Scientists are using sound to measure wind speed
Shouting into the wind – scientists are using sound to measure wind speed
With the increasing focus on renewable energy sources, how can we find the best places to put new wind farms? NIWA scientists are using several new tools, including one which uses sound waves, to help answer this question.
If we want to get the best generating capacity out of wind turbines, we should put them in places with the highest average speeds. The wind in a particular place consists of a few storms, some calm periods, and everything else in between. If we put all these conditions together, we get the average wind speed.
In New Zealand, the good generating sites have been in areas with average wind speeds of about 30 to 35 km/h, with the turbine blades at fairly low heights above ground.
But there are not as many suitable areas in New Zealand as you might think, according to a report released today by NIWA’s National Centre for Climate–Energy Solutions.
“We may have to go higher above the ground to tap the high wind resources”, said Dr Andrew Laing.
In countries overseas where wind energy is becoming a significant contributor to electricity generation, there has been a trend for wind turbines to be larger and higher above the ground.
Dr Laing said that NIWA had been improving the network of wind recorders over the country by installing automatic instruments that recorded hourly wind speeds. These recorders were generally 10 metres above the ground, so more information was needed on the wind at heights of 30 to 100 m – where the wind turbines are.
“One tool we are using to measure wind at these greater heights is the sodar, sometimes called an acoustic sounder. This can simultaneously determine wind speed and direction anywhere between 20 m and 1500 m above the ground by using sound waves in the same way that a radar uses radio waves.”
NIWA has programs that model winds around New Zealand and in many other countries. They can cover the whole country, even down to individual hills.
“This means that we can provide the
information generators need when they are assessing a
particular site. We can design the layout of a wind farm,
and even design the turbines themselves to ensure they don't
fly apart in extreme