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Much water is lost from open water supply resevoirs by evaporation. The problem is worsened by warm winters. One solution is to cover the resevoir, but this is impractical for large lakes.
Solution: Tip vast quantities of ping pong balls into the water. These would float on the surface, and form
a flexible covering, leading to a considerable reduction in evaporative loss.
US patent 3,401,818
http://www.google.c...s=1&as_maxy_is=2006
floating spheres to stop evaporation [xaviergisz, Dec 20 2006]
black balls in LA
http://www.treehugg...r-plastic-balls.php
used to prevent UV from creating chemical reactions in water [metarinka, Dec 22 2010]
Baked! - More black balls in a reservoir
http://www.theguard...servoir-los-angeles
[hippo, Aug 12 2015]
They are black to block UV
http://www.amusingp...ed-with-400000.html
[scad mientist, Aug 13 2015]
[link]
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I don't think this would work. The balls wouldn't form an airtight covering and I don't think they would provide much insulation. |
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What i thought this was from the title was a half-baked and bad back idea i had couple of days ago. A gutter on the sides of a ping pong table because 80% of ping pong shots miss by less than 5 inches and my back is getting blown out with the bending. |
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I don't know if this would work to reduce evaporation in practice. If the ping pong balls turn (like the point of a ball point pen), you might end up with more wet surface rather than less. |
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Still, it would look odd, and it *would* solve the ping pong ball storage problems of the world... |
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I reckon that the balls would trap a relatively stable layer of air just above the surface, which would become saturated with water vapour by evaporation. As long as the saturated air remains trapped, further evaporation will be inhibited. Condensation will occur on the undersides of the balls. If the balls rotate, I would expect the water to drain to the underside, due to the hydrophobic nature of the plastic. |
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Peter Sealy (I think) in a now deleted annotation, raised some serious environmental issues: irrigation of the surrounding area, and reduced illumination of the water leading to fish mortality. To these I would add reduced oxygenation of the water. |
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The first of these I would not see as a problem, as, presumably, the surrounding area got on quite well before the resevoir was formed. The illumination problem could be addressed by using transparent spheres. Oxygenation is a tricky one. Probably a separate oxygenation plant, in the form af a splendid fountain, would be needed. |
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What if the ping pong balls had
some sort of magnets in them
which would connect the balls
together and cease the rotation
of the balls and cover the
water a little better. and of
course they dont have to be
ping pong balls you know? not
REAL ping pong balls at least..
maybe smaller ones would work
better? |
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to counter the ball rotation you could just make them slightly heavier in one place. contacts are made that way so they stay righted. what about something other than a sphere? if they were weighted, one side would always be down and the sides in contact with the other objects could be flat. if they were triangular or hex shaped less surface would be exposed as they would lock together. |
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oh hmmmm... if one side was a bit thicker to properly orient them, and the material was right the bottom might actually act as a lens to introduce more light into the water. the only problem i see now is alage, i mean with all this extra surface for it to grow on i think it will just run amuck. so i guess that spawns another halfbaked idea: a solar powered floating craft that automaticaly scrubs the little floating things. then we could collect all the alage to feed to farm animals and or the fish down below. |
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the idea of a fountain to add oxygen back to the water defeats the purpose, as it increases the surface of the water to oxygen it also increases evaporation. |
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i think the insulation provided by the bals might prove to be an interesting poroblem, some pool covers (called solar covers) are made of a thick bubble wrap, and all these little orbs might do the same. |
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dunno, just my buck'o three on the matter. |
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If you use two different ball sizes the gap between the large balls can be filled giving better coverage. I actually think I saw this or something like it as a pool cover for solar heated swimming pools. Kept evaporation down so pool stayed warmer. |
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Thanks for reviving this idea, [Kirk]. It sounds like a nifty idea. On a large scale (eg lake powell) it would probably be impractical. However a small scale application like a cattle feed pond in the desert might be very practical. App #2 - in places like the Namib desert artificial watering holes are created to concentrate wildlife for better ecotour experiences. These balls would be perfect in this situation. You would need to make them from pith or something degradable, since some might get eaten by things that mistake them for eggs. |
