designer
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| posted on 3/11/11 at 09:43 AM |
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Wind power
I am an electric numpty, so the question is: are these any good?
Missouri General 1600 Watt Wind Turbine Generator 12volt 11Blade 3 phase output | eBay
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Bluemoon
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| posted on 3/11/11 at 09:55 AM |
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Not sure but looks like the kind of thing that will not last long in the UK's wet and humid atmosphere...
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cliftyhanger
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| posted on 3/11/11 at 10:38 AM |
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1600 watts, at 12 V. That is massive! Current must be 125A, not sure how 3 phase works, but guess it means 40A a phase??
Looks very interesting though.
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hughpinder
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| posted on 3/11/11 at 02:59 PM |
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The power you can get from the wind is proportional to the swept area and wind speed cubed. The standard ones with 3 blades extract a large proportion
of the theoretical enegy, and I dont believe a 11 blade design will get much more. The link posted gived a power output at certain rpm, but does not
link that to the wind speed you need to get xxx rpm. A 5 ft turbine like the one there would have to be in a gale to produce 1600W, I did some aspects
of the design had been quite well done though. Note: wind speed increases 20% for every doubling of the height above the ground (approximately), so a
tower 2.5* as high will give double the output for your turbine.
Have a look at some of the info on these sites:
http://www.scoraigwind.com/
http://www.builditsolar.com/Projects/Wind/wind.htm
Regards
Hugh
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BenB
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| posted on 3/11/11 at 03:24 PM |
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Well they were getting 120 amps at over 15v off three of them in a 20mph gust. The wind this year has often been in the 10-20mph range (officially in
London the average yearly wind speed is just over 10mph). Which means a single one might put out 20amps average, up to 40 in a good gust. That's
300 watts average. Not bad....
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bobinspain
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| posted on 3/11/11 at 03:39 PM |
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FWIW
I was talking to my neighbour this morning about his wind generator. We're on the Med coast around 75 metres up a mini-mountain. His mill is
elevated above his substantial property by about 20 metres. I asked if his installation was a go-er financially, to which he replied, "no
chance, but I feel I'm doing my bit." He's considered upgarading to a self-feathering, much larger unit to take advantage of the
off/onshore strong breezes we get most of the year here, (aware that power generation is a function of the cube of the wind speed). He's a clued
up bloke and having done his sums, he's come to the conclusion that it's simply not worth it on financial grounds. When the wind blows
like buggery (as it does in winter), he reckons he wont be able to capture the excess power generated without significant expenditure on other
equipment. (presumably, capacitors/batteries or whatever).
He put me off the idea of giving it a try. He's also into solar in a big way, with a big tracking array (at the side of his tennis court!)
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sickbag
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| posted on 3/11/11 at 05:00 PM |
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Not accounting for loses through friction, etc, but to get 1600 watt out you would need to put 2 HP of effort into it - that's a lot of wind for
a small fan like that.
Finally back on the job!
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twybrow
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| posted on 3/11/11 at 05:07 PM |
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Microgeneration isn't worth it unless you want green bragging rights at the pub. As said, a feather version will have a much greater optimsed
wind range compared the type proposed above.
There are efficiency improvements by increasing the number or blades on a rotor, but the efficiency is cancelled out by menas of diminishing returns,
as the cost of adding more blades goes up. Then, as you get to this number of blades, there are shadowing and other aero effects that mean the next
blade isn't in clean air, negating the need for additional blades (why do you think that all commercial turbines use 3 blades/rotor...?).
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grafter
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| posted on 3/11/11 at 05:31 PM |
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I did a Wind Power module in College so know a little bit about these and there are lots of manufacturers out there with all kinds of designs that
they claim all wonderfl things about which may or may not be true.
When considering the purchase of any Wind Turbine there are two things you need to do, the first is carry out a Wind Survey at your site @ the height
the turbine will be at (This can be done very cheaply by purchasing a wireless anemometer for about £100 on eBay) for ideally 1 year. After logging
the wind speed for this period you should then have the number of Hours the wind was at a specific speed slice for your site in the logging period.
You then get the power curve graph from the manufacturer (Expected power ouput for it at each wind speed slice) for the turbine you are looking to
purchase and you multiple the Duration (@ each speed from your survey) by the power (for each speed on the graph) to get the expected total power
output for that turbine over a 1 year period.
So you can then determine if it is worth purchasing a specific model for your site depending on your expected ouput requirements over a 1 year period.
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