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And celebrities are always falling for them.  (thanks for posting this, Fran)

There is a certain amount of energy available in a certain cross section of wind.  Betz' Law (1919) states that the maximum theoretical amount of energy that can be captured from a rotor is 59.3%.  When losses and mechanical inefficiencies are taken into account, modern turbines achieve coefficients of performance at between .4 and .5, or 70-80% of theoretical.

When you add all kinds of expense to capture the same amount of energy a simple cheap rotor captures, like permanent magnets to "float" the turbine, you've already lost the game.  Plus, in the video, the CEO or whatever says the turbine reaches maximum output at 28 mph (45.1 kmh).  In most urban areas around the world, that might be 20 -60 hours a year.

We now return you to conventional reality.

"Life shrinks or expands in proportion to one's courage." - Ana´s Nin

by Crazy Horse on Fri Jan 9th, 2009 at 03:49:40 AM EST
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Hmm, I can see how electromagnets or cryogenics (for superconductors) would be a loss, but I don't see why "permanent magnets" per se would be too expensive.

Most economists teach a theoretical framework that has been shown to be fundamentally useless. -- James K. Galbraith
by Migeru (migeru at eurotrib dot com) on Fri Jan 9th, 2009 at 04:11:52 AM EST
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As opposed to a simple bearing?  rare earth PMs can become quite expensive, especially at small scale.  otoh, permanent magnets have been used in the generators of gearless or hybrid turbines for years now, and are quite efficient.

"Life shrinks or expands in proportion to one's courage." - Ana´s Nin
by Crazy Horse on Fri Jan 9th, 2009 at 04:23:26 AM EST
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