Wind Power Density is a useful way to evaluate the wind resource available at a potential site. The wind power density, measured in watts per square meter, indicates how much energy is available at the site for conversion by a wind turbine. Classes of wind power density for two standard wind measurement heights are listed in the table below. Wind speed generally increases with height above ground. Mean wind speed is based on the Rayleigh speed distribution of equivalent wind power density.
Wind speed is for standard sea-level conditions.
In general, sites with a Wind Power Class rating of 4 or higher are now preferred for large scale wind plants. Research conducted by industry and the U.S. government is expanding the applications of grid- connected wind technology to areas with more moderate wind speeds. AWEA Home Page 1998 by the American Wind Energy Association. May be freely distributed provided this notice is included. All other rights reserved.