domestic wind turbine


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Old 11-15-07, 08:08 PM
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domestic wind turbine

Lately i've been in this mood to become more energy independant, and i've been tossing the idea around in my head to build my own wind turbine.

Like I said, just tossing around the idea, but i've got some questions.

Right to the question on my mind...I see a lot of small turbines are dc, which would be fine, but why couldn't a guy take a gas powered generator and rip the altenator out of that, connect it to a rotor and get an ac current that wouldn't require conversion and storage? And could then hook it up to a generator panel and just power simple things like lighting circuits?

Also a guy would have to stop the rotor automatically if the wind got to fast. what would be a simple and effective way to do that?

I know I couldn't power my whole house without an enourmous turbine, but a small one to do my lighting would be enough for me.
 
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Old 11-16-07, 03:37 AM
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Gas generators run at high RPM to generate 120 volts. Typically 1800 or 3600 RPM. You'd need some serious wind to approach that. Gearing it up is a possibility, but the load resistance would be too much for a small turbine and it wouldn't spin.

A DC turbine would supply power to charge batteries, which in turn would be connected to an inverter, which would supply 120VAC to your lighting circuit.
 
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Old 11-16-07, 04:09 AM
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And it's not just creating 120 volts. You have a wattage demand that you have to deal with. If your needs are low, then you may be able to do this. I, too, have been looking into the wind turbines, versus solar panels, etc. The wind turbines that are commercially available can be had for a few thousand dollars, which means your payback may not come in for 15 years. But, they have all the amenities, such as rpm control braking in high winds, computer blade orienting, feathering, etc.
 
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Old 11-16-07, 08:42 AM
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Originally Posted by nova_gh View Post
why couldn't a guy take a gas powered generator and rip the altenator out of that, connect it to a rotor and get an ac current that wouldn't require conversion and storage?
The wind is not as powerful or consistent as the gas engine, so the power produced would be weak, erratic and not useful. The turbine needs to charge a battery bank which then feeds an inverter.

Also a guy would have to stop the rotor automatically if the wind got to fast. what would be a simple and effective way to do that?
It's best not to. If you intentionally slow the turbine, you're throwing away energy that could be captured. Commercial turbines do have braking systems that engage when wind is high enough to damage the machine, but how would you know the limit on a homemade unit?

You might want to look at http://www.otherpower.com. The website has several guides for building homemade wind turbines. If you're interested in a small, commercially-produced turbine, look at http://www.pacwind.net
 
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Old 11-16-07, 03:22 PM
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Elaborating on Rick's reply... the single biggest difficulty with wind power at pretty much any scale is how hard it is to keep the generator spinning at a constant speed, and therefore keep your output near 60Hz. In fact, 60.03Hz is considered out of tolerance for the power company (they run clocks off the AC frequency). There aren't many ways to maintain that kind of accuracy on a wind unit, particularly a small one.
Inside a turbine is actually an AC generator, but the smaller ones rectify to DC since the manufacturer assumes it's being sent to a battery/inverter setup. Most car alternators are the same way, they generate AC and rectify.
That said, if you can get any kind of wind turbine on top of a nicely tall mast, you can probably get quite a bit of juice out of it. Enough to justify the initial expense after some years.
 
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Old 11-16-07, 04:00 PM
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The ones you see in the west generally are over 400' tall with a blade span of nearly 200', or more than the wingspan of a 747; they travel relatively slow, are geared to turn a generator at a constant speed, and use computers to regulate the speed of the fan. Just more info.
 
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Old 11-16-07, 06:23 PM
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i have an altenator (brand new) that I could use because I'll never use it since i got rid of the car. So now i'd just need some way of storing the power. Then, i'd need to invert it, I would probably have to add up what i'd be planning for wattage and get the right size inverter.

If i used my altenator, would i need to do some kind of voltage regulation or would the altenator put out (at the right speeds) a usable voltage?
 
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Old 11-16-07, 08:06 PM
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The alternator should put out a nearly fixed voltage (14.4 for auto use). They way they're built, reducing the RPM reduces the output amperage, not the voltage. So if it's slow you get less power, but it's still capable of charging the batteries. Bear in mind though that a typical car alternator is rated around 75 amps max output, or around 1000 watts. Which means it'd support a continuous inverter output of about 850 watts, or a bit over 7 amps. If you're going to go to the expense and time of wiring up batteries and an inverter, why not go with a setup that produces more power?
 
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Old 11-17-07, 12:11 PM
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Originally Posted by mukansamonkey View Post
If you're going to go to the expense and time of wiring up batteries and an inverter, why not go with a setup that produces more power?
More power is always good . Would you suggest doing a bigger turbine (possibably trading my altenator for a larger one) or do you have something totally different in mind?

The numbers in my mind is i'd like to do something to obtain about 20 amps and/or 2400w @ 120v.
 
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Old 11-17-07, 12:39 PM
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That automobile alternator is going to need to spin upwards of 4000rpm minimum to get its rated output. That will require some pretty hefty step-up gearing to work from a wind turbine.
 
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Old 11-17-07, 01:00 PM
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domestic wind turbine

Forget about the wind turbine for such a small demand on bunch of backyard garage parts.

You would be better off looking at other areas to save a buck.

One of the reasons wind turbines are being used is because they can sell power back to the utility when the power generator is not required. A utility will not buy any power from a small, unreliable source without the proper controls.
 
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Old 11-17-07, 01:11 PM
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Originally Posted by Concretemasonry View Post
A utility will not buy any power from a small, unreliable source without the proper controls.
While this statement is true, you will also not be allowed to use such a source. You won't get a permit for it and you obviously won't be able to install such a setup without a permit.

If you do install a proper setup, in most areas of the country the utilities are required to buy excess power from you.
 
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Old 11-17-07, 01:32 PM
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Originally Posted by racraft View Post
... in most areas of the country the utilities are required to buy excess power from you.
And in many areas they have to pay you 2x what you pay them for a kw hour.
 
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Old 11-18-07, 09:05 AM
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Oh I wish!! We are getting solar panels next week but the power company only pays wholesale for what you produce (excess) when net metering. You still have to buy at retail. Luckily the incentives from the power company to put in the panels themselves cuts the cost by about 75%.

In our research the turbine towers have to be so tall and can be fairly large, it did not fit our location. Solar panels have almost no maintenance, no moving parts to break, and are nice and low profile. Some folks setting up wind turbines in urban and suburban settings are getting backlash for unsightliness and noise.
 
 

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