Wind farms are growing fast, and old blades are piling up. Most blades contain glass fibers locked inside a tough epoxy plastic. Today, many end up shredded, burned, or buried in landfills. Now a team in Denmark reports a gentler route to wind turbine blade recycling. Indraneel Chowdhury and Esben Lindgaard led the work at Aalborg University. Engineers from Siemens Gamesa in Spain and Denmark joined them. Siemens Energy Austria also took part. The team published its study in Composites Part A, an Elsevier journal. Importantly, the paper is a Journal Pre-proof. In other words, the journal accepted it on November 2, 2026. Final editing, however, continues. Its DOI, for reference, is 10.1016/j.compositesa.2026.110422. In short, the team dissolved the plastic and pulled out whole fabric sheets. Such sheets could go straight into new parts.
The team used a resin called recyclamine epoxy. It breaks apart in warm acid, unlike ordinary blade epoxy. In their tests, a warm acetic acid bath removed about 98.1% of the plastic. Acetic acid gives vinegar its sour taste, although this bath was far stronger. The fabric layers came out intact and kept their original pattern. After that, the team made new panels from the recovered fabric. These panels kept about 91% of their lengthwise pulling strength. They also kept 95% of their bending strength. Crosswise strength, on the other hand, fell to about 69%. The bath also weakened with reuse and stopped working in its fifth cycle. On top of that, all tests used small flat panels, not real blades. In this article, we explain how the process works and where its limits lie.
Why Wind Turbine Blade Recycling Matters
Nearly 200 nations agreed at COP28 in 2023 to triple renewable energy by 2030. The paper notes that wind power sits at the center of that goal. In 2023 alone, the world added a record 117 gigawatts of wind capacity. Blades, meanwhile, keep getting longer to capture more energy. Our guide to modern wind turbine rotor theory explains why blade shape matters so much. Most blades use glass fiber composites, which pair strong fibers with a hard plastic glue. Ordinary blade epoxy forms permanent chemical crosslinks as it cures. As a result, the plastic cannot easily melt or dissolve later. The authors write that industry built blades with little thought about disposal. As a result of this, decades of old blades now need a better destination. For this reason, makers now test resins designed for later recycling.
Why Shredding and Burning Fall Short
Today, three main routes handle old blade material. Mechanical recycling grinds blades into short fibers and powder. It costs little and scales well. On the other hand, the paper notes that ground fibers lose about half their strength. Pyrolysis heats blades until the plastic breaks down. That keeps 70% to 90% of fiber strength, but it uses lots of energy. Other chemical methods use harsh acids at 100 °C or hotter. According to the paper, those methods often damage the fibers too. In addition, all three routes recover only loose fibers, not whole fabrics. Loose fibers, by contrast, cannot replace the woven layers that give blades their strength. In fact, Siemens Gamesa already uses blades with recyclable resin at a German wind farm. That resin also dissolves in a mild acid. The new study tests whether whole fabric layers can survive this kind of process.
How the Recyclamine Epoxy Experiments Worked
The team started with a stiff glass fabric that blade makers use. All its fibers ran in one direction, held together by thin polyester stitches. Next, they soaked the fabric with recyclamine infusion resin. A vacuum pulled the liquid resin through the fabric layers. The team then cured the panels with heat. They made thin panels about 5 millimeters thick with eight layers. In addition, they made thick panels about 16 millimeters thick with 26 layers. After that, they placed the panels in a 3-liter glass tank. The tank held 30% acetic acid in purified water at 80 °C. A magnetic stirrer kept the liquid moving. Visible dissolving began about 30 minutes after the panels went in. Full details appear in the Composites Part A pre-proof. Overall, the team kept the temperature below 100 °C on purpose.
Results From the Acid Bath
The acid attacked weak links built into the resin. Outer layers peeled away first, and the bath then worked inward. On average, separating every fabric layer took 13 to 24 hours. Next, the team washed and dried the freed fabrics. They compared four washing liquids and found that plain purified water worked well. The team then measured how much non-fiber material the bath removed. In the first round, they loaded more and more panels into one bath. Panel volume rose from 4.5% to 53.3% of the liquid’s volume. Even so, the bath removed about 98.1% of non-fiber mass on average. The removal stayed between 96.7% and 99.4% across those loads. As the authors stress, their weighing method cannot separate resin loss from other small losses. In practice, the fabrics still looked and handled much like new ones.
Fig. 1: Key Results of the Fabric Recovery Study
Reusing the Bath for Blade Recycling
A practical process must reuse its chemicals many times. For this reason, the team kept the same 3-liter bath for further rounds. They did not filter it or add fresh acid. Over about four weeks, they ran three more cycles. In cycle two, the bath removed about 97.5% of non-fiber mass. By cycle three, removal dipped to 95.8%. In cycle four, it fell further to 91.2%. Results, at the same time, grew more variable from panel to panel. During the fifth cycle, the bath stopped working under the test conditions. Even after 48 hours, the fabric layers would not separate. Dissolved resin probably built up in the liquid, the authors suggest. Even so, they did not measure the bath’s chemistry between cycles. For this reason, the exact limit for blade recycling at large scale remains unknown. Even so, cycle five gives engineers a first rough saturation point.
