(Radical improvement of an earlier idea.) A simple, cheap, fully-automatic machine that captures rain there where it falls constantly - in the intertropical convergence zone [see link]. Please hold on for the Grand Finale, the illustration, in the last link.

The idea is based on a combination of *existing* technologies (I will show them in links).

Water is the blue gold of the 21st century, etcetera.

The aim: capture rainwater in a big water bag, when full, transport to water-scarce coastal communities and mega-cities (Los Angeles, San Diego, Jeddah, Bombay, Shanghai, Lagos).

1. The big waterbag has inflatable platforms that fold open when it rains (about once every day, 6 to 8 mm on average) [Big waterbags exist, see link]

2. The pumps to get the rainwater into the motherbag and to inflate the platforms are powered by flexiple thin film solar cells that charge batteries when it's sunny and calm (also several hours per day in that zone)

[The large surface of the plaform has two functions that, if taken apart would be too costly, so they fit together, nicely: weather resistant plastic thin film solar exists - see link; rainwater harvesting using large surfaces is not new]

3. The motherbag and platform will remain spread open most of the day, but in case of bad weather can be deflated and pulled in too. The daughter-platforms only open when it rains. When it doesn't, they're pulled in, in order to reduce tear and drag.

4. The batteries that operate the entire thing are located in the robotic tug; this unmanned tug moves the bags to where the rain is best (calm rain, and lots of it, but no storms). The tug will also transport the full bag to shore, or to a meeting point where another tug takes over.

[unmanned nautival vehicles, fully automatic, exist, they have travelled the Atlantic ocean, all by themselves, satellite controlled, see link]

If necessary, we use fully-automated kite-tug assist [exists, see link]

5. Several clusters of platforms act as an interconnected weather station, sending data to a central computer, and to each other, and so they can determine where it's best to go next.

That's it. Brilliant, I know, I know.

And now the grand finale, the fantastic illustrations!!! [see link]

EDIT: I forgot to add: Obviously, a simple solar tracker is embedded in the entire system; the platforms have a 'zig-zag', 'wave' form (don't know the English word), and the solar panels are fitted on one side of the 'wave'; when charging, the pneumatic tubes can position the panels in the most optimal vertical direction, whereas the entire tug can place the platform in the optimal horizontal direction.
-- django, Aug 26 2006

Tropical Rainfall Measuring Mission http://trmm.gsfc.na...year_TRMM_climo.gif
Six year benchmark map - you can see the intertropical convergence zone, and the water-scarce coastal mega-cities [django, Aug 26 2006]

Big water transport bags http://www.alshinda...ater_transport.html
It is simple, fresh water floats on salt water, and if the bag breaks, there's no environmental disaster [django, Aug 26 2006]

Flexible thin film solar panels http://www.powerfilmsolar.com/
We all know they exist!!! [django, Aug 26 2006]

Next-generation robots take the plunge http://news.bbc.co....ci/tech/3373511.stm
They are out there... [django, Aug 26 2006]

If necessary, we use a kite http://www.skysails.info/index.php?L=1
The work, they are good, they deploy and steer themselves fully automatically [django, Aug 26 2006]

FANTASTIC ILLUSTRATION 1 http://i3.photobuck...onharvestergood.jpg
It is going to rain - open up! This system has an area of half a square kilometre - it's huge! [django, Aug 26 2006]

FANTASTIC ILLUSTRATION 2 http://i3.photobuck...arvestergoodsun.jpg
This is entirely different! It has rained, now it only charges its batteries - you can see it, it's sunny! The black surfaces are the solar panels. Allright, brilliant! [django, Aug 26 2006]

REALISTIC FANTASTIC PICTURE http://i3.photobuck...iesel/breakeven.jpg
In this realistic fantastic picture you also find numbers [django, Aug 26 2006]

Dear god. It's glorious. [+]
-- daseva, Aug 26 2006


A thing of beauty is a joy forever. [+]
-- pertinax, Aug 26 2006


Breaking news, as can be seen in the realistic fantastic picture, break-even will occur after 166 years!! I need to appoint my successor now. Any candidates?
-- django, Aug 26 2006


Can't you use duct tape to lower the cost? Maybe even get break even point down to 164 yrs.
-- NotTheSharpestSpoon, Aug 26 2006


I see no mention of an anti-birdshit mechanism.
-- normzone, Aug 26 2006


at a breakeven of 165 years, how exactly is this close to even appearing to be in the general region of the possibility of being considered remotely like anything in the history of humanity to something that is Cheap?
-- jhomrighaus, Aug 26 2006


[Normzone], it was your bird shit that made me rethink the entire thing!! The new system never keeps open its platform for longer than is needed to harvest one splash of rain. After that, it gets retracted and the shit will drop in the sea, not in my system. Never in my system!!
-- django, Aug 26 2006


//history of humanity [...] is Cheap? // [jhomrighaus], at the Halfbakery we are allowed to treat humanity the way we want! I sell tropical water, not some cheap French bottle! With my water, you get a NASA-certified satellite certificate indicating which cloud your water comes from. We track all these things. This is luxury water!!

