"Sound radar" promises wind modelling breakthrough

Researchers at the University of Salford have revealed plans for an acoustic radar device they claim could revolutionise the planning processes for new wind farms by providing developers with highly accurate 3D models demonstrating local wind flow.

Wind at proposed turbine sites is measured using wind speed sensors mounted on masts, but according to Dr Sabine von Hünerbein of the University's School of Computing, Science & Engineering, the data that results is often not accurate enough to ensure wind turbines are located in the optimum locations.

"Getting the location right is a big challenge, particularly in the UK where onshore turbines tend to be located on ridges or hills," she explained. "When you are working on a ridge, for example, the wind flow and turbulence can be very different just 100 metres further down the ridge and the approaches are just too simple to detect those differences."

To tackle the problem Von Hünerbein's team are working on a £330,000 project to investigate the use of an acoustic radar device called a Sodar to measure wind flow.

"Sodars use a loud speaker to send out beeps of noise into the atmosphere," explained von Hünerbein. "Those sound waves get reflected back by wind flow and temperature variations and that gives you a good idea of where the turbulence is. If you use three speakers you can get a 3D view ranging from a height of 20 metres to 300 metres – from that you can work out the best location and height for the turbine and get a measure of how much strain the turbines will face."

Sodar systems are typically used by meteorologists and do not provide accurate enough data for wind farm developers, but von Hünerbein is confident that she has worked out a way to enhance the accuracy of wind speed measurements to within 0.1m/sec.

"We've worked out a signal processing mechanism that means instead of sending out uniform beeps, we can send out sound at different frequencies and then analyse its behaviour," she explained. "It allows us to get much richer data from each pulse of sound and results in five times as many data points."

The research team are now working to build a full scale Sodar device featuring the new signalling mechanisms and hopes to be in a position to test the system by the end of next year. Should the technology prove successful, Von Hünerbein said the university would then look to partner with a Sodar manufacturer to commercialise the technology.