On Wed, 9 Sep 2009 01:27:07 -0700 (PDT), NT wrote:

usually its proportional to wind speed cubed, which is quite
significant, so things may be worse than they look

The energy available is but that need not be the same as the energy
produced by a wind driven generator.

Take a look at the graphs he

http://www.wind-power-program.com/smallturbinecomp.htm

The power out v wind speed from 5 to 10m/s is pretty linear...

--
Cheers
Dave.