October 1, 2022
  • October 1, 2022

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

By on August 26, 2022 0
Enlarge / Old wind turbine blades are usually sent to landfills, which rather undermines the concept of sustainable energy production.

Imagevixfr/Getty Images

Wind energy is a rapidly growing industry, with a 53% increase in new installations in 2020 alone, according to the Global Wind Energy Council. The massive fiberglass blades can be as long as half a football field and keep getting bigger – the bigger the blade, the greater the power output. This is a problem when the blades outlast 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 developed a new polymer resin that can not only be recycled into a new generation of turbine blades, but also into materials for a wide range of commercial applications. These include making car taillights, diapers, kitchen sinks, and even edible gummy bears. He described his research at a meeting of the American Chemical Society in Chicago this week.

Dorgan calls his approach “molecular flexibility,” inspired in part by a paper he once read by Isaac Asimov, describing a future where people would be able to resynthesize raw protons, neutrons, and electrons into anything. they wanted. “It’s almost like the replicator of star trekwhere they can just turn atoms into whatever they want – ice cream floats, or new clothes, or whatever,” Dorgan said in a press conference at the meeting of the ACS: “Of course, we are far from the idea of ​​the replicator, but we were inspired by this stuff.”

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

Michigan State University's John Dorgan holds up a sign made from a new recyclable resin.
Enlarge / Michigan State University’s John Dorgan holds up a sign made from a new recyclable resin.

YouTube/American Chemical Society

Dorgan Lab made its new composite resin by dissolving PLA in a synthetic monomer called methyl methacrylate (MMA), resulting in a syrupy resin. They used vacuum pressure to pull the resin through the fiberglass, causing that resin to harden into strong fiberglass panels. These panels can be recycled by dissolving them in fresh monomer, allowing researchers to re-melt new panels for the next generation of wind turbines. “The holy grail in polymer recycling is always going from application to application,” he said. “We can do that with these materials. We’ve gone through several cycles and shown that the mechanical properties can be maintained.”

The next step is to fabricate medium-sized turbine blades and test them in the field. But Dorgan admits its resin is not yet ready to scale to the level required to meet the current needs of the wind industry. There simply isn’t enough bioplastic produced by his process in the lab, and developing a full-scale production 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 adding a little more polymer into the mix, and it’ll be perfect for injection molding, a common manufacturing technique for plastics. Dorgan also produced cast stone, which he later used to make a full-size kitchen sink, and the MSU Spartan logo.

Beyond this simple mechanical processing, Dorgan found he could chemically modify these materials for more recycling applications. “We can actually digest one of the components of the PLA polymer just by using a simple base, like an alkaline solution,” he said. “Think of baking soda or baking powder in the kitchen, something quite mild in terms of chemical activity.”

This breaks PLA down into an environmentally harmless metabolite called monolactic acid, and allowed Dorgan to recover polymethyl methacrylate (PMMA) in the material, more commonly known as plexiglass, used to make car windows and taillights. . Increasing temperature can convert PMMA to polymethacrylic acid, a super absorbent polymer used in diapers. Another byproduct of alkaline digestion is potassium lactate, which Dorgan has been 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,” said Dorgan. “It’s all part of the global carbon cycle, and we’ve shown that we can go from biomass on the ground to sustainable plastic materials and back to food.”