The wind (air flow) can be measured with an Anemometer. There are many types of anemometers. There are propeller anemometers, cup anemometers, vane anemometers, sonic and laser anemometers. For purposes of a wind project the most useful are Cup Anemometers for wind speed measurements, and Vane Anemometers for Direction data.
The Cup Anemometers are used to measure the wind speed. These four cup anemometers produce signals that are captured and stored in a Data Logger. There are several Data Logger service providers such as Hobo Manufacturing, and Fat Spaniel that provide basic Data Logging capability.
The point of all this effort to determine the average wind speeds at your site is ultimately to calculate (estimate) your projects Energy Production. Energy Production is the point of a wind energy facility, and is the key to your projects profitability. In the next chapter, Choosing your Hardware, we investigate the actual wind generator hardware you’ll choose based on your sites actual conditions.
All wind generator manufacturer’s have specification sheets (Spec. Sheets). From these physical characteristics the energy production can be estimated. Usually, manufacturers will report a Power Curve, and an Energy Curve.
The Power Curve is useful to give you instantaneous power outputs for any given wind speed, but it’s the cumulative effect of all of these ever changing wind speeds over time that really matters: the Energy Production.
The Energy Curve will often give you Monthly figures for given Wind Speeds, or by Wind Zone. Once you identify your site’s Wind Zone, then zero-in on the subtle wind aspects of your site. The altitude of your site, the height that your wind data is sourced from, and the local topography and obstacles will have keen effects on your actual output. The manufacturer’s Energy Curve will normally list an estimated Energy Production in KWH in monthly totals. Look up your average wind speed, reference these Energy Charts and if presented in Monthly totals multiply by 12 for Annual Energy Production. You’ll use this number in your economic analysis.