Conservation of Energy

http://www.state.hi.us/dbedt/ert/electgen.html

Wind, initially is in the form of kinetic energy, thus it has the equation: 1/2mv^2, where m is the mass, and v is velocity of the air. Using the fact that the mass is equal to the volume times the density, we can rewrite the equation for kinetic energy as

k.e. = 1/2V*p*v^2, where V is the volume, and *p*
is the density of air.

Furthermore, the volume through a surface is equal to the area of the surface times the velocity of the air, times the time, thus the equation becomes

k.e. = 1/2*p*v^3At, where A is the area of the surface
and t is the time.

Since power is energy per unit time, the available power is

P = 1/2*p*v^3A

This equation is of interest, since it demonstrates that wind power is a function of the velocity cubed. In fact it would not be practicle to put a wind generator, unless the site averaged at least 14 miles per hour of moving air.

The equation would be the ideal amount of power, in practice the maximum power is about 59% of this value, and of that 59%, 70 percent can be converted to electrical power, the rest is lost to friction, heat, and other irreversibilities. This is one of the draw backs of using electrical power by wind generation.