First, the claim that Cape Wind's 130 giant turbines will produce 468 MW of electricity: That will be the facility’s maximum output. It will actually produce at an average rate far below that, likely one-third, or only 156 MW.
Considering that there is already over 35,000 MW of wind capacity installed in the U.S. (for an average rate of production of 10-12,000 MW), this project hardly represents a game-changing contribution.
And considering that the average electrical load in the U.S. is about 500,000 MW, it will take a hell of lot of such industrial installations to make any meaningful contribution.
And considering that the wind is a fickle resource, those installations will always be in addition to more reliable generators.
Conservation could easily obviate the paltry contribution from wind — and save so many otherwise off-limit areas (coastlines, ridgelines) from development.