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Wind power density decreases as you get closer to the ground, because obstructions slow the wind. Also, turbine blades spinning close to the ground are noisy. Also, the cost of tower construction goes up as the height increases.
I suggest airship-shaped balloons with a big prop for a tail. As
the wind blows the balloon pulls against the tether but the autorotating effect adds lift so the altitude is maintained. There is a light-weight generator in the tail and power is transmitted down the teather.
Yes, it would be a hazard to navigation and yes, there is a limit to the spacing, but this idea could provide power to off-grid areas that could not otherwise economically generate electricity.
Maybe . . .
http://bz.pair.com/fun/WindsAloft.html
[36Kb image] Eyesore? [bristolz, Oct 04 2004, last modified Oct 06 2004]
(?) FA330 autorotating kite observation platform
http://www.germanvt...0folder/fa330b.html
Minimum airspeed 17mph or it cannot maintain altitude:- Removing energy through generation would have further affected lifting capability [FloridaManatee, Oct 04 2004, last modified Oct 06 2004]
Maybe like this?
http://news.bbc.co....ci/tech/1248068.stm
this has been done in the bakery before [Trodden, Oct 04 2004, last modified Oct 06 2004]
Similar idea
http://www.halfbake...20wind_20generators
[Trodden, Oct 04 2004]
IEEE Spectrum: "U.S. Researchers Argue for Harnessing Wind Power"
http://www.spectrum...ceenergywinddc.html
Added 24 Sep 03 | "Writing in the journal Science, Mark Jacobson and Gilbert Masters of Stanford University argue that wind power is both safer and cheaper than coal, the top U.S. energy source." [bristolz, Oct 04 2004, last modified Oct 06 2004]
Wired: Windmills in the Sky
http://wired-vig.wi...2278,67121-,00.html
"Australian engineer Bryan Roberts wants to build a power station in the sky -- a cluster of flying windmills soaring 15,000 feet in the air..." [bristolz, Apr 24 2005]
Safer, light-weight version
Low_20Mass_20Mill
Generator on the ground, pwr xmission via mooring lines. [James Newton, Jun 27 2006]
[link]
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Nice idea -
although a bit of an eyesore. |
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You'll probably need an elf-destruct mechanism on the balloon just in case the tether snaps in a wind gust. Could you imagine a squad of these blown loose in a hurricane, eventually dropping in on random cities with the blades still spinning? |
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Thanks [hippo]; corrected. |
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The balloon is intended for farming homesteads near larges fixed obstructions. Not too much of an eyesore and less of an ear-sore than its fixed alternative. |
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[krelnick]'s idea of an elf-destruct is noted and could be easily achieved. It would probably involve a child with a BB gun. |
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Would be a hazard to aircraft, so you'd need flashing lights and such. But, yeah, there's a lot more wind up there. Perhaps you could use giant kites instead of balloons? |
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I don't think it has to be an eyesore. Get a fun environmental artist like Christo to design them. |
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//Perhaps you could use giant kites instead of balloons?// |
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I considered kites. This idea was based on my anno in the Glow-in-the-dark-kites idea. The problems with kites are: |
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Without wind, the prop will fall to the ground - possibly injuring people below. |
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The kite would have to be re-launched manually. |
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The kite would be blown about in the wind, posing more of a hazard to aircraft. |
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These problems were solved by designing it as a lighter than air system, but that had problems of its own. |
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A balloon on a 200 foot tether would be blown sideways in wind. Straining against its tether, it would be pulled down towards the ground. |
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The autorotation effect of the blades would hopefully partly counter the effect by adding lift. |
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Ah, I think I oriented the balloon envelopes the wrong way. I bet they're supposed to be vertical with the tether attached to the nose, huh? Rats. |
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Given the speed of high altitude winds, the tethers
should be more slanted, too. |
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My first [Bristolz] illustration - I'm off to break out the Champagne! |
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//Ah, I think I oriented the balloon envelopes the wrong way. I bet they're supposed to be vertical, huh?// |
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No, actually your illustration is perfect, for zero wind conditions. The only difference from the original picture in my mind is that the teher would have attached on to the nose. But for low wind conditions, blade startup would be best in a horizontal position. So, perhaps a sliding tether line from the belly to the nose. Hence, your pic is perfect. |
