Alternator for Low Wind Speed Wind Turbine.

MechaMZ

Hi

I've a wind turbine which have to run under a very low wind speed, from 2-3m/s.

Currently, I'm using Envirotek V20, the result is around 1.5V-2.5V, and current is 0.3mA or nearly zero.

My aim is to achieve 50W.

Any suggestion for the alternator which I should use?
p/s: without aided by any gear arrangement.

thanks alot.

russ_watters

Are you sure you have 50W of available wind energy at 2-3m/s? The alternator's size, unless it is absurdly large, doesn't affect the output power much.

LURCH

Along with what Russ said; if the windspeed is that slow, I don't think any change of alternator is going to give you the Watage you're trying for. The only thing I can think o ffor increasing output is increasing input. Since you can't incrase the wind's speed, I suppose this will mean increasing the size of your airfoil blades. Catching more wind at the same speed will increase the energy that is being input into your system.

MechaMZ

Quote by LURCH

Along with what Russ said; if the windspeed is that slow, I don't think any change of alternator is going to give you the Watage you're trying for. The only thing I can think o ffor increasing output is increasing input. Since you can't incrase the wind's speed, I suppose this will mean increasing the size of your airfoil blades. Catching more wind at the same speed will increase the energy that is being input into your system.

think this is a good idea..

I will try out with an experiment..

thanks alot..

russ_watters

What is the size of the turbine? We can help calculate the available energy and likely capture.

MechaMZ

Quote by russ_watters

What is the size of the turbine? We can help calculate the available energy and likely capture.

I'm using this currently..
www.envirotekpower.co.uk/V20info.html

but I'm going to redesign the turbine blade..
currently, I have few designs. they are most likely same as these examples
http://www.peswiki.com/index.php/Ima...lien_95x95.jpg
http://www.peswiki.com/index.php/Ima...Wind_95x95.jpg
www.hi-energy.com.tw/selection-6-english.htm
www.oregonwind.com/

just not sure which can really function good in low wind speed, 2m/s-3m/s
I think I have to run a few test on them..

by the way, you are so kind, really thanks :)
and I'm very appreciate..

p/s: sry for the urls..

MechaMZ

Besides change the size of wind blades, Do you think it's possible to generate 50W with a gear system?

my v20 now is able to achieve 165rpm @ 4.3m/s, and the current produce is almost 0! (even the wind speed reach 8m/s)

do you think just because the alternator is a lousy one?

many thanks:)

russ_watters

More gearing will only hurt you - it doesn't amplify energy and you lose energy from friction.

According to the site, that turbine only generates 3W (.25A @12V) at 4.5m/s using a turbine with a cross sectional area of .18 m^2. I don't have time to run through the energy calculation for the wind right now, but my gut tells me that if theirs can only generate 3W, you have no hope of generating 50W with a turbine that small.

MechaMZ

Quote by russ_watters

More gearing will only hurt you - it doesn't amplify energy and you lose energy from friction.

According to the site, that turbine only generates 3W (.25A @12V) at 4.5m/s using a turbine with a cross sectional area of .18 m^2. I don't have time to run through the energy calculation for the wind right now, but my gut tells me that if theirs can only generate 3W, you have no hope of generating 50W with a turbine that small.

how about with only 2 gears, as to increase the rpm of alternator.

wind turbine with a bigger gear, and small gear for alternator. So my alternator able to turn more round as wind turbine gear turns one round.

or I can let alternators connected in series since my project can involves more than 1 wind turbine and alternator.

thanks alot

russ_watters

Well, you could certainly run 20 of them in parallel, or hook 20 up to a common alternator.

But again, just changing the gear ratio does not change the energy you can generate. You'll increase the rpm, but decrease the torque.

russ_watters

The wind energy available to one of those turbines, by the way, at 4.5 m/s is 8 watts. That's based on a kinetic energy calculation: 1/2 mv^2 = .5*(4.5*.18*1.29)*4.5^2 = 8. A total system efficiency of just under 40% is pretty good, so I wouldn't expect you to be able to beat their performance.

1.29 kg/m^3 is the density of air.

MechaMZ

this fact is really disappoint me :(

but how about increase the wind turbine size and with the help of gear ratio?

thanks again

MechaMZ

I found this design is able to generate around 200 watts @ 10mph, 4.4704 m/s.

unfortunately it is horizontal wind turbine.

and it's able to generate 200W @ 4.4704 m/s, because it is horizontal?

MechaMZ

Dear Russ,

I've found this, which is able to generate 150 Watts in a 10 mph wind!!

Wow!!

MechaMZ

the link is http://www.stiltman.com/html/wind_power.html

russ_watters

Quote by MechaMZ

Dear Russ,

I've found this, which is able to generate 150 Watts in a 10 mph wind!!

Wow!!

That person think's he's found a revolutionary new way to capture wind, but he hasn't. His own tests should tell him that:

We averaged 20 mph winds, which spun the wind turbine at 120 to 130 rpm, which translates to speed of circumference of the 4 ft dia. sail-disk of 17 - 18 mph, which is 85-90% of the wind speed, spinning the bicycle wheel on high gear at 52/14 = 3.7 x 130 = 481 rpm x 27” = 47 mph. There was not enough torque to turn the powerful bicycle motor (with it’s 1.25” roller and much magnetic and frictional resistance at that speed ~ when we geared down it could almost balance the friction of the motor, but we didn’t generate much power. [emphasis added]

russ_watters

Quote by MechaMZ

but how about increase the wind turbine size and with the help of gear ratio?

Yes, the physical size of the turbine is the key factor in determining how much power it can generate.

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MechaMZ	Alternator for Low Wind Speed Wind Turbine. Tweet Hi I've a wind turbine which have to run under a very low wind speed, from 2-3m/s. Currently, I'm using Envirotek V20, the result is around 1.5V-2.5V, and current is 0.3mA or nearly zero. My aim is to achieve 50W. Any suggestion for the alternator which I should use? p/s: without aided by any gear arrangement. thanks alot.

russ_watters Mentor	Are you sure you have 50W of available wind energy at 2-3m/s? The alternator's size, unless it is absurdly large, doesn't affect the output power much.