Fotos

Wind turbines in Belgium.
Wind turbines use blades which convert airflow into force normal to the blade (much like an airplane's wing). since the blades are attached to a shaft, the shaft rotates.
The shaft is usually magnetic, and it's motion results in a constant change in the magnetic field it produces. The shaft is surrounded by conducting coils, and the change in the magnetic field induces current in the coil.
The kinetic energy of the wind was thus converted to electric energy.
The induced current is fed into a digitally controlled converter, which converts the current into the standard 50Hz current which is used in the national power grid.