Across Europe, the first big wave of turbines is reaching the end of its original design life and the industry is discovering that what might be a green energy source while running can become far less so when its lifespan is expended.
Data from ORE Catapult, a UK government‑backed research and innovation centre for offshore renewable energy, indicates that decommissioning could add up to 325,000 blades globally by 2050 if turbines typically retire after 25 years. “The first generation of wind turbines is at the end of their first service life, and we now see a lot of demands and lots of questions like: ‘What do we actually do at the end with these quite huge parts of infrastructure?’” asks Anne Velenturf, associate professor in circular economy at the University of Leeds.
In Europe, the sector has adopted a self-imposed landfill ban for wind turbine blades that came into force earlier this year. That’ll tackle the problems of today – but experts and engineers are working on what will happen when the first big generation of turbines reach the end of their useful lifespan.
There are a number of issues with wind turbines, but at the heart of the problem is polymer chemistry. Most turbines use a thermoset polymer within their blade matrix resin, “which is very difficult to recycle for scientific and technical reasons,” says Vasileios Koutsos, professor of materials engineering at the University of Edinburgh.
Blades are engineered to survive decades of fatigue, UV exposure and weathering, but that same weather-prepping makes them awkward at end of life. Thermosets cure into a hard, crosslinked network “full of covalent bonds,” says Koutsos, which makes them difficult to break down. “Usually it is not biodegradable, and it cannot be melted and reused for other applications,” he says.
Existing turbine blades can go down two main recycling routes, says Koutsos. Chemical processes try to break those bonds and recover usable feedstocks, usually as a liquid resin. “However, this is very challenging and very expensive,” explains Koutsos, in large part because they include coatings, adhesives, lightning protection systems and repairs, all of which complicate processing and sorting.
The alternative is mechanical processing, which is simpler. Recyclers can grind and mill the material into small particles that can be embedded into other polymers to make other products. Mechanical processing is “less expensive than the chemical route,” he says, but it rarely returns the material to an equivalent performance level. That means in practice that many high-performance composites become filler for construction products.
In the longer term, engineers need to change what blades are made from, says Koutsos. “They’re trying to use alternative types of polymers, not thermosets, but thermoplastics,” he says, because thermoplastics can be reheated and reshaped. But blade manufacturing is done at huge scale and composite blades involve resin infusion in huge moulds. “There’s no easy solution,” he admits.
Even designing perfect materials wouldn’t solve all the bottlenecks in recycling massive turbines. Their scale makes dismantling and transportation a project in its own right, meaning it’s more feasible to try to break down and recycle them close to where they stand.
A better solution for sustainability, reckons Velenturf, is to improve end-of-life processing but also try to eke out a longer life from turbines. “The key thing to consider is whether we can design them to last for much longer than the current standard design life of 20 to 25 years,” she says. “If we can design a wind turbine to last twice as long, we then also basically halve the environmental impacts from the material sourcing and processing.”
“The good news,” she adds, “is that is technically entirely possible.”
There are already some elements of a circular economy in place via breaking down old turbines for parts to be reused at other installations. “The parts are being used to repair turbines that are still in operation here in Western Europe,” she says. Half of turbines in Germany and Denmark are reused, often on the same continent.
Velenturf challenges the industry claims that 80 to 85% of turbines are already recycled, adding that evidence is not being shared. She says clearer ‘close-out reports’ should show what has actually been reused and recycled, and what proves hard to dismantle and transport.
Velenturf believes that thinking about how to better handle the end of a turbine’s life will be vital. Wind’s rapid scale-up – it is expected to reach 18.5% of global electricity by 2030 in the International Energy Agency’s Net Zero Emissions scenario – offers the chance to bake in circularity now, with the industry learning from the current crop of turbines being decommissioned and disposed of in practice.
But as much as this is an engineering problem, it is also vital that those higher up the business chain buy into the impetus, says Velenturf. “There’s a need for developing viable, circular business models so that these technical solutions can also be implemented into practice,” she says.
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