Well Pierre, When I start to consider such structures, I note factors such as
- How to support blades at a speed of 4 times the wind speed, so in a 30 mph wind, your blades are traveling at 120 MPH.
- 4 G’s of centrifugal force, even at a 1-mile diameter
- How big, How heavy? How to support against centrifugal force and the reversing wind force?
- Blades only effective during portions of the travel
- Possible shielding of downwind blade by upwind blades
- suboptimal blade performance even at the most effective portions of the circle, due to no camber
- Tunnels or bridges to get inside the circle?
Here are pictures of rows of turbines in Tehachapi:
Tehachapi Pass wind farm - Wikipedia
The rows are spaced apart enough to allow fresh wind to dilute the expanding, slow-moving wakes of the previous row.
I agree that a mega-large rotating structure sounds good in some ways, but someone would have to provide sufficient details of something workable. To just pick a few factors “out of the air”, without a complete analysis is how the “Professor Crackpots” of the world like to operate. But you can’t just pick out a few favorable aspects to consider - the whole picture must be examined. I like the “idea” of coming up with this “idea”, but at some point, we would need a complete “idea” to consider, not just an idea for an idea.