The growing reliance on wind energy is leading to an increase in the number of wind turbines in operation. But when these turbines near the end of their useful life, they, like any other waste, end up in landfills. 

Unfortunately, it is expected that by 2050, the global waste from wind turbine blades could surpass 43 million tonnes. This has led to concerns about environmental impact as the wind turbine blades are mostly built of non-recyclable material. 

Researchers have been actively seeking a sustainable solution, and the National Renewable Energy Laboratory (NREL) has presented one such alternative. 

Interestingly, they have created a new type of wind turbine blade resin from bio-derivable resources. The new resin is designed to be chemically recyclable, allowing the components of the blades to be recovered and reused.

This will prevent old blades from being discarded in landfills. This new resin is called PECAN, which stands for PolyEster Covalently Adaptable Network. 

An NREL scientist holds small cubes of the PECAN resin. Image: Werner Slocum, NREL.

“The PECAN method for developing recyclable wind turbine blades is a critically important step in our efforts to foster a circular economy for energy materials,” said Johney Green, NREL’s associate laboratory director for Mechanical and Thermal Engineering Sciences.

The researchers used this biomass-derivable resin to create a prototype 9-meter blade. Interestingly, they found that the new resin matches the performance of the current industry standard of blades. The currently used blades are manufactured using thermoset resin. 

Currently, the wind blades can be mechanically recycled after the end of their 20-year lifespan. The recycling process includes shredding the old blade for use as concrete filler.

These new resin-based blades offer a simple recycling method. In the testing, a mild chemical process was able to fully break down the resin prototype blade in a mere six hours.

“The chemical recycling process allows the components of the blades to be recaptured and reused again and again, allowing the re-manufacture of the same product,” the authors noted in the press release. 

Prototype endured weathering

According to the press release, the team began their research on PECAN resin with the end goal in mind i.e., recycling wind blades. 

For this, they started experimenting with various feedstocks.

Interestingly, the resin they created using bio-derivable sugars went against the traditional notion that a recyclable blade would be less effective. A concern about these materials is that they could make the blade more susceptible to 'creep', a process where the blade loses its shape. 

“Just because something is bio-derivable or recyclable does not mean it’s going to be worse,” said Nic Rorrer, the corresponding author.

Rorrer added: “It really challenges this evolving notion in the field of polymer science, that you can’t use recyclable materials because they will underperform or creep too much.”

The chemical recycling process breaks down the blade into its constituent components, which can then be re-manufactured into new products. This makes it a circular approach to materials management.

Remarkably, the composites made from PECAN resin retained their shape and endured accelerated weathering. 

Although wind blades can be very large, the smaller 9-meter prototype demonstrated the manufacturing techniques required for producing larger ones for commercial use.

The findings were reported in the journal Science.