Q: Why are there only three blades on wind generators?

A: In short, trial and error have proven the three-blade model is the most efficient, unobtrusive way of harnessing the wind, said Douglas Johnson, owner of Bay Winds, a wind energy company based in Appleton.

Wind generators can have two to three blades, but three is preferable to two, Johnson said, because three is considered more proportional and is also quieter than models with two blades.

"With two blades, there's a lot more chatter," he said. For owners of wind farms, this added noise can be a headache.

With wind generators, the faster the blades turn, the more energy they generate. Adding more blades can slow the movement, making the turbine less effective.

"If you put more blades on it you're blocking the wind from going through," Johnson said.

Wind turbines use some of the same fundamental technology as coal and nuclear power plants, said Ingrid Kelly, renewable energy project manager for the Energy Center of Wisconsin, a private, nonprofit organization that aims to improve energy sustainability. Each turbine consists of a shaft with a magnet that revolves inside coils of wire. When wind turns the blades, it also turns the shaft, generating electricity.

Wind power is still a growing industry in Wisconsin, but turbines work best in open, windy areas. In such areas, including Wisconsin's vast farmland, Kelly said, wind turbines can positively affect rural economies.

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