Two versions exists: small ones are efficient enough to power a wall of light while large ones are used for industrial and mining activities. The latter require the Wind Corridor to channel powerful wind currents over the Dust District and into its blades.
The Duke of Serkonos, Luca Abele, had the Grand Guard install the smaller versions all around Karnaca to power his security devices. The levers at the base of their rotors are used as a brake to stop the blades from turning, effectively shutting down the power feed to nearby walls of light. This is mainly used when the wind blows too strong, which can overcharge walls of light. The blades can also be destroyed with an explosion.
Maintenance of the windmills is the responsibility of engineer crews, whose duties are detailed in the book Windmill Operation.