With about 15km of atmosphere from surface to top, it's difficult to imagine that a hundred or so meters of windmill will have much of an effect on the overall weather pattern. Weather patterns around large cities like Chicago or New York are shifted more by the heat properties of asphault, concrete and metal than by the wind obstructions created by masses of tall buildings.

The REAL problem is corporations with huge capital investments in energy production from fossil fuels can see the looming threat that renewable energy sources present to their projected earnings streams. As corporations, they are duty-bound to INCREASE shareholder value. This means using all resources at their disposal to mitigate or eliminate all threats to future earnings growth. They are highly motivated to maintain the status quo -- even if that means doing harmful things like buying and suppressing new technologies. There are enough instances of this to choke a google (try: oil companies alternative patent). Unless citizens and politicians suddenly evolve spines and overthrow corporate rule, don't expect major changes in the energy supply until the last well runs dry.