New Delhi: Researchers at the Indian Institute of Technology, Mandi have used microwaves to recycle polymer composites to make wind turbine blades in a rapid and eco-friendly manner, according to officials. This method is rapid and sustainable compared to currently used methods like landfills and thermal-based recycling, they said.
The findings of the research have been published in the Resources, Conservation and Recycling Journal. According to the team, there is a worldwide impetus to adopt renewable sources of energy such as wind energy to overcome the drawbacks of fossil fuel-based energy. India is the fourth largest installer of wind energy systems and as of July 2022, its total installed wind power capacity was 40.893 GW. Wind power is harnessed through the installation of wind turbines (windmills) in strategic areas in the country. The blades of these wind turbines are made of polymer composites that are polymer systems in which fibres such as carbon fibres and glass fibres are incorporated for strength.
"We have developed a sustainable microwave-assisted chemical recycling (MACR) process to recycle glass fibre reinforced polymer (GFRP) composite waste. Also, we used microwaves to aid the chemical degradation of GFRP composites with hydrogen peroxide and acetic acid. "Both hydrogen peroxide and acetic acid are eco-friendly chemicals, the former used extensively as a disinfectant or antibiotic and the latter being vinegar," said Sunny Zafar, Assistant Professor, School of Mechanical and Materials Engineering.
Zafar explained that at the end of the service life of the wind turbine blades, the de-commissioned structures made of glass fibres in epoxy polymers are demolished and either landfilled or incinerated. "Both methods of disposal add to environmental pollution and cost. It is predicted that about 2,00,000 tons of composite waste would be generated by wind turbine blades between 2024 and 2034 all over the world. This negates the environmental benefits offered by wind energy. Furthermore, restrictions on landfill disposal and ?uctuating raw material costs could increase the costs of these composites used in wind turbine blades," he said.
The IIT Mandi team has developed a rapid and eco-friendly method to recycle the fibres present in the composites used in making wind turbine blades. "A particular uniqueness of this work was that no harsh chemicals were used in the extraction and the green-chemistry approach was used. The recycling method that we have developed can lead to a profound shift in recycling technologies, which can help the country move towards a circular economy for wind turbine blades," said Venkata Krishnan, Associate Professor, School of Chemical Sciences, IIT Mandi.
The researchers found that the decomposition rate of epoxy in their method was 97.2 per cent with recovery of the glass fibres. The recovered glass fibres were tested and their properties were compared to those of virgin fibres. "The recovered fibres retained nearly 99 per cent of the strength and greater than 90 per cent of other mechanical properties as compared to the virgin fibres," Krishnan said.
