The U.S. now hosts over 157,000 wind turbines. If each tower holds three blades, and each blade’s weight is about 65 glass fiber-reinforced polymer (GFRP), that’s a lot of plastic. Even if each turbine lasts an estimated 30 or so years, those blades will still need to be reckoned with.
Critics challenging wind power often claim that the turbine blades can’t be recycled but are often buried, potentially leeching harmful pollutants into the groundwater.
Perhaps in an attempt to blunt that claim, a group of researchers has developed a method to break down the blades without harsh chemicals, then recover glass fibers that can be incorporated into new, stronger plastics, they report in the journal Resource, Conservation, and Recycling.
Recycling Wind Turbine Blades
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). (Image Credit: WSU)
The researchers developed a fairly simple, relatively low-tech, and non-toxic approach to do just that. They cut GFRP into approximately two inch-sized blocks. Then, they soaked the material in a pressurized, superheated zinc acetate salt and water solution for about two hours. Finally, they extracted the broken-down fibers and added them into new plastic.
“It works very well, especially considering the mild conditions that we applied,” Cheng Hao, who worked on the project as a Washington State University graduate student and an author of the paper, said in a press release. “The solvent is a green solvent, and also, the temperature is acceptable for this purpose.”
Since zinc acetate is used in medicines, such as in throat lozenges and as a food additive, it is considered relatively mild and safe. The researchers also recovered most of that catalyzing salt by filtering the solution after the process was completed.
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Exploring Different Solutions
The technique could be quite timely, as the first generation of turbine blades — made in the 90s — are coming to the end of their lifespans. While thermoplastics (used in milk bottles) melt easily, GFRPs have proven more stubborn to reprocess.
The broken-down GFRPs can actually be used to make new, stronger thermoplastics. The researchers are exploring different chemical conditions for the solution that would reduce the amount of pressurization (and, therefore, energy) needed to break down the GFRPs. They are also aiming to create a new class of turbine blades that are easier to recycle.
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Before joining Discover Magazine, Paul Smaglik spent over 20 years as a science journalist, specializing in U.S. life science policy and global scientific career issues. He began his career in newspapers, but switched to scientific magazines. His work has appeared in publications including Science News, Science, Nature, and Scientific American.
