Method for recycling wind turbine blades almost ‘waste-free’
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A method for recycling wind turbine blades has been developed that uses pyrolysis to break the composite materials into their constituent parts – phenol and fibre.
According to the researchers from Kaunas University of Technology (KTU), Lithuania, the extracted materials can then be reused and the process is virtually waste-free.
Wind turbine blades made from glass fibre-reinforced polymer (GFRP) laminate composites can serve for up to 25 years, but after that they typically end up in landfills. The material is recognised as hard-to-break-down and has become a real challenge for the renewable energy industry.
It is estimated that wind turbine blades account for 10 per cent of Europe’s fibre-reinforced composite material waste.
Concerns have been raised that with the increase in renewable facilities, wind turbine blade waste will increase to around two million tonnes globally by 2050. With many countries banning composite materials from their landfills, recycling the used wind turbine blades becomes a challenge that researchers around the world are trying to solve.
“More and more countries have been committing to the net-zero goal by investing in renewable energy resources, including wind energy,” said KTU researcher Dr Samy Yousef.
“However, the recycling of the wind turbine blades, which are as long as a football field, very sturdy and include plastic, is the main problem. Without a feasible solution to it, we cannot say that wind energy is fully sustainable and environmentally friendly.”
Due to its strength, shaping simplicity and low manufacturing costs GFRP composites are also used for other purposes such as car manufacturing, maritime vessels, oil and gas production, construction and sporting goods.
Aircraft, wind energy and electronics are among the industries which use GFRP the most, with the global demand increasing annually by 6 per cent.
GFRP composites are typically either thermoset or thermoplastic. In either case, they roughly consist only of two components – resin, and fibre which is typically carbon fibre or fibreglass.
The researchers applied pyrolysis, which is a form of thermochemical treatment, to different batches of composites – fibreglass thermoset and fibreglass thermoplastic and were able to extract most of its raw materials.
“The volatile components are basically phenol, which can be used for further production of resin, and the fibre residue can have numerous applications after purifying it chemically – for fibre-reinforced concrete, polymer composites, fibre flooring. Our method is virtually waste-free with some small emissions, which is standard in this kind of conversion operation,” Yousef added.
The experiments were conducted using the samples prepared at a laboratory that had compositions similar to those used for making wind turbine blades, and not the wind turbine blades themselves. Therefore, the researchers still need to assess the effect of the paint coating, which covers the real turbine blades.
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