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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.

 

This paper demonstrates the concept of adaptive repurposing of a portion of a decommissioned Clipper C96 wind turbine blade as a pole in a power transmission line application. The current research program is aimed at creating a path towards sustainable repurposing of wind turbine blades after they are removed from service. The present work includes modelling and analysis of expected load cases as prescribed in ASCE 74 and NESC using simplified boundary conditions for tangent pole applications. Load cases involving extreme wind, concurrent ice and wind, extreme ice, differential ice, broken conductor, and broken shield have been analyzed and governing load cases for bending, shear, and torsion have been examined. Relative stiffnesses of different parts forming the wind blade’s cross section (i.e., shell, web, and spar cap) are determined. The corresponding stresses associated with each part under the governing loads are compared to allowable strength values which are determined from composite laminate theory and modelling of the known laminate structure of the E-Glass FRP material. Stresses and deflections obtained are compared with governing reliability-based design criteria and code requirements. The results of the structural analysis indicate that the wind blade can resist the expected loads with reasonable safety factors and that the expected deflections are within permissible limits. Recommendations are provided for detailing and modification of the wind blade for a power pole application in which crossarm and davit connections are highlighted, and foundation details are emphasized.