They are good but you don't always have good wind. Good add on though for solar.
Small wind turbines no longer worth it?
- Thread starter rhino
- Start date
OzSolar
Whatever you did, that's what you planned.
I've yet to bump into someone that can make this statement after more than 12 months of actual experience with small wind. Please share the make and model of small wind turbine you are referencing.
12VoltInstalls
life passes by too quickly to not live in freedom
I can’t speak to whatever he meant but the small hand-wound vawts that do milliwatt output can work down to as little as 6mph winds. But that’s milliwatt output! Wind only works where it works- and in northern New England that’s not all the time , for sure. There’s like 14 450’ tall turbines less than a mile from me on a pretty high ridge; they don’t turn all they time.
Yaetek and not 12 months try 5 years. And it's still keeping my battery at 13.2 volts. I'm not using it for a inverter or running home electricity. It runs some lights in the work shop and maintains the battery that's as far as I have needed it for now. Now any more than that and I would go on up on the watts with a bigger turbine.
Several years ago I had a Windtura 750w. It was seemingly well built except the cheap 3 wire slip ring. It was more of an experiment to see if it would do anything to help me on on days when panels were covered in snow and cloudy. It barely did anything in the low constant winter winds. Would get some positive input with large gusts to my 24v bank. Then after a few years the rotating slip ring seized and a huge storm broke the top of my mast off and it crashed down, bent up the blades. Its still there on the ground, im sure the heavy 3 phase generator is still in good shape. Waste of money and a learning experience. I could see it somewhat working if you were in a very constant windy area and put it way up on a super strong mast.
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OzSolar
Whatever you did, that's what you planned.
$2,000 for 20kWH per month vs. $2,000 for 200kWh per month?
I've seen several Yaetek's and NONE of them worked. One of the many cheap knock off's of the already cheap SWP Air 4XX. I saw plenty of those and they all self destructed within months but if they didn't they never produced any significant energy. When compared to the cost and reliability of solar small wind can look pretty ugly.
A 20 watt solar panel would keep a few lights going here and there.
If we ignore that very few Yaetek's (or SWP Air 4XX) will work for 5 years we can then take a look at at the math. It doesn't look like you can buy the Yaetek's anymore by the way.
To purchase something like that turbine today from Primus plus the shortest tower kit (10m) which would be ineffective at 99% of sites plus sourcing the locally required pipe for the tower you are at least $2k and best case will produce 20kWH per month. Some day's it might produce 2 KWh but most days it will produce nothing.
Put that same amount of money into solar and you'll get at least 190 kWh's per month of actual usable and predictable daily energy plus a 25 year warranty on the modules.
I just think it's interesting to actually look at the numbers for small wind.
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I was lucky on the pipe part my cousin owns his own welding shop. It's on a 30 ft pole do $80 he had some leftover of the 1/2 wall pipe from a boat mourning dock. It's not dependable it's just a hobby for me. I agree solar for serious power is more reliable and a better investment. I did notice the yaetek is not available anymore. Back when I bought it was $99 so I wasn't expecting to much.
brandnewb
Going for serious. starting as newb
it's only a hassle because there is nothing open source yet that actually does what it is designed to do.
I hope to be the first to offer that so hang tight for a decade or 10 as I keep running into issues that hinder prototyping.
But once complete the world may benefit
OzSolar
Whatever you did, that's what you planned.
That's cool. Wow! $99 and still plugging away! That thing deserves a spot in the secret safe with the 500MPG carburetor.
If you have low expectations and low costs from wind that's completely different thing then what I'm constantly warning people about. Keep us updated please!
brandnewb
Going for serious. starting as newb
hahahhahhaha brilliant
and in some ways also disheartening as I am hoping there is some hope for everyone to have some benefit from the wind in the future.
I would like to get a wind turbine just to get maintenance power when I am not at the cabin over the winter when I litterary get zero sun production for at least 3 months. 100 watts per day on average if I am away for say 50 days in a row, is a heck of a lot better than zero.
What kind of gear would it take to get that? I have good wind conditions, the cabin is on an island right at the shore.
What kind of gear would it take to get that? I have good wind conditions, the cabin is on an island right at the shore.
OzSolar
Whatever you did, that's what you planned.
Take a look at Hugh Piggott's blog. His plans will help you build a very solid turbine that will give you years of service.
