Linear Generator

[tmac]

I've built a very small wind turbine for a starter project just to go through the steps. It is a VAWT and was fun to learn on.

Now I'm interested in generating more so I was thinking about putting a generator higher up. Problem is I live in a residential area so putting up a 40+ foot tower isn't going to happen.

I know the wind up high is much more powerful so I was thinking of trying the following:

A weather balloon floating about 80-100 feet above the ground connected to a linear generator at ground level. The balloon's lift would be just slightly less than the weight of the rotor. The bouncing of the balloon in the wind should then generate electricity in the stator.

It is very similar to the setup used by a lot of wave power designs except that I'd be using air instead of water. Gusts are better than steady winds.

Q1) Does anyone have any design info on a linear generator or know of any location that would? I would like to build it rather than buy it but either will do.

Q2) Is there any boundary layer where gusts prevail?

Q3) Is there any shape for the balloon that would catch and release the wind better? Something that would maximize the bouncing.

I don't know if it will work but there is only 1 way to find out for sure. The method does have several good points to it:

1. All the hardware is at ground level
   
2. If it does break and fly away so what? That is what weather balloons are supposed to do.
   
3. There would be no tower required just 100 feet of strong fishing line (or some else).
   
   

Any comments, suggestions, ideas & critiques of this method are welcome.

Thanks for your time

[rossw]

I hate to rain on your parade.... but this is just plain silly.

Daily (diurnal) variations in air pressure will cause you to be forever adjusting for that "just balanced" point. Air pressure changes as different air masses come through will be even more pronounced.

Wind will have a nearly horizontal vector that will pull the balloons sideways and completely override any vertical component.

The "lifting" ability of the balloons is quite small, so the amount of power will be little, and stacking enough balloons to overcome that problem will result in such a large balloon mass that any movement will be very slow (meaning less output from your linear generator)

Of course, Helium is not an inexpensive gas.... and it escapes from weather balloons at an alarming rate. You'll be pulling them down to re-inflate them probably daily.

At best, you might make a few watts......but I doubt it would even cover the cost of the gas, let alone make any useful power.

There's also the issue of neighbours complaining, councils demanding permits, airports getting all upset about the balloons (or what might happen if they get away and foul commercial aircraft engines!)

The benefits of having everything on the ground are valid though

Keep thinking..... you might turn up something workable!

[vawtman]

Could you possibly post a pick of your vawt and its surroundings?

 Vawts are perfect for residential areas no high towers and no noise from the blades.They thrive on swirly winds.

[alancorey]

For using a linear generator you might be better off getting a line over a tree and trying to make power from the swaying of the tree pulling the line.  Very hard to detect from much distance.  Use a slingshot or arrow to put up fishing line, then use that to pull up heavier line.  Still won't make much power, but cheaper than helium.  The generator could be a linear one (like shake flashlights), or maybe you could use a capstan arrangement to turn a shaft and use a rotary generator.  There's a lot of force at times so you'll want springs or something that will give before the line breaks.  I haven't done it, but I put up wire antennas this way hung from about 1/8 inch nylon line.  They stayed up until abrasion on the limbs chewed through the lines.

  Alan

[tmac]

I do have some pictures of it that I'll put up. Like I said it was a very small one for practice. I am copying a design that looks very interesting www.gual-industrie.com but on a much smaller scale (mine is 10" across). Any direction wind with a great power curve.

The other one I was thinking of trying is the www.tmawind.com version. Problem is that the guides only work to max efficiency for winds from a certain direction.

The other one that looks interesting is http://peswiki.com/index.php/Directory:Neo-AeroDynamic

The major problems with VAWTs are they use a lot of material to build and are at ground level. If you live on a mountain the ground level might not be a big problem.

[tmac]

Thanks for the feedback. I had no idea weather balloons leaked so much. I come up with lots of ideas. Most pretty bad according to the wife! She will be delighted to be correct again (always?).