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3403 posts

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# 142984 31-Mar-2014 09:11
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Hi All

I am looking for a compact wind turbine that is professionally made (not a back yard converted washing machine)
which is compact in size.

I look at the main options and see
 - AirBreeze, $2200, 200 watts. Cant justify spending that much when i only want 50 watts of power
 - Great Watt S-700 $600, 200-400 watts, Rotor diameter 1.2m

So we have cheap and large, or expensive and still overpowered.

What I am after is a wind turbine that is smaller, and puts out less power, without being a jaycar learning cheap plastic kitset and one that I can get spare parts for - which excludes the washingmachine conversions you occasionally see on trademe.

Because I only need 12v 30 to 50 watts I would hope that there is something on the market in NZ with a rotor diameter less than 75cm

I did however see along the hutt valley expressway near melling? there is a weather station of some sort with a mini turbine on top that looked perfect - but I couldnt get a photo of it on streetview later - spotted it a little too late to take a pic with my camera.

Has anyone got any suggestions of a model?




Ray Taylor
Taylor Broadband (rural hawkes bay)
www.ruralkiwi.com

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2130 posts

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  # 1015827 31-Mar-2014 09:44
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Have you checked out Yachting suppliers?

And are you sure you only need 50W? you may be without generating wind for long periods, 50W doesn't sound like a lot,

Why not solar?




Location: Dunedin

 




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  # 1015853 31-Mar-2014 10:22
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andrewNZ: Have you checked out Yachting suppliers?

And are you sure you only need 50W? you may be without generating wind for long periods, 50W doesn't sound like a lot,

Why not solar?


This is a backup to solar - I have a 120 watt panel below the pole that the turbine is mounted on.

Looking at the local sunlight hours charts, it drops to 4 hours per day in the middle of winter.
The battery bank has 5 days of power (to 50% SOC), but it takes 26 sunlight hours which is up to 6 more days, before it will be back up to 100% SOC

So I was thinking I would suppliment it with a small wind turbine so if we get a windy day or night during a period of successive overcast days, it will be enough to give the batteries a bit of a topup since the load is only 25 watts.

Plus the batteries will last longer if they are discharged less in each cycle.

The yachts in the local marina all seem to use the AirBreeze marine model




Ray Taylor
Taylor Broadband (rural hawkes bay)
www.ruralkiwi.com

There is no place like localhost
For my general guide to extending your wireless network Click Here




 
 
 
 


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  # 1015860 31-Mar-2014 10:42
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I'd be interested to hear what you come up with.

I was doing similar investigations a while back, I decided I'd be better off doubling the solar panel size.
My initial investigations led me to believe that you loose 80% output for winter, and 80% output in for poor weather. So in theory on a terrible winter day you should still get something out of the panels.


I have no real world experience here, but does your solar panel even cover the load in the winter on a good day? 

25W x 24hrs = 600W Daily Usage
120W x 4hrs = 480W Daily Output




Location: Dunedin

 


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  # 1015868 31-Mar-2014 10:50
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Remember that unless you've done research on an area and have the turbine about 50m high (maybe more) you'll only generate an average 20-25% of it's rated power, so about 200-300w would be required. try Trademe or even alibaba if you're alright with importing.

(the most efficient wind farm in NZ runs at an average 46% of rated load, the average NZ wind farm is at 42%)

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  # 1016073 31-Mar-2014 15:45
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I know you probably want to buy something, but how about a car alternator with a vertical turbine blade?  There are lots of interesting design, check out Google Images for "vertical wind turbine".  An alternator will directly charge a battery and is designed for lateral force on the bearing.




You can never have enough Volvos!


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  # 1016253 31-Mar-2014 22:07

Problem with a car alternator, is that alot of them need to have a small amount of electricity fed into them to initially power the field coil before it will start producing power. That's why alot of alternators require a connection to the cars ignition power circuit. And the ones that don't get this initial power via the "battery" warning light circuit.


And will a wind turbine spin an alternator fast enough for it to produce any useful power? And if it does, in high winds the alternator might over rev and destroy your wind turbine. This is because the voltage regulator in the alternator reduces the field current with increasing RPM. Which means less torque is required the higher the RPM. (assuming constant load on the output)

Normally wind generators are setup to not have any voltage regulation. Higher wind speed means ever increasing output voltage and current. And a shunt circuit is installed to drain off (waste) any excess energy to prevent the battery's from being overcharged.

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  # 1016270 31-Mar-2014 22:49
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Most common car alternators will go to 12,000rpm max, but need a supply voltage to excite them. Exactly as you stated.

Some commercial truck and marine alternators are self exciting. most will go to 6000 rpm. most regulators in these kick in at 1400 to 2000 alternator rpm.

You can purchase a smart regulator to start charging at a lower RPM, but this needs a power supply to excite it. The alternator tends to kick in like a switch, on or off, so your wind turbine may stall as it kicks in.

