What are some advantages and disadvanteges of using a horizontal and a verticle windmill?

Answer 1

I guess you're thinking about the types used for wind power. (I know a little about the other types, but I'd be going on forever if I included them to)

Horizontal (axis) machines need to be turned to face the wind to produce power (wind can sometimes be arranged to turn the vanes, or machine can be turned out of the wind to slow/stop it)

horizontal machines need to either transmit mechanical shaft power to the ground via a large heavy gearbox/shaft, or mount a heavy alternator at/near the vanes' axis of rotation (This increase the stress on the upright support, and hinders maintenance. You also need something like slip rings to allow the electric power down)

Good to see that others have heard of the vertical windmill (I recon that they're probably a better starting point for for wind power!)

The simplest vertical wind-turbine are much like those spinning signs you sometimes get near garages(?) on roads. They work in a similar way to a Cup anemometers, and don't need to be turned to face the wind. ( I'd recon many modern anemometers are probably small sub watt wind-turbines)

There's little need for complex gearboxes/shafts/slip rings, as the alternator is fixed on/with respect to the ground
Think the main problem is it's much more difficult to stop them from overspending in high winds. (how fast do the spinning signs go round when it;'s windy). They can be stopped from being powered by the wind, by have a shutter to cut of the wind, but that adds complexity

There's also the problem of the vertical shaft bending in the winds load (supposed to be less of a problem for a horizontal shaft windmill) Also vertical windmills are problem less efficient. They should however be far cheep to design build, not needing long slender aerodynamically shaped blades. (I wonder if they produce the same kind of noise) I also wonder if they'd be a much problems for birds.

Answer 2

Here's a disadvantage for vertical windmills: wind generally doesn't blow vertically.