Lightning No Match for Wind Turbine Blade Protection System
Standing hundreds of feet above ground, wind turbines — like tall trees, buildings, and telephone poles — are easy targets for lightning. Just by virtue of their height, they will get struck.
Lightning protection systems exist for conventional wind turbine blades. But protection was needed for blades made from a new type of material—thermoplastic resin composites — and manufactured using an innovative thermal (heat-based) welding process developed by scientists at the National Renewable Energy Laboratory (NREL).
Thermoplastic materials, like plastic bottles, can be more easily recycled than the thermoset materials commonly used to make wind turbine blades today. While thermoset materials need to be heated to cure, thermoplastics cure at room temperature, which reduces both blade manufacturing times and costs.
NREL’s patent-pending thermal welding process for thermoplastic blades allows for these benefits and even adds to them by replacing the adhesives currently used to bond blade components. The use of welding instead of adhesives eliminates the downsides of added weight and cracking potential.
While thermal welding offers benefits, it also requires adding within the blade a metal heating element — which can attract lightning. As a result, a team of NREL researchers led by Robynne Murray and supported by General Electric (GE) and LM Wind Power (a GE subsidiary) invented a new lightning protection system to keep the novel thermoplastic materials safe.
Thermal Welding Goes for the Patent
In 2018, Robynne Murray, an NREL engineer who specializes in advanced manufacturing methods and materials for wind turbine blades, received a two-year NREL Laboratory Directed Research and Development award to research thermal welding of thermoplastic wind turbine blades.
To make one of these new blades, a vacuum pulls liquid thermoplastic resin into the fiberglass material that is placed in a mold for each blade half. To weld the blade halves together, scientists sandwich a conductive material — such as an expanded metal foil or carbon fiber — between the two blade components and attach a wire to a power source. This creates the heating element. As current flows through this element, the thermoplastic materials melt. Once they are melted, the current is switched off and the bond cools under pressure.
Murray’s research demonstrated that thermal welding can effectively bond thermoplastic wind turbine blade segments. She submitted a patent application on the process in 2018.
A Pathway for Lightning
Thermal welding works. But it leaves the conductive heating element, which can attract lightning, within the blade.
“Thermal welding is an important step in the progression of commercializing thermoplastic materials for wind blades, but what happens when lightning strikes a thermal-welded blade? That was an unanswered question and a big concern,” Murray said. “For thermal welding of thermoplastic blades to become commercially viable, it is critical that the conductive bond lines be protected from a lightning strike.”
Partnering with GE and LM Wind Power, Murray submitted a research proposal to the U.S. Department of Energy’s (DOE’s) Technology Commercialization Fund (TCF). TCF awards are designed to advance technology developed at national laboratories toward commercialization while encouraging lab-industry partnerships.
“With our partnership with GE, a company that can take the thermal welding process to commercialization, our TCF was a strong proposal,” Murray said. “Together, we wanted to determine whether we can protect these blades from lightning strikes and eliminate a big reason to stop us from using the technology.”
In 2019, the team received $150,000 in TCF funding; GE matched that amount.
The research partners set up shop in NREL’s Composites Manufacturing Education and Technology (CoMET) Facility to demonstrate that thermoplastic blades sealed using thermal welding can be protected from lightning strikes.
The team infused an expanded aluminum foil into the blade skin to divert lightning current away from the metal heating elements. They then completed experiments using a simulation that showed that a lightning strike would not cause blade failure with the lightning protection system in place.
Lightning protection To build a lightning shield for their innovative wind turbine blade design, the research team added an expanded aluminum foil layer (left) and a carbon-fiber heating element at the bond lines (right) to enable thermal welding of the blade parts. Photos by NREL
Lightning strike. Researchers used a lightning simulation technique to see where lightning might strike the blade and found that, typically, electricity hit the tip of the blade or one of the edges—but not inside the blade or welded seams where it could cause excessive damage. Photo by NREL
Physical damage tests — which subject the blades to high currents of electricity — demonstrated that about 80% of the electric current went into the expanded aluminum foil layer for lightning protection and not into the blade skin. The carbon fiber beneath the damaged area of the tip was also unscathed.
The research confirmed the design can protect wind turbine blades against failure caused by lightning strikes.
“LM Wind Power and GE Research were excited to work with NREL on the development of this technology and appreciated the support by DOE’s Technology Commercialization Fund. Thermal welding technology for thermoplastic, recyclable wind blades offers a significant opportunity to impact the sustainability and carbon footprint of wind blade structures,” said James Martin, director of blade platform deployment for LM Wind Power. “NREL’s focus on mitigating the lightning damage risks associated with the electrically conductive elements in the welded bond is a key challenge to be overcome, and their work has helped mature the technology toward potential commercialization.”
Still More Questions To Answer
The project has already delivered two strikes against lightning. Murray’s work developing a market-ready thermal welding system, however, is still at bat.
“We answered the question about lightning. But there are more questions to answer and more work to be done,” Murray said. “The next step for us is to do structural validation of thermally welded blade bond lines and blade tip segments. I hope we can do this in the next year or so.”
Read more about this project in Wind Engineering.
