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During the height of last month’s heat wave, millions of people in northern New England were urged to conserve energy, and some utilities fired up expensive, dirty sources of power to meet demand. But at the same time, at least two wind farms in Maine and Vermont were ordered to reduce the amount of electricity they provided.
Even when the energy is needed most, weakness in the rural system linking wind turbines to the power grid mean that wind companies are routinely taken offline or have their output reduced.
‘‘This is a fact of life,’’ said John Carroll, spokesman for Central Maine Power, which is responsible for the bulk of the grid in Maine.