Comparative Life Cycle Assessment (LCA) of Traditional and New Sustainable Wind Blade Construction

Abstract

The introduction of renewable energy sources (RESs) in the electricity grid mix is essential for a greener world. Wind offshore energy, known for its high flexibility and social acceptance, plays a significant role in this transition. However, the disposal of non-recyclable epoxy–GFRP wind blades produced and installed in the 1990s and 2000s poses environmental challenges. This study explores the development of a novel wind blade using sustainable materials, aiming to enhance eco-friendliness. A comparative life cycle assessment (LCA) highlights the environmental benefits of replacing epoxy with a thermoplastic recyclable resin in GFRP blades. The findings demonstrate a substantial reduction in environmental footprint, with a 30% decrease in climate change impact, a 97% reduction in freshwater ecotoxicity and a 95% reduction in marine eutrophication. It is evident from the LCA that the replacement of epoxy with a thermoplastic recyclable resin in a GFRP blade substantially reduces its environmental footprint and significantly contributes to the circular economy of RESs.

1. Introduction

The introduction of renewable energy sources (RESs) in the European electricity grid mix is one of the most important challenges of the last decades for energy production. Indeed, the design, construction and management of renewable resources, as well their integration in the current grid mix, are crucial to improve the environmental profile of energy production and use. Reducing the carbon footprint of electricity generation is an important action to be tackled by the European Commission in the European Green Deal [1]. It encourages energy providers to embrace greener production with the use of innovative and sustainability energy technologies.

Wind turbines are one of the most popular renewable resources thanks to their flexibility, minor land occupancy and high conversion efficiency. In 2022, the European Commission promoted an increase in wind energy production with their REPowerEU program [2], and increased support for the EU-based wind industry is expected to enable 32 GW of new wind power capacity over the next years.

Offshore wind energy has huge potential to become a main pillar of Europe’s green electricity mix because wind resources are stable and abundant, and public acceptance is high [2]. For this reason, great attention is given to the whole value chain of the offshore wind sector since all aspects of new wind infrastructure have an impact on the overall environmental footprint of this technology. Up to now, most wind turbine blades (manufactured since the late 1980s) have been produced using epoxy–GFRP composites since this material satisfies the material property requirements for the wind sector: good fatigue strength, less weight to decrease gravitational forces and high stiffness to provide stability [3]. Considering the tough environment of the offshore wind sector, the need for high-performance materials is even more pronounced: erosion and fatigue damage, driven by harsh conditions, are significantly shortening the lifespan of these offshore installations, leading turbine manufacturers and owners to focus on selective coatings and products that could improve the resistance of blades to degradation influenced by the marine environment. For example, polyurethane-based coatings are used to prevent rain and leading edge erosion [4,5], and improved protection systems are established by developing formulations with different additives for increased erosion resistance and toughness. These interventions increase the durability of the wind infrastructure and thus maintain efficiency during the operational stage of the wind turbine.

Wind energy is one of the most important and widespread sources of electricity that is helping to increase the share of RESs over the whole electricity production industry. When reaching their end of life, however, these large structures encounter an important issue: the proper disposal of decommissioned wind blades when they have reached their operative lifespan (approximately 25 years). This issue is growing as wind blades become larger (100 m or longer). In the past years, the landfilling of these materials was the selected end-of-life (EoL) scenario since a proper recycling technology for thermoset blades of this large size was not available. Hence, the increasing amount of waste due to the landfilling process has started to become a concern for wind energy sustainability. Recently, several alternative strategies have been introduced, starting from research activities: GFRP blades can be mechanically recycled and added as feedstock in the cement kiln process due to their low cost [6], and thermal or chemical separation of the composite constituents can also be used to recover the glass fibers and/or the polymer matrix [7]. The mechanical recycling of GFRP composites in the WTBs can be achieved after the shredding, crushing and grinding processes to incorporate recycled GFRP in the form of powders, fibers and aggregates into concrete (construction) [8,9], filaments (3-D printing) [10], wood (coating) [11] and composite panels (floor tiles or plastic road barriers) [12] as a reinforcing material or filler material. These approaches can be considered long-term and sustainable solutions for managing the huge amount of GFRP waste to reduce the environmental impact and landfill tax of WTB composite waste. On the other hand, the elevated cost of solvolysis (thermal recycling process) hinders its economic feasibility in recycling GFRP composites from WTBs [13]. Various EoL approaches have been considered for the commencement of an advanced circular economy. In an effort to use recyclable resin, Siemens Gamesa, in 2021, produced a wind turbine blade that can be recycled at the end of its life through an acid solution. These recyclable blades were recently installed for the Kaskasi offshore wind project in Germany. They consist of 38 turbines (Siemens Gamesa 9-MW, from Siemens Gamesa Renewable Energy, S.A.U., Vizcaya, Spain) and have an installed capacity of 342 MW [14]. In 2022, another project, ZEBRA (Zero Waste Blade ReseArch), by Arkema (Arkema, Colombes, France) and LM Wind Power companies, designed and produced 100% recyclable blades from thermoplastic resin to prevent thermoset waste and facilitate future recycling [15]. However, further analysis must also be carried out to verify the recycling technique for this novel blade. Nevertheless, the problem remains very complex due to several factors, i.e., technological feasibility, cost-efficiency, industrial scale-up, yield and quality of recovered materials, environmental impacts and legislation concerns; in the present and close future, all these hurdles should be tackled by scientists and industrial players in a coordinated effort.

