University research studies potential of bladeless wind turbines

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Engineers from the University of Glasgow (Scotland) have performed a new study on the use of sophisticated computer simulations for bladeless wind turbines (BWTs) to identify how future generations of the technology could be built for maximum efficiency. According to researchers, findings could help BWTs, which are still at an early stage of R&D, from small-scale field experiments to practical forms of power generation for national electricity grids. This work, titled “Performance analysis and geometric optimisation of bladeless wind turbines using wake oscillator model,” has been published in Renewable Energy.

According to Composites Manufacturing, BWTs “consist of a cylinder built of resin-reinforced carbon fiber or glass fiber that is anchored to the ground by a rod” and sways in the wind, like lampposts in inclement weather. As the wind blows against them, BWTs create vortices — alternating swirls of air that rock the entire structure back and forth. When the frequency of the rocking matches the structure’s natural tendency to vibrate, the motion is amplified significantly, and the increased motion is converted into electricity. This process is called vortex-induced vibration.

In its paper, the team shows how they used computer modeling techniques to simulate the performance of thousands of variations of BWT design. The results cast new light on the interplay between mast dimensions, power output and structural safety in winds between 20 and 70 miles per hour.

Key findings include an optimal design for BWTs which creates a “sweet spot” that balances power generation with structural strength. The design, a 65-centimeter-diameter, 80-centimeter-tall mast, could safely deliver a maximum of 460 watts of power, significantly outpacing the performance of even the best-performing, real-world prototypes built to date, which have delivered a maximum of 100 watts.

The team’s model also demonstrated the limits of other designs, which could potentially generate more power, but wouldn’t hold up to real-world conditions. In the paper, the University of Glasgow team illustrates how different designs of BWTs could, in theory, generate up to 600 watts, but at the cost of structural integrity.

Ultimately, the team believes their methodology could provide the foundation for scaling up BWTs to utility-grade systems generating 1 kilowatt and beyond, making them much more practical for use by renewable energy providers.

“What this study shows for the first time is that, counter intuitively, the structure with the highest efficiency for extracting energy is not in fact the structure which gives the highest power output,” explains the University of Glasgow’s James Watt School of Engineering Dr. Wrik Mallik, one of the paper’s authors. “Instead, we have identified the ideal midpoint between the design variables to maximize the ability of BWTs to generate power while maintaining their structural strength. In the future, BWTs could play an invaluable role in generating wind power in urban environments, where conventional wind turbines are less useful. BWTs are quieter than wind turbines, take up less space, pose less of a threat to wildlife and have fewer moving parts, so they should require less regular maintenance.”

James Watt School of Engineering’s professor Sondipon Adhikari, also one of the paper’s authors, says they hope this research will help spur industry to develop new BWT design prototypes. “Removing some of the guesswork involved in refining prototypes could help bring BWTs closer to becoming a more useful part of the world’s toolbox for achieving net-zero through renewables,” says Adhikari. “We plan to continue refining our understanding of BWT design and how the technology can be scaled up to provide power across a wide range of applications. We’re also keen to explore how metamaterials — specially designed materials which have been finely tuned to imbue them with properties not found in nature — could boost BWTs’ effectiveness in the years to come.”

James Watt School of Engineering master’s student Janis Breen also contributed to the paper.