Gummy bears that were wind turbines in their past life may not sound too appetizing. But, what if it's edible and tastes like ordinary gummy bears? Doesn't sound so bad now, does it?

Scientists at the Michigan State University have created a distinct turbine material that can be revived and recycled into new turbine blades or a variety of other products, including countertops, car taillights, diapers, and even gummy bears.

This innovation can have far-reaching consequences. Over the years, wind power has become an increasingly popular form of renewable energy. But, when it's time to replace the huge turbine blades that convert wind into electricity, disposal is an enormous problem.

In 2020, Bloomberg reported that about 8,000 wind turbines will be removed in each of the next four years in the U.S. alone. Europe has about 3,800 coming down every year through at least 2022, according to BloombergNEF. Most of these were built more than a decade ago when installations were less than a fifth of what they are now.

The problem is only going to get worse.

Scientists presented the results of their study — the new composite resin suitable for making these behemoths — at the fall meeting of the American Chemical Society (ACS).

"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 over and over again in an infinite loop," John Dorgan, Ph.D., who presented the work at the meeting, said in a statement. "That’s the goal of the circular economy."

Wind turbine blades are made of fiberglass and can be half a football field in length. A handful of companies have found ways to recycle fiberglass into lower-value materials but most discarded blades end up in landfills. "Larger wind turbine blades are more efficient, so companies keep making bigger and bigger ones," Dorgan said. "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."

Dorgan and colleagues made the new turbine material by combining glass fibers with a plant-derived polymer and a synthetic one. The material was strong and durable enough to be used in turbines or automobiles. The researchers dissolved the panels in a fresh monomer and physically removed the glass fibers. This allowed them to recast the material into new products of the same type. Most importantly, the recast panels had the same physical properties as their predecessors.

The novel resin can be used for a variety of other applications. The team produced cultured stone, by mixing the resin with different minerals, 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," said Dorgan. The recovered material can also be crushed and mixed with other plastic resins for injection molding, which is used to make laptop covers and power tools.

The material could even be upcycled into higher-value products. Digesting the thermoplastic resin in an alkaline solution released poly(methyl methacrylate) (PMMA), a common acrylic material for windows, car taillights, and many other items.

When the temperature of the digestion converted PMMA was raised, it formed into poly(methacrylic acid), a super-absorbent polymer that is used in diapers. Interestingly, 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.

Next, the researchers hope 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 actually start making wind turbines out of these materials," Dorgan said.

Dorgan added that there is no 'yuck' factor in eating candy that was once part of an old wind turbine. "A carbon atom derived from a plant, like corn or grass, is no different from a carbon atom that came from fossil fuel. 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," he said.

Human beings are intrinsic to the global carbon cycle so economic circularity will require unbiased interconversion of carbon between materials, fuels, and food. In this work, a recyclable polymer resin suitable for composites manufacturing that can be partially converted into an edible food ingredient is demonstrated.

Present generation plastics and composites have concerning sustainability metrics including high embedded energy and associated greenhouse gas emissions, low recyclability rates, and generation of microplastics pollution. Long fiber composite materials are notoriously difficult to recycle but are critical for wind turbine, lightweight vehicle, and other sustainable technologies. An economically viable, fully recyclable, composite resin consisting of biobased polylactide (PLA) dissolved in methyl methacrylate (MMA) is demonstrated. Physical properties of thermoplastic composites produced from the reclaimed resin show true “turbine-to-turbine” recycling is possible. Various end-of-use options are established; regrinding of thermoplastic composites produces short fiber moldable materials. Base catalyzed digestion of either thermoplastic or thermosetting resins produces poly(methyl methacrylate) or the superabsorbent poly(methacrylic acid). Distillation of the digestate produces methanol, water, and food grade potassium lactate; the resulting lactate has been incorporated into gummy bear candies and consumed by the presenting author. Judicious formulation of polymer resins enables complete circularity in low-embedded energy materials; exploitation of triggerable degradation provides varied and intriguing end-of-use recycling options.