Wind energy

The second entry is la surface balayée, the disc the blades sweep through, and the verb behind it is balayer, to sweep with le balai, the broom. Away from the turbine that verb lives in two fixed phrases, and neither survives being carried across word for word. Balayer devant sa porte, to sweep in front of one’s own door, is said of somebody who lectures others while his own record is untidy: avant de donner des leçons, qu’il balaie devant sa porte. English says « put your own house in order », or reaches for glass houses, and leaves the broom out of it. The second is balayer d’un revers de main, to sweep aside with the back of the hand, which is how an argument, an objection or a proposal is dismissed without being examined. There the two languages nearly share a picture, since English also « brushes aside » an objection, but the French gesture is ruder: a flick of the wrist rather than a brush. Neither phrase has anything to do with rotors. On this page the verb is literal: the blades sweep a surface, and its size decides how much wind the machine can catch.