Testing Panels Made From Recycled Glass Fabric
Next, the team built new panels with the recovered fabric. They used the same resin, vacuum method, and heating steps. After that, a testing machine pulled and bent the panels. Along the fiber direction, recycled panels kept about 91% of their tensile strength. They also kept 92% of their tensile stiffness. In bending, they kept 95% of their strength and 84% of their stiffness. Crosswise pulling, in contrast, told a different story. There, panels kept only about 69% of their strength and 75% of their stiffness. Crosswise strength depends mostly on the plastic and the bond to each fiber. In other words, the fibers survived better than the fiber surface did. Recycled panels also came out about 25% thicker with the same number of layers. They held fewer fibers per volume and slightly more air pockets.
Explainer: How a Mild Acid Splits the Resin
Ordinary epoxy behaves like a net with knots tied everywhere. Once cured, its chains link into a permanent three-dimensional web. Recyclamine works differently because its hardener contains special cleavable links. These acetal-based links stay strong in normal use. In warm acid, on the other hand, they break apart. As a result, the net comes loose and the plastic dissolves into the liquid. The glass fibers, meanwhile, do not dissolve, so the fabric remains behind. Tests with infrared light and heat showed the recycled and new fabrics behaved similarly. A drop of fresh epoxy also spread across both fabrics in a similar way. Our article on eco-friendly technology innovations covers other ideas in this space. Microscope images, though, revealed small bits of leftover plastic inside some fiber bundles. That leftover plastic likely explains the thicker recycled panels.
Turning Dissolved Resin Into a Binder
The dissolved plastic did not simply go to waste. For this reason, the team mixed some used bath with sodium hydroxide. This step neutralized the acid, and solid polymer then dropped out of the liquid. The team washed, dried, and ground this solid into fine powder. In total, they collected about 100 grams. The authors warn that this amount does not show a true recovery rate. Next, they sprinkled the powder between four dry fabric layers. Heating at 80 °C then glued the stack into one easy-to-handle sheet. Blade factories often use such binders to hold fabric layers before adding resin. This test, however, stayed at the proof-of-concept level. The team did not compare the powder with commercial binders. Likewise, they did not test how the powder affects final strength.
Fig. 2: How a Mild Acid Splits Recyclamine Epoxy
Challenges in Wind Turbine Blade Recycling
The authors call their process a partial closed loop. Closed-loop recycling turns old products back into the same kind of product. Such loops, the paper argues, can cut waste, costs, and material losses from landfills. Blade makers, in turn, could save on raw materials. Here, the fabric returns to new composite panels. The powder, in contrast, does not become fresh epoxy resin. On top of that, the team did not recover or recycle all the liquids. The leftover salty water and wash water still need proper treatment. According to the paper, these waste streams require attention before any scale-up. In particular, the MADE4WIND project page describes industry work on recovered fabrics. The European Union’s Horizon Europe program funded this study through MADE4WIND. In the same way, the authors report no competing interests. Overall, each energy technology now faces its own end-of-life puzzle.
Limits the Researchers Report
To begin with, this paper is a Journal Pre-proof, so details may still change. Every test also used small flat panels, not curved blade sections. Real blades contain other materials, such as foam cores, paint, and metal parts. Second, the bath weakened over four cycles and failed in the fifth. Third, the team did not measure energy use, chemical use, emissions, or costs. For example, no one yet knows the price per ton for this method. In addition, leftover plastic inside fiber bundles made the recycled panels thicker. That residue may also explain the weaker crosswise strength. The authors say future work should test recovered fabrics in curved shapes like real blades. They also want to study how the fabric drapes and packs during remanufacturing. For these reasons, larger trials must come next.
Conclusion: What Comes Next for Old Blades
This study offers a promising step for wind turbine blade recycling at the fabric scale. A warm acetic acid bath dissolved recyclable epoxy and freed whole glass fabric layers. New panels kept 91% to 95% of their main strengths along the fibers. At the same time, crosswise strength dropped to about 69%. The bath also weakened with reuse. On top of that, the tests used only flat panels. Even so, keeping fabric intact could add far more value than shredding. Such work brings together chemists, materials scientists, and mechanical engineers. Our story on recovering silver from old solar panels shows a similar challenge. Next, researchers must show the method works on curved parts and at larger scale. They must also count its energy use and costs. For now, the process remains an encouraging lab result.
References
Chowdhury, I. R., Bjerg, R. L., Broberg, P. H., Jensen, L. R., Bak, B. L. V., Hierro-Olabarria Salgado, F. J., Stecher, H., Di Gennaro, A. K., & Lindgaard, E. (2026). Low-temperature and partial closed-loop chemical recycling of glass fibre-reinforced recyclamine epoxy composites with fabric-scale recovery. Composites Part A: Applied Science and Manufacturing. Advance online publication (Journal Pre-proof). https://doi.org/10.1016/j.compositesa.2026.110422
Recovering whole glass fabric without shredding is a strong visual hook and stays fair about industry partners. Consider stressing that mild-acid recycling depends on the resin system, so it is not a universal blade fix. A constructive edit is one sentence on what independent plants would need to demonstrate. Readers should independently review and verify the claims in the source paper.
Editorial note
Wind-blade recycling made the ENTECH list because renewable energy’s waste problem is often invisible to new engineers. This note frames the story for learning, not for a rubber stamp. Independently verify the claims with the composites study and related technical sources.
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