If you want to buy a turbine "off the shelf" that might give a few watts here and there take a look at the Primus turbine which is based on a design from SWWP. Below is thier energy chart but cut that monthly production by at least 50% when making a decision about this. IE: the best that turbine will do at 6 m/s site is 15kWH per month.
brandnewb
Going for serious. starting as newb
ok, you sound like you have favorable wind conditions.
My current status quo in terms of battle plan is like this;
* Check out local code and see the maximum allowed turbine diameter.
* Check out local avg wind conditions. One can try and find a near community station at for example windly.com. But the more nothern one gests it might get less populated with stations. In the worst case buy your own weather station. It's not too expensive.
* check out if there is anything reasonable to be expected here, in terms of power generation potential using the local code restrictions and the avg. wind speed.
*If favorable then plunge in, you can join me in this endeavor
* start with the turbine. Do measurements that I do not know about yet. I am learning as we speak.
* then design your alternator to match. I for one did it all wrong and started with the alternator out of some prestige thing. Have no fear though. If one needs a brutal alternator then I can be of service.
I posted the below in another thread, but I's probably worth repeating. In addition, since @Messier11 is in a cold climate with substantial snowfall/freezing temperatures you also have to deal with the turbine freezing up, getting locked because of all the snow. If this is all known and you still want a turbine, go with the numbers @OzSolar mentions.
Wind doesn't scale to small turbines. You're dealing with two fundamental issues:
- The Betz Limit
- The Power in Wind equation
The Betz Limit is basically a theoretical number of the maximum efficiency you can possibly get. At most, only 59.3% of the kinetic wind energy can be used to spin the turbine and generate electricity. Remember this is a theoretical limit; in practice, you're going to be closer to 40%.
The Power in Wind equation is given as:
P = 1/2 x ρ x A x V³
Where:
P = power in Watts
ρ = air density (kg/m³, at about 1.2 at sea level)
A = Swept area of the blades (m²)
V = Velocity of the wind
So, no matter how good your turbine is, you will get in practice at most 40% of the wind energy converted to electricity. To capture the wind energy in the first place, you have two variables to increase (one in your control, the other not): swept area and wind velocity. The smaller you make the turbine, the faster you need to spin to make any meaningful energy. The only variable you control is the swept area, which means making the blades as big as possible. Also notice that the velocity is cubed in that equation, so you'll generate much, much less power at low wind speeds; don't assume this is linear or even exponential!
In other words, it doesn't work because physics.
Wind doesn't scale to small turbines. You're dealing with two fundamental issues:
- The Betz Limit
- The Power in Wind equation
The Betz Limit is basically a theoretical number of the maximum efficiency you can possibly get. At most, only 59.3% of the kinetic wind energy can be used to spin the turbine and generate electricity. Remember this is a theoretical limit; in practice, you're going to be closer to 40%.
The Power in Wind equation is given as:
P = 1/2 x ρ x A x V³
Where:
P = power in Watts
ρ = air density (kg/m³, at about 1.2 at sea level)
A = Swept area of the blades (m²)
V = Velocity of the wind
So, no matter how good your turbine is, you will get in practice at most 40% of the wind energy converted to electricity. To capture the wind energy in the first place, you have two variables to increase (one in your control, the other not): swept area and wind velocity. The smaller you make the turbine, the faster you need to spin to make any meaningful energy. The only variable you control is the swept area, which means making the blades as big as possible. Also notice that the velocity is cubed in that equation, so you'll generate much, much less power at low wind speeds; don't assume this is linear or even exponential!
In other words, it doesn't work because physics.
brandnewb
Going for serious. starting as newb
ok, I'll admit I have never taken into account yet freeze conditions yet. ;(
I am not giving up on turbines just yet though.
We here in the NL have not had a good freeze for a while. Last I remember was -20C that lasted for like 4 days. Since then it is getting less cold and less cold
I am not giving up on turbines just yet though.
We here in the NL have not had a good freeze for a while. Last I remember was -20C that lasted for like 4 days. Since then it is getting less cold and less cold
brandnewb
Going for serious. starting as newb
Yes that is indeed how it looks yes? But can you please apply a bit more nuance?
For example, from what diamater do the physics start to give hope? We are investing alot in wind parks after all so there must be some kind of a tipping point.
brandnewb
Going for serious. starting as newb
to check out what could be a reasonable expectation one can check out this
www.omnicalculator.com
you\ll need your local code max diam and avg wind speed though
Wind Turbine Calculator
The wind turbine calculator finds the power output, efficiency, RPM, torque, and revenue of a wind turbine (either HAVT or VAWT).
www.omnicalculator.com
you\ll need your local code max diam and avg wind speed though
brandnewb
Going for serious. starting as newb
and that is why I am suggesting that people with large pieces of land with little to no local codes, given there is wind, can fully utilize it.
