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Wind turbine a starter question rsegoly 02-25-2008
Posted by Gordon Richmond on February 26, 2008, 2:12 pm
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>This design seems to be of interest. It accepts wind from any
>direction and handles turbulent wind quite well. It makes absolutely
>no noise. i.e. 0 dB. It cannot reach overspeed like other convention
>wind turbines. Once it reaches it's designed speed, all excess
>airflow simply flows around it. The downside is that they are
>relatively expensive at $5,000 per unit. So, I have decided to make
>the attempt of building my own. The biggest challenge will be
>balancing the entire unit to minimize any vibrations. I've started my
>project by purchasing three 12 foot sections of three inch diameter
>black plastic plumbing pipe. I've cut these sections into 4 foot
>lengths. I will then cut each pipe lengthwise into three equal width
>blades. I should then have 27 curved plastic blades to begin my
>project with. So, far the total cost has been $69. I estimate no
>more than $500 for my entire project, which means that I can build ten
>units to match the cost of one professionally built unit. I'm an
>adventurous sort of fellow, so here goes...
http://www.youtube.com/watch?v=q7ffNWkefyY
>
>> Hello,
>>
>> Sorry for being layman but I am just starting to look at this topic.
>>
>> Is there any good article or site summarizing implementations and
>> existing solutions, for home wind turbine (a turbine which can mounted
>> on a roof with reasonable cost).
>>
>> I'd like to see beyond the actual solutions approach from different
>> governments, and cost studies, as we starting to look at this topic
>> today in my country.
>>
>> Any link and direction will be appreciated.
>>
>> Roni

You might want to Google for "Savonius Turbine", as it sounds by the description
of your
project that it will become one such.

There have been endless discussions here about various kinds of wind turbines. I
think the
consensus is that the "propellor-style" are vastly more efficient. Much harder to
hand-build one as a "one-off" due to the complex shape of the blades. Savonius
are much
less efficient, but easy to build as a DIY project.

I think you will find that a Savonius rotor that narrow (made of 4" pipe) wil
spin very
prettily in a strong wind, but develop almost no torque.

Gordon Richmond

Posted by Buy_Sell on February 27, 2008, 7:01 pm
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 Gordon, I'm guessing from your post that you have misunderstood what I
am trying to explain. Here is another video of a racecom type VAWT
working side by side with a savonius type wind generator. You be the
judge. The best comparison to this design would be the whirly bird
ventilators that you see on the roofs of some houses.
http://www.youtube.com/watch?v=0KVaVNTGh2s&feature=related

> >This design seems to be of interest. It accepts wind from any
> >direction and handles turbulent wind quite well. It makes absolutely
> >no noise. i.e. 0 dB. It cannot reach overspeed like other convention
> >wind turbines. Once it reaches it's designed speed, all excess
> >airflow simply flows around it. The downside is that they are
> >relatively expensive at $5,000 per unit. So, I have decided to make
> >the attempt of building my own. The biggest challenge will be
> >balancing the entire unit to minimize any vibrations. I've started my
> >project by purchasing three 12 foot sections of three inch diameter
> >black plastic plumbing pipe. I've cut these sections into 4 foot
> >lengths. I will then cut each pipe lengthwise into three equal width
> >blades. I should then have 27 curved plastic blades to begin my
> >project with. So, far the total cost has been $69. I estimate no
> >more than $500 for my entire project, which means that I can build ten
> >units to match the cost of one professionally built unit. I'm an
> >adventurous sort of fellow, so here goes...
http://www.youtube.com/watch?v=q7ffNWkefyY
>
> >> Hello,
>
> >> Sorry for being layman but I am just starting to look at this topic.
>
> >> Is there any good article or site summarizing implementations and
> >> existing solutions, for home wind turbine (a turbine which can mounted
> >> on a roof with reasonable cost).
>
> >> I'd like to see beyond the actual solutions approach from different
> >> governments, and cost studies, as we starting to look at this topic
>

>> today in my country.
>
> >> Any link and direction will be appreciated.
>
> >> Roni
>
> You might want to Google for "Savonius Turbine", as it sounds by the
description of your
> project that it will become one such.
>
> There have been endless discussions here about various kinds of wind turbines.
I think the
> consensus is that the "propellor-style" are vastly more efficient. Much harder
to
> hand-build one as a "one-off" due to the complex shape of the blades. Savonius
are much
> less efficient, but easy to build as a DIY project.
>
> I think you will find that a Savonius rotor that narrow (made of 4" pipe) wil
spin very
> prettily in a strong wind, but develop almost no torque.
>
> Gordon Richmond


Posted by Gordon Richmond on February 28, 2008, 1:56 pm
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>Gordon, I'm guessing from your post that you have misunderstood what I
>am trying to explain. Here is another video of a racecom type VAWT
>working side by side with a savonius type wind generator. You be the
>judge. The best comparison to this design would be the whirly bird
>ventilators that you see on the roofs of some houses.
>http://www.youtube.com/watch?v=0KVaVNTGh2s&feature=related

Interesting video, but I don't know if it proves anything. We saw the two
turbines there,
the Savonius stalled, and the squirrel-cage job slowly spinning. The operator
walks up,
stops the latter with his finger-tips, and moves the other with his other hand,
IIRC.

