Wind Turbine Efficiency

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All you need to know about wind turbine efficiency

Wind turbine efficiency is one of the most controversial topics of conversation whenever wind turbine technology is discussed. The reasons for this are many and this single topic is used by both sides in the wind energy debate. Getting to the real facts about wind turbine efficiency requires understanding how wind energy works in general and more specifically how efficiency is measured.

To start the discussion, it is a simple fact that a wind turbine generator will produce energy from a passing breeze as long as the wind is of a sufficient velocity to spin the blades. Most people miss this fact when they discuss alternative power and concentrate instead on how much of the power in this passing wind is converted. This is really a little bit of a moot point since the wind would have been blowing anyway and unlike a fossil fuel generator, you are not trading coal for electricity where the efficiency rating might be a bigger concern.

The next discussion around wind turbine efficiency usually settles on how much of the average wind in an area the wind turbine generators can convert to useful electricity. The real answer to this question is that it varies since there is a wide variance in both size and capacity for the larger wind turbine designs. The larger the wind turbine is, the higher the wind speed needed to turn it and the more power it will produce. If too large a wind turbine is built in an area with a slower average wind than is needed to turn the blades, the efficiency will be very low. If however the wind turbine is sized correctly for the area, it can be spinning 70-80% of the time and be operating at peak efficiency for up to 30% of that time.

All wind turbines have a specific design point that they operate at their maximum efficiency and this relates directly to a given wind speed. If a particular wind turbine is designed to operate best at a 20 mph wind, anything higher or lower that this will produce less than maximum efficiency. Even still, many of these modern wind turbines have the ability to adjust this design point through modifications to the generator while the blades are spinning. Specialized electronics can turn on and off additional coils in the generator to adjust this design point for varying wind speeds. This means that these wind turbine generators can produce a large amount of power over the course of the year.

Wind turbine technology has to be sized correctly for each area

Even under the best environmental and design conditions, there is an absolute theoretical limit of 59% efficiency that is known as the Betz limit on converting wind power to electrical power. This number has been proven and accepted by most experts in the field as the maximum conversion efficiency that even the newest wind turbine technology can aspire to under the best of conditions. This still represents a lot of available power from wind turbines that can be used to offset conventional generating methods that are used today. This wind power is renewable, clean, has no environmental impact and represents a great way to help supply our growing need for power.