About an alternative type of wind energy facility
This has been tried to some extent; Strata in London was a skyscraper that was built with three wind turbines at the top, with a deliberate design to funnel wind into them. There are other examples.



Siting renewable energy generation in cities is very attractive, partly because many people feel that the "industrial" feel fits better there, but also because it locates sources of generation close to sources demand. For some other technologies, such as photovoltaics, this is indeed a good approach. However, it doesn't tend to work out that way for wind.

There are three main disadvantages to urban wind:


"Dirty air" : Not what it literally sounds like (that's also true in cities, but wind turbines don't mind). The wind that is funnelled through, around and above buildings is sometimes accelerated, but it is also made turbulent, and wind turbines do not like turbulent flow. Turbulence increases the unwanted forces that turbines experience (i.e. forces that do not help them make electricity), and makes them less efficient.
Economies of scale: The amount of power that a wind turbine can generate, in a given wind speed, is proportional to the square of its diameter. Which is to say, size matters. In the countryside, onshore rotors commonly reach 80m diameter (offshore are much larger). In cities, this size would not be practical or acceptable. That means that a much larger number of turbines would be needed to generate as much power, which would be more expensive and have more visual impact.
It isn't all that windy: The power that a turbine of a given diameter can generate is proportional to the cube of the wind speed. Because of this, small differences in wind speed are very important to wind farms. Most cities simply do not experience such high windspeeds as rural hilltops do.


A fourth reason may be public acceptance; while people may view a few token turbines on rooftops as a good thing, the quantity needed to make a substantial contribution to national demand would drastically change a city's skyline, and might meet with disapproval similar to many rural wind farms. However, I have no evidence for this.