Bioplastic for wind turbine blades can be recycled into gummy bears
As wind power comes to play a larger role in the renewable energy mix, some scientists are casting their eye deeper into the future to address the issue of waste. We've seen some inventive ideas around how giant turbine blades might be saved from landfill at the end of their lives, and a team from Michigan State University (MSU) have just thrown another one into the mix with some wide-ranging, and delicious, potential.
As increasingly bigger wind farms kick into gear around the world, and operators turn to increasingly bigger blades to run them, the question of waste is only becoming more pertinent. The thermoset composites making up the turbine blades of today cannot be recycled, and with a lifetime of around 25 years, some studies have suggested there'll be more than 40 millions tonnes of the material in landfill by 2050.
We've seen scientists develop self-curing resins that could improve the recyclability of turbine blades, and big-name energy companies such as GE and Siemens Gamesa conjure up their own recipes that could see them recycled into other valuable products. Lending their expertise to the dilemma is a team of MSU chemical engineers led by John Dorgan, who only sees the problem getting 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 his team have developed a new resin for turbine blades that consists of glass fibers and both plant-derived and synthetic polymers. The material was fashioned into panels that were tested for strength and durability, with the team finding they met the performance requirements for use in turbines, or even automobiles.
Most impressive, however, was the recycling potential of the new resin. The panels could be dissolved and the glass fibers removed, enabling the material to be cast into new products. The team mixed it with different minerals to produce cultured stone that could be put to use as kitchen countertops, and say it could be mixed with other plastic resins to make things like laptop covers.
“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,” said Dorgan. “That’s the goal of the circular economy.”
In one experiment, the team used an alkaline solution to digest the resin, which reduced it to acrylic materials for use in windows and car tail lights. This process also produced potassium lactate, which can be purified and turned into candy, a theoretical possibility the team felt obliged to test out.
“We recovered food-grade potassium lactate and used it to make gummy bear candies, which I ate,” Dorgan said.
The scientists are looking to build on these promising results by making moderately-sized turbine blades for field-testing, though scaling up will have its challenges.
"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.
The team presented its research at the Fall meeting of the American Chemical Society this week.
Source: American Chemical Society