• Energy Research

The background to this research is that across the world there will be 200,000 tonnes of wind turbine blade waste to be disposed of each year from 2033. The purpose of the research is to compare the relative sustainability of alternative ways to deal with this waste, these being: landfill, incineration with heat recovery, co-processing in cement kilns, making furniture and bridge fabrication. The method is to use the UN Sustainable Development Goals (SDGs) to select 11 metrics for sustainability. The use of the SDGs adds to the objectivity of this process overcoming one of the principal weaknesses of Multiple Criteria Decision Analysis (MCDA). Quantitative information methods from Life Cycle Assessment, Geographic Information Science, census data and real options analysis of R&D, alongside qualitative information from Delphi studies and Strengths/Weaknesses/Opportunities/Threats analysis are combined in the assessment. Three MCDA methods are used, each calculates economic, social and environmental sustainability indices for the end-of-life alternatives which are then combined into integrated sustainability indices. A novel Delphi stopping condition based on consensus, consistency and convergence is used. The primary result is that bridge fabrication is the most sustainable alternative with furniture making in second place. Co-processing, incineration with heat recovery and landfill are progressively less sustainable alternatives. This result is robust to substantial changes in the selection of experts’ opinions, the weights for MCDA and the values of the metrics. These findings offer researchers and policymakers a robust decision making process, applicable to situations where choices are made on sustainability criteria.

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.

Abstract The End-of-Life (EOL) stage of the first commercial wind farms is fast approaching and uncertainty remains in how to deal with their non-biodegradable Fibre Reinforced Polymer (FRP) composite wind turbine blades. Repurposing options could potentially delay large volumes of material entering unsustainable waste streams such as landfill or incineration and contribute to the circular economy. To plan waste management methods as well as inform the collective team of policy makers, decision makers and local governments, it is essential to understand and assess the geographical variability in the quantity of potential FRP composite blade waste material. Decisions regarding EOL blades are complex due to the varying numbers of blades and diversity in models, therefore it is essential that decommissioning plans are tailored for each location. This research introduces an innovative spatiotemporal approach to investigate the magnitude of the problem and quantify blade waste material associated with the EOL stage of wind turbine blades using the island of Ireland case study. The technical and spatiotemporal variability is assessed through an integrated Geographical Information Science (GIS) framework and online dashboard for decision-making. The findings indicate that for the island of Ireland approximately 53,000 tonnes of composite material will reach the EOL stage by 2040 with highest material densities located in the west and southwest of the island. The integrated GIS approach provides important information on blade type and model to assist decision-making on the design of repurposing strategies for FRP composite blades and provides an exemplar for other countries.

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.