US scientists recycle wind turbine blades to make 3 times stronger plastic

“This recycling method is scalable, cost-effective, and environmentally friendly, providing a sustainable solution for reusing large quantities of glass fiber reinforced waste,” said Jinwen Zhang, corresponding author and a professor in the School of Mechanical and Materials Engineering. 

70 percent recycled glass fibers from wind turbine blades

The existing recycling methods struggle with GFRP, a thermoset material that’s difficult to break down. 

In this new work, the wind turbine blade GFRP material was recycled by cutting it into small pieces. The team then soaked it in a safe salt solution of zinc acetate under heat and pressure to break it down, using the resulting components to create stronger plastics.

They successfully extracted undamaged glass fibers and resins from wind turbine blades. The scientists then incorporated these materials (up to 70 percent recycled glass fibers) into thermoplastics, creating stronger composite materials

“It works very well, especially considering the mild conditions that we applied. The solvent is a green solvent, and also the temperature is acceptable for this purpose,” said Cheng Hao, a former graduate student in the School of Mechanical and Materials Engineering and co-first author on the paper.

Interestingly, adding recycled glass fibers and resins from wind turbine blades to nylon plastic significantly increased its strength (over three times) and stiffness (over eight times). 

Also, it was discovered that this recycled material can strengthen other common plastics like polypropylene and those used in milk jugs and shampoo bottles.

“As long as we can break the cross-linked network into smaller pieces, and they are melt processable, we can compound that with nylon and get a new composite. We are not separating the resin from the fiber—we just blend everything with nylon and get a new composite,” explained Baoming Zhao, co-first author and research assistant professor in the Composite Materials and Engineering Center.

GFRP hard to recycle

GFRP is hard to recycle because it’s a thermoset material as compared to easily recyclable thermoplastics like those in milk bottles. 

Thermosets are cured and cannot be melted down and reformed, making it difficult to break them down into reusable components.

The difficult-to-recycle glass-fiber-reinforced material constitutes about two-thirds of blade weight and also generates a 15 percent material waste during their manufacturing process.

Wind turbines built in the 1990s are now becoming obsolete, presenting a major disposal problem. 

The accumulation of discarded wind turbine blades is projected to become a massive environmental concern, with annual waste reaching 2.9 million tons by 2050 and a total of 43 million tons accumulated.

That’s why there’s an urgent need to find sustainable ways the growing waste. 

“As wind energy grows, recycling and reusing wind turbine waste is becoming increasingly urgent,” added Zhang in the press release.

Researchers are refining their recycling process to require less pressure, making it simpler. They’re also working to create future wind turbine blades that are inherently fully recyclable.

The findings were published in the journal Resource, Conservation, and Recycling.