But when it’s time to decommission one, a wind turbine’s strength can become a weakness. Because the blades are designed to be so durable, the materials used to build them can’t currently be recycled. And about 43 million tons of these blades will be decommissioned by 2050.
The new work describes a way to recover the main components of wind turbine blades, breaking down the plastic that holds them together without destroying the material’s primary building blocks.
“We need sustainable energy, but we also have to consider the waste, and we have to find solutions for that,” says Alexander Ahrens, a postdoctoral researcher at Aarhus University in Denmark and the lead author of the new study.
Wind turbine blades are made with strong plastic called epoxy resin. Because of the chemical bonds created when epoxy resin solidifies, it can’t be melted and squished into a new shape to be reused, like the plastic that makes up water bottles or milk jugs. In this case, fibers are also mixed into the resin for extra strength. This kind of reinforced material—called fiberglass when the supporting fibers are made using glass—is often used for high-intensity applications like airplane wings and boats.
“Because these materials are so durable, there’s not really right now a technology that is fit for recycling them,” Ahrens says.
Some methods do exist for breaking down fiberglass, but these approaches usually render the epoxy portion unusable and often damage the glass fibers as well. The researchers at Aarhus set out to develop a method gentle enough to let the main components be used again.
The resulting approach takes aim at chemical bonds that lock the plastic into place and “chews them up like Pac-Man—just chews up the epoxy and liberates those glass fibers,” says Troels Skrydstrup, a professor of chemistry at Aarhus and another author of the new study.
To break down the epoxy materials, researchers submerged them in a mixture of solvents and added a catalyst, which helped accelerate the chemical reaction. They heated everything up to 160 °C (320 °F) for between 16 hours and several days, until the target material was fully broken down.