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I'm sure I've seen this idea baked somewhere before... |
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Time to kick this one uptop. Instead of pingpong balls, this could be done with large chunks of styrofoam. As regards plant life, the decrease in solar radiation might be compensated by the increase in substrate for things to grow on (the bottom of the styrofoam). The foam would be in large blocks, the better to cut light. They could be partly anchored to avoid lofting up and leaving in windstorms. |
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I was thinking about this today. We're in a drought here in Australia, and something like this might help. |
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Are there any water engineers who can help calculate how much water could be saved using this idea? |
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...bah, a few thousand litres of crude oil would cover a large reservior quite well, and almost eliminate evaporation. |
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[raisin]! how come you didnt publish your idea? Its
great ([+]). |
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[Mickey] could you have ping pong tables for the
public around the reservoir, in order to build up
public acceptance of the solution? |
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this is actually baked, I think the original poster might have beat the idea to the market, but they use balls ( larger than ping pong balls, about the size of a tennis ball). They aren't intended to block evaporation so much as UV radiation hitting the water, but they do help somewhat by reducing available surface area. |
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link goes to a photo, it's used in Los angeles |
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What about using duckweed? It seems to do a good job of covering the water surface. I don't know what effect it has on illumination, oxygenation etc, but ponds full of duckweed usually seem to have plenty of other wildlife living in them, so I'd guess that it's not too harmful environmentally. |
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We use mini ping-pong balls on the surfaces of waterbaths in
the lab, for long incubations at high temperatures (up to
95°C). They do greatly reduce evaporation. |
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Like normal ping-pong except for the cars. |
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spheres are the wrong shape for this. What you need is a bunch of floating triangles, squares or hexagons. if there's enough of them they should self-organise |
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I do enjoy asking how many ping pong balls will fit in a school bus while I'm interviewing candidates. |
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The answer doesn't matter as much as the look on their face and how they choose to respond. Basically what I'm looking for is the ability to respond constructively when faced with unplanned circumstances. |
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//if there's enough of them they should self-
organise// Hasn't worked for Labour. |
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I'm surprised they went with black balls. Were they cheaper?
From the photograph they look like they're 70-80 mm range
and apparently 36 cents each. Bulk ping pong balls from
Amazon are only 6 cents each. With ping pong balls you
cover about 91mm2 whereas the balls they're using are 380
mm2. That's 0.066 cents per mm2 for ping pong balls vs
0.095 cents per mm2 for the ones they're tipping into the
lake. The added packing efficiency and albedo are also in
favor of the ping pong balls. Did a government agency
overspend? |
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//Did a government agency overspend ?// rhetorical question, I presume. 6c/sq in. is almost $9/sq ft. They could have built the world's largest gazebo for that and had enough left over to fund policing of the area, to keep the many herds of elephants native to the region from peeing in the pond. |
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Dunno why black... maybe radiation at night is greater than radiation during the day ? |
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oil barrels and galvanized steel come in at less than $6 sq
foot. Massive pontoons would have been cheaper. |
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//I'm surprised they went with black balls. Were they
cheaper?// |
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I've been waiting for somebody to address this. They're
supposed to retard evaporation yet they make them
black to absorb as much heat as possible thus
transferring that heat to the water. |
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//Did a government agency overspend?// |
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...and get it wrong at the same time? That's pretty much
what government specializes in. |
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Maybe there's a reason for the dark color but I haven't
been able to find it anywhere. |
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The second link (as well as the one I added) say that they
use black balls to block UV to avoid creation of bromate in
the water. In some of the later pictures in that article it is
apparent that the balls do self-organize to some extent. I
wonder if they also help reduce evaporation or if that's
purely speculation. I could see that although the balls
reduce the light reflected by the lake, the part of the ball
that gets hot is above the water, so much of that heat
could be transferred to the air. |
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