The atmosphere is the largest solar collector on the planet. Air currents are caused by changes in temperature and pressure, and are primarily powered by the Sun. Humans have been harnessing wind energy for thousands of years to power sailing ships. More recently, wind energy collectors have been used to power water pumps, grain mills, and electricity generators. Dozens of practical systems are currently available for both large scale and small scale electricity generation. These include both horizontal and vertical axis systems.
A more comprehensive essay on the merits of wind power and the different types of system available for small scale use is being planned. Please check back for further updates.
In the meantime, here is a short video presentation on Wind Energy.