From a sustainability point of view, the higher attention and urgency paid to environmental climate change and an increasing amount of plastic waste has led to the development of a methodology called life cycle assessment (LCA). This structured and yet standardized approach, born in the early 1970s after the oil crisis, is aimed at the quantification of all the environmental impacts associated with the lifetime of a product, a service or a process. Ruled by international standards such as ISO 14044:2006 [16], LCA has become over the decades a key tool for the eco-friendly design of new products as well as the identification of the environmental burdens of a product, process or human activity from raw material acquisition through production and use until waste management [17], enabling a shift from a linear to a circular and sustainable economy. In this framework, several studies regarding the LCA of RES systems and materials have been published in the last decades; for instance, in [18], the authors underscore the significance of material selection in photovoltaic, solar and wind systems from an LCA perspective, also identifying gaps in recent research. Additionally, in [19], the environmental impacts of two different wind turbines are analyzed so as to highlight the importance of the proper selection of construction materials and the great boost given by blade recycling to the whole environmental performance of turbines. Being critical during the end-of-life stage, recent LCA studies such as [20] have focused on different recycling technologies for wind blades and their limitations, providing the audience with relevant cues for further research and implementation on more efficient and sustainable strategies.

In this context, the MAREWIND project [21] was launched in 2020 by 20 research centers and industrial partners all over Europe with the support of the European Commission through its Horizon 2020 funding program. The project has explored new materials, gathered experimental data and created predictive models to enhance durability, reduce maintenance and achieve a lower environmental impact for the offshore wind sector [22]. Within the research activities, different materials have been explored and tested in relevant environments, and proper sustainability assessment studies have been conducted. In particular, an innovative wind blade was manufactured, aiming to improve its recyclability while maintaining adequate mechanical properties. Moreover, the sustainability of these solutions was evaluated thanks to the life cycle assessment (LCA) methodology, which was applied to the manufacturing process of the blade in order to compare its environmental footprint with one of the selected commercial benchmarks.

This study contributes to the field by providing a detailed comparative analysis of two distinct material systems, highlighting the advantages of adopting more sustainable materials in the wind energy sector. In particular, this article investigates and compares the performance of composite materials used in the innovative wind blade with traditional materials used in the offshore wind blade sector. The study aims to evaluate and quantify the environmental impacts of these materials through a life cycle assessment (LCA) comparative analysis.

Section 1.1 provides an overview of the state of the art (SoA) in wind blade manufacturing, while Section 1.2 reviews previous LCA studies within the offshore wind industry. In Section 2, the materials used in wind blades are introduced, along with a detailed description of the LCA iterative phases in accordance with the relevant ISO standards. Section 3 presents a case study that highlights the technical specifications of the wind blade and the application of the LCA methodology to the materials. In Section 4, the environmental results obtained for the two different scenarios are analyzed, leading to the identification of the main environmental impact areas and opportunities for improvement in the sustainability of offshore wind blade production.

Finally, major conclusions are drawn in Section 5.

The findings of this project are expected to inform future research and development efforts, guiding the industry toward more environmentally friendly and sustainable wind turbine technologies.

1.1. Wind Blade Manufacturing State of the Art

This section describes the SoA wind turbine blade (WTB) manufacturing process using the vacuum-assisted resin transfer molding (VARTM) process and adhesive bonding to manufacture and assemble the WTB components. This fabrication technique is used for both small and large WTBs, ranging from 13 m (turbine capacity of 0.225 MW) to 120 m (turbine capacity of 15 MW). The VARTM process has gained popularity as a reliable and cost-effective alternative to autoclave molding for large-scale high-performance composite production, which is especially interesting for the renewable energy industry. The novel 13 m wind blade prototype produced in the MAREWIND project was selected for the purpose of describing the manufacturing process in this paper, as presented in Figure 1.

Details are shown in Figure 2.