Break-even has just been recalculated and now stands at a mere 68 years.
-- django, Aug 26 2006


wouldnt it be cheaper to distil water in these (coastal) cities?
-- arvin, Aug 26 2006


most municipal projects have a 15 or 30 year bond life, which makes them cost effective in less than half the time.
-- jhomrighaus, Aug 26 2006


Amortisation be damned! I'd bun for the illustrations alone, but the completeness of the system design implied by those illustrations is what does it for me.

I do have some niggling doubts about environmental effects. I'm sure fresh rain is important to ocean ecologies somehow, and sunlight definitely is. Moving the platform from place to place should minimise that.

Have you considered anchoring these offshore with a floating freshwater bag-pipeline back to the point of need?

Layer enough panels to also pipe power back to shore, integrate some windpower, wavepower and an oyster farm/ algal biodiesel plant, and you'll amortise in no time.
-- BunsenHoneydew, Aug 27 2006


This is the most detailed design of a half-baked idea ever. Even a 3D rendering. Bun!
-- ixnaum, Aug 28 2006


Why can't people just move, if they're thirsty? But that does not address the spirit of the idea here I think. So skip it. Anyway you're gonna need a shitload of cash to become a part of the supply chain for the emerging global fresh2O fiasco. People around here (alaska) like to build big pipelines (they claim that they wrote the book) and the possibility of a water pipe to the lower 48 has already been discussed at the legislative level. But then again they've got about 25 billion dollars "in the bank" so to speak and it's literally driving them insane as they argue about the quickest method to waste it.
-- Drain Bramage, Aug 28 2006


All hail the MotherBag!
-- bungston, May 09 2007


What drafting package do you use?
-- shapu, May 09 2007


In technical jargon, a big floating bag of water is known as a "dracone." Because I like that word so much, I must bun you for your "draconian" measures intended to ensure safe water supplies for all.
-- ye_river_xiv, May 10 2007


Could you arrange for some sort of low- cost, bouyant flexible pipeline? If it were long enough, you would be able to reach directly from the shore to the floating bags.

In this case, you would be able to fill the bags directly from a shore-based tap: this would be quicker and cheaper than harvesting rainwater, it seems. And [+] anyway.
-- MaxwellBuchanan, May 10 2007


This should be rigged up with the Geshem Project. [+]
-- skinflaps, May 10 2007


BUN FOR "MOTHERBAGS!" Damn that's funny.

Float the pipeline below the surface to protect from the worst of the chop and passing surface traffic. Suspend from buoys with solar panels to power kicker pumps, and avoid the hassle intermittent delivery: a few hundred thousand gallons, every single day that the sun shines.

If these things provide shade, they may also attract fish. As such, they could become an integral part of a fish nursery, adding yet another slice to the amortization pie.

The best bit is they barely project above the surface, so they don't ruin the view if they're more than a mile offshore. You won't see them from the beach.
-- elhigh, May 10 2007


You should not worry about the bird sh1t in the water. Almost all fresh drinking water systems have some fecal material in them. Birds, bats and insects are unavoidable. The slightest hole in a water tower, and they have many for venting purposes, will allow these critters in...once in, they very rarely find their way out again and usually die and eventually rot right in the water we drink. Their little nasty molecules dissolve into the vast quantity of a million gallon tank and are dilluted quite nicely. They are then aggressivly neutralized by the disinfectant chemicals we put in the water...chlorine, iodine, and certain other oxidizing agents render the harmufl bacteria these little animals introduce into our water into very harmless packets of simple compounds we easily digest with no harm what-so-ever. This grotesque knowledge of mine is the primary reason I only drink water that has been processed through reverse osmosis...the only filtration system that is capable of filtering out even viruses.
-- Blisterbob, May 11 2007


I prefer the more traditional method of rendering water safe to drink.
-- MaxwellBuchanan, May 11 2007


//and there is no global warming// do you live in Texas ? [d]..... plug in your single brain cell before attempting to construct your answer.
-- xenzag, May 12 2007


//and there is no global warming// do you live in Texas ? [d]..... plug in your single brain cell before attempting to construct your answer.
-- xenzag, May 12 2007


If a certain Texan has only one brain cell, that would explain his black-and-white view of the world. He's incapable of having more than one decision at a time:

"Yes, there are WMD's." "No, there is no global warming." "Yes, I'm the decider." "No, I will not listen to the American people."

No offense if you really are from Texas, [-d].

[blister], I really didn't want to know all that. I mean, I sort of knew it, but I really, really, REALLY didn't want to KNOW know it, you know? (spits) Well, back to bottled water, with its tasty hint of dead blind cave shrimp.
-- elhigh, May 14 2007



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