Wind turbine, California, USA. Wind turbines are used to generate electricity from the winds formed by the heating of the Earth by the Sun. They are an environmentally-friendly source of energy, as they release no toxic waste products and do not rely on a limited resource for fuel. This wind turbine is part of the Tehachapi Pass Wind Farm, once one of the largest wind farms in the world. Wind turbines were first installed here in the 1980s, with upgrades as technology improved. Tehachapi Pass, in the Tehachapi Mountains, connects the San Joaquin Valley and the Mojave Desert. Photographed in October 2011.