Water Windmill

A water windmill pumps rather than generates. Its rotor turns a crank atop a tower, which drives a long steel rod down the well to a piston pump at the bottom, so wind lifts the water by mechanical linkage alone. Nothing is wired and nothing is burned. That is why it looks nothing like a wind turbine: a turbine spins fast to make electricity, this one pulls hard to move water.

The many narrow blades fill most of the circle they sweep, and that crowded shape gives far more turning force from rest than a generator's two or three slim blades. Starting force is what a piston pump needs to break a standing column of water free in a light breeze. Whether a site suits one is set by the wind of its calmest month rather than the yearly average, because that lull is what the storage tank must carry: roughly 4 m/s (9 mph) in the worst month is where a mill becomes worth its tower. Height matters as much as rotor size, since wind speeds up sharply above anything obstructing it, so a mill in the lee of a treeline or barn underperforms for life. Past about 5 to 6 m (16 to 20 ft) of lift the pump cylinder must sit below the water on rods rather than suck from the surface.

Output is a low steady trickle, so the mill fills a tank holding several days of use and troughs or taps draw from it. Storm protection is mechanical: the hinged tail vane folds above a certain wind until the rotor turns edge-on and stops catching the gale. That hinge is the machine's whole defence, and when it seizes from a missed service the rotor overspeeds and wrecks itself in one storm. Annual attention to the pump leathers, rod couplings and gearbox oil separates a machine that lasts decades from one that fails in its first year. It costs less to buy than a solar pump but asks far more routine labour, and because it runs short in calm weather rather than in cloud it complements solar instead of duplicating it.