Wind turbine blades could be recycled into sweets

Wind power is a popular form of renewable energy, but disposal becomes an issue when it’s time to replace the huge turbine blades.

To tackle this, scientists have created a new composite resin suitable for making these behemoths that could later be recycled into new turbine blades or a variety of other products, including countertops, car taillights, nappies, and even gummy bears.

“The beauty of our resin system is that at the end of its use cycle, we can dissolve it, and that releases it from whatever matrix it’s in so that it can be used repeatedly in an infinite loop,” said John Dorgan, a professor at Michigan State University (MSU). “That’s the goal of the circular economy.”

Most wind turbine blades are made of fibreglass, and can be half the size of a football pitch. And although some companies have found ways to recycle glass fibre into lower-value materials, most discarded blades end up in landfills.

“Larger wind turbine blades are more efficient, so companies keep making bigger and bigger ones,” Dorgan explained. “Often, wind farms will actually replace the turbine blades before the end of service life because the farms can generate more electricity with bigger blades.”

In creating a new solution to this issue, Dorgan and his colleagues at MSU developed a new turbine material that combines glass fibres with a plant-derived polymer and a synthetic one.

According to the researchers, panels made of this thermoplastic resin were strong and durable enough to be used in turbines and cars.

The team then dissolved the panels in a fresh monomer and physically removed the glass fibres, allowing them to recast the material into new products of the same type. Recast panels had the same physical properties as their predecessors, they stressed.

Besides new wind turbines, the novel resin could be used for a variety of other applications, according to the research team.

By mixing the resin with different minerals, the team produced cultured stone that could be transformed into household objects, such as countertops and sinks. “We’ve recently made a bathroom sink with the cultured stone, so we know it works,” Dorgan said.

The team could also crush the recovered material and mix it with other plastic resins for injection moulding, which is used to make items such as laptop covers and power tools.

The materials could also be recycled into higher-value products. For example, digesting the thermoplastic resin in an alkaline solution creates poly(methyl methacrylate) (PMMA), a common acrylic material for windows and car taillights, while raising the temperature of the digestion converted PMMA creates poly(methacrylic acid), a super-absorbent polymer used in nappies.

Also, the alkaline digestion also produced potassium lactate, which can be purified and made into candy and sports drinks. “We recovered food-grade potassium lactate and used it to make gummy bear candies, which I ate,” Dorgan said.

Now they have shown that the resin has suitable physical properties for wind turbines, the research team hopes to make some moderately sized blades for field testing.

“The current limitation is that there’s not enough of the bioplastic that we’re using to satisfy this market, so there needs to be considerable production volume brought online if we’re going to make wind turbines out of these materials,” Dorgan noted.

Regarding the use of discarded wind turbines to create sweets, Dorgan doesn’t find an issue with it.

“A carbon atom derived from a plant, like corn or grass, does not differ from a carbon atom that came from a fossil fuel,” he said. “It’s all part of the global carbon cycle, and we’ve shown that we can go from biomass in the field to durable plastic materials and back to foodstuffs.”