Researchers have developed an eco-friendly method to recycle wind turbine blades without the use of harsh chemicals. the process allows them to recover high-strength glass fibers and resins, which can be repurposed into stronger, more durable plastics.
The difficulty in recycling turbine blades is well known. They are typically made of glass fiber-reinforced polymer (GFRP), a composite material that has traditionally been difficult to recycle. Unlike thermoplastics – which can be melted down and reused – GFRP is made with thermosets, which are cured and not easily broken down.
Left: wind turbine blade waste; Middle: treated and dried wind turbine blade glass-fiber reinforced polymer (GFRP); Right: injection-molded plastic containing 70% recycled GFRP (photo by WSU).
With early-generation turbine blades from the 1990s reaching the end of their service life, the need for sustainable recycling methods has become urgent, especially since GFRP accounts for roughly two-thirds of a blade’s weight. Additionally, about 15% of GFRP is wasted during blade manufacturing.
In the new process, the team at Washington State University cut the blade material into two-inch pieces and soaked them in a low-toxicity organic salt solution – zinc acetate – in superheated, pressurised water for two hours. This mild solution, commonly found in throat lozenges and food additives, helped break down the composite and allowed for the recovery of usable glass fibers and resin. These recovered materials were then mixed directly into thermoplastics, creating composite plastics with up to 70% recycled content.
Testing revealed impressive results: when the recycled material was added to nylon, it made the plastic over three times stronger and eight times stiffer. The recycled fibers also reinforced other common plastics, like polypropylene and the types used in milk jugs and shampoo bottles. Additionally, the team was able to recover and reuse most of the zinc acetate solution through simple filtration, making the process both efficient and sustainable.
Cheng Hao, a former graduate student in the School of Mechanical and Materials Engineering and co-first author on the paper said: ‘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.’
Jinwen Zhang, corresponding author and a professor in the aforementioned School, added: ‘As wind energy grows, recycling and reusing wind turbine waste is becoming increasingly urgent. This recycling method is scalable, cost-effective, and environmentally friendly, providing a sustainable solution for reusing large quantities of glass fiber reinforced waste.
‘The ease of the catalyst recovery enhances the overall sustainability and cost-effectiveness of the method.’
Baoming Zhao, co-first author and research assistant professor in the Composite Materials and Engineering Center said: ‘For this work, we didn’t need to fully break down all the bonds and push the reaction to completion. 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.’
The full research can be read here.
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