Wind energy - Betz' Law

Graphic interpretation of Betz' law

The energy in wind is a lot like the hot air in drivers. If a bit that's up the front runs out of energy and stops, all the ones at the back just plough into the back of the stopped one at the front, get angry, uncooperative, and everyone gets a lap full of coffee. Nobody's going anywhere. Wind doesn't get coffee stains - that would just be silly - but wind cant go very far when there's some uncooperative,  stationary wind up the front with no energy. So we find ourselves faced with some kind of limit.


If you take all the energy out of wind you cant get any energy out of the next bit, because in no time, the whole place is gummed up with stationary wind. So we find ourselves forced to slightly less greed, and only take a percentage.

We are forced to take less that 59%. Albert Betz did some apparently good work in finding this theoretical maximum limit for us. I say apparently, because aside from a stack of numbers and letters, his equations include things like triangles and a very great many dots where previously I thought such dots never went. In short, to me they mean nothing. Besides, my keyboard doesn't have a triangle key, so we are just going to have to take his word for it. Anyway, in reality we cant get 59% , because of all kinds of inefficiencies, and my frustrating lack of an infinitely thin rotor in my pile of junk. The best part is we really don't need 100% efficiency because there is plenty more wind where that came from, and the stuff is free.


 Hmm, perhaps Nobel simply didn't like triangles.