Energy Options > Wind Power

Stupid questions about wind

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tamo42:
There is a bit on this in mollisons permaculture notes.  You need the right landforms though.  Think of canyons in mountain passes and how the wind howls through them.  The same can be done on a smaller scale.

phuttan:

I think the only really useful method would be to place windmills where land formations naturally funnel the wind. Like positioning windmills in a deep saddle along a long high ridgeline or in a canyon that naturally concentrates the wind. Studying the area and determining the best location would work, but trying to build things up to the point of creating a man made effect would not be practical. You would have to build a mountain or valley. Just my two cents.

Pat

AtADeadRun:
In theory, yes, Mangy, the restriction will cause faster airflow.  Total energy, however, remains constant, so pressure drops, which would cause the turbine to behave oddly, I believe.  Moreover, to get any sort of significant effect, you'd have to have a *big* funnel, so it'd only be useful for a static, non-rotating (in the horizontal axis sense) turbine where one could be assured that the wind would almost always blow from the same direction.  If you've got that, you've already *got* the geographic funneling discussed by phuttan and tamo.  Trying to put a funnel big enough to have an effect on a horizontal axis turbine would just tear the turbine off the tower the first time the wind shifted faster than the servos could turn to match the new direction.

Rorschach:
No mini tornado, but wind concentration is underway.

People are working on this and there are actually some in production:
http://gigaom.com/cleantech/kleiner-perkins-doubles-down-on-a-%e2%80%9cshrouded%e2%80%9d-wind-turbine-design/
http://green.autoblog.com/2008/12/31/new-wind-turbine-could-dramatically-increase-generation-efficien/
http://www.stormbladeturbine.com/
http://www.enflo-windtec.ch/english/turbine.html

Why do this? 
Betz Limit:
http://www.symscape.com/blog/virtual-wind-turbine-breaks-betz-law
http://www.windturbines.net/wiki/Betz%E2%80%99_Limit
http://en.wikipedia.org/wiki/Betz'_law
http://www.windturbine-analysis.netfirms.com/intro-betz.htm

Power is related to the velocity of the airflow cubed:
http://www.awea.org/faq/windpower.html
http://www.ftexploring.com/energy/wind-enrgy.html

Can we break Betz limit? 
http://www.ecofriendlymag.com/sustainable-transporation-and-alternative-fuel/can-we-overcome-the-betz-limit-in-windpower-extraction/ (pro)
http://www.ifb.uni-stuttgart.de/~doerner/diffuser.html (skeptical)

So in short people are proposing that Betz limit, the total theoretical efficiency, can be 'broken' by shrouding/funneling the wind  to the turbine.  That is the percentage of energy extracted from the wind can be increased above the theoretical 59.3 percent of a simple wind mill design.  Hope this was helpful.

phuttan:
Thanks for the links. Very interesting reading.

Pat

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