Tidal Power Turbine Demonstrates Thermoplastic Blades

In June 2021, Verdant Power, a U.S. tidal energy company, announced it had produced more power than any other marine energy project in the United States to date, but that was not the only first for this project. In collaboration with Verdant Power, researchers from the National Renewable Energy Laboratory (NREL) constructed and validated the performance and durability of thermoplastic composite blades on Verdant Power’s tidal turbines in New York City’s East River. This was the first time thermoplastic composite blades had been applied to a large-scale tidal power turbine. These materials have the potential to revolutionize the marine energy industry by improving performance and sustainability, and can make the manufacturing process faster and more energy efficient.

In October 2020, Verdant Power’s TriFrame mount, which holds three three-bladed underwater tidal turbines, was installed at the Roosevelt Island Tidal Energy project site in New York City’s East River. With strong tidal currents that change direction multiple times per day, the river offers an ideal location for demonstrating the performance of marine energy turbines. During their first six months in the water, the tidal turbines, which featured thermoset epoxy resin blades, generated more than 275 megawatt-hours of energy—a U.S. record for marine energy production.

The project’s next step was to determine how the same tidal turbines would perform with thermoplastic composite blades. Using blade tooling and geometry details provided by Verdant Power, NREL researchers working at the lab’s Composites Manufacturing Education and Technology Facility produced full-scale thermoplastic composite blades nearly identical to the traditional thermoset epoxy blades initially used on the TriFrame mount.

By swapping one set of the thermoset epoxy resin blades in the TriFrame mount with thermoplastic composite blades manufactured by NREL, researchers could compare the underwater performance of each type of blade. Thermoplastic composite blades have shown improved structural properties when submerged and have the potential to be recycled and reused at the end of their lives. The research will confirm whether the innovative thermoplastic composite blades experience less structural degradation in water than traditional thermoset epoxy resin blades.

 In May 2021, the Verdant Power team raised the TriFrame out of the river and replaced the thermoset epoxy resin blades on one of the tidal turbines with three new, NREL-manufactured thermoplastic composite blades. In October 2021, the Verdant Power team once again raised the TriFrame out of the river—this time retrieving NREL’s thermoplastic composite blades. During the underwater deployment, the thermoplastic composite blades produced the same amount of energy as the thermoset epoxy resin blades.

Next, the team will measure the blades’ structural properties to determine the impact of seawater on the thermoplastic materials. NREL’s research demonstrates the potentially game-changing thermoplastic composite material for marine applications at a meaningful scale.