The nacelle of a 1.5MW turbine weighs around 70 tons, the three blades together weigh more than that, about 75 tons (25 tons each). Then, there's the the pole.
If you understand moments at all, put 150 tons or so on the end of a 100 meter stick then try to hold it near the other end, with no wind.
Smaller turbines, like used for homesites, would probably work. But, they put out so little energy it's not really worth it. These things are only putting out their rating at windspeeds of over 30 mph. Even the best wind sites do not average winds like that.
A utility-grade wind farm would consider a 7-8 m/s (15.65-18.0 mph) windspeed average as good (Class 4 or better).
Tulsa doesn't come close to that. We're in a Class 2 wind zone, average of only 7-9 mph.
The top of a building would boost that to some degree due to up drafts on the sides of the building.
But, the increased average windspeed required of the smaller turbines would offset that.
Besides, you're really only distributing the load if you build up to the same capacity as one larger turbine. The structure still wouldn't handle it. So, must settle for small, relatively meaningless, output.
Take a look at this small wind turbine's power curve:
Bergey 10kW Turbine Power Curve Spec Sheet (PDF)Then look at GE's 1.5MW turbine's power curve:
GE 1.5MW TurbineThat should make it abundently clear.
The GE turbine reaches 80% of its' rated output at 10 m/s, peak at 12 m/s.
The Bergey doesn't get to 80% until around 15 m/s and peaks at 17 m/s.
The GE will be producing 80% of its output while the Bergey is only outputting 30% of theirs.
And, in Tulsa type winds, the Bergey will never reach peak, or even 80% most times, short of a tornado.
The small turbines simply aren't very efficient, and cost almost 4x that of the larger ones in terms of $/kW.
