Question from newbee (drain pipe turbines)?

[David O'Daniel]

Just glancing over your group & not read nearly enough yet perhaps but I
hope that the group won't mind a newbee posting.

I have questions on several things but for now, I'll stick to just 1.

I had seen a show on China (perhaps now several years ago) where rural
people would have a pipe that they would put in the nearby river or
stream to make electricity, where they were too far from the city grids
to have electricity otherwise. My guess was that they were some version
of a water-screw turning some generator inside. From what I recall, it
looked like a round pipe, maybe 5" wide and 3' long, and assuming a cord
running from it to the farmer's house (but I may just be assuming that &
visualizing it out of my expectations but can't truly say for sure that
I clearly remember a connecting cord/wire but it just has to have had
one).

Anyway, they were said to be cheap, esp if some farmer in China who may
make $3 a week or whatever ridiculously small amount, could still afford
them, I'm thinking that they could be cheap enough for anyone to buy. Or
they maybe were donated by the Chinese government otherwise,

Has anyone else hear of these water pipe type generators or know what
I'm even talking about as existing? Can they be gotten in the USA and
couldn't they be used in any building's drainage/rain pipe?

Yes, if so, they would only be working during strong rain-storms. It
seems though that such times are when the normal electric power tends to
go out, not during sunny weather. Also, for backups to solar panels
during cloudy/rainy weather. (Similar argument could be said of wind
power with more wind during times of storms when the clouds would reduce
solar).

For now though, anyone heard of these devises? I'm not sure if just rain
water runoff would be enough to make them work, not being nearly as
strong as the flow of a stream but maybe they could power a small bulb
during a blackout, if nothing else. Just wondering though.

Thanks for help/responses.


David
(AKA Bo)

 

[Scott]

I have to say I never heard of such a device. Though they're cunning
these Chinese. However it works, there's not going to be a great
amount of power avilable from any such a device. You'd be lucky to
get 20watts I would think. Keep a small light bulb going.

Depends on what you're using it for. A continuous 20-watt supply would be
enough to cover *all* of the daily power needs in our small RV. We spend a
lot of time camped not very far from a fairly swift river, in a shady spot
where our 130-watt solar panel can't really cut it. If I could buy an
easily portable 20-watt water wheel for a good price, it would be *well*
worth trying!

 

[David O'Daniel]

?Goog?, though yes, upon googleing archimedies water screw & electric,
there was one idea to use the idea for apparently the escaping gases
(smoke) from I think factories, to generate electricity. I just glanced
over the listings though.

Pondering it, I was wondering if, not just the area water was collected
from (roof size draining down into it) = volume of water, but then also
the length/height of the screw & pipe it is in. The gas idea would have
the force upwards, reversed, of course. Still, it seems that, given the
volume of water or just say the mass, the force could be calculated for
the initial surface impact (like basically a windmill), but unless the
waterscrew has so much tension/resistance on it that the water doesn't
push down on it enough to turn it, after it would produce the force to
turn the screw in the initial area, it would continue to run down the
surface of the screw. The tension would need to be adjusted so that the
length doesn't create more resistance than the force it would add into
the system. If then longer always = more fore pushing down, gravity
pulling on the water, then rather than a windmill type sheel, it would
be better to have a long pipe. Wind might loose horizontal energy but
I'm not sure gravity would ever run out vertically. Even the buoyancy of
gas, vertical perpetual energy as long as the resistance is less than
the force turning the screw.

Shouldn't this work? Shouldn't such systems be most useful running down
through high skyscrapers vertically & instead of one line of water-dam
turbines, a system the length of a whole river perhaps, if the water out
is still being pulled forward/down by gravity just as much as it is when
the water enters the system?


Bo

 

[Scott]

On Sun, 4 Oct 2009 03:35:57 -0500, in alt.energy.homepower,

?Goog?

Sorry, that's a flag that my usenet filter attaches to articles originating
from Google Groups, I just forgot to remove it on the followup.

Shouldn't this work? Shouldn't such systems be most useful running down
through high skyscrapers vertically & instead of one line of water-dam
turbines, a system the length of a whole river perhaps, if the water out
is still being pulled forward/down by gravity just as much as it is when
the water enters the system?

Without knowing exactly why, it seems to me that an Archimedes screw isn't
really going to work all that well in reverse. A plain old Pelton wheel
would seem a better place to start.

 

[David O'Daniel]

<Scott wrote>: "Without knowing exactly why, it seems to me that an
Archimedes screw isn't really going to work all that well in reverse. A
plain old Pelton wheel would seem a better place to start."

Looking up "pelton wheel" briefly, it seems to be just a more efficient
paddle-wheel with the wheel facing parallel to the water-flow. Though a
series ow wheels along a river or vertically down a building seems that
it would get energy out of the down-flowing/falling water, it also seems
that they would take up a heck of a lot of room & materials, with each
then connecting to either individual dynamos or to a gear-combined
single shaft that would make timing of each wheel a factor. Seems a lot
more complicated than a single screw 10s or hundreds of meters long
turning the single shaft it is built around.

If the water actually slows, wheels would need to be spaced to optimal
distances to catch the water after it gains energy again (according to a
bit of one article on the Pelton wheel).

In any case, again though the Chinese did it years & maybe a decade ago
in the outward form of a pipe somehow. Somehow extremely simple, mobile
& compact. As far as I know though, inside that tube could have been a
tone of complex technology rather than the simple, millenia old
technology. May be a long (or arguably, "wide") Pelton wheel turned
face-on into the water like a jet-engine turbine or some rotating air
vents on top of ventilator shafts of buildings but then it would be
becoming a version of a screw again. Anyway, just speculating.


Bo