The blade is manufactured from glass fiber (GF)-reinforced polymer composites and composed of the following seven components: 1. root; 2. pressure side shell; 3. suction side shell; 4. suction side spar cap; 5. pressure side spar cap; 6. trailing edge (TE) web; 7. leading edge (LE) web. The pressure and suction side shells are non-structural components and consist of 0° and +/−45° fibers called triaxial (TRIAX) GF plies and a balsa wood core to improve shell stiffness. The pressure and suction side spar caps and root sections are structural components and consist of 0° fibers called unidirectional (UD) GF plies, which provide resistance to the bending loads. The suction side shell, spar cap and root section are manufactured as one component (fused together) in the suction side skin mold and are referred to as the suction side skin component; see Figure 3. This reduces the number of components to be infused and assembled from seven to four. The same process is used for manufacturing the pressure side skin component. The LE and TE webs are also structural components consisting of TRIAX and UD GF plies to provide resistance to the torsional loads and transfer loads between the suction and pressure side skins and spar caps. The LE and TE webs require a mold each. An example of the skin and web dry GF ply layup process, prior to the VARTM process, can be seen in Figure 4.

Next, the dry GF plies laid up in the skin and web molds are impregnated with liquid thermoset or thermoplastic resin using the VARTM process. This process (Figure 5) requires a breather layer, peel ply, a flow medium (mesh) and a delivery system (resin pot, silicone tubes, spiral wire and connectors) to be laid above the glass fiber. The complete layup is enclosed under vacuum using a vacuum bag. The vacuum creates a pressure difference that allows resin to be drawn from the resin pot into the vacuum bag to facilitate the impregnation and consolidation of the resin with the GF reinforcement. The infusion process is typically conducted at room temperature (RT) with a vacuum pressure between 0.7 and 0.9 bar depending on the resin type.

Once all blade components are infused, they are trimmed and dry fit together. Finally, the blade is fully assembled by adhesively bonding the components together by first bonding the webs into one skin, followed by the second skin, as shown Figure 6.

1.2. Life Cycle Assessment (LCA) for Wind Technologies

With the increasing shift toward renewable energy, wind power plays a pivotal role in global efforts to mitigate climate change and reduce dependency on fossil fuels. However, while wind energy is seen as a sustainable alternative, the production, operation and disposal of wind turbine components introduce environmental impacts across their life cycle. Life cycle assessment (LCA) has become an essential tool for evaluating these impacts comprehensively, providing insights into how wind energy systems can be optimized for greater sustainability.

A comprehensive LCA not only considers the operational efficiency of wind turbines but also addresses the environmental burdens associated with material extraction, manufacturing and EoL disposal. According to a review by Mendecka and Lombardi [23], LCA studies have shown that while the operational phase of wind turbines contributes the least to greenhouse gas emissions, the manufacturing and EoL phases can have significant environmental impacts, particularly due to the resource-intensive nature of turbine materials and the challenges of disposing or recycling large-scale components like blades in the context of offshore applications. Recent studies have evaluated the environmental impacts of floating offshore wind farms in Italy, revealing the complex dynamics between material demands and operational benefits at sea [24]. Similarly, models like the IEA 15-MW Offshore Reference Wind, developed by the National Renewable Energy Laboratory (NREL), offer valuable baseline data for assessing the sustainability of offshore systems at a larger scale [25]. These studies underscore the need for standardized, robust data to evaluate and compare environmental impacts across different offshore projects.

The end-of-life phase of wind turbines, particularly blade disposal, is another area of critical focus. Emerging research shows the potential of recycling and repurposing decommissioned blades to reduce waste and improve resource efficiency. For instance, Nagle et al. investigated second-life applications for decommissioned blades, demonstrating environmental gains through repurposing initiatives [26]. Other studies, such as those examining EoL disposal strategies in China and the United States, further emphasize the potential carbon reduction benefits of recycling and material recovery, contributing to a circular economy in wind energy [20,27].

With this background, this paper discusses the application of LCA to compare the environmental burdens of traditional wind blade construction versus a newly proposed sustainable design. Through this comparative analysis, the study aims to highlight the life cycle benefits of adopting more sustainable materials and designs, ultimately contributing to more environmentally friendly wind energy technologies.

2. Materials and Methods

This section describes the production of innovative wind blades, in terms of materials and processes, at EireComposites (Éire Composites Teo., Galway, Ireland) facilities in Ireland as compared with traditional materials used for this product. Later, the life cycle assessment (LCA) methodology is presented and detailed in its four iterative steps, according to ISO regulations. Hence, the method is applied by RINA (RINA Consulting S.p.A., Genoa, Italy) on the object of the study, i.e., the wind blade, in its two configurations (standard vs. innovative), in order to compare their environmental impacts.

