Technocrat

Windchargers with Maglev Bearings

zogger
Mon Nov 12 16:21:49 -0800 2007
Electronics.
manage

A company in China is producing windchargers-small size for now, like for backup or modest offgrid aplications-that use permanent magnet levitating bearings. This not only ups efficiency, but allows the windchargers to be used in more marginal areas where normal windchargers might not be practical, their start speed and cut in speed, according to their specs, is pretty low. To top this off, they offer a package you can see at their site, combo solar/wind hybrid systems for street lighting. The wind charger sits at the top of the pole, the solar PV panels slightly below, along with a battery, you have a self powered street light.

ed: flip over to the main page on that site and they talk about the bearings part. supposedly they have plans to scale this up to over one megawatt size. Dropping needed windspeed is really a big deal in the wind biz, just huge areas of the planet can take advantage of this sort of tech then. I couldn't find a good schematic on their site though for how they have the permanent magnets set up. I would imagine at rest they still need regular bearings.

Law of diminishing returns

mcrbids
Mon Nov 12 21:32:39 -0800 2007
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Maglev bearings are nice - they reduce friction at lower speeds. When you have a windmill running at its best capacity, modern bearings cause only maybe 5% friction. But at lower speeds, near the "threshold point", bearings can represent much more, even 60% of the total system friction.

This is because the amount of friction is largely constant, while the power available in the wind is not. Remember the relationship between speed and energy - 2x the speed, 4x the power. This exponential growth is why airplanes today are only marginally faster than those made in 1960. (2x faster = 4x friction)

Reducing the power needed will help... a bit. But remember that we're only reducing a very small amount of actual energy in lost friction!

Is that enough to make a difference? Sure is, but it's not going to make it feasible that the Mongolian outback have Los Vegas lighting.

more than that

zogger
Tue Nov 13 11:06:46 -0800 2007
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I think you are underestimating what it means to have X-millions of more square miles fall into the "practical for windchargers now" range. For instance, I have a small one similar in size to what these guys have (300 watt model aeromarine brand), but where I live the wind potential is just not there, not worth it to even erect a tower and set it up as our average windspeed just isn't enough, it would sit there. With the magnetic bearings model though, I think it would be useful here. The usual figures are you need 6-7 meters a second average speed to make it practical, these guys beat that handily, and it also means at least initially that towers won't need to be as tall to get useful energy. I'm talking small scale homeowner/cabin/offgrid sizes, say 2 kw and under, those whopper megawatt and up sized machines are an entirely different matter. There's one company that had plans for a vertical axis hugemongous wind tower using magnetic bearings (these others are the common horizontal axis) out in the US southwest but nothing from them other than some artists renditions and a near blank website so I won't bother linking.

Scale of generation

Anthony Sorace
Tue Nov 13 15:32:33 -0800 2007
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Somebody help me out here. Is it fair to take the kWh number from my electric bill, multiply by 1000 to get Wh, and divide by (24*30) to get average watts, or am I missing something? If so, it looks like it'll take three of these to power even a smallish US home. Understanding that the intention isn't particularly for Joe Consumer to set up in his (um, my) backyard, am I right on the scale?
Scale of generation
12345
Fri Jul 18 03:51:32 -0700 2008
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This might help put things into perspective:

Small Wind Turbine Basics

http://otherpower.com/windbasics1.html

 

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