They aren't exactly of the same scale these satellite images. Also, the silos and wind turbine foundations don't look too different. Here is one prior to back fill. Should be similar sized in the 3-4MW range, ~140m tall.
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And here is the top view of another one. (don't it look like the photo of the one they had with the shelter removed? well backfilled)
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The way they marked it up is kind of useless. When you are building the silo or wind turbine, you will have spoils excavating something that big that needs to piled somewhere for the back fill. You will also have run offs somewhere to dewater/ dust suppression. It is kind of weird why they have weather shelter in place though. Would warrant checking the prevailing wind directions to see if its headed in the direction of town from the top of these hill sides as a possible reason.
I kinda imagine aside from the foundation, they would have probably poured the crane pad near the road side as well to facilitate turbine installation, which may explain why it looked like the shape it does since a continuous single block pour is cheaper with less formwork.
Is the structure in Jilantai permanent or temporary? If these are temporary construction aids, then isn't it completely different straight away? I note that on the side of the one in Jilantai, they marked it as blower/ environmental control, where as on these ones in Yumen, I see trucks parked there, potentially taking the spoils elsewhere.
Not sure if the satellite resolution is high enough to see the anchor bolts. If you see the anchor bolts around, then it is definitely turbine foundations!