2.1. Wind Blade Materials: Traditional vs. Innovative

Most wind turbine blades are manufactured from glass fiber and non-recyclable epoxy–thermoset resin that limits the end-of-life solutions for wind turbine blades. Glass fibers are produced by melting silica sand and other minerals at elevated temperatures and drawing them into fine strands, which are then coated with a sizing agent to improve adhesion to resin systems. However, the production of glass fiber has a significant environmental impact, with one ton of material producing around one ton of CO₂ emissions, along with large amounts of waste and emissions of pollutants [28]. Despite this, glass fiber is a relatively inexpensive and widely available material with excellent mechanical properties, making it suitable for use in wind turbine blades. As a result of the glass fiber’s enticing performance-to-price ratio, glass fiber products account for 95% of the total products utilized for reinforcement in the composites industry [29]. Glass fiber can be recycled, and novel resins are being developed to recover and reuse it from end-of-life blades.

As renewable energy continues to grow, there is an increasing interest in developing more sustainable and environmentally friendly resin materials for the matrix of WTB composites. Epoxy resins are produced by combining two chemicals to create a thermosetting polymer that hardens into a strong, durable material with excellent adhesive properties. The production of epoxy resins involves significant energy consumption and emissions of greenhouse gases, particularly CO₂. According to industry estimates, the production of one ton of epoxy resin produces around 5.7 tons of CO₂ emissions [30]. Additionally, the production process generates waste and emissions of pollutants such as volatile organic compounds (VOCs) and particulate matter. Therefore, it is of considerable importance to develop sustainable alternatives to epoxy resins, such as bio-based resins and recyclable thermosets. Overall, the use of epoxy resins in wind turbine blades is a trade-off between their excellent mechanical properties and the environmental impact of their production.

Recently, Arkema™ developed novel recyclable low-viscosity thermoplastic (TPR) methacrylic Elium^® resins based on polymethyl methacrylate (PMMA) for infusion technology that feature mechanical properties comparable to those of epoxy resins. These liquid resins can be employed in various engineering composite applications like marine, automotive, aerospace and WTBs [31]. The dissolution of Elium^® resin reinforced with glass fibers was analyzed, and the matrix and full-length fibers with unaffected mechanical properties compared to virgin fibers were recovered [6].

Elium^® 191 XO/SA was selected as the innovative resin system for the MAREWIND project, as it has a low exotherm to produce large parts with thick sections suitable for larger WTBs. A general comparison was made between the innovative Elium^®191 XO/SA system and the conventional Epoxy Prime 37^® system (

Table 1. Comparison of uncured Elium^® 191 XO/SA and Epoxy Prime 37^® properties.

Property	Elium®191 XO/SA	Epoxy Prime 37®
Composition	Three parts: Acrylic resin (50%w) Accelerator (50%w) Initiator: peroxide (MEKP)	Two parts: Epoxy resin Initiator: Ampreg® 3X Slow hardener
Viscosity	100 cP at 25 °C	181 cP at 25 °C
Curing process	Infusion and cure at RT Post-cure for 2 h at 80 °C or 16 h at 40 °C	Infusion and cure at RT Post-cure for 7 h at 65 °C or 16 h at 50 °C
Gel time	210–260 min at 25 °C	240 min at 25 °C
DNV approval	In progress	Yes

). As seen from the table, there are two options for the thermal post-curing time that can be used after the VARTM process and 16 h curing at RT before demolding the blade. In this study, the blade undergoes a moderate post-curing treatment at 40 °C and 50 °C (recommended by the manufacturer) for Elium^®191 XO/SA and epoxy Prime 37^®, respectively, to achieve maximum mechanical and physical properties, including a high glass transition temperature. There is a slight difference in the post-curing temperature (energy consumption) of the curing process for both resins. Post-curing at 80 °C for the thermoplastic resin can reduce the post-curing time to 2 h compared to 7 h for the thermoset resin. Following the manufacturing process, represented by the infusion and curing process of the thermoplastic resin, reduces defect rates such as the void rate to about 1%, which can be neglected.

A comparison of the mechanical properties of the Epoxy Prime 37^®-based and Elium^® 191 XO/SA-based composites is shown in

Table 2. Mechanical properties of UD GF/Elium^®191 XO/SA and UD GF/epoxy composites.

Test Property	Method	UD GF/Elium®191 XO/SA	UD GF/Epoxy
0° Tensile strength (MPa)	ASTM 3039	770.53	782.00
0° Tensile modulus (GPa)		45.20	39.00
90° Tensile strength (MPa)	ASTM3039	27.70	46.50
90° Tensile modulus (MPa)		12.63	11.90
0° Compression modulus (GPa)	ASTM D6641	53.96	45.13
90° Compression modulus (GPa)	ASTM D6641	12.36	15.68
In-plane shear modulus (GPa)	ASTM D3518	3.50	3.67

. The results showed that Elium^® 191 XO/SA presents comparable mechanical properties to the conventional epoxy in terms of the tensile, compression and in-plane shear test results. Other benefits that the innovative Elium^® composite material has over the traditional epoxy composite material include the possibility of welding WTB components together instead of requiring adhesive bonding by reheating/remelting the thermoplastic resin. The sustainable/recyclable Elium^®-based composites can be dissolved in chloroform and recovered in methanol; thus, both the matrix and full-length GFs can be recovered using recycling operations [32]. In addition, recent studies investigated two blades, one composed of GF/Elium^® composite and the other composed of traditional GF/epoxy composite, and showed that the fatigue behavior of the GF/Elium^® composite blade showed increased damping, and thus reduced operational loads, compared to traditional epoxy-based composite blades [33,34].

