Horizontal Axis Wind Turbines (HAWT), the giant propellers that dot the landscape in various parts of the country, are just about done. Technologically, we’ve pretty much hit the limit of size & efficiency given the current state of the art. Also, economically, and politically, HAWTs are just barely viable since they are expensive to build, erect, and maintain, and each one needs a rather healthy footprint of land, just to make a rather small amount of power. However, there is another wind-power option.
Vertical Axis Wind Turbines (VAWT) require a fraction of the foot print, are much easier and cheaper to construct & erect, and a whole lot easier to maintain. They are not individually capable of producing as much power as a HAWT, but, we are learning, that a cluster of VAWTS, positioned correctly, can collectively surpass the efficiency and power output of a HAWT, without being an expensive eyesore.
It is still unlikely that industrial scale WT installations of any type will be capable of providing base level power, but a small cluster of VAWTs could very well be an attractive rooftop option for a Wal-Mart, or an industrial site, or a business park, to help offset their energy costs and impacts.
…or, a residential rooftop. About 65% of the days here near the west end of the Columbia Gorge bring enough wind velocity to get useful power from a VAWT or several.