The EOLIAN project – Bio-based, repairable and recyclable vitrimer composites and advanced sensors for highly reliable, sustainable wind blades – has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement no. 101147532. The multidisciplinary project consortium brings together ten organisations from five countries.

EOLIAN is aiming to develop wind turbine blades offering numerous advantages over current thermoset composite blade designs. EOLIAN blades will deliver a longer service life, be simpler to maintain and repair, and easier to repurpose and recycle at the end of their use, offering a more sustainable solution over their complete life cycle.

The EOLIAN blade will be manufactured using bio-based repairable and recyclable vitrimer composites reinforced with natural basalt fibres, and recyclable sensors and actuators will be integrated into the blade to enable structural health monitoring (SHM) and de-icing functions. All the design phases will be supported by advanced multiscale modelling to ensure the highest performance levels, and life cycle assessment (LCA)-based environmental analysis will guarantee the most sustainable approach.

To demonstrate the technologies developed within the project, EOLIAN will manufacture, test and benchmark a prototype sensor-assisted vitrimer-based composite blade of 12 m in length.

Today, around 85-90% of a wind turbine’s total mass can be recycled. Components such as the foundation and tower have established recycling practices. The blades are more challenging to recycle, mainly due to their complex design and the glass fibre and carbon fibre reinforced thermoset composites used in their manufacture. Technologies to recycle exist to blades exist but these solutions are not yet widely available or economically competitive. The options for direct repurposing end-of-use blades are limited and this is likely to remain a niche market.

The EOLIAN project will explore the possibilities of using vitrimer-based composite materials in wind blades. Vitrimers combine the performance of thermoset polymers with the processability benefits of thermoplastics and enable the manufacture of composite structures that are easier to reuse and recycle, and repair.

Vitrimers will pave the way to different end-of-life opportunities for wind blades.

• Reuse: Vitrimer composites can be reprocessed after cure, which allows the reuse of parts through simple thermoforming (heating and re-shaping). A vitrimer composite wind blade could be reformed into a shape suited to a new application, such as a component for a wind turbine nacelle.

• Recycling: Chemical recycling can separate the vitrimer matrix and the reinforcing fibre. The recovered materials could be used to manufacture new composites parts for wind energy, and other, applications.

If an end-of-use blade is not suitable for either of these processes, it can simply be shredded mechanically and the resulting materials used to form new parts.

Repair: Vitrimers also possess ‘self-healing’ properties. When subjected to mechanical stress or temperature changes, the reversible bonds within the vitrimer can break and reform, effectively ‘healing’ minor damage. This means delamination and microcracks in the composite could be repaired simply by applying heat.

Sustainability: EOLIAN will develop sustainable vitrimer composites incorporating >60% bio-based vitrimer. The synthesis of polyimine vitrimers using sustainable building blocks such as vanillin and epoxidised vegetable oils will be explored. The project will also aim to replace synthetic glass fibre reinforcement with basalt fibres, natural mineral fibres produced from volcanic basalt rock.

New sustainable vitrimer composites – reprocessable, repairable, and easily recyclable – will provide a step change in how wind turbine blades are maintained, reused and recycled in a circular economy.

A structural health monitoring (SHM) system with integrated heating system will be incorporated into the EOLIAN blade. This will be achieved using in-mould electronics processes to embed erosion and ice detection sensors and a heating system into the composite material.

The SHM system will enable rapid identification of damage so that the blade can be repaired quickly, while activating the heater will prevent ice accretion before it can affect the blade’s aerodynamic efficiency. Simple, in-the-field repair of a range of blade damage will be possible through localised heating of the vitrimer composite using portable handheld equipment. Addressing damage early will eliminate the need for more extensive repairs, or even premature blade replacement, later on.

These innovations will help to extend the blade’s service life, reduce unplanned downtime, maintain the turbine’s performance and safety, and reduce maintenance costs.

The EOLIAN blade will offer longer a lifespan, better maintainability and reliability, together with higher sustainability and recyclability.

• 20% longer lifespan than current blades
• 20% faster to repair
• 75% reduction in ice accretion
• 40% reduction in blade recycling cost
• 15% lower wind turbine life cycle costs

The EOLIAN project will begin with experimental development of the epoxy-imine vitrimer composite based on chemistries which would be the most suitable candidates for wind blade manufacturing. Initially, the experimental information of the relevant vitrimer chemistries that will be investigated. Next, molecular modelling and finite element modelling will work together to extract the associated material models which will enable faster screening of the proposed vitrimer chemistries by quantifying the effect of different chemistries on mass density, glass transition temperature (Tg), coefficient of thermal expansion (CTE), permeation properties and moduli of the vitrimer.

After selecting the most appropriate chemistries, the vitrimers will be prepared and dedicated materials characterisation performed. Finally, fibre reinforced vitrimer composites will be prepared and their performance compared with composites currently used in wind turbine blades. Based on the findings from the materials characterisation campaign, vitrimer production will be upscaled to enable the manufacture of a vitrimer-based composite blade. The blade’s performance and durability will be assessed through fatigue, lightning strike and other tests in order to ensure the material satisfies the requirements of wind turbine operators.

In parallel to this work, the project will develop a structural health monitoring system to enable the early identification of typical blade damage, such as that due to erosion, icing, and lightning strike.

Finally, the vitrimer blades will be recycled using chemical and mechanical processes to demonstrate the possibilities for reusing the secondary materials produced. As part of the project, a wind blade section based on reclaimed material will be manufactured through a fully circular approach. A dedicated life cycle engineering assessment, considering environmental impact and cost, will also be performed. A comparison with current wind blade composites will highlight the potential for vitrimer blades to reduce environmental impacts and costs throughout the wind turbine’s life cycle.

These activities will be complemented by EOLIAN’s dissemination and exploitation plan. Activities will encompass end-user/stakeholder engagement, the establishment of a project advisory consisting of experts and policymakers, and the development of standardisation guidelines, exploitation strategies and a roadmap for commercialisation.