Thing is the wind isn't constant so you still need all the unfriendly enviromental stuff sitting in standby for when there is no wind. Also the wind isn't very good at picking up up just around lunch and dinner time. Mind you Nukes arn't very good at that either hence why they are best paired with a pump storage scheme.
So by the time you have built the wind turbine which produces loads of CO2 from making the materials and the concrete etc and then built the backup generation capability your actually not really saving any CO2.
Hmm... The wind power lobby claims that in practice it's not too big an issue. There are pilot projects looking at shutting-down energy intensive industries for short periods (e.g. industrial refrigeration plants, aluminium smelting) to deal with peaks in demand, rather than keeping large gas fired plants stations in reserve. Even home freezers may soon be able to to shut down for brief periods to the same effect. Ditto for air conditioning. Long distance powerlines may mean that if all of Britain is becalmed, we may still be able to import power from the continent (and vice-versa). Obviously, this all has costs which ought to be factored into the price of renewable energy.
A distant relative had a scheme for powering the world by generating energy whenever vehicles passed over sleeping policemen. There are fairly fundamental reasons why this simply won't work. Likewise for a recently-opened department store which has a 'green' program to generate a few hundred watts of energy as shoppers walk over energy-producing tiles on the floor.
When it comes to all the wind-power schemes though, none of the examples I gave seem to break any laws of physics. Perhaps they would work, but would be inordinately expensive. Or perhaps they simply can't make a big enough difference to make larger-scale wind power viable. They're quantitative questions, and the only way to answer them will be through extensive computer modelling. But modelling is only as valid as the data it's fed and the methods
chosen to perform the analyses, and it's easy to get silly answers by doing something wrong.
As a layperson I simply don't feel that I have any valid intuition about whether or not these windpower schemes are feasible and I'm not certain that anybody else truly knows either. However, I certainly can't dismiss them outright either. It seems to me that the best plan of action is to proceed gradually, without over-committing to any single power source.