Glass fibers from retired wind turbine blades can be converted into high-capacity silicon-carbon battery anodes, turning a growing waste problem into valuable energy storage materials.
(Nanowerk Spotlight) Wind turbines have become a defining symbol of the global transition away from fossil fuels. Their sleek white blades, rotating on hillsides and offshore platforms, generate clean electricity for millions of homes. But there is a problem lurking at the heart of this energy transition: those massive blades, some stretching longer than the wingspan of a Boeing 747, are exceedingly difficult to recycle.
Made primarily from glass-fiber-reinforced plastics, the composite materials that give turbine blades their strength and lightweight durability also make them nearly impossible to break down into useful components. As the first generation of commercial wind turbines approaches the end of its operational lifespan, the world faces an emerging waste crisis.
Industry projections suggest that retired blades could accumulate to 225,000 tons by 2030 and potentially exceed 43 million tons by 2050. Currently, more than half of these decommissioned blades end up in landfills or are incinerated, processes that squander valuable raw materials and create secondary environmental burdens.
Some blades find second lives as construction fillers or get ground up for cement production, but these low-value applications fail to capture the true potential embedded in the materials. Glass-fiber-reinforced plastics account for roughly 85% of global blade installations, with a typical blade containing about 50% glass fibers by weight.
Researchers are now beginning to unlock that potential. A study from Tsinghua University that we covered in our Nanowerk Spotlights (“A flash of heat turns old wind turbine blades into graphene”) last year, demonstrated that carbothermal shock, a millisecond-scale heating process reaching approximately 3,000 K, can transform shredded blade fragments into silicon carbide and graphene for electronics and advanced composites.
Now a different research team has shown that the same waste stream can yield an entirely different class of high-value material: battery anodes.
A study published in Advanced Functional Materials (“Upcycling Wind Turbine Blade Waste into Hierarchically Porous Silicon–Carbon Anodes for High‐Performance Lithium‐Ion Batteries”) takes a complementary approach. Researchers at Hebei University of Technology and the Center for High Pressure Science & Technology Advanced Research in China have developed a multistep chemical process to transform the silica-rich glass fibers from retired wind turbine blades into high-performance silicon-carbon composite anodes for next-generation lithium-ion batteries.
Recycling and reparation of retired wind turbine blades for porous reczcled micron-sized, carbon-coated silicon anode materials of lithium-ion batteries. (Image: Reproduced with permission from Wiley-VCH Verlag) (click on image to enlarge)
The battery industry has been searching for better anode materials to meet soaring demand for energy storage in electric vehicles and grid-scale applications. Silicon has emerged as a particularly promising candidate because its theoretical specific capacity of 3,579 mAh g⁻¹ dwarfs that of the graphite anodes currently used in most commercial batteries.
Yet silicon presents its own engineering challenges: it swells dramatically during charging, expanding by more than 300% as it absorbs lithium ions, then contracts during discharge. This repeated expansion and contraction pulverizes silicon particles, causing batteries to degrade rapidly and lose capacity.
The Hebei process begins with mechanical separation and crushing of blade fragments, followed by pyrolysis at 600 °C to burn away the organic resin matrix and release the glass fibers. These fibers, composed predominantly of silica, then undergo a carefully controlled alloying reaction with magnesium powder at 650 °C. This chemical transformation converts the silica into a mixture of magnesium silicide and magnesium oxide.
A subsequent nitridation step, performed at 750 °C under flowing nitrogen gas, converts the magnesium silicide intermediate into magnesium nitride while releasing silicon atoms that reorganize into a porous framework. This phase transformation is the key to creating the material’s porosity: the magnesium nitride can then be dissolved away by acid washing along with the magnesium oxide, leaving behind an interconnected network of voids within the silicon structure. The resulting porous silicon framework has 28% porosity.
The critical innovation lies in how this multistep process creates a hierarchical pore structure within the silicon particles. Mesopores measuring approximately 4 nm across enhance the movement of lithium ions through the material. Larger macropores exceeding 50 nm act as reservoirs for the electrolyte and provide buffer space to accommodate silicon’s notorious volume changes during charging cycles. This architectural design allows the material to expand inward rather than outward, preserving structural integrity through hundreds of charge-discharge cycles.
The researchers applied a thin carbon coating to the porous silicon scaffold using chemical vapor deposition with ethylene gas. This conformal layer, measuring roughly 4 to 7 nm thick, creates a continuous conductive network across the electrode surface while stabilizing the interface between the electrode and the electrolyte. The carbon coating also suppresses unwanted chemical reactions that would otherwise consume lithium and degrade battery performance.
Testing revealed impressive results. The carbon-coated porous silicon composite maintained a specific capacity of 1,256 mAh g⁻¹ after 300 cycles at 1 A g⁻¹. The material achieved an initial coulombic efficiency of 89%, meaning that 89% of the lithium stored during the first charge was successfully retrieved during the first discharge. By the tenth cycle, this efficiency stabilized above 99.9%, indicating minimal ongoing losses.
Electrode expansion measurements provided further evidence of structural stability. After 300 cycles, the carbon-coated composite showed total thickness expansion of only 35%, compared to 90% for uncoated porous silicon. This dramatic reduction in swelling translates directly to longer battery life and improved safety.
Full-cell testing paired the silicon-carbon anode with a commercial lithium iron phosphate cathode. These complete batteries retained 92.4% of their initial capacity after 150 cycles, with coulombic efficiency exceeding 99.9% after the first ten cycles.
The researchers also conducted techno-economic analysis and life cycle assessment to evaluate practical scalability. Their modeling assumed a recycling facility processing 10,000 metric tons of blade-derived silica annually. The calculated minimum selling price for the recycled porous silicon came to $10.83 per kilogram, a figure competitive with alternative silicon sources. Plant capacity emerged as the dominant factor affecting costs, with larger facilities achieving better economies of scale.
Environmental impact assessment showed that the process imposes limited burdens across most indicators. Contributions from key reagents like magnesium and hydrochloric acid remained below 3% for metrics including global warming potential and abiotic depletion potential.
The authors acknowledge that certain environmental indicators, including acidification potential and terrestrial ecotoxicity, are influenced by the use of magnesium, hydrochloric acid, and ethylene. They suggest that future optimization should focus on greening key reagents and integrating renewable energy into the process. However, the study does not directly compare the total energy input of this multistep chemical approach against faster alternatives such as carbothermal shock processing, which operates in milliseconds rather than hours.
Together, the Tsinghua and Hebei studies suggest that retired turbine blades could supply feedstock for multiple advanced materials industries. One process yields silicon carbide and graphene for electronics; the other yields silicon-carbon composites for batteries. Rather than treating decommissioned blades as disposal problems requiring landfill space, these complementary strategies reposition them as valuable inputs for high-technology manufacturing.
As wind power installations continue expanding globally and aging turbines reach retirement, technologies that extract genuine value from their composite components will become increasingly important for maintaining the environmental credibility of renewable energy infrastructure.
For authors and communications departmentsclick to open
Lay summary
Prefilled posts
Nanowerk Newsletter
Get our Nanotechnology Spotlight updates to your inbox!
Thank you!
You have successfully joined our subscriber list.
Become a Spotlight guest author! Join our large and growing group of guest contributors. Have you just published a scientific paper or have other exciting developments to share with the nanotechnology community? Here is how to publish on nanowerk.com.
