Wind turbine rotor blades are made from glass or carbon fibre reinforced composites and are extremely difficult to recycle at the present time. In Germany, Veolia is working to actively identify solutions to give the blades a new lease of life.
Up to 50,000 tonnes of rotor blade materials are expected to arrive in waste reception centres between now and 2020.
Wind power has been booming since the 2000s. It is no longer a surprise to see these immense windmills working at full capacity in the countryside or off the coast. And this is excellent news as wind turbines produce clean renewable energy. However, the picture is not so rosy when the time comes to recycle them.
Despite the fact that wind turbines have an estimated lifespan of 20-30 years, many of them can no longer be operated profitably due to the cut of governmentally subsidised feed-in-tariffs. Now that the first generation – those installed in the 1990s – are coming to the end of their service lives, the issue of how to recover the waste materials is coming to the fore. The first turbines to be dismantled have revealed an unexpected complication: wind turbine design is not always eco-friendly.
The rotor blades in particular are a problem although they are only 2% to 3% of the mass of an entire windmill. They are made with use of glass fibre (the older ones) or carbon fibre (the more recent models). These composite materials have the advantage of making rotor blades lighter and more robust but they are proving complicated to recycle. Up to 50,000 tonnes of rotor blade waste materials are expected to arrive at waste reception centres between now and 2020 without having an established recycling solution. Finding ways of giving them a fresh lease of life is therefore a major challenge.
Rotor blade saw
Veolia in Germany has started developing solutions. As one of the earliest and the world’s third biggest producer of wind energy, Germany has a large number of wind turbines to replace and is actively seeking effective solutions for recycling those, which are now to be decommissioned.
Dismantling a wind turbine is not an easy task. Traditionally, they are split into four large sections: the concrete base, the mast, the rotor blades (usually three), andthe nacelle. Each section is either very heavy or very long . Very large and polluting vehicles are needed to transport them to a waste treatment facility. Just imagine the size of the convoy needed to transport rotor blades with a length of 17m for the turbines installed in the 1980s, 80m for those made today, and even 125m for those that will be commissioned in the future! It is almost mission impossible! However, the hundreds of thousands of rotor blades fitted worldwide which are coming to the end of their service lives need to be processed. In late 2016, there were 341,000 wind turbines running worldwide, according to the Global Wind Energy Council. This figure will rise significantly over the next few decades with the accelerated development of wind energy. This is why Veolia has developed a rotor blade saw which can be used to cut up the blades into small pieces on-site, making them easier and more environmentally-friendly to transport.
An innovative solution has also been developed to recycle blades made from glass fibre. They are crushed and mixed with other components and become an excellent solid fuel for the cement industry, replacing traditional fossil fuels, such as fuel oil as well as using the glass fibre residues within the cement matrix
Carbon fibre is resisting recycling efforts
Recycling carbon fibre blades is another matter. Generally, carbon fibre is a material of the future because it is solid and light. It also features prominently in the car, aeronautical and sports industries.
However, at the present time there is no recovery process for retired carbon fibre based products. For wind turbine recycling, Veolia is currently studying a range of solutions including pyrolysis (a thermal process already tried and tested for the aeronautical industry) and even solvolysis. A process that would be promising in order to recycle fiber and polymer resin at the same time. But there is no facility capable of undertaking it at an industrial scale in Germany. The Veolia experts are hoping to find a viable solution in the coming years.
It is vital that a solution is identified given the exponential development of wind power and the need to replace many wind turbines over the coming years. What if wind power developments could open the way to recycling all carbon fibre materials?
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