Based on these results, it is evident that the innovative Elium^® 191 XO/SA resin system is an excellent alternative to the non-recyclable traditional epoxy resin-based composites for the WTB industry.

2.2. Life Cycle Assessment (LCA) Methodology

The life cycle assessment (LCA) is a comprehensive, structured and internationally standardized methodology that aims to evaluate the environmental impacts associated with a product, process or service over its whole life cycle. This method aims to identify and quantify the consumption of materials and energy, as well as the production of emissions and waste into the environment, related to the life cycle (as a whole or as a part of it) of a product/process taken as the object of the study.

LCA is one of the three methodologies of the so-called life cycle thinking (LCT) approach. The other two methodologies include life cycle costing (LCC) and social life cycle assessment (SLCA). This implies that LCT is a comprehensive procedure used to assess environmental, economic and social impacts through LCA, LCC and SLCA, respectively, to enhance the viability of a product during its lifecycle. LCT gives a holistic overview of the sustainability performance of the products. Hence, it has gained recognition over the last years in several industrial sectors, both for new products (eco-design studies) and for improving benchmarks.

LCA is ruled by a set of international standards, such as ISO 14044:2006 [16], and guidelines (e.g., ILCD Handbook [35]), which report in detail the procedures, purposes and iterative processes required to perform the assessment. According to these norms, LCA is articulated in four main phases:

• Goal and scope definition;
• Life cycle inventory analysis (LCI);
• Life cycle impact assessment (LCIA);
• Interpretation of results.

These 4 phases are iterative since they can be integrated, modified and adjusted during the study in order to comply with the main objectives of the assessment, which are stated in the first step (i.e., goal and scope).

A brief and exhaustive description of the 4 iterative phases of LCA is reported in the following subsections.

2.2.1. Goal and Scope

The first step of LCA is the definition of the goal and scope, which is crucial for the success of the study. In the goal definition, the intended application and the purpose of the study should be clarified, while the scope includes the definition of important parameters that characterize both the object of the study and the methodological procedures of the LCA. For example, the following parameters should be unambiguously stated:

• The object of the study (i.e., a product, a process, a service).
• The functional unit (FU), i.e., the metric (i.e., parameter, value, unit), which provides a reference to which the data collected are related (and to which the results of the assessment are compared).
• The system boundaries, i.e., the framework (as processes, life cycle steps, etc.) within which the study is carried out.
• The methods for impact assessment, including impacts to be considered and the interpretation to be performed.
• Assumptions and limitations, if any.

2.2.2. Life Cycle Inventory (LCI)

The LCI phase directly involves building up an inventory, including a set of flows (inputs/outputs) characterizing the object of the study. Data collected should be consistent with the purposes of the goal and scope (e.g., FU, boundary conditions, etc.). The system under analysis could be divided into main processes, each one including several inputs (e.g., energy, raw materials, etc.) and outputs (e.g., product, waste, emissions, etc.). Data to be collected are different in source and purpose: background data (referring to background processes) are usually secondary data coming from the literature, databases, data banks, etc., while foreground data (referred to foreground processes) are mainly primary data directly collected from data providers (e.g., technology owners, industrial developers, researchers, etc.). The LCI, including primary and secondary data, is reviewed and consolidated at the end of the data collection.

2.2.3. Life Cycle Impact Assessment (LCIA)

After inventory construction, an LCA model is developed using dedicated software (e.g., GaBi^®, SimaPro^®, etc.) with the aim to re-create the realistic process consequentiality, including all input/output flows collected in the LCI. Once the model is created, the software calculates the environmental impacts related to the life cycle stages of the product considered for the study (all or just some of them; it depends); this process is known as the impact assessment (LCIA). The LCIA aims at aggregating the long list of interventions typically found in practice into a small set of indicators. The purpose is to identify processes that contribute most to the overall impact, to compare products or to garner support for promising technological innovations [36]. According to the impact categories selected for the study, this correlation between environmental interventions and impact categories is expressed through a set of indicators that are related to a specific aspect of environmental affection (e.g., ecotoxicity, ecosystems, resource use, etc.).

