Are wind turbine rotor blades sustainable?

Looking at a modern wind turbine from a distance, it's hard to really imagine the dimensions of these tall spots on the landscape. The generator and rotor blades are usually too far away and too high up to be measured. On windy days they are moving. Only when they are on the ground being transported, assembled or while being taken apart do you really get the sense that they are absolutely huge!

Currently in Germany, the expansion of wind power generation is slowing and only a few new wind farms are being approved and built. But there is still a lot of maintenance needed on the many existing ones, especially if the country wants to reach its energy transition goals.

Generators and blades have to be regularly repaired and sometimes replaced, either because the material is tired and there is a risk of accidents or because the wind farm is set to be enlarged. In the end, wind turbines have a limited operational life. This leaves huge piles of massive old turbine blades that are very difficult to recycle or reuse. Many end up in landfills or are burned.

Around 90,000 blades, and counting

"We currently have around 30,000 land-based wind turbines. Multiply that by three, then you have the number of rotor blades spinning on land, diligently generating green electricity," Wolfram Axthelm, managing director of the German Wind Energy Association (BWE), told DW.

Some question whether these German wind energy facilities can continue to operate in the foreseeable future or if they will need to be dismantled and replaced by new, more efficient systems.

"At the moment, the dismantling of wind farms is a minor topic," said Axthelm. "Still, we have around 10,000 tons of rotor blades a year that are dismantled and recycled."

In Bremerhaven, there is a plant "that processes the blades for thermal recycling for the cement industry. There, this fiberglass composite material is used instead of heavy oil."

Vattenfall's ambitious plan

Others in the industry are not so convinced about the current recycling quota. The fundamental problem is the size and composition of the blades, which are mostly made of fiberglass or carbon-fiber-reinforced plastics bonded with resins. Besides being difficult to transport, there are no chemical processes to separate the individual composite materials from one another in an economical way.

"It is no longer acceptable that composite material waste from the wind power industry is disposed of in landfills," said Eva Philipp, head of Vattenfall's Environment and Sustainability Unit Business Area Wind, in October 2021 when the utility company announced it would immediately start to reuse or recycle old rotor blades.

By 2025, the company expects to recycle 50% of its rotor blades. By 2030, it expects to hit 100%. Given the difficulties in separating various composites because of a lack of readily available chemical processes, this plan seems very ambitious.

Getting the individual parts apart

East Friesland, a region bordering the Netherlands and the North Sea, is one of the preferred locations in Germany for onshore wind farms. Being close to the sea, the wind almost always blows. And there are no mountains, large hills or tall buildings in this flat terrain to get in the way. Here operators have gained years of experience in the construction of wind turbines and their dismantling; they have also seen how hard it is to recycle the fiberglass blades.

"For most of the components — including steel, cement, copper wire, electronics and gearing — recycling loops have been established," Matthias Philippi, spokesman for the wind farm operator Enertrag AG, told the East Frisian Rheiderland newspaper recently.

Christian Dreyer from the Fraunhofer Institute for Applied Polymer Research also confirmed that, in contrast to composite materials, there is no problem to recycle the metal parts.

Dreyer, who is a specialist in composites and a professor at the Technical University of Applied Sciences Wildau, points to the generator, which is filled with a lot of copper, as one example. It can be "easily recycled" in a profitable way, he told DW. Being able to recycle the specialized carbon composites, which are up to 20 times more expensive than other parts, would be worth much more, he concluded.

Making one out of two?

The terms "reuse" and "recycle" give the impression that turbine blades now spinning in the sky will soon be able to continue to do their job just by being overhauled. Or that two of them, reassembled as a larger, more powerful blade, could supply green electricity.

"No, it doesn't mean that," clarified Eva Philipp from Vattenfall. If a wind farm "can no longer be operated, then the components are usually so worn out that they have to be recycled or the rotor blade is used in another way, for example, as partition walls."

The idea of building a new blade out of two old ones is also unrealistic for the head of the German Wind Energy Association, Wolfram Axthelm. "No, that's not up for debate at the moment." Nevertheless, he thinks the energy company's plan is realistic. "Other companies have also announced that they will be ready to increase the proportion of recycling they do by 2030." 

A lack of pressure in the sky

Efforts to achieve more sustainability would initially cost a lot of money, said Philipp. "We are not seeing any savings at the moment, we see this as a topic that we have to deal with — in the context of how we deal with waste, new laws and the circular economy," she said. "At the moment, recycling turbine blades is more expensive than burning them. Of course, we hope that these technologies will become cheaper as they develop."

Christian Dreyer sees part of the problem with the German government and current regulations. "They don't yet force us to recycle the parts," he said. At the same time, further research needs to be carried out because, he assumes, "that sooner or later regulations will come. By then a solution would be far along in its development."

 This article has been translated from German.