The challenge associated with recycling wind turbine blades

Recycling wind turbines made from composite materials presents significant challenges that have become a growing concern as the number of decommissioned turbines increases. Making wind turbines with composite materials provides the necessary strength and durability to withstand harsh conditions but recycling the blades at the end of their life cycle is proving a difficult task.

How the blades are made

The blades are generally made using fibreglass-reinforced plastics (FRP) or carbon fibre-reinforced plastics (CFRP) which provide excellent strength, weight and flexural properties, crucial for the performance of a blade during its lifecycle.

Once the design is completed, large moulds are created and treated with a release agent to prevent the blade from sticking during the curing process. Inside these moulds, sheets of fibreglass or carbon fibre are carefully layered. Each layer is oriented to maximize the blade’s strength and rigidity.

After the layering is complete, the resin infusion process begins. This involves infusing the mould with resin, usually epoxy, often using a vacuum-assisted resin transfer moulding (VARTM) technique. This method ensures that the resin thoroughly saturates the layers of fabric, creating a solid and uniform structure. The mould is then heated to cure the resin, which hardens the composite materials and binds everything together.

Once the blade is cured and is out of the mould they go through rigorous inspection and testing to ensure its quality. This includes visual inspections and non-destructive testing (NDT) methods like ultrasonic testing or X-rays, along with mechanical tests to verify structural integrity. The blade is also balanced to ensure it operates smoothly without causing vibrations or undue stress on the turbine.

The lifespan of a wind turbine blade

The typical lifespan of a wind turbine blade is around 20 to 25 years, depending on various factors such as the design, material, environmental conditions, and maintenance practices. After this period, blades often need to be replaced due to wear and tear, and degradation.

Historically, many of these old blades have been sent to landfills because they are difficult to recycle due to breaking down and recycling the composite materials used in their construction.

The problems with recycling

The matrix of different composite materials used makes it a challenge to separate them back into reusable components. Unlike metals, which can be melted down and reformed with relative ease, composites require more energy-intensive and sophisticated processes to break down. Current recycling methods, such as mechanical grinding, pyrolysis, and solvolysis, are either not fully efficient or are economically unviable on a large scale.

Mechanical grinding involves shredding the blades into smaller pieces, which can then be used as fillers in other materials. While this method is relatively straightforward, it does not fully recycle the materials and often results in a lower-quality product that has limited applications. Pyrolysis, which involves heating the materials in the absence of oxygen to break them down into oil, gas, and a solid residue, can reclaim some of the base materials. However, this process requires high temperatures and sophisticated equipment, making it costly and energy-intensive. Solvolysis, which uses solvents to dissolve the resins in the composite material, shows promise but is still in the developmental stage and has yet to be proven on a commercial scale.

Another problem is the lack of established infrastructure and standardised procedures for recycling wind turbine blades. The industry has not yet developed a consistent approach to handling decommissioned turbines, leading to variability in recycling practices. This inconsistency can result in inefficiencies and increased costs, further complicating the recycling process.

Additionally, there are economic and regulatory hurdles to consider. Recycling composite materials from wind turbines is not always cost-effective, particularly when compared to landfilling or incineration. Without financial incentives or regulatory mandates, there is little motivation for companies to invest in recycling technologies. Moreover, the absence of strict regulations regarding the disposal of composite materials can lead to environmental issues, as these materials can take hundreds of years to break down in landfills, potentially releasing harmful substances into the environment.

The growing number of wind turbine blades that will soon reach the end of their operation life the end of their operational lives exacerbates these problems. As the renewable energy sector continues to expand, the issue of how to sustainably manage the disposal of wind turbine blades becomes more pressing. Estimates suggest that by 2050, millions of tons of composite waste from wind turbine blades will need to be managed globally.

Solutions

The recycling of wind turbines, particularly the blades, has seen significant advancements recently. Here are some of the latest innovations:

Two of the most promising innovations come from two of the largest turbine manufacturers, Siemens Gamesa and Vestas. Siemens has developed a fully recyclable wind turbine blade that can be recycled at the end of its lifecycle without altering the blade's properties, making the process more efficient and sustainable. Danish giant Vestas announced in 2023 that it had combined newly discovered chemical technology developed within the CETEC initiative, and partnerships with Olin and Stena Recycling that can be applied to blades currently in operation and once matured will eliminate the need for blade redesign or landfill disposal of epoxy-based blades when they reach the end of their lifecycle.

These innovations are part of a growing effort to make the wind energy sector more sustainable by addressing the challenge of recycling wind turbine components, particularly the blades, which are typically made from composite materials that are difficult to recycle using traditional methods.