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Windmills are hazards to hawks, which try to land on the spinning blades. These things might be high enough that hawks wouldn't try to land on them. But those stupid hawks - you never know. |
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Killing hawks still beats this elf destruction. |
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Why not just put lots of windmills on the top of mountains, the windmills could have plugs on them so that the mountain climbers could plug in a heater, or kettle to compensate for the presence of the windmills. |
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This has been halfbaked already, I read an article in popular mechanics - December my local edition, featuring an Australian who has a very similar idea, but the propellers are horizontal and they provide enough downforce to keep the device up. The idea was very well illustrated I will try to find on-line link. |
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//Why not just put lots of windmills on the top of mountains// |
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A ridge is an _ideal_ place to site a conventional windfarm, as are valleys and passes - such as Banning, CA. |
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This idea is intended for lowland locations where there are obstructions. |
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//popular mechanics - // ... //the propellers are horizontal and they provide enough downforce to keep the device up. // |
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The prop is mounted on a horizontal axis at first, but under windy conditions, it creates lift (see my link on the FA330) pulling against the tether, tipping the balloon closer to upright. |
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Why do this (after all it's less efficient that purely horizontal axis)? Because otherwise, the balloon would be pulled closer to the ground. |
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I saw this exact idea in a magazine a few years back, and loved the concept (I’ll see if I can find a reference for you). |
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I’m wondering if the design could be improved upon even more? |
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How about an airship designed in the shape of a pipe - (but with a flat outer surface, slightly convex inner surface), with one or more turbines placed inside? The unit could then be tethered, and balanced for zero wind, on the intake-side at the base. |
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(1) As the wind speed grew, the ship would increase it’s relative angle of attack (pivoting around the mount) and stay more vertical. I know your design does this too, but the rotor may be exposed to more turbulent air, and less airflow (see 3). |
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(2) The rotors will be internal, so if the whole machine fell to earth, there’d be a better safety margin, for ground dwellers and the mechanical components. |
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(3) The pipe-shape will fly more efficiently, as any air coming in, is slightly compressed and sped-up as it passes the rotors (also increasing efficiency), whereas a blimp shape compresses the air to the greatest degree quite far from the rotors. The tail-rotor will be spinning in quite a turbulent airstream (also slower). With jetstream-velocity air, a series of smaller, axial-turbine-like, rotors may be more efficient. |
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(4) The airship could have a variable geometry exhaust nozzle to maximize turbine efficiency at any wind speed. It could also be used to steer the blimp. |
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(1) Design is slightly more complex. |
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Another consideration may be adding lightweight solar panels to the upper surface. Although their output would probably be negligible compared to the wind power, they could provide ample power for a separate transceiver array that may be quite useful in many areas. High speed internet, telephone, TV, all that. They’d also provide enough power to illuminate the tether and blimp (with those darned LEDs of course). This would allow the wind-turbines to be a completely independent system, for providing ground power only. |
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Tether considerations: Instead of using a rope-like tether, how about a aerodynamic (teardrop) shape? This would allow room inside the tether for things like Raycons and LEDs, and perhaps an exterior copper mesh to conduct lightning. It’d also cut down on drag (causing the blimp to have to hold more of a nose up attitude to compensate, and reducing efficiency). |
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If this works, multiple blimps could be daisy chained along the tether to take advantage of wind at a much broader range of altitudes simultaneously. Since the tether is up there, ya’d may as well use it. |
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I thought this was going to be a means
of harvesting the passenger-generated
methane on long-haul flights to reduce
fuel consumption. |
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