade length. Resin burnout tests and mechanical testing in tension and compression were performed to determine the material and mechanical properties of the composite materials in the blade. Additionally, a four-point edgewise bending test was performed on a 4-meter section of the wind blade to evaluate its load carrying behavior. The results of these tests revealed that the LM 13.4 blades are suitable to be re-utilized as girders for a short-span pedestrian bridge. An overview of the design of the BladeBridge currently under construction in County Cork, Ireland is presented, including details on the architectural and structural design processes.
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Structural Re-Use of De-Commissioned Wind Turbine Blades in Civil Engineering Applications
The production of wind energy worldwide has increased 20-fold since 2001. Composite material wind turbine blades, typically designed for a 20-year fatigue life, are beginning to come out of service in large numbers. In general, these de-commission blades, composed primarily of glass fibers in a thermoset matrix, are demolished and landfilled. There is little motivation for recycling the composite materials, as the processes for reclaiming the fibers (solvolysis, pyrolysis) have not been proven to be economically viable. This research seeks to establish structural re-use applications for wind turbine blades in civil engineering infrastructure, hypothesizing that advanced composite materials may be an attractive alternative to conventional infrastructure materials (e.g. steel, reinforced concrete). This paper presents an analysis and materials characterization of a 47 meter Clipper C96 wind blade. The primarily numerical analysis is accompanied by materials characterization taken from an un-used Clipper blade donated to the project from the Wind Turbine Testing Center (WTTC). The paper presents a brief background on wind turbine blade adaptive re-use, proposing a hypothetical load bearing application of the Clipper wind blade as an electrical transmission tower structure carrying axial compression, along with flapwise and edgewise bending forces. The paper summarizes the composite laminates and cross-section geometries of the blade and establishes the axial and flexural stiffnesses of the blade at multiple sections along the blade length. From a first-order estimation of applied loads for the tower application, the resulting stresses in the composite materials are estimated and compared to the design material properties for the wind blade as originally constructed.
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- Award ID(s):
- 1701413
- PAR ID:
- 10147573
- Date Published:
- Journal Name:
- Proceedings, American Society for Composites 2019 Annual Meeting
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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