.......They break and cost a lot of money to fix .....
Thanks for this comprehensive piece.
In May 2007 I traveled north from Colorado into Wyoming thence west in to Idaho and onward to Oregon. Early on I ran into large wind farms of 25 or more wind mills. I counted them just to get a feel.
I noticed from the outset there were always some not working. I began to count them as well. In Idaho,on the Snake river plain, I got off the hiway and actually drove several miles to the farm and got a close up look of both working and non working units.
The bottom line is that averaged over numerous sites spread across hundreds of miles, about 10% of the units in each farm were inoperative. It seems to me that in addition to the numbers mentioned above for each unit, you can subtract an additional 10% or so from the aggregate farm number for inoperatve units.
The subsidies are for building them. Maintaining them is a cost that is not subsidized. If one quits and it is going to be expensive to fix, they just build another because it is subsidized.
Another reason they don't all run at the same time is there is not sufficient capacity in the power line that takes the power away.
In the Evanston Wyoming area, only about 25% are running at one time. They are a different 25% at different times, but that shows it is not because of mechanical failure.
It would take a fairly major power line to take 4 megawatts, and the power line that is there is not that big, nor is the substation that takes the power and connects it to the line.