Anemometer measures wind speed. It's shaped with little cups---hollow half-spheres. That looks very logical as the cups grab the wind and the other side is rather streamligned to cut through the air as it spins.
So why are there no wind turbines designed like this? (At least, I've never seen them.)
You could go further and make the cups ellipsoidal (more pointy). You could even add a inner shield, maybe like half a torus, around the inside to further streamlign the cups and help them grab wind.
This would be a vertical axis wind turbine (VAWT). Been looking around at VAWTs on Youtube for a while and found a lot of interesting designs, but never seen one with cups. Why not? I know I've seen anemometers spinning around very rapidly in good winds, so its seems logical.