[Image above] Transport of the 100% recyclable wind turbine blade developed by the ZEBRA consortium for testing at LM Wind Power’s test and validation center in Denmark. Credit: ZEBRA consortium
This month, the International Renewable Energy Agency released the latest version of its Renewable Capacity Statistics report, which presents renewable power generation capacity statistics for the past decade (2012–2021). As expected, renewable energy continued its upward trend, accounting for 38% of global installed capacity by the end of 2021.
Yet as more renewable infrastructure is installed, it is equally important to consider how these technologies will be decommissioned at the end of their life. This consideration is particularly urgent for the wind industry—while about 85% of turbine component materials can be recycled or reused, the blades are made up of fiberglass, a composite material that is difficult to recycle.
We’ve intermittently covered initiatives and advancements in recycling wind turbine blades on CTT. Today, we feature two new developments announced last month by university and industrial researchers.
Benefits of catalytic pyrolysis for recycling wind turbine blades
On March 15, Kaunas University of Technology (KUT) in Lithuania announced a new blade recycling method developed by KUT researchers and colleagues at the Lithuanian Energy Institute and Akhbar Elyom Academy, Egypt.
The group, led by KTU researcher Samy Yousef, conducted several experiments on decomposing glass fiber-reinforced polymer (GFRP) into its constituent parts. In the latest paper published in Fuel, the researchers studied the benefits of using catalytic pyrolysis to decompose GFRPs.
Pyrolysis is the process of thermally decomposing materials at elevated temperatures in an inert atmosphere. Catalytic pyrolysis incorporates catalysts into the pyrolysis process to lower the reaction activation energy and thereby reduce the required pyrolysis temperature.
Last October, the researchers published a study that found filler additives in GFRPs, which are added to enhance mechanical and electrical performance, can act as catalysts during pyrolysis, with high effect on the formulated compounds and their yield. The positive findings from this study led them to conduct the latest study, in which they used a commercial catalyst (highly siliceous aluminosilicate zeolite, ZSM-5) rather than fillers in the pyrolysis process.
Through analysis using thermogravimetric Fourier-transform infrared spectroscopy and chromatography–mass spectrometry, the researchers determined that the catalyst and heating rates play an important role in recovering phenol compounds from the epoxy resin, with the highest yield (66%) obtained at 5°C/min and a ZSM-5:GFRP mass ratio of 2. These compounds can be used in production of new chemicals and reagents.
“Based on that, the pyrolysis process supported by ZSM-5 zeolite can be used to recover phenol from GFRP,” the researchers conclude.
The paper, published in Fuel, is “Catalytic pyrolysis kinetic behaviour of glass fibre-reinforced epoxy resin composites over ZSM-5 zeolite catalyst” (DOI: 10.1016/j.fuel.2022.123235).
Production of first 100% recyclable blade prototype using thermoplastic resin
As mentioned in an earlier CTT, finding ways to recycle existing blades is not the only approach to improve wind energy sustainability. Developing new chemical formulas for blades that are easier to decompose needs to happen as well.
On March 17, General Electric announced production of the first prototype of a 100% recyclable wind turbine blade. The blade was developed by the ZEBRA (Zero wastE Blade ReseArch) consortium, which is led by French research center IRT Jules Verne and brings together industrial companies including Arkema, CANOE, Engie, LM Wind Power (a GE Renewable Energy Business), Owens Corning, and SUEZ.
The 62-meter (203-foot) blade is made using Arkema’s Elium resin, which is a thermoplastic resin well-known for its recyclable properties, together with new high-performance glass fabrics from Owens Corning.
LM Wind Power designed and built the blade at its Ponferrada plant in Spain, and it will now start full-scale structural lifetime testing at its test and validation center in Denmark. Once these tests are finished, end-of-life recycling methods will be validated. The project should finish by the end of 2023.
“With this project we are addressing two crucial industry challenges. On one hand, we are progressing on our Zero Waste Blades vision by preventing and recycling manufacturing waste. On the other, we are taking blade recyclability to a new level: the end-of-life thermoplastic composite blade material has high value in itself and can be readily utilized in other industries as material compounds but can also be depolymerized and the resin reused in the production of new blades,” says John Korsgaard, senior director of engineering excellence at LM Wind Power, in the GE press release.
Learn more about the project in the video below.