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In recent years, the sustainability of wind power has been called into question because there are currently no truly sustainable solutions to the problem of how to deal with the non-biodegradable fibre-reinforced polymer (FRP) composite wind blades (sometimes referred to as “wings”) that capture the wind energy. The vast majority of wind blades that have reached their end-of-life (EOL) currently end up in landfills (either in full-sized pieces or pulverized into smaller pieces) or are incinerated. The problem has come to a head in recent years since many countries (especially in the EU) have outlawed, or expect to outlaw in the near future, one or both of these unsustainable and polluting disposal methods. An increasing number of studies have addressed the issue of EOL blade “waste”; however, these studies are generally of little use since they make predictions that do not account for the manner in which wind blades are decommissioned (from the time the decision is made to retire a turbine (or a wind farm) to the eventual disposal or recycling of all of its components). This review attempts to lay the groundwork for a better understanding of the decommissioning process by defining how the different EOL solutions to the problem of the blade “waste” do or do not lead to “sustainable decommissioning”. The hope is that by better defining the different EOL solutions and their decommissioning pathways, a more rigorous research base for future studies of the wind blade EOL problem will be possible. This paper reviews the prior studies on wind blade EOL and divides them into a number of categories depending on the focus that the original authors chose for their EOL assessment. This paper also reviews the different methods chosen by researchers to predict the quantities of future blade waste and shows that depending on the choice of method, predictions can be different by orders of magnitude, which is not good as this can be exploited by unscrupulous parties. The paper then reviews what different researchers define as the “recycling” of wind blades and shows that depending on the definition, the percentage of how much material is actually recycled is vastly different, which is also not good and can be exploited by unscrupulous parties. Finally, using very recent proprietary data (December 2022), the paper illustrates how the different definitions and methods affect predictions on global EOL quantities and recycling rates.

 

This paper describes repurposing projects using decommissioned wind turbine blades in bridges conducted under a multinational research project entitled “Re-Wind”. Repurposing is defined by the Re-Wind Network as the re-engineering, redesigning, and remanufacturing of a wind blade that has reached the end of its life on a turbine and taken out of service and then reused as a load-bearing structural element in a new structure (e.g., bridge, transmission pole, sound barrier, seawall, shelter). The issue of end-of-life of wind turbine blades is becoming a significant sustainability concern for wind turbine manufacturers, many of whom have committed to the 2030 or 2040 sustainability goals that include zero-waste for their products. Repurposing is the most sustainable end-of-life solution for wind turbine blades from an environmental, economic, and social perspective. The Network has designed and constructed two full-size pedestrian/cycle bridges—one on a greenway in Cork, Ireland and the other in a quarry in Draperstown, Northern Ireland, UK. The paper describes the design, testing, and construction of the two bridges and provides cost data for the bridges. Two additional bridges that are currently being designed for construction in Atlanta, GA, USA are also described. The paper also presents a step-by-step procedure for designing and building civil structures using decommissioned wind turbine blades. The steps are: project planning and funding, blade sourcing, blade geometric characterization, material testing, structural testing, designing, cost estimating, and construction.

 

Millions of tons of GFRP composites are expected to stockpile in the next 20-30 years from decommissioning wind turbine blades, which are made primarily of these materials. Responsible and attractive solutions are currently being studied by several research teams across Europe and the United States. The Re-Wind Network is one of these research teams that focuses on developing strategies and methodologies to transform the decommissioned wind blades into ready-to-use civil infrastructure (e.g., pedestrian bridge girders and power transmission poles). This paper reports on testing of a part of a full-sized power transmission pole prototype, made from a decommissioned GE37 wind turbine blade, and loaded in the gravity direction mimicking expected loads during its “new” lifetime. Full-scale connection testing is summarized and combined with the results of the test on the 5.5 m high full-size section of the prototype to obtain safety factors for various structural components under different expected load cases (these include gravity, wind, and ice loads). Structural Integrity of the various components of the power pole is studied to prove efficacy of the proposed second-life application of the decommissioned wind blade as a power transmission pole. Recommendations to improve the design for the planned future field full-blade prototyping are emphasized.