2.2.4. Interpretation of Results

The last phase of LCA is the interpretation of results obtained by LCIA. The analysis, indeed, is concluded with the identification, quantification, checking and validation of information obtained from the impact results. The outcomes of this procedure are conclusions and recommendations for the study.

3. Case Study: Comparative LCA of Traditional and Innovative Wind Blades

This section presents the framework and findings of a comparative life cycle assessment (LCA) conducted to evaluate the environmental performance of manufacturing two composite wind blades: a conventional SoA design and an innovative blade developed within the MAREWIND Project.

3.1. Goal and Scope for Wind Blades

The primary goal of this study is to evaluate the environmental performance of manufacturing an innovative composite wind blade developed within the MAREWIND Project and compare it with a SoA composite wind blade of similar design and functionality. This analysis aims to identify the potential environmental benefits of the new construction, especially regarding its material composition, mechanical properties and recyclability.

The product under comparison is a GFRP composite wind blade with a prototype length of 13 m. Two material configurations are compared: the standard blade (epoxy–GFRP) and the novel one (thermoplastic–GFRP). Specifically, the SoA composite blade uses an epoxy-based thermoset resin (Prime 37^®), while the novel MAREWIND blade introduces an innovative thermoplastic resin (Elium^®)-based composite. The new resin system confers additional functionalities, including recyclability and the ability to weld or disassemble components through heating, which addresses the issue of EoL waste management in traditional wind blade designs. The compared blades share structural similarities in design, despite the difference in materials, for a fair comparison.

The scope of this study is limited to a cradle-to-gate analysis of the manufacturing process, excluding installation, operation, maintenance and EoL phases. The cradle-to-gate approach is chosen to focus on the manufacturing phase, identifying key environmental impacts and opportunities for improvement in material selection and production processes. This scope allows for a clear comparison between traditional and innovative wind blade designs, highlighting the benefits of new materials without the variability of downstream processes. Additionally, it aligns with the MAREWIND project’s goals of enhancing sustainability in wind energy systems by providing targeted insights into the manufacturing stage. The FU of the present study is defined as one prototype-scale (13 m long) composite wind blade manufactured at ÉireComposites’ facilities in Ireland. The manufacturing process includes four key stages: 1. tool preparation, 2. kiting/layup, 3. infusion and 4. oven curing. The process is identical for both the SoA and MAREWIND blades. By focusing solely on the manufacturing phase, this study seeks to isolate the environmental impacts arising from the production of materials and the assembly of composite structures.

3.2. Life Cycle Inventory for Wind Blades

The LCI phase of this study focuses on gathering data relevant to the manufacturing processes of the SoA and MAREWIND wind blades at a product level. Both blades undergo the same four-stage manufacturing process, consisting of the following:

• Tool Preparation: This stage involves setting up tools and molds for the composite layup process, ensuring a proper foundation for the infusion of materials.
• Kiting/Layup: During this stage, glass fibers are layered in unidirectional (UD) and triaxial (TRIAX) orientations to meet design specifications. The SoA and MAREWIND blades use the same glass fiber types but differ in resin systems, with the SoA blade using an epoxy thermoset resin and the MAREWIND blade using a PMMA-based thermoplastic resin (Elium^® 190 XO/SA).
• Infusion: In this stage, the resin is infused into the layered fibers, ensuring that the composite structure is well-bonded. The infusion process for both blades is similar, though the MAREWIND blade’s PMMA-based resin requires specific handling techniques to optimize curing and ensure recyclability.
• Oven Curing: Finally, the blades are cured in an oven, solidifying the composite structure. While both blades undergo a similar curing process, the thermoplastic resin in the MAREWIND blade offers advantages in terms of recyclability, as it allows for reheating and remelting, enabling disassembly at the end of life (EoL).

Due to proprietary constraints, specific data on material composition, technology and energy consumption remain confidential, but aggregated values and process descriptions are provided to ensure transparency in the comparative assessment.

3.2.1. Material Composition and Key Parameters for Wind Blades

Although detailed proprietary data on material compositions and activity data cannot be disclosed, the following general information is available:

• Fibers: Both blades use glass fibers with similar densities and mechanical properties, though slight differences in tensile and compression modulus values are observed. The SoA blade exhibits a 0° tensile modulus of 39 GPa, while the MAREWIND blade shows an improved 0° tensile modulus of 45.20 GPa.
• Resin Systems: The SoA blade uses Prime 37^®, a two-part epoxy thermoset resin, which does not offer recyclability. In contrast, the MAREWIND blade uses thermoplastic resin (Elium^® 190 XO/SA), allowing for recyclability and enhanced mechanical properties.
• Density: The density of the composite materials used in the SoA blade is approximately 1100 kg/m³, whereas the MAREWIND blade’s material has a slightly lower density of 1010 kg/m³, contributing to potential weight savings and lower material requirements.

