I propose a small "closed curcuit" unit, described below, which could be connected in a continuous pipe, to distill sea water in large quantities at low cost.

Each unit, the size of a small row-boat, would be devided into two sections: the boiling section and the saved water section. A fresnel lens (or perhaps water filled bags to achieve the same) heat the dark-tinted water section, which is thermaly insulated from the rest of the sea water. The boiling steam is then passed into the clean "water storage", where it condenses. The steam pipe is partially submerged in the sea, and so is the water storage, itself a long and thick pipe with an air snorkel, so that water can be extracted. The water storage has fins to let off the heat into the sea water. When water is being extracted from storage, the steam pipe automatically closes via a pneumatic-mechano contraption.

This distilled water could be pumped up to mountains and entered into the underground water system, turning to drink water, in over-pumped areas. Or it could be used for irrigation and for showering (for drinking you need minerals in the water otherwise you get cretin [edit: corrected from Creton] disease, brain dammage or skin boils - as what happened to residents of the Jewish portion of Jerusalem during the 1947 siege, who drank only boiled cistern water).

I got this halfdea after watching the funny GreenPowerScience.com movie on how simple and fast it is for the Ruhals to distill water from a mud-pond, using a large Fresnel lens to boil water in a bottle with solar energy, and just have it go into another bottle and condense.
-- pashute, Jun 01 2008

the ruhals do it manually http://greenpowersc...e.com/SEAWATER.html
Distilling sea-water in a single water bottle [pashute, Jun 01 2008]

Aquacone http://www.greenhom...ter_filters/106608/
"The AquaCone™ is a floating water purifier that distills any naturally occurring water into safe drinking water. There is no pumping involved and no filters to clog. The AquaCone™ is lightweight, fully portable and makes enough for a daily supply of safe drinking water, while requiring only solar energy to power it." [Klaatu, Jun 01 2008]

Ultra-Cheap Solar Water Distillation Ultra-Cheap_20Solar...ater_20Distillation
Solar water stills were discussed in this earlier related idea, too. [jurist, Jun 01 2008]

DeSal Ships DeSal_20Ships
bigger & better! [simonj, Jun 02 2008]

Cretons http://en.wikipedia.org/wiki/Cretons
You don't want Creton disease. Seriously. [david_scothern, Jun 02 2008]

Cretin desease http://en.wikipedia.org/wiki/Cretinism
Originally caused by water that has no Iodine in it [pashute, Jun 03 2008]

I've often thought about how straightforward this would be. I could even be implemented on a large scale on unused oil platforms.
-- phoenix, Jun 01 2008


BUN.I like the progressive, man on the ground, design. Does the water pick up salt when boiled?
-- plynthe, Jun 01 2008


// Does the water pick up salt when boiled? //

No. This is distillation. The salt solution becomes more concentrated as water evaporates. Eventually the evaporation chamber has to be flushed to remove the built-up salts. This can be done with sea water as the salts will redissolve in water which is not saturated.

Care is needed that the energy in the evaporator charge is not simply dumped by cold flushing.
-- 8th of 7, Jun 02 2008


Bun. (sp: cretin, btw - not that it matters)
-- david_scothern, Jun 02 2008


Would it be easier (cheaper) to pump the steam up the hill and condense it back to liquid at the top.
-- Ozone, Jun 02 2008


Thanks [david]. editing the Cretin (sp).

Thanks [Ozone] - great idea! Actually I was thinking of that (kind of like controlling clouds). The problem is that the steam would probably condense half way up, unless the pipes are heated all the way up. Lets call it CloudMachine. You could use the energy too. The downside is that you need a country's permission to have pipes going up, while with this idea you get water offshore, so no-one's permission needed. On the other hand, if you are already inserting the water into the mountain streams then you are anyways getting country permission for piping, so there you go! I'll give it a sepparate HB post, or maybe you wish to?
-- pashute, Jun 03 2008


[Jurist and Simoni] Looking at the two links which basically show similar