John Dorgan says he ate the gummy bears himself. “We recovered food-grade potassium lactate and used it to make gummy bear candies, which I ate,” the Michigan State University chemical engineer said in August 2022, when he presented a recyclable resin for wind turbine blades at the American Chemical Society’s fall meeting in Chicago.<\/p>\n\n\n\n
“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,” Dorgan said in the ACS release. “That’s the goal of the circular economy.”<\/p>\n\n\n\n
He put it more simply to Scientific American<\/a>: “We’ve specifically designed a system with the end of life in mind.”<\/p>\n\n\n\n Dorgan holds the David L. and Denise M. Lamp Endowed Chair in Chemical Engineering at Michigan State. His team combined glass fibers with a plant-derived polymer and a synthetic one, the ACS says.<\/p>\n\n\n\n The plant part is polylactide, or PLA. The synthetic part is methyl methacrylate, the liquid that chemists turn into acrylic, and the PLA gets dissolved in it to make what Scientific American called a “syrupy resin.”<\/p>\n\n\n\n Vacuum pressure pulled the resin through the glass fibers until it hardened. Panels made this way were strong and durable enough to be used in turbines or automobiles, according to the ACS.<\/p>\n\n\n\n Scientific American put a typical blade at about 170 feet (52 meters), roughly the length of an Olympic swimming pool. The U.S. Department of Energy<\/a> expects American blade waste to hit roughly 200,000 to 370,000 tons a year by 2050, with the range set by whether blades last 15 or 25 years.<\/p>\n\n\n\n “To start with is just the fact that they’re very large, and they’re meant to be very durable,” said Aubryn Cooperman, then a wind energy analyst at the National Renewable Energy Laboratory, who was not involved in developing the resin. “So they’re just a hard thing to disassemble and move around.”<\/p>\n\n\n\n The other issue, she said, “is that they’re made from materials that are as low-cost as possible [that will] still get the performance you need.”<\/p>\n\n\n\n The DOE says 85 percent to 90 percent of a turbine’s mass, not counting foundations and underground wiring, is steel, aluminum, copper, iron and other easily recycled material. Blades, nacelle covers and rotor covers make up only 6 percent to 14 percent, and those composite parts have mostly gone to landfills.<\/p>\n\n\n\n There are some alternatives for the more than 210,000 blades that DOE counted on 72,130 U.S. turbines in July 2022, such as grinding old blades for a Missouri cement plant<\/a>, recovering glass fiber with heat in Tennessee<\/a> or the chemical process Sweden is testing to take blades apart<\/a>.<\/p>\n\n\n\n Dorgan, speaking to Scientific American, put most of the blame on cost. “The main problem is: it’s simply uneconomic to do it,” he said. “It’s cheaper to just bury it in the ground than it is to reprocess it into something useful.”<\/p>\n\n\n\n “Larger wind turbine blades are more efficient, so companies keep making bigger and bigger ones,” Dorgan said in the ACS release. “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 2021, 2,307 blades from 12 U.S. projects were retired through partial repowering, DOE figures show.<\/p>\n\n\n\n In the lab, the team soaked finished panels in fresh monomer, which dissolved the hardened resin, and then physically removed the glass fibers. The recovered syrup went into new panels that had the same physical properties as the originals.<\/p>\n\n\n\n “Physical properties of thermoplastic composites produced from the reclaimed resin show true ‘turbine-to-turbine’ recycling is possible,” the authors write in their conference abstract. A thermoplastic is a plastic that can be softened with heat or dissolved and reshaped after it sets.<\/p>\n\n\n\n Mixed with minerals, the resin becomes cultured stone, a cast material used for countertops and sinks. “We’ve recently made a bathroom sink with the cultured stone, so we know it works,” Dorgan said.<\/p>\n\n\n\n Two years earlier, the MSU College of Engineering<\/a> reported that graduate student Harshal Bambhania had taken the resin to Marblecraft, a marble company in Fowlerville, Michigan, to cast a prototype drop-in bowl for vanity and kitchen counters.