Technology

Neutralising wind turbine noise

 By Benjamin Plackett

Some people love wind turbines, praising the elegance of a swift moving manmade object against the background of an often beautiful countryside or seascape. Others hate them—often locals who have grown tired and irritated with their noise. It’s such a common complaint that the United Kingdom’s government has even considered banning overly-noisy wind farms amidst a review of the annoyance they can cause local residents…

The wind also supplies a significant amount of renewable energy to national grids, not least in the U.K. where on and off-shore wind farms contribute to about 11 percent of the country’s energy consumption. For this trend to continue and to grow, complaints from local residents need to be taken seriously. That’s what motivated an international team of scientists to tackle the noise pollution of wind turbines.

For a solution, they turned to owls for inspiration. The birds of prey hunt in near silence by suppressing the noise of their flapping wings to sound frequencies beyond the human hearing range. The researchers — from Lehigh University, Virginia Tech, Florida Atlantic University and the University of Cambridge — wondered if they could design the blades of wind turbines so they acted more like an owl’s plumage. “The whole thing is inspired by what the owl does,” says Conor Daly, a mathematician and fluid mechanics expert who contributed to the research as a Ph.D. student at the University of Cambridge.

Some people hate wind turbines, irritated with their noise

Daly and his colleagues took microscopic photos of owl down, which showed that it consists of hairs that first rise alongside the feathers and then later bend in the direction of the airflow to form a canopy over the feathers. This canopy disrupts the airflow and prevents the formation of wind vortexes, which are responsible for much of the noise caused by flapping wings or rotating wind turbines.

The scientists then ran a series of computer models to test and design a canopy they could readily attach to wind turbine blades based on the owl’s down canopy. “To do a retrofit instead of a redesign is important because you don’t want to advocate for a complete replacement because that’s a burden to the technology’s adoption,” explains Daly. During their experiments, the team has significantly reduced the noise radiating from wind turbines fitted with their attachment, which can be 3D printed from plastic. Perhaps just as importantly, the addition of the attachment does not affect the amount of electricity produced. “It’s significant to reduce sound without compromising on energy,” boasts Daly.

SEE MORE: From oil to wind by RP Siegel

about the author
Benjamin Plackett
I’m a journalist based in London. I report on all things science, tech, and health for a number of different publications. My work has been published by The Daily Dot, Inside Science and CNN among others. I earned my M.A. in Journalism at New York University and my B.Sci in Biology from Imperial College, London.