This image definitely conveys a windless day. You might want to consider using a vertical crop instead of a square crop for this image, as the negative space on the left draws attention away from the windmills more than complementing the windmills. The image also has a flat look overall and could use a little post processing help.
stationary objects moved by non-stationary things is an interesting take on the challenge. I hope you're not getting any crooked horizon comments cause those things look pretty vertical to me :-)
When I saw this challenge this was the first thing I thought about. Great minds think alike. Good clean photo. In my picture I wanted the sun setting or rising to bring the wind mills out of the open. Plus it gives the sky a color.