Compléter BBC NewsVersion en ligne Solar plant par Julen Nieto 1 steam light night Seville electricity sun sky court Spanish Outside Seville , the are building a new golden tower surrounded by six hundred reflectors , each one half the size of a tennis . They behave like sunflowers , naturally following the arc of the across the . Focusing the sun's to a single point all day long , the intense heat turns water to that generates more than 20 gigawatts of a year . And when all nine solar towers are complete , they will provide enough electricity to power the whole city of day and .