Wind energy is a critical component of the global transition to sustainable energy systems and an attractive alternative to fossil fuels, due to benefits that include renewability, low environmental impact, and economic advantages. By 2050, it is estimated that wind energy will make up around a third of total UK electricity demand, with this increase representing a significant End-of-Life (EoL) and Circular Economy (CE) challenges. While wind energy is considered a green and sustainable technology, it will result in roughly 200,000 tonnes of waste produced by blades reaching their EoL by 2034, considering each kilowatt of wind power requires 10 kgs of blade material (10 kg kW^-1) [1]. Conventional strategies such as incineration and landfill of EoL wind turbine blades (WTBs) do not provide a sustainable solution and can lead to health and environmental issues. Hence, the EoLO-HUBs project seeks to solve EoL problems associated with Wind Turbine Blades (WTBs) with a view of prioritizing a sustainable CE. As part of the recycling process of WTBs there is a need to implement systems for the dismantling of WTB technology without jeopardizing the environment and maximizing the recovery of recyclable materials.

The recycling of WTBs involves overcoming the complexities of processing composite materials, managing high costs, and developing infrastructure to ensure these components can be effectively reused or repurposed. Recycling of carbon/glass fibre reinforced plastic (CFRP/GFRP) composites extensively used in WTBs is difficult due to their complicated build and inhomogeneity [2]. Compared with other parts of the wind turbine, such as the tower, nacelle or hub, which are generally constructed using various metals, the WTB provides a significant challenge in terms of reuse, repurpose, recycling and recovery. The importance of recycling composite materials found in WTBs cannot be ignored when considering the current manufacturing process and decommissioning of these materials. The processes to manufacture these materials requires high energy consumption of many fossil fuels (183-286 MJ/kg for CFRP, 13-32 MJ/kg for GFRP [3]), while decommissioning leads to high amounts of CO₂ and CO emissions (incineration), as well as deep water and ground pollution (landfilling) [2]. Within the United Kingdom, wind energy accounts for ~33% of the use of CFRP materials, the second-largest use after aerospace and defence ~36% [3]. This highlights the importance of efficient decommissioning and recycling processes for these materials to meet sustainability goals, as outlined in the sustainable development goals (SDGs), such as Clean Water and Sanitation, Affordable and Clean Energy and Climate Action.

A key aim of the EoLO-HUBS project is the development of innovative recycling technologies, focusing on two technologies in particular, chemical processing (solvolysis) and heat treatment (pyrolysis) [3]. The objective is to improve the efficiency of recycling processes, leading to lower costs and higher levels of materials recycled. Development of advanced inspection and flexible decommissioning tools are seen as a key means to achieve this. The Manufacturing Technology Centre Ltd (MTC) has been tasked with developing a tool that can accurately determine the position and composition of the materials and structures present in a WTB, such that an automated cutting path can be generated to optimize the yield of recyclable materials obtained throughout the recycling process, limit contamination and optimize the cutting process. This focuses on achieving two main objectives: (1) the development of enhanced inspection tools for accurate digitalization of the internal and external blade structure and (2) design of a software tool for decommissioning assistance to minimize waste and costs cutting based on the geometrical and material data obtained from the WTB.

To identify the most appropriate inspection systems to support the cutting path generation, a series of rigorous steps will be undertaken to identify the most appropriate inspection system. This will include filtration of potential technologies, validation trials using the most suitable technologies on representative samples, and finally a demonstration of the inspection system on an actual WTB section.

Digitization of the WTB will be achieved using two technologies based on Metrology and Non-Destructive Testing (NDT) data to provide large scale internal and external mapping of the WTB. Fusion of the internal data will be used to create virtual twins of the complex structure, allowing for optimization of the NDT tool inspection path and ultimately the optimization of the cutting tool path for efficient EoL recycling processing of the WTB. The generated virtual twin provides future proofing of the inspection procedure of WTBs by building a platform enabling virtual testing, process refinement and integration of more complex process functions such as automation which could lead to further cost and materials savings.

Figure 1: An image showing a WTB section (a), and digitisation using a Metrology based system to create a point cloud representation of the external surface and highlighting processing steps to create a CAD model (b).

The goal is to improve the efficiency of the EoL recycling process with a CE in mind, leading to reduced waste material and processing of reclaimed materials by limiting contamination and reducing costs of recycling by optimization of the cutting paths and reclaimed material. Ultimately, lowering the impact of emissions and environmental threats throughout the wind turbine life cycle.

For more information about MTC’s work in EoLO-HUBs you can contact Gian Piero Malfense Fierro ( gianpiero.malfensefi@the-mtc.org ) and for more information on other technologies of the decommissioning stage of wind turbine blades, check out our Circular Technologies articles here.

References