Some people have used a generator and voltage regulator off a small Kubota garden tractor. AC output about 36v that the regulator concerts to 14.4v DC.

Cheers
Darren

 
 
 
 


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  # 1016271 31-Mar-2014 22:50
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I was thinking about the field current just after posting.  Could have a "wind detector" switch (tiny turbine, or pendulum) to connect the field when there is sufficient wind.  Not off-the-shelf, but not hard either.

A normal turbine is the only power generator so you need to optimize that design.  However, this is for top-up generation when there is not enough sunlight (and likely decent wind due to rainy weather).

If a car engine runs at up to 6 000 RPM and the pulleys are about the same size, then let's assume the alternator also runs at up to 6 000 RPM.  Suppose the maximum wind speed is 130km/h.  That's 130 000 / (6 000 x 60) = 36cm per revolution.  Typical wind speed of 1/4 to 1/2 of that (30-60km/h) will be a good operating point.




You can never have enough Volvos!


gzt

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  # 1016290 31-Mar-2014 23:42
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raytaylor:I am looking for a compact wind turbine that is professionally made (not a back yard converted washing machine)

OTOH the design has been thorough multiple iterations and there are people around doing it for a while semi-commercially. A good product at the right price from an experienced builder might be worth looking at.

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  # 1016291 31-Mar-2014 23:42
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The major issue with home built devices is that voltage typically increases with speed. Commercial units include regulators to keep the output at the desired level and increasing the current.




Location: Dunedin

 


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  # 1016307 1-Apr-2014 05:47
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I wonder if the weather station thing was a generator or just a wind speed sensor?

Yeah the AirXMarine generators are expensive but one feature I like is auto-feathering of the blades in strong stormy winds. I think they are wound for 3 phase to it's rectifier so it can provide more power.

I've seen cheap china units that the local auction house used to sell, but I know what you mean... they inclinde to be big and have a rather high cut in speed requirement too.






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  # 1016990 2-Apr-2014 09:11
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andrewNZ: The major issue with home built devices is that voltage typically increases with speed. Commercial units include regulators to keep the output at the desired level and increasing the current.


I'd be using an MPPT regulator so voltage increase usually can go up to 100v and still be okay




Ray Taylor
Taylor Broadband (rural hawkes bay)
www.ruralkiwi.com

There is no place like localhost
For my general guide to extending your wireless network Click Here




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  # 1016993 2-Apr-2014 09:21
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I work in MW scale wind and to be honest, these days small scale solar beats the pants of small scale wind.  You could probably buy several times the capacity in solar as you would in wind, and there will be less maintenance issues as well.  Unless you have a well sited site (e.g. on a hilltop) small scale wind turbines will struggle to make anything useful.  Even our wind monitoring masts are solar powered. 

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  # 1017009 2-Apr-2014 09:52
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We've tried the converted alternator thing.
Planned as cheap (made from surplus stuff) and simple, in the search for efficiency and survivability it fast became more complex & unwieldy.
We had Blade, hub & bearing failures. Introduced Geared drive, self furling, and other modifications as we went along. Spent many, many hours on it, modifying things, calculating outputs, averaging windspeeds..
It was all very interesting & there's a ton of good ideas on the internet but, I'd say OP's plan is the best - with one caveat - Completely Oversize it.
Buy a small commercially manufactured turbine. Try those small marine ones, you get what you pay for.



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  # 1017017 2-Apr-2014 10:07
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We have a chinese unit at another site which I purchased from the local importer as a test.
But the pole that we engineered to mount, vibrates in wind because the blades dont seem to be balanced properly.
The locking bolt for the blades on that unit was reverse threadded, so as the turbine spins, it can only tighten the locking nut (in theory)

 

Anyhow, a week after we put it up, the blades were found in the next paddock. So i have used loktight paste and it seems to be holding them on well. But I would rather use something that is smaller.

For this project I ended up deciding to use 2x 120watt solar panels and this vertical unit.

http://www.amazon.com/WGV75-12V-Vertical-Turbine-Generator/dp/B00BTWBX6I/ref=sr_1_1?ie=UTF8&qid=1396383390&sr=8-1&keywords=vertical+wind+turbine


Not sure if the controller is mppt but it should be enough to do what we need it to.

Load is 24 watts
24x hours of load = 576 watts
4x hours of sun = 960 watts
6x hours of overcast @ 20% = 288 watts
Battery bank = 480ah @ 12v or 2,880 watts usable to 50%

Which means there is 10 days of overcast weather capacity and 12 sunlight hours to recharge back to 100% (3x days at 4 sun hours per day)
The wind turbine will add a bit of a boost so the batteries are kept at a slightly higher state of charge during an overcast period as the batteries last longer if each daily discharge cycle is shallower.

Will let you know how the vertical turbine is working out in a few months.




Ray Taylor
Taylor Broadband (rural hawkes bay)
www.ruralkiwi.com

There is no place like localhost
For my general guide to extending your wireless network Click Here




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