Wind turbines can only supply electricity when the wind blows, and as long as inexpensive energy storage remains elusive, utility companies will have to combine wind with a resource that can be banked in reserve, like gas.

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Yet wind is far from a perfect source of electricity, since the wind blows when and where it will.

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The researchers modeled their study on the electric grid in Illinois, which depends on a large number of coal and gas plants, and where the wind blows strongest at night, when demand is lowest.

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