While researchers started looking at thermoplastics because of their recyclability, it turns out they offer other benefits that may be even more important to the wind industry. For example, the use of thermoplastics would make it possible to thermo weld parts of the blade together. “Right now, we have two blade skins that we glue together with an adhesive,” says Berry. “Down the road, we could possibly get rid of that adhesive, just put the two skins together and then heat up the sections where they’re touching to bond them together. We could have better, more reliable and possibly less costly blades because of that thermal welding potential for thermoplastic resin systems.” Thermoplastic blades might also be easier to repair in the field.
Although IACMI researchers are still investigating whether thermoplastic blade production would be faster than thermoset, thermoplastic does have another advantage because it doesn’t require post-curing in an oven. That would save time, labor and processing time, in addition to capital costs related to oven purchases. Those savings could reduce blade costs as well.
Berry says the next step will be to make a full-size blade component – probably a large root section with over 100 mm thick walls – to test its exotherm.
“This blade has helped us to understand the challenges and learn more, but it’s just at the beginning,” says Berry. “We have several years’ worth of innovation between now and when thermoplastic resins may be used on megawatt-size wind turbine blades.” That work will include more coupon-level testing (for static, fatigue, lifetime, tensile strength, compression, shear and erosion) so that wind blade designers and manufacturers will have a complete database of the composite’s properties.
The goal is to take this promising manufacturing innovation and bridge the gap from research to commercialization, says Berry. “We’re here to work with our partners so that we can give them the base of what they need to make these decisions and to commercialize this technology to spread further into the market,” he says. Advances in blade manufacture could, in turn, improve the cost effectiveness of wind energy and drive a greater reliance on this renewable resource.
ACMA just released the Wind Blade Repair Recertification and has updated its Wind Blade Repair Certification materials. For more information, visit www.compositescertification.org.