I was asked a really good question that I didn't know the answer to...

[admin]

A neighbor of mine asked how you figure out the best height to place a wind turbine?  Is this a trial and error thing or are there some good engineering formulas you can apply?

Also, I imagine that the higher the turbine is off the ground the more support it needs.  Do Wind Power companies help you figure this out?  What about community regulations in Texas Hill Country?  I live in Hays county (outside Dripping Springs) and am therefore not subject to most building codes, but isn't there a national code or something?  Thanks for your help. 

[The Sun]

Not sure specifically about Hays County, but here are some guidelines for successful "commercial applications"

A leader in Texas wind power
 
 
Wind power energy page for LCRA 
Since 1995, LCRA has generated wind power at the Texas Wind Power Project in Culberson County, about 100 miles east of El Paso.
 
LCRA has supported development of wind power — a nonpolluting source of renewable energy — from its beginning in Texas. In 1995, LCRA invested in the state's first commercial scale wind project. It now purchases 116 megawatts (MW) of wind power capacity from three West Texas wind farms and continues to increase its commitment to wind power.

Turbines are used in nearly all electrical generating technologies, and wind power is no different. The blades — or rotors — of a wind turbine are similar to airplane blades. Strong, steady winds cause the blades, some as long as 130 feet, to rotate a turbine. The rotating motion of magnets in the turbines causes an electric field that can generate a flow of electrical current.

Wind turbines are usually mounted on towers from 100 feet to 300 feet tall because wind speed increases with height. Turbines operate best in areas where wind speeds are 16 mph to 20 mph at a height of 50 meters. Wide open West Texas, where the winds whip across the plains, is an ideal location for wind projects, also called wind farms.

For residential, you need a 10 mph average wind speed to benefit from a wind turbine.  I have seen residential wind turbines mounted on top of houses, on 20 to 40 foot polesect.  It depends on the use and surroundings.  In Austin, the average wind speed is just under 10 mph.  At my house, I would bet the "wind farm" that it is higher.