Quote Originally Posted by yesdachi
Wouldn’t the harnessing of the wind be considered using relative perpetual motion as an energy source? like the tital power?
Perpetual motion refers to an object forever moving without outside interference. Also perpetual motion will not use energy from within the system, it is a kind of forever moving equilbrium.

Windmills are not a closed system, they rely on an external energy source:

Sun Fusion energy -> Photons -> Heat up Earths Atmosphere -> Creating Winds -> Move windmills.

The Universe, unlike humans, likes to share things, particular energy. As such the laws of thermodynamics mean that a perpetual motion machine is not possible. What most people refer to as perpetual motion is an object that is getting energy from some outside force to keep it moving.