In the case of the Cape Wind project, the environmentalists and local opponents demanded and got a reduction in the number of turbines from 170 down to 130 (and I predict that the number will drop further due to continuing opposition). Here's what the Cape Wind project will do when it is eventually built:
The project is a big win for Siemens who will supply 130 3.6 MW towers, outbidding GE, Vestas, and other competitors. Siemens has already sold over 1,000 of these large off-shore turbines. The Cape Wind facility will generate a maximum electric output of 468 megawatts with an average anticipated output of 182 megawatts. At average expected production, Cape Wind could produce enough energy to power more than 200,000 homes in Massachusetts, or charge 200,000 electric cars.
So, if we had 170 instead of 130 turbines, we'd have another 144MW in power (40x3.6), and an average of 238MW (1.4MW average production x 170 turbines) instead of 182MW . Tell me again how the opposition is helping the environment?
Since each megawatt of power can provide energy to roughly 1,000 homes, that's at least another 56,000 homes that have to obtain power from other sources (primarily coal and natural gas), rather than the wind power project.
Considering that air quality remains a serious issue, blocking the wind power project (along with nuclear power and other alternative energy projects) means that the air quality will continue to worse than it should be. In fact, Massachusetts gets failing grades across the board for air quality for ozone, and a mixed bag on particulates.
It boils down to "do as they say, but don't do as they do" and NIMBY (not in my backyard).