Wind turbine blades could someday be recycled into sweet treats
American Chemical Society
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| This is the graphic the American Chemical Society published with their report. I am not making any of this up. Credit: John Dorgan |
Wind
power is an increasingly popular form of renewable energy. However, when it's
time to replace the huge turbine blades that convert wind into electricity,
disposal is a problem. Now, scientists report 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, diapers
and even gummy bears.
The
researchers will present their results 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," says John Dorgan, Ph.D., who is
presenting the work at the meeting. "That's the goal of the circular
economy."
Made
of fiberglass, wind turbine blades can be half a football field in length.
Although some companies have found ways to recycle fiberglass into lower-value
materials, most discarded blades end up in landfills. And the disposal problem
is likely to get worse. "Larger wind turbine blades are more efficient, so
companies keep making bigger and bigger ones," Dorgan says. "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 at Michigan State University made a new turbine material by combining glass fibers with a plant-derived polymer and a synthetic one. Panels made of this thermoplastic resin were strong and durable enough to be used in turbines or automobiles. The researchers dissolved the panels in fresh monomer and physically removed the glass fibers, allowing them to recast the material into new products of the same type. Importantly, the recast panels had the same physical properties as their predecessors.
In
addition to new wind turbine blades, the novel resin could be used for a
variety of other applications. 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," says Dorgan. The researchers
could also crush the recovered material and mix it with other plastic resins
for injection molding, which is used to make items like 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. Raising the temperature of the digestion converted PMMA into
poly(methacrylic acid), a super-absorbent polymer that is used in diapers. 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 says.
Now
that the researchers have demonstrated that the resin has suitable physical
properties for wind turbines, they 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 notes.
And
is there a "yuck factor" involved in eating candy that was once part
of a wind turbine? Dorgan doesn't think so. "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 says. "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."
The researchers acknowledge funding from the David L. and Denise M. Lamp Endowment.