VAWT (Vertical Axis Wind Turbine)
Vertical Axis Wind Turbines (VAWTs), spin around a vertical axis instead of the traditional horizontal axis. While the difference may sound trivial, it in fact VAWTs have a number of key improvements:

Function much better in turbulent wind (typical of rooftops in urban and suburban areas)

Can be mounted directly on a rooftop, doing away with the tower and associated guy lines

Spin at slower speeds than horizontal turbines, decreasing the risk of injuring birds and also decreasing noise levels

Start producing power at slower wind speeds than horizontal turbines

Perform equally well regardless of wind direction. Rebates Contributing to the rise in this new wind technology are recent government incentives and tax rebates. In Ontario, for instance, not only do homeowners save the PST on the purchase of their wind turbines, but in 2006 the provincial government committed to paying 11 cents for every kilowatt-hour sent back to the grid -- close to double what consumers have to buy their power for. Similar incentives have led countries like Germany and Spain to become world leaders in wind power production.