 

In recent decades, the widespread use of wind power has led to the rise of a new environmental issue
in the form of wind turbine blade waste. To combat the landfilling and incineration of what is
projected to be millions of tons GFRP blades, the Re-Wind Network aims to find solutions to
repurpose wind blades in structural applications. This paper reports on the design and analysis of three
options for an 18.5 meter pedestrian bridge made using decommissioned 53-meter blades. Maximum
strains and deflections found through structural analysis of these BladeBridges are used to assess the
feasibility of each option.

 

This paper presents two case studies of the repurposing projects of decommissioned wind turbine blades in architectural and structural engineering applications conducted under a multinational research project is entitled “Re-Wind” (www.re-wind.info) that was funded by the US-Ireland Tripartite program. The group has worked closely together in the Re-Wind Network over the past five years to conduct research on the topic of repurposing of decommissioned FRP wind turbine blades. Repurposing is defined by the ReWind team as the reverse engineering, redesigning and remanufacturing of a wind blade that has reached the end of its life on a turbine and taken out of service and then reused as a load-bearing structural element in a new structure (e.g., bridge, transmission pole, sound barrier, sea-wall, shelter). Further repurposing examples are provided in a publicly available Re-Wind Design Catalog. The Re-Wind Network was the first group to develop practical methods and design procedures to make these new “second-life” structures. The Network has developed design and construction details for two full-size prototype demonstration structures – a pedestrian bridge constructed in Cork, Ireland in January 2022 and a transmission pole to be constructed at the Smoky Hills Wind Farm in Lincoln and Ellsworth Counties, in Kansas, USA in the late 2022. The paper provides details on the planning, design, analysis, testing and construction of these two demonstration projects. 

The first generation of wind turbines are being retired, and a tremendous number of wind tur-bine blades are coming out of service. Architects and engineers are developing re-use ideas for these blades and are wrestling with their complex geometries and materiality. This paper details a four-phase process for reconstructing the geometry of wind turbine blades, starting from a point-cloud scan and finishing with a digital model that represents the blade and its associated properties. The process builds on earlier work that created an airfoil database to store the nor-malized coordinates of publicly available airfoil profiles. This profile database is traversed to match airfoil shapes to cross-sections found in the point-cloud. Root, transition, and airfoil shapes are matched to cross-sections along the full blade to reconstruct the outer geometry. Based on data from the interior of the blade, the structural spar box is reconstructed. The addi-tion of thickness and material property data allows for calculation of section properties at multi-ple stations along the blade. The resulting 3D geometry and the associated data is used for ar-chitectural design and engineering calculations to develop second-life applications for wind blades. The paper demonstrates the workflow through examples from a GE 37-meter blade and an LM 13.4-meter blade. 

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. 

Fiber reinforced polymer (FRP) composite materials have been used in a variety of civil and infrastructure applications since the early1980s, including in wind turbine blades. The world is now confronting the problem of how to dispose of decommissioned blades in an environmentally sustainable manner. One proposed solution is to repurpose the blades for use in new structures. One promising repurposing application is in pedestrian and cycle bridges. This paper reports on the characterization of a 13.4-m long FRP wind blade manufactured by LM Windpower (Kolding, Demark) in 1994. Two blades of this type were used as girders for a pedestrian bridge on a greenway (walking and biking trail) in Cork, Ireland. The as-received geometric, material, and structural properties of the 27 year-old blade were obtained for use in the structural design of the bridge. The material tests included physical (volume fraction and laminate architecture) and mechanical (tension and compression) tests at multiple locations. Full-scale flexural testing of a 4-m long section of the blade between 7 and 11 m from the root of the blade was performed to determine the load-deflection behavior, ultimate capacity, strain history, and failure modes when loaded to failure. Key details of the testing and the results are provided. The results of the testing revealed that the FRP material is still in excellent condition and that the blade has the strength and stiffness in flexure to serve as a girder for the bridge constructed.