3.2.2. Energy Consumption and Environmental Impact Data

Energy consumption and emissions data specific to each manufacturing stage are recorded but remain confidential. However, it is noted that the manufacturing process at ÉireComposites’ facilities in Ireland aligns with industry best practices for GFRP composite production. Emissions associated with tool preparation, material infusion and oven curing are aggregated to provide a comparative analysis of the environmental footprint for both blades. For the MAREWIND blade, the thermoplastic resin offers additional environmental advantages in future reuse and recycling, which are considered qualitatively in this study.

3.2.3. Exclusions of the Study

This product-level LCI excludes downstream stages such as installation, operational energy consumption, maintenance and EoL management. The recyclability and potential for material recovery offered by the MAREWIND blade’s thermoplastic resin are further analyzed in a separate turbine-level LCA, which is out of the scope of the present article.

3.3. Results (Impact Assessment) for Wind Blades

Life cycle assessment (LCA) is applied to the manufacturing of a 13 m long prototype composite wind turbine blade in standard (SoA) and MAREWIND (Inno) configurations, which is the FU of the study discussed in this report. The selected impact assessment methodology is Environmental Footprint 3.1 (EF 3.1) [37], within which the 16 most relevant indicators are considered. The software used is the Gabi v.2023.2 Professional database. In

Table 3. LCA results of SoA vs. Inno composite wind blade (FU: 1 wind blade, manufactured).

EF 3.1 Indicator	Unit	SoA Wind Blade	Inno Wind Blade	Variation
Acidification	[Mole of H+ eq]	2.99 × 103	3.29 × 103	10%
Climate change—total	[kg CO2 eq]	7.28 × 105	5.07 × 105	−30%
Ecotoxicity, freshwater—total	[CTUe]	4.13 × 107	1.26 × 106	−97%
Eutrophication, freshwater	[kg P eq]	6.88 × 10	4.79 × 10	−30%
Eutrophication, marine	[kg N eq]	1.27 × 104	6.61 × 102	−95%
Eutrophication, terrestrial	[Mole of N eq.]	6.99 × 103	6.14 × 103	−12%
Human toxicity, cancer—total	[CTUh]	9.70 × 10−4	6.53 × 10−4	−33%
Human toxicity, non-cancer—total	[CTUh]	1.89 × 10−2	6.50 × 10−3	−66%
Ionizing radiation, human health	[kBq U235 eq]	3.47 × 104	2.59 × 104	−25%
Land use	[Pt]	2.31 × 106	1.36 × 106	−41%
Ozone depletion	[kg CFC-11 eq]	3.16 × 10−2	1.34 × 10−2	−58%
Particulate matter	[Disease incidences]	2.93 × 10−2	2.84 × 10−2	−3%
Photochemical ozone formation, human health	[kg NMVOC eq]	2.01 × 103	1.82 × 103	−10%
Resource use, fossils	[MJ]	1.27 × 107	8.36 × 106	−34%
Resource use, mineral and metals	[kg Sb eq]	1.90	1.64	−14%
Water use	[m3 world equiv]	1.47 × 105	1.87 × 105	27%

, the results of the impact assessment are outlined, comparing the baseline with the innovative wind blade.

4. Interpretation of Results

From the global results, it is evident that the innovative composite wind blade manufacturing process enables an important reduction in environmental burdens for most of the EF 3.1 impact indicators considered in the study. In particular, a massive reduction is observed in eutrophication, marine (−95%) and ecotoxicity, freshwater (−97%). A decrease is also observed in the climate change indicator (−33%) because of the different selection of raw materials (e.g., thermoplastic vs. thermosetting resin), as well as the global optimization of the process in terms of energy consumption. An increase is only reported for water use (+27%) and acidification (+10%). In this case, the reason for these higher impacts is again imputable to the value chain of new materials used (e.g., thermoplastic resin), the production process of which affects these two indicators. A graphical representation of the results is also visible in Figure 7.

The chart confirms the reduction observed for the innovative manufacturing process in almost all the impact indicators. In order to better understand the impact breakdown for the manufacturing stages (hotspot analysis) of each of the compared wind blades, the following graphs are discussed.

In Figure 8, the hotspot analysis is applied to standard wind blade production processes. The most impactful phase is the infusion process, in which most raw materials (i.e., resin, hardener, glass fibers) and auxiliaries (i.e., consumables, mostly in plastic) are used. Later on, the kiting/layup process follows, where natural resources (i.e., balsa wood, used for the core of the blade) are also employed, along with other chemicals.