But then again I have never taken into account the freeze aspect yet
But then again I have never taken into account the freeze aspect yet
Of course - which is why I deliberately stated 'small wind turbines'. Wind makes sense on large scale, large turbines purely because it is the only variable you control in the formula. Let's do the math:
P = 1/2 x ρ x A x V³
Let's assume we have a constant 10mph (4.5 m/s, 16km/h) wind. The average in Sweden is 7 to 8 mph.
First, let's take a 'small' wind turbine with a blade length of 2 meters, swept area becomes r² x pi = 12.5 m². Putting the numbers in the formula this gives:
P = 1/2 x 1.2 x 12.5 x 4.5^3 = 683.5W -> this is the theoretical available wind power.
Now, from your link we can see that the actual efficiency μ is somewhere in the region of 30%. In every case, even a magical turbine, gives you an absolute maximum efficiency of 59.3% - the Betz limit. Let's assume we have the highest real efficiency of the very best turbines - 40%.
This means that our small turbine has a maximum output of around 274W.
Let's double the blade length to 4m. Thanks to the exponential in the area calculation, we get a swept area of 50m². Keeping everything else the same, we get a theoretical max power of 2734W, and a realistic output of 1100W. So, by doubling the blade length, we get a 4x power increase.
Now let's increase the wind speed slightly. Assume we have a decent pole to put it on, and put it where we get a 15mph wind (6.7m/s, 24km/h). For our small turbine, we now get a theoretical power output of 2256W, or 902W realistic. For our larger turbine, we get a theoretical power of 9023W, or 3609W realistic. So by just having an additional 2m/s wind speed, we increase the output by a factor of 3.
Now, to put this into perspective: one of the smallest commercial wind turbines you can get today has a blade length of 7.5 meters. A typical 1MW turbine sits around a blade length of 30 meters.
brandnewb
Going for serious. starting as newb
so, sorry to put is so bluntly, you are still 99.99988% convinced that my projects as wel as this thread\s premise is doomed to fail?
brandnewb
Going for serious. starting as newb
for all readers here. What our good friend is doing is correct.
Smacking some sense in our brains and expectations.
However, never stop thinking outside the box.
Imagine if Albert Einstein never did?
Smacking some sense in our brains and expectations.
However, never stop thinking outside the box.
Imagine if Albert Einstein never did?
I'm following your progress and want to see what you come up with and what the results are. That's also why I'm not arguing against what you're doing in your thread, and I support your endeavor. This however is the thread "Small wind turbines no longer worth it?", and I'm just posting my arguments as I did in the very first reply to OP in this thread.
brandnewb
Going for serious. starting as newb
I am just a dumb ass. Which wishes I had a big piece of wind flud land in a rural area so >I could build a 10m diameter turbine.
Then things would start to change yes?
Then things would start to change yes?
brandnewb
Going for serious. starting as newb
ugg. you are correct, point taken. totally the wrong thread for my rambling.
OzSolar
Whatever you did, that's what you planned.
While were on the subject of rants.
The big font is the point I'm trying to make and what follows is my own ramblings.One nuance that is rarely if ever talked about with small wind is that you will get almost of all your monthly energy in a short period of time and if you're off grid your batteries will quickly be full and you'll end up wasting most of it.
And that's assuming you've got a wind turbine that's working to factory specs which you don't because there's never been one made that does.
If you've ever lived with a commercially made small wind turbine AND actually monitored it what you'd see is that your turbine might be spinning but it's making almost no usable energy most of the time. The real world cut in wind speed for most machines is a very STEADY 12 mph. I wish I still had all of that old data to show you but it was stunning. All of the Bergey 10's that I monitored averaged 5 to 10 kWh per day but could shoot up to a 120kWh on the windiest days. This is a wind turbine that is rated to do 13,000 KWH/year at a 12 mph site. That's 35 kWH/day.
I'll stop here but the short version of the story is that Bergey has been getting away with some very serious overstatements (flat out lies) going on 4 decades now and they are supposedly making the best turbine ever made. They've been the recipient of 10 of millions of dollar in grants and have had a small army of degreed engineers working on thier turbine for decades it still sucks.
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