Article courtesy of NREL.
The US Department of Energy (DOE) has released an encouraging new report revealing that 90% of wind turbine materials are already recyclable using existing infrastructure, but tackling the remaining 10% needs innovation.
That’s why the Biden administration’s Bipartisan Infrastructure Law has allocated over $20 million to develop technologies that address these challenges.
Why this matters
The wind energy industry is growing rapidly, but questions about what happens to turbines at the end of their life are critical. Recyclable wind turbines means not only less waste but also a more affordable and sustainable energy future.
According to Jeff Marootian, principal deputy assistant secretary for the Office of Energy Efficiency and Renewable Energy, “The US already has the ability to recycle most wind turbine materials, so achieving a fully sustainable domestic wind energy industry is well within reach.”
The report, titled, “Recycling Wind Energy Systems in the United States Part 1: Providing a Baseline for America’s Wind Energy Recycling Infrastructure for Wind Turbines and Systems,” identifies short-, medium-, and long-term research, development, and demonstration priorities along the life cycle of wind turbines. Developed by researchers at the National Renewable Energy Laboratory, with help from Oak Ridge and Sandia National Laboratories, the findings aim to guide future investments and technological innovations.
What’s easily recyclable and what’s not
The bulk of a wind turbine – towers, foundations, and steel-based drivetrain components – is relatively easy to recycle. However, components like blades, generators, and nacelle covers are tougher to process.
Blades, for instance, are often made from hard-to-recycle materials like thermoset resins, but switching to recyclable thermoplastics could be a game changer. Innovations like chemical dissolution and pyrolysis could make blade recycling more viable in the near future.
Critical materials like nickel, cobalt, and zinc used in generators and power electronics are particularly important to recover.
Key strategies for a circular economy
To make the wind energy sector fully sustainable, the DOE report emphasizes the adoption of measures such as:
- Better decommissioning practices – Improving how turbine materials are collected and sorted at the end of their life cycle.
- Strategic recycling sites – Locating recycling facilities closer to where turbines are decommissioned to reduce costs and emissions.
- Advanced material substitution – Using recyclable and affordable materials in manufacturing.
- Optimized material recovery – Developing methods to make recovered materials usable in second-life applications.
Looking ahead
The DOE’s research also underscores the importance of regional factors, such as the availability of skilled workers and transportation logistics, in building a cost-effective recycling infrastructure. As the US continues to expand its wind energy capacity, these findings provide a roadmap for minimizing waste and maximizing sustainability.
More information about the $20 million in funding available through the Wind Turbine Technology Recycling Funding Opportunity can be found here. Submission deadline is February 11.
Read more: The California grid ran on 100% renewables with no blackouts or cost rises for a record 98 days
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Mazda is finally stepping up with plans to build its first dedicated EV. The upcoming Mazda EV will be made in Japan and based on a new in-house platform. Here’s what we know about it so far.
The first dedicated Mazda EV is coming soon
Although Mazda isn’t the first brand that comes to mind when you think of electric vehicles, the Japanese automaker is finally taking a step in the right direction.
Mazda revealed on Monday that it plans to build a new module pack plant in Japan for cylindrical lithium-ion battery cells.
The new plant will use Panasonic Energy’s battery cells to produce modules and EV battery packs. Mazda plans to have up to 10 GWh of annual capacity at the facility. The battery packs will power Mazda’s first dedicated EV, which will also be built in Japan using a new electric vehicle platform.
Mazda said it’s “steadily preparing for electrification technologies” under its 2030 Management Plan. The strategy calls for a three-phase approach through 2030.
The first phase calls for using its existing technology. In the second stage, Mazda will introduce a new hybrid system and EV-dedicated vehicles in China.
The third and final phase calls for “the full-fledged launch” of EVs and battery production. By 2030, Mazda expects EVs to account for 25% to 40% of global sales.
Mazda launched the EZ-6, an electric sedan, in China last October. It starts at 139,800 yuan, or around $19,200, and is made by its Chinese joint venture, Changan Mazda.
Based on Changan’s hybrid platform, the electric sedan is offered in EV and extended-range (EREV) options. The all-electric model gets up to 600 km (372 miles) CLTC range with fast charging (30% to 80%) in 15 minutes.
At 4,921 mm long, 1,890 mm wide, and 1,485 mm tall with a wheelbase of 2,895 mm, Mazda’s EZ-6 is about the size of a Tesla Model 3 (4,720 mm long, 1,922 mm wide, and 1,441 mm tall with a 2,875 mm wheelbase).
Inside, the electric sedan features a modern setup with a 14.6″ infotainment, a 10.1″ driver display screen, and a 50″ AR head-up display. It also includes zero-gravity reclining seats and smart features like voice control.
The EZ-6 is already off to a hot sales start, with 2,445 models sold in November. According to Changan Mazda, the new EV was one of the top three mid-size new energy vehicle (NEV) sedans of joint ventures sold in China in its first month listed.
Will Mazda’s first dedicated EV look like the EZ-6? We will find out with Mazda aiming to launch the first EV models on its new in-house platform in 2027. Stay tuned for more.
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