Researchers at Tsinghua University have developed a method using flash Joule heating to convert decommissioned wind turbine blades into valuable silicon carbide and graphene. The process upcycles hard-to-recycle composite waste into industrial additives while significantly undercutting the greenhouse gas emissions and expenses of conventional disposal techniques.
Modern wind turbine blades withstand decades of extreme temperatures, heavy wind gusts, UV radiation, and lightning strikes. That durability creates a severe disposal challenge when a turbine reaches the end of its typical twenty-year operational lifespan.
Thousands of tons of composite blade waste accumulate annually across China, Europe, and the United States. Much of the material historically ends up in landfills.
According to projections cited by Euronews, annual decommissioned blade waste in Europe alone is expected to rise from 20,000 tonnes in 2025 to 55,000 tonnes by 2030 as older fleets reach their end-of-life. Meanwhile, WindEurope, the European wind industry association, introduced a voluntary industry-wide landfill ban that came into effect last year and is urging EU policymakers to enshrine the ban into formal legislation to further accelerate sustainable recycling. Countries such as Germany and Austria have likewise instituted outright landfill bans on composite waste, forcing the renewable energy sector to seek scalable alternatives to traditional dumping.
Flash Joule Heating Transforms Composite Waste Into Industrial Materials
Scientists at Tsinghua University applied a technique known as flash Joule heating to break down the stubborn fiberglass and carbon-rich polymer resin that make up the blades. As described in a study published in Chem Circularity, the process involves a high-current electrical pulse applied to conductive raw materials. This pulse rapidly raises their temperature to about 2,000 degrees Celsius, equivalent to 3,632 degrees Fahrenheit, in milliseconds.
During this intense thermal reaction, carbon bonds with silica from the fiberglass to form silicon carbide, an exceptionally hard and heat-resistant compound. Simultaneously, remaining carbon atoms reorganize into graphene, a nanoscale honeycomb lattice prized for its strength and electrical and thermal conductivity. In laboratory experiments, pulverized blade waste mixed with nearly pure elemental carbon yielded a composite consisting of 34 percent silicon carbide and 66 percent graphene. Lead author Hao Bi, an environmental engineer at Tsinghua University in Beijing, told Gizmodo that a typical experiment successfully converted about 56 percent of the initial mixture into this silicon carbide and graphene composite.
Reinforcing New Epoxy Resins With Recovered Graphene and Silicon Carbide
The recovered silicon carbide and graphene mixture can be incorporated directly into fresh epoxy resins to manufacture next-generation rotor blades. Adding a concentration of just 0.3 percent by weight increases the resin’s Young’s modulus by 27 percent and its tensile strength by 11 percent, while improving resistance to deformation by 27 percent under tension and 9 percent when bent. A concentration of just 0.1 percent boosts the material's thermal diffusivity by 41 percent, allowing heat to disperse more efficiently throughout the structure.
The mixture of silicon carbide and graphene can be incorporated back into resins for new wind turbine blades, improving their mechanical and thermal properties,
said Bing Deng, senior author and chemical and environmental engineer at Tsinghua University.
Deng also noted the circularity of the approach, stating that it represents upcycling rather than basic recycling. We’re turning something that has little value into something that’s worth much more,
he said.
Pyrolysis Turns Waste Processing into a Profit
Conventional recycling methods carry substantial financial and environmental burdens. Pyrolysis uses heat to break down polymers into oil and gas. Pyrolysis runs about $460 per ton, whereas chemical dissolution using solvents costs about $1,800 per ton, according to Hao Bi, an environmental engineer at Tsinghua University. Both conventional pathways require wind farm operators to pay for waste processing.
With conventional recycling methods, you have to spend money to process the waste. But our method could actually turn a profit of about $80 per ton because the recovered silicon carbide and graphene are valuable,
Bi said. By comparison, pyrolysis costs about $460 per ton, while chemical dissolution costs about $1,800 per ton.
In addition to economic advantages, the flash Joule heating technique drastically reduces carbon output. The study estimates that the process cuts greenhouse gas emissions by 92 percent compared with chemical dissolution and by 83 percent compared with heat-recovery methods like pyrolysis.