May 17, 2022

Almost “waste-free” method of recycling wind turbine blades

A method of recycling wind turbine blades has been developed that uses pyrolysis to break down composite materials into their building blocks – phenol and fiber.

According to researchers at 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 laminated glass fiber reinforced polymer (GFRP) composites can last up to 25 years, but after that they usually end up in landfills. The material is recognized as difficult to decompose and has become a real challenge for the renewable energy industry.

It is estimated that wind turbine blades represent 10% of fiber reinforced composite material waste in Europe.

Concerns have been raised that with the increase in renewable installations, wind turbine blade waste will reach around two million tonnes worldwide by 2050. With many countries banning composite materials from their landfills, Recycling used wind turbine blades is becoming a challenge that researchers around the world are trying to solve.

“More and more countries are committed to achieving net zero by investing in renewable energy resources, including wind power,” said KTU researcher Dr. Samy Yousef.

“However, recycling wind turbine blades, which are as long as a football field, very sturdy and contain plastic, is the main problem. Without a workable solution, we cannot say that wind energy is entirely durable and environmentally friendly.

Due to its strength, simplicity of forming and low manufacturing costs, GFRP composites are also used for other purposes such as automobile manufacturing, marine vessels, oil and gas production, construction and sporting goods.

Aerospace, wind power and electronics are among the industries that use GFRP the most, with global demand increasing by 6% per year.

GFRP composites are generally thermoset or thermoplastic. In either case, they basically consist of only two components – the resin and the fiber which is usually carbon fiber or fiberglass.

The researchers applied pyrolysis, which is a form of thermochemical treatment, to different batches of composites – fiberglass thermoset and fiberglass thermoplastic and were able to extract most of its raw materials.

“The volatile components are mostly phenol, which can be used for further resin production, and the fiber residues can have many applications after their chemical purification – for fiber-reinforced concrete, polymer composites, floor coverings Our method is virtually waste-free with some small emissions, which is standard in this type of converting operation,” Yousef added.

The experiments were conducted using the samples prepared in a laboratory that had compositions similar to those used to make wind turbine blades, not the wind turbine blades themselves. Therefore, researchers have yet to assess the effect of the paint coating, which covers the actual turbine blades.

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