One day we will recycle wind turbine blades into tasty gummy bears

Wind power is a fast-growing industry, with a 53 percent increase in new installations in 2020 alone, according to the Global Wind Energy Council. The solid fiberglass blades can be as long as half a football field and get bigger and bigger – the bigger the blade, the more electricity is produced. This poses a problem if the blades last longer than the mechanical parts of the turbines. They are usually sent to landfills, which undermines the whole concept of sustainable energy production.

Fortunately, John Dorgan, a chemical engineer at Michigan State University, has come up with a new polymer resin that can be recycled not only into next-generation turbine blades, but also materials for a wide variety of commercial applications. These include the production of car taillights, diapers, sinks – even edible gummy bears. He described his research this week at a meeting of the American Chemical Society in Chicago.

Dorgan calls his approach “molecular flexibility,” inspired in part by an article he once read by Isaac Asimov, in which he describes a future where humans could resynthesize raw protons, neutrons and electrons into anything they wanted. “It’s almost like the replicator of Star Trekwhere they can turn atoms into anything they want — ice floats, or new clothes, or whatever,” Dorgan said at a press conference at the ACP meeting. “Sure, we’re a long way from the replicator idea, but we’ve got I got some inspiration from that sort of thing.”

Dorgan has long worked with one of his favorite polymers: polyactides, or PLA, originally developed for making biodegradable, sustainable packaging. PLA can also be used as a fiber to make textiles and clothing. Dorgan’s current Department of Energy-funded project involves exploring how to make wind turbine blades in more energy-efficient ways. So naturally he wondered if PLA could be used as a recyclable binder resin.

The Dorgan lab made their new composite resin by dissolving PLA in a synthetic monomer called methyl methacrylate (MMA), resulting in a viscous resin. They used vacuum pressure to pull the resin through glass fibers, curing that resin into solid fiberglass panels. Those panels can be recycled by dissolving them in fresh monomer, allowing the researchers to convert new panels for the next generation of wind turbines. “The holy grail in polymer recycling is always going from one application back to the same application,” he said. “We can do that with these materials. We have gone through several cycles and we have shown that the mechanical properties can be preserved.”

The next step is to make some medium sized turbine blades and test them in the field. But Dorgan admits his resin is not yet ready to scale up to the level needed to meet the current needs of the wind power industry. There just isn’t enough of the bioplastic produced by its lab-based process, and coming up with a large-scale manufacturing process will take some time.

Fortunately, it is also possible to reuse the resin for other applications, both downcycle and upcycle. For the first, take the material and shred it, maybe add a little more polymer to the mix, and it will be perfect for injection molding, a common manufacturing technique for plastics. Dorgan also produced an engineered stone, which he then used to make a large sink, and the MSU Spartan logo.

Aside from that simple mechanical processing, Dorgan found that he could chemically modify these materials for more upcycled applications. “We can actually digest one of the components of the PLA polymer with just a simple base, such as an alkaline solution,” he said. “Think baking soda or baking soda in the kitchen — something that’s quite mild in terms of chemical activity.”

This breaks down the PLA into an environmentally friendly metabolite called monolactic acid and allowed Dorgan to recover the polymethyl methacrylate (PMMA) in the material — more commonly known as plexiglass, which is used to make car windows and taillights. By raising the temperature, the PMMA can be converted into polymethacrylic acid, a superabsorbent polymer used in diapers. Another by-product of the alkaline digestion is potassium lactate, which Dorgan was able to purify for food-grade applications. He even used it to make gummy bears in the lab.

And yes, he ate those gummy bears with no ill effects. “A carbon atom derived from a plant, such as corn or grass, is no different from a carbon atom derived from a fossil fuel,” Dorgan said. “It’s all part of the global carbon cycle and we’ve shown that we can go from biomass in the field to sustainable plastic materials and back to foods.”