Would you bet thousands of dollars to make par in a game of golf without a putter?
Wind map is like a driver club in golf. It will get you near the hole. A putter, not unlike an anemometer, will get you in the hole and make you a winner.
Lets take a look why wind site surveys with anemometers are necessary to supplement your wind map data.
- Wind maps are created from historical wind data collected at sparsely spaced measurement stations like our airports and coastal observations stations. So unless you live at an airport or a coastal observation station, a wind map will be more of a rough guide line whether to even consider wind energy.
- Within a few hundred meters/feet above ground, wind is highly effected by local terrain, topography and vegetation and as we know, the highest Megawatt wind turbines barely reach over 200 meters. Most all residential scale wind turbines rarely reach above 50 meters or 164ft. And the lower to the ground the wind is, the more it is effected and slowed down by the ground itself and whatever is growing or build on it.
- A wind survey performed at the height of your future wind turbine is in only accurate way to assess if it will perform as advertised. If you don’t have the capability or budget, then place an anemometer as high as you can and away from any objects like houses and trees. You can then extrapolate the increase in wind speed above your anemometer based on local surface features. Here is a tool to estimate wind speed higher than your measurements: Vertical Wind Shear Profile Calculator
Remember: Using only a wind map to make you decisions about wind turbine placement is like hoping for a hole in one…and we all know how often that happens even in the PGA tour.