Wind turbine blades might look elegant, even ballet-like, as they glide through the air. But, much like ballet, achieving that simple grace requires complex, advanced engineering.

NREL researchers build a 13-m thermoplastic blade at NREL’s CoMET facility. Photo from the National Wind Technology Center at the NREL Flatirons Campus. (Photo by Ryan Beach / NREL)

A team of National Renewable Energy Laboratory (NREL) researchers are furthering their revolutionary combination of recyclable thermoplastics and additive manufacturing (better known as three-dimensional [3D] printing) to manufacture advanced wind turbine blades. The advance was made possible by funding from the U.S. Department of Energy’s Advanced Manufacturing Office—awards designed to stimulate technology innovation, improve the energy productivity of American manufacturing, and enable the manufacturing of cutting-edge products in the United States.

Led by NREL senior wind technology engineer Derek Berry, the team’s novel techniques could revolutionize how wind turbine blades are manufactured.

Winds of Change

Today, most utility-scale wind turbine blades have the same clamshell design: two fiberglass blade skins are bonded together with adhesive and use one or several composite stiffening components called shear webs. This manufacturing process has been optimized for efficiency over the past 25 years—but, in reality, it has changed very little.

That needs to change.

To make wind turbine blades lighter, longer, less expensive, and more efficient at capturing wind energy—improvements critical to the Biden Administration’s goal to cut greenhouse gas emissions in part by increasing wind energy production—researchers must entirely rethink the conventional clamshell.

To start, the NREL team is focusing on the resin matrix material. Current designs rely on thermoset resin systems like epoxies, polyesters, and vinyl esters, polymers that, once cured, cross-link like brambles.

“Once you produce a blade with a thermoset resin system, you cannot reverse the process,” Berry said. “That makes the blade difficult to recycle.” As more and more wind turbines are installed every year, new wind turbine blades should be designed to be repurposed or even recycled to prevent them from undercutting the green economy they are meant to help build.

Different Materials, New Methods

Derek Berry and his team of NREL researchers did just that. Working with the Institute for Advanced Composites Manufacturing Innovation in NREL’s Composites Manufacturing Education and Technology (CoMET) Facility, the multi-institution team developed systems that use thermoplastics, which, unlike thermoset materials, can be heated to separate the original polymers, enabling end-of-life recyclability.

Thermoplastic blade parts can also be joined using a thermal welding process that could eliminate the need for adhesives—often heavy and expensive materials—further enhancing blade recyclability.

“With two thermoplastic blade components, you have the ability to bring them together and, through the application of heat and pressure, join them,” Berry said. “You cannot do that with thermoset materials.”

Moving forward, NREL, along with project partners TPI Composites, Additive Engineering Solutions, Ingersoll Machine Tools, Vanderbilt University, and the Institute for Advanced Composites Manufacturing Innovation, will develop innovative blade core structures to enable the cost-efficient production of high-performance, very long blades—well over 100 meters in length—that are relatively low weight.

By using 3D printing, the research team can produce the kinds of revolutionary designs needed to modernize turbine blades with highly engineered, net-shaped structural cores of varying densities and geometries between the structural skins of the turbine blade. The blade skins will be infused using a thermoplastic resin system.

If they succeed, the team will reduce turbine blade weight and cost by 10% (or more) and production cycle time by at least 15%, a huge leap (or pirouette) for wind energy technology.

In addition to the prime AMO FOA award for additively manufactured thermoplastic wind turbine blade structures, two subgrant projects will also explore advanced wind turbine manufacturing techniques. Colorado State University is leading a project that also uses 3D printing to make fiber-reinforced composites for novel internal wind blade structures, with Owens Corning, NREL, Arkema Inc., and Vestas Blades America as partners. The second project, led by GE Research, is dubbed AMERICA: Additive and Modular-Enabled Rotor Blades and Integrated Composites Assembly. Partnering with GE Research are Oak Ridge National Laboratory, NREL, LM Wind Power, and GE Renewable Energy.

Learn more about NREL’s advanced manufacturing and wind energy research and explore the CoMET capabilities.

Article courtesy of National Renewable Energy Laboratory (NREL).

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