Home Guy wrote:

When you look at an ordinary fan, it has large blades that occupy a
significant portion of the cross-sectional swept area.

When you look at a wind turbine, the blades are very thin, occupying a
very minimal amount of swept area, allowing much of the wind energy to
flow right through or between the blades.

If a fan has fan blades that are designed to *efficiently move air*,
then why won't that same basic blade design also be *efficiently moved
by air* ?

Basic aerodynamics/physics. A fan blade is a wing. The larger the blade, the
more drag (energy loss). Fans are designed to move a large volume of air and
aren't particularly concerned about how much electrical power is used to do it.

Wind tubines have the opposite requirement. The blades are designed to be as
efficient as possible as the larger the blade, the more wind is required.