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An odd thing I learned about wind turbines recently is that their peak efficiency is capped at exactly 16/27, or about 60%:

https://en.m.wikipedia.org/wiki/Betz%27s_law






it's not odd if you think about what that law is saying. The wind turbine extracts kinetic energy from the wind. If it could extract 100% of the kinetic energy, then the air would simply stop. So incoming air would "pile-up" after the turbine (since it has v=0).

Since that is impossible, the air must have some speed after crossing the turbine to make space for the incoming air. The details of that law are simply, how much can you slow it down?


I think the odd part is the weirdly specific integer ratio with large-ish numbers. You expect numbers like 1/2 and maybe 3/4 in fundamental laws, but 16/27 earns a double-take.

This very accurately describes my own reaction!



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