<\/p>\n\n\n\n “Presently, unsaturated polyester resins are used extensively in fiberglass composites for boat building, kitchen and bathroom countertops, and sinks from cultured stone,” Bambhania explained. “However, there is a growing awareness that styrene has several shortcomings. It is not based on renewable resources, is a volatile organic compound, and indicated as a potential human carcinogen.”<\/p>\n\n\n\n “Preliminary calculations show a 40 percent reduction in greenhouse gas emissions (CO2 equivalent) compared to current technologies,” he said.<\/p>\n\n\n\n “What would really drive recycling of wind turbines is if you could turn them into something that’s worth more money or by using it to [make high-value] products out of it,” Dorgan told Scientific American.<\/p>\n\n\n\n Grinding panels up for injection molding, the process behind computer housings and power tools, works too, but he told the magazine that route would not be particularly valuable.<\/p>\n\n\n\n The chemical routes start with an alkaline bath, which is basically the opposite of an acid. Soaking the resin in one released poly(methyl methacrylate), better known as PMMA or plexiglass, the clear acrylic used for car taillights and windows.<\/p>\n\n\n\n When the researchers turned up the heat, that PMMA changed into poly(methacrylic acid), a super-absorbent polymer that goes into diapers, according to the ACS.<\/p>\n\n\n\n The candy ingredient came out of that same alkaline step. Distilling the leftovers produced methanol, water and potassium lactate, a salt used to preserve food, and the abstract notes, a little dryly, that the lactate “has been incorporated into gummy bear candies and consumed by the presenting author.”<\/p>\n\n\n\n The ACS release says purified potassium lactate could end up in sports drinks as well.<\/p>\n\n\n\n That release also raised the obvious question of a “yuck factor.” Dorgan doesn’t think there is one. “A carbon atom derived from a plant, like corn or grass, is no different 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.”<\/p>\n\n\n\n Scientific American reported that he doesn’t necessarily see homemade candy as the main way to get blades recycled, and that his goal is to change attitudes. “I’m trying to push the boundaries of how people think about recycling,” he said. “It’s about creating additional options and getting people to think about ‘What really are the limits on recycling?’ And as far as I know, nobody’s ever reprocessed a durable composite material into something that can be eaten.”<\/p>\n\n\n\n “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.<\/p>\n\n\n\n All of the tests described in 2022 used lab-made panels. At the time, the team said it hoped to make some moderately sized blades for field testing.<\/p>\n\n\n\n The gummy bear and recycling results were described in a conference abstract and a press release, and a full journal paper would give outside scientists much more to check.<\/p>\n\n\n\n “Anything that makes it easy to recycle, that makes it less costly to recycle, increases the chances of more recycling happening,” Cooperman said, adding that Siemens Gamesa, General Electric and Vestas are among the companies working on the issue.<\/p>\n\n\n\n The research was presented at the American Chemical Society’s Fall 2022 meeting in Chicago, and the ACS press release and abstract<\/a> were published on August 23, 2022.<\/p>\n\n\n\n The researchers acknowledge funding from the David L. and Denise M. Lamp Endowment.<\/p>\n\n\n\n Photo: John Dorgan \/ American Chemical Society<\/p>\n","protected":false},"excerpt":{"rendered":" John Dorgan says he ate the gummy bears himself. “We recovered food-grade potassium lactate and used it to make gummy … <\/p>\nA resin made from plants and acrylic<\/h2>\n\n\n\n
Why old blades are hard to recycle<\/h2>\n\n\n\n
From turbine panels back to turbine panels<\/h2>\n\n\n\n
A sink cast from the same resin<\/h2>\n\n\n\n
Plexiglass for taillights and polymer for diapers<\/h2>\n\n\n\n
How the gummy bears were made<\/h2>\n\n\n\n
What still stands in the way<\/h2>\n\n\n\n