What do I take away from this? First, possibly the only reason the Savonius
wasn't turning
is that it is a little shorter than the other, so has less effective capture
area for the
wind at that location; second, that the actual energy being captured by the
squirrel cage
rotor is very slight at that wind-speed, since the operator was able to stop it
with so
little effort. Tells me that the difference between the two rotors MIGHT be
explained
solely by a difference in static friction in the bearings. Or, conversely, the
squirrel-cage rotor MIGHT be slightly more efficient than the Savonius in very
light
winds.

Problem is, there isn't very much energy available to be taken out of very light
winds.
You'd need an extremely large rotor to get useful power out faint breezes like
that
depicted in the video. A large rotor means expensive to build, and it will
require a
strong supporting structure. Even if it is inherently resistant to overspeeding,
it still
has to resist the sideloading imposed by strong winds.

And you really don't want to use an auto alternator as a component of a wind
generator.
Cheap is the only thing they have going for them. They have a DC field, which
means a
constant power drain to energize the field; permanent magnets are much better.
They are
also, by design, high-speed devices. Look at one installed in a car; it may have
a 2-inch
pulley on it, belted to a 6-inch pulley on the engine's crankshaft. At about 800
RPM idle
on the engine, that alternator is turning 2400 RPM, and is just getting into its
sweet
spot. Most wind devices don't turn anywhere near 800 RPM, so you would have to
use even
more gearing to get the RPM up to where a car alternator would put out, and
gearing adds
friction, and reduces efficiency.

Folks here will tell you that a permanent magnet DC motor as used in exercise
treadmills
makes a very good choice for a windmill dynamo. I see discarded treadmills in
the Trochu
dump every few weeks or so, so I could get me a motor for free if wanted one.
(yeah, I'm
not that far outside Calgary myself) Or you could go to Princess Auto and find
any one of
a number of small DC motors that would be appropriately sized for your prototype.

I'm not trying to disabuse of the idea of building a VAWT, just trying to
suggest that you
be realistic in your expectations. Perhaps a large row of cheap, dumb, homemade
VAWTs
might give more power for less investment than one commercially-made
propellor-type.

Gordon Richmond

Posted by Buy_Sell on February 29, 2008, 3:25 am
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Nice to hear that you are in the neighborhood, Gordon. I've collected
many permanent magnet DC motors from the metal recycling yards. Oddly
enough, most of them were still fully functional. It makes you wonder
why people throw things away? I've brought home a 240volt DC elevator
motor from Calgary metals. This beast weighs 525 lbs. and it produces
electricity even if I kick it over with my foot. I purchased it for
$100. I can get it to motor with only a 12 volt battery.

I've often wanted to build a dome house and I had the idea of mounting
this motor vertically at the peak with a huge whirly bird turbine that
covered the entire outside of the dome house. Now, that would be one
heck of a wind generator. When it was spinning, you would still be
able to view out the windows. I have no expectations of wind power
but with the wind always blowing, I just can't leave this form of free
energy alone. Wind machines can be built from inexpensive recycled
components. I can't say the same for PV. I do own four PV panels
that are approximately 1 foot X 4 foot in size each. I use them
mostly for keeping my vehicle batteries charged up all the time.




Posted by J Chace on February 28, 2008, 1:07 am
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Hi Roni
Are you in a sunny location? You ask about mounting on a roof. That would
limit you to a small wind machine, and even that is not going to work very
well as the machine would be too close to the roof and wind interference
would limit your already small machine to very disapointing results. And
unless you are in a exceptionally good wind site, and a dismal sun site, you
would get much more power from PV. Wind gennies seem cool and good, but I am
in a pretty good wind area, and when my small machine threw its blades in
the last storm around 6 months ago, I have not even bothered to lower the
tower and replace them, as I get over 95 % of my electrical charging from my
280 watts of PV, a relatively small PV setup, which totaled around three
times the cost of my 500 watt turbine. In areas of good sun and average wind
speeds, think PV first for real electrical generation and a wind generator
(unless it is a big one, with a costly tower) as a added bonus for
OCCASIONAL boost during high wind occurances. And I would forget about
mounting on a roof completely in any case. Sorry this is not really an
answer exactly to your specific points and strays from the topic a bit, but
hope it helps clear up some common misunderstanding (you are not alone, we
were all in love with them at some point) about the value and good
application of small wind turbines. I do miss it at times though during
cloud windy days and nights and must get to fixing it soon. it is a good
BONUS power source, unpredictable as the wind, but SOMETIMES helpful. In my
sunny location, I can count on my PV but get little from my wind turbine.
Good luck.
Jeremiah

> Hello,
>
> Sorry for being layman but I am just starting to look at this topic.
>
> Is there any good article or site summarizing implementations and
> existing solutions, for home wind turbine (a turbine which can mounted
> on a roof with reasonable cost).
>
> I'd like to see beyond the actual solutions approach from different
> governments, and cost studies, as we starting to look at this topic
> today in my country.
>
> Any link and direction will be appreciated.
>
> Roni



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