Measuring Wind with Light

STUTTGART

Wind energy holds promise as a renewable source for the future, but measuring the incoming energy of a wind turbine accurately to generate power estimates still remains tricky.

For the newer generation of windmills with large turbines, conventional met mast measuring techniques are inadequate.

Researchers led by the University of Stuttgart are seeking an alternative and believe that light might provide the answer.

Researchers are seeking to develop a laser-based system for measuring wind speed and direction to generate accurate power estimates.

They are developing a lidar (light detection and ranging) system to take wind measurements at offshore wind farms. Its working principle is based on the Doppler effect. Airborne aerosols, which are assumed to flow with the wind, reflect an emitted laser beam or pulse. Normally eye-safe infrared light is used. The frequency of the received light changes depending on the speed of the reflecting aerosols, so by quantifying the change in frequency from the measured light spectra, the wind speed can be estimated.

Although the technology has been used in atmospheric research for decades, the investigators are seeking to adjust the technique to the particulars of wind energy.

The laser-based system has the potential to perform measurements in a more flexible and economic way than previous methods have and is considered a likely candidate to replace systems such as anemometers mounted on a met mast.

Current research is focused on two main areas: power curve assessment and wind field measurement from the nacelle.