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Haochen Li standing in a lab at the University of Tennessee

Flexible Turbines Could Upgrade Wind Energy Capture

To harness the energy of moving air, most wind turbines have blades with airfoils (cross-sections) that have swept (slightly twisted) profiles and are angled into the wind. As wind moves over the blade, the asymmetry creates lift, letting the turbine spin and capture energy.

It also means that the turbines are only effective when they point into the wind.

By contrast, Wells turbines have symmetrically teardrop-shaped airfoils rotated 90 degrees from the airflow. Wind from either side pushes on the tapering end of the airfoils, making Wells turbines spin in one constant direction.

“Wells turbines are a crucial component in the field of renewable energy,” said Haochen Li, an assistant professor in the UT Department of Civil and Environmental Engineering (CEE). “Their ability to capture energy in both directions makes them highly effective for wave energy applications, where the direction of airflow frequently changes.”

Along the coast, Wells turbines are enclosed in slanted, air-filled columns with bases open to the sea. As waves crest, the air inside the columns is forced toward the beach; when the water troughs, the air flows toward the sea.

Thanks to their symmetrical blades, the Wells turbines capture energy the whole time—but unfortunately, they don’t capture all the energy available in each gust.

“Wells turbines have an airfoil perpendicular to the airflow, which means the wind doesn’t really have an angle of attack,” said Jeffrey Lind, a sophomore working in Li’s Water Infrastructure Laboratory or Ψ (Psi) Lab. “That gives the Wells turbine large efficiency problems.”

Engineering is Math That Makes a Change

Improving the Wells turbine without compromising on its simple, low-maintenance design will require combining computational and experimental approaches.

With inspiration from his stepfather, a nuclear engineer, Lind taught himself to code at age seven. He made simulations of rocket engines for fun during the Covid pandemic. Now, as a math major with an interest in renewable energy, Lind was a clear choice to run the computational side.

“Undergraduates often bring new ideas and fresh perspectives to research problems, which can lead to innovative solutions,” Li said. “Jeffrey’s strong analytic, mathematical, and computational modeling skills will contribute significantly to this project’s success.”

For his part, Lind is excited to be experiencing mathematics through an engineering lens.

“Pure mathematics is quite abstract and has less ability to make visible changes,” he said. “This project is an interesting intersection of computer science, math, and physics that lets me enjoy the application side.”

Flexible Turbines Could Capture More Energy

Lind is simulating how Wells turbines would perform if their blades were less rigid, an avenue that Oak Ridge National Laboratory (ORNL) researcher Kellis Kincaid began exploring a few years ago.

“If you make the edge of the blade flexible, you get more of a pressure difference and fundamentally more force going in the rotational direction,” Lind explained. “Our goal is to optimize the design by simulating performance over a large set of elasticities and blade profiles.”

In collaboration with Kincaid and ORNL scientist Mirko Musa, former Ψ Lab member Neil Patel (BS ‘24) created eight-inch Wells turbines based on Lind’s simulated designs, then tested them in tiny wind tunnels. Lind compared the tunnel airflow with the energy captured by the turbines to validate or adjust his simulations.

Lind’s latest two-dimensional models project that flexible blades could let Wells turbines capture 17% to 19% more energy than the current standard, which would be enormously helpful in creating a carbon-neutral grid.

“By utilizing wave energy, Wells turbines contribute to reducing reliance on fossil fuels, thus lowering greenhouse gas emissions and supporting sustainable energy initiatives,” Li said.

Benefits of Research Go Both Ways

There is a long way to go before full-scale turbines see that 17% efficiency gain, but Lind has already gained plenty.

“This project really helped show me that there is merit to non-theoretical things, like engineering,” he said. “With pure math, you can develop a theoretical model, but you can’t necessarily implement it into reality.”

Lind’s new perspective is exactly why Li includes undergraduates in Ψ Lab research.

“Research projects provide undergraduate students with hands-on experience in real-world applications of their academic studies, enhancing their understanding and skills,” Li said. “Moreover, it allows for mentorship opportunities, fostering the next generation of researchers and engineers.”


Izzie Gall (865-974-7203,