In particular, for climate change—total, the highest contribution comes from the infusion stage, which accounts for 73.8%. The kiting/layup stage contributes 20.2%, while the oven curing stage is responsible for 5.8%. Regarding the resource use, fossils indicator, the infusion stage again has the largest share at 76.3%, followed by the kiting/layup stage with 18.7%. The oven curing stage contributes 4.5%, and the tool prep stage has a minimal contribution of 0.2%. In both categories, infusion is the dominant process in terms of impact, while the other processes only involve a minimal consumption of materials or energy; hence, their impact on the global environmental performance of the SoA wind blade manufacturing is lower.

Analyzing the breakdown of the Inno composite wind blade LCA results (Figure 9), the most impactful process instead is kitting/layup; even if the mass of fibers and balsa wood is quite the same as in the SoA process, the difference is that the resin type selected for infusion changes. Indeed, the use of a thermoplastic resin lowers the environmental impacts with respect to SoA, giving rise to a relative increase in the share of the kitting phase among the whole impacts of the manufacturing process. Going deeper into the results, for climate change—total, the infusion stage has the greatest impact, contributing 73.8%. The kiting/layup stage follows with 20.2%, while the oven curing stage accounts for 5.8%. In terms of resource use, fossils, the infusion stage again plays the largest role, contributing 76.3%, followed by the kiting/layup stage at 18.7%. The oven curing stage accounts only for 4.5%, and tool prep has a minimal impact with just 0.2%. When considering the water use indicator, the infusion stage continues to be the dominant contributor, representing the largest share.

Overall, the infusion stage is consistently the primary contributor, while the other production phases have minor impacts on all categories.

In general, the Inno composite system offers an improvement in the environmental profile due to the selection of more sustainable materials (e.g., thermoplastic resin instead of epoxy resin) that have a relevant role in reducing the footprint of the novel composite wind blade.

5. Conclusions

Research on more sustainable materials and processes is crucial for a complete and comprehensive green transition in the energy sector. The implementation of RESs has led to the introduction of innovative systems and technologies in order to reduce the extraction and consumption of fossil fuels. In this framework, wind offshore energy is one of the most efficient and promising green technologies and is going to increase its presence in the European electricity mix in the next decades. However, some efforts should still be made to develop materials and methodologies that could improve the environmental profile of RES technologies, focusing on alternative and recyclable products. Indeed, the issue of the disposal of large thermoset composite structures (e.g., wind blades) at their end of life poses challenging questions on the sustainability of the whole offshore wind energy value chain.

This paper discusses a comparative life cycle assessment (LCA) study of traditional and new sustainable wind blades from the cradle to the gate. Considering the challenges faced by offshore wind turbine blades (e.g., erosion and fatigue), researchers seek improved materials and coatings to extend their lifespan. For example, the MAREWIND EU project, from which this study takes cue, explores new materials and predictive models to enhance the durability and reduce the environmental impact of wind offshore systems. In this framework, an innovative composite wind blade is developed, aiming at improving recyclability while maintaining desired mechanical properties. The LCA methodology is applied to compare the environmental footprint of the manufacturing process and materials of the novel blade with those of a traditional one, identifying hotspots and areas for improvement. The results of the analysis highlighted that the production of glass fiber and epoxy resins used in traditional wind blades has significant environmental impacts; thus, the use of a thermoplastic resin in the novel wind blade strongly contributes to a reduction in the carbon footprint of the wind turbine structure. In particular, the LCA results highlight the substantial environmental benefits of the new design, including a 30% reduction in climate change impact, a 97% reduction in freshwater ecotoxicity and a 95% reduction in marine eutrophication. Moreover, the manufacturing process of large composite structures, particularly the use of VARTM and adhesive bonding, is reported to represent the largest contribution to the total environmental impacts of the wind blade because of the raw materials. In the innovative solution, the use of more sustainable materials allows for a reduction in the impacts while maintaining the required mechanical properties. Additionally, the recyclability of the innovative wind blade addresses the end-of-life waste management issue; indeed, the use of a thermoplastic epoxy, being recyclable, is a key aspect that enables a strong decrease in the environmental burdens with respect to the standard EoL scenarios of epoxy-based composite wind blades (e.g., landfill or incineration).

Looking forward, the scalability of this innovative solution presents exciting opportunities for widespread adoption across the wind energy industry. As the demand for renewable energy grows, the ability to produce more sustainable, recyclable wind turbine blades could play a pivotal role in reducing the overall environmental impact of wind energy production. Industry adoption will depend on further technological advancements, cost reductions and regulatory support. Policy frameworks that incentivize the use of sustainable materials, alongside research into more efficient manufacturing techniques, could accelerate the transition to greener wind blade production.

This study emphasizes the urgent need for the wind energy sector to adopt more sustainable materials and processes to not only enhance the environmental performance of wind turbine blades but also address the challenges of disposal and waste management. Moving forward, this research lays the groundwork for future innovations in wind blade production, with the potential to shape a more sustainable and circular wind energy industry.