Companies in the U.S. and Europe are trying out a variety of wind blade recycling solutions. According to an article in Energy News Network, Global Fiberglass Solutions is slicing them into pellets that can be used for flooring and other construction materials, while Bloomberg reports that the Danish company Miljorskam is grinding them up into highway noise barriers.
For more than two years, ACMA has been working with IACMI, CHZ Technologies, Continental Structural Plastics, A. Schulman and the University of Tennessee, Knoxville, to develop a technology that recycles wind blades and other thermoset composites. The goal is not only to reclaim the glass and carbon fibers, but also to recover the energy used in their production.
The team began with the testing of several different composites using CHZ’s Thermolyzer™ technology at an undisclosed location. The facility is designed to recycle a wide variety of materials, including composites, railroad ties, utility poles and plastics. It can handle between six to 10 tons of material a day.
The Thermolyzer uses continuous, oxygen-free, pyrolysis to break down the composite materials into glass fibers and/or carbon fibers, as well as a clean gas that can be used for powering the process. The equipment also converts any toxic materials in the composite into inert salts.
During the project’s first phase, the Thermolyzer processed composite materials from four different sources: a tractor panel that contained both glass and carbon fibers; a GFRP sheet molding compound (SMC) automotive panel; a wind turbine blade cap made with carbon fiber; and wind blades that contained glass fiber, balsa wood and other materials.
“Each of these materials had different resins and different fibers that had some unique characteristics. They had to be processed in a way that optimized the recovered fiber properties,” says Chuck Ludwig, managing director of CHZ Technologies. That required adjusting the temperatures and dwell times. For composites that contained glass fiber, the team also modified the process to reduce the strains and stresses on the glass fibers so that they would retain as much of their modulus and rigidity as possible.
The team sent some of the reclaimed fibers back to the University of Kentucky and its other industry partners for cleaning, testing and processing into composite materials.
During the project’s second phase, which began in 2019, the focus has been on recycling wind blades and optimizing the process to produce a consistent glass fiber on the back end. “We ended up making a modification to the equipment and put in a port configuration and a new output design to ensure a minimal amount of physical stress on the fiber,” says Ludwig.
Another change was improving the consistency of the material that was fed into the Thermolyzer. The wind blades, which started out at 157 feet long and weighing about 15,000 pounds, were first cut into sections. After going through a mobile field shredder at Shred-Tech in Canada, the blade remnants measured a few inches wide and about a foot long. Approximately 1,000 pounds of those large pieces were further reduced with another shredding. The goal was to minimize the amount of very large pieces in the mix and make the remnants more uniform. These pieces were then sent to Germany for recycling in the Thermolyzer.
The composite remnants were processed in two batches. “[During Phase A] we swept through from the low end to the high end of the temperature range, and we found a temperature range that was the processing sweet spot,” Ludwig says. Phase B confirmed that finding.
“You want the temperature and the processing conditions set so that as you feed the material in on a continuous process, you’re getting the very best flow. You’re getting an optimization of what you believe will be the right kind of fiber properties,” he says. “By having a lower temperature and a really consistent optimal throughput, we’re likely to have the very best processing conditions that you could get for the wind turbine blades.”
CHZ believes that it could run the machine continually every day with this material and replicate the test results. “Our goal is to optimize the properties on the back end and make them consistent so they can be reused in the same type of application. You don’t want to find that the recycled material works really well one day and the next day it doesn’t,” Ludwig says.
The team was able to regain just over 200 pounds of fibers during this process. Oak Ridge National Laboratory (ORNL) has retained some of the fiber and is sending the rest to end users, who will test the material’s properties, add a binder and then try it out in different composite applications. Initial results should be available this summer.
Taking the Next Steps
CHZ Technologies plans to bring its Thermolyzer technology to the United States within the next two years. The company is working with ORNL on a lab-size (2.5 to 4-ton) Thermolyzer that will be optimized for composites. “They have lots of different materials that that they want to work with and test,” says Ludwig.
The Federal Emergency Management Agency has been watching these experiments closely. Violent hurricanes over the last few years have left about 800,000 boats damaged or destroyed, and there are very few places to dispose of them. Since most have composite hulls and interior cabins, the Thermolyzer process might offer a solution. “The fact that the boats have some metal and wood doesn’t matter; we could end up processing that and recover the glass or carbon fiber that’s used and keep it out of the landfills,” says Ludwig.
CHZ is getting ready to supply a Thermolyzer to a plant in Youngstown, Ohio, as well. “We have a relationship with Youngstown State University, which has a renewable recycling curriculum,” says Ludwig. “We would like to put in an R&D center to do the testing near the university. It could be a place where we can train young men and women who are going into the recycling industry.”
The power industry has expressed interest, too. Utilities not only have end-of-life wind blades that they need to dispose of, but also electric poles that contain toxic chemicals. The Thermolyzer could reduce the poles to a renewable natural gas and biochar. With further research, the gas could be converted into other products, such as green ammonia or liquid fuels. There would be enough gas produced not only to power the recycling process, but also to help generate additional electricity. (Recycling composites takes more energy, so there’s no excess gas produced. For other materials, however, the Thermolyzer requires about 20% of the produced gas to run, leaving the remaining 80% for other uses.)
Ludwig says that as power companies convert their coal plants to natural gas, they could build a Thermolyzer on the plant property. The utilities could use it to keep their wind blades out of landfills and to create useful chemicals and gas from the poles, railroad ties, tires and plastics (even those from the ocean, which can’t normally be recycled). They’d be able to create an income stream by bringing in other materials, including composites, to be recycled as well.
It’s important to both the power and the composite industries to find a solution to the problem of these wind blades. “The wind industry was kind of a glamour industry on the renewable side of energy. Now it is showing a very ugly part [with the end-of-life wind blades],” Ludwig says. With technologies like the Thermolyzer, these industries could erase that negative image and replace it with a positive one as creators of non-polluting energy and reclaimers of valuable materials.
Work on these and other recycling/reuse technologies will continue to grow because the composites industry understands that it’s the right thing to do, Maxey says. “We are still a fairly small industry, but we recognize the need and the opportunity for collaboration,” he says. “Folks really want to solve these problems, and they’re willing to do it together. To me, that makes all the difference because we’re going to get there that much faster.”
