Wind turbines installed under a viaduct, illustration. This is based on a concept developed by researchers studying the potential use of wind turbines under bridges and viaducts. A number of studies have been carried out into such engineering projects. 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.