Author: Laura Stroud
Photo by Marten Bjork on Unsplash
When we think of wind turbines, we usually associate the tall towers with renewable energy and reducing our impact on the planet. But, to actually construct these wind turbines non-recyclable resins are used. Once weathering and wear-and-tear renders these blades unusable, they then will contribute to the overwhelming amount of plastic pollution we aim to avoid. There is hope, however, that a new resin found by researchers at the National Renewable Energy Laboratory (NREL) in the United States can replace these old materials.
The NREL researchers published findings on a new resin that can be used in wind turbine blades this summer. This new resin is derived from organic materials and was tested as performing at the same level, or better than, certain resins currently being used. The main draw is that this resin can be chemically recycled, meaning it can be dissolved to be reused or repurposed. The new material was named in the journal Science as ‘PECAN’; PolyEster Covalently Adaptable Network (Clarke, R. et al, 2024)
Why is wind energy so important?
Wind energy is a vital source of renewable energy and will play a role in reducing our global reliance on fossil fuel, in turn reducing carbon emissions. Wind turbines do not directly produce air pollutants while being used to generate electricity. Analysis has suggested that wind produced energy could replace more than 30% of total global energy produced by the mid-21st century, and reduce carbon dioxide emissions by up to 14872 mega-tons in this time. (Long, Y. et al, 2023)
Once up and running, wind turbines can continue to run with a lesser negative impact on the climate than ‘traditional’ energy production methods. But currently wind turbine blades are made using non-recyclable resins. Once these degrade over time and require replacement, usually lasting around 20-25 years of use, they cannot be recycled (Majewski, P. et al, 2022). At best, they can be reduced to small plastic shredding for use in structures. This means that to truly minimise impact on our climate, these problems in wind turbine production need addressed.
How is PECAN better?
Image: NREL
Firstly, the manufacture of PECAN is less intensive on energy requirements than contemporary alternatives. Made using bio-derivable sugars, in order to produce this resin companies would have to switch their raw materials. But, the production process is similar, so might help industrial transition without needing to greatly change processes.
When comparing performance of wind turbines materials, a key performance indicator is how susceptible to ‘creep’ that material is. This is the extent to which the shape deforms with time, which would obviously impact on the energy harnessing abilities of the turbine. This paper suggests that PECAN was able to perform at the same level as blades constructed with thermoset resin (the traditional, non-recyclable option), or better than thermoplastic resins (the other recyclable alternative).
The published results from testing resin deformation, compared to industry alternatives. Image from: Clarke, R.W. et al (2024)
Finally, this resin can be chemically recycled. This process would be used after the blades are no longer performing well over time. The unusable turbines can be broken down and converted back to raw materials for reuse in future production can reuse them. The paper heated the prototype blades in methanol in order to do this.
What could this mean going forwards?
Although these experiments were on 9 meter blades, it is exciting proof of process. These same processes are used on industry-standard blades but on much larger scales, usually 60 to 100 meters in length. At the other end of blade lifetime, the chemical recycling process was rapidly able to deconstruct these 9m blades in only 6 hours.
One of the vital takeaways from this paper is that bio-derivable and recyclable materials can be used without compromising on performance, which is a concern held by some industries still. Furthermore, the paper demonstrates that PECAN is ‘drop-in’ ready, as it can be manufactured using existing techniques. This paper marks an exciting step forward in exploring bio-derived materials as replacements for non-recyclable materials with finite lifetimes.
References
Clarke, R.W. et al (2024) Manufacture and testing of biomass derivable thermosets for wind blade recycling. Science, Vol 385, 854-860.
Long, Y., Chen, Y., Xu, C., Li, Z., Liu, Y., Wang, H. (2023) The role of global installed wind energy in mitigating CO2 emission and temperature rising, Journal of Cleaner Production, Vol 423, 138778.
Majewski, P., Florin, N., Jit, J., Stewart, R.A. (2022) End-of-life policy considerations for wind turbine blades, Renewable and Sustainable Energy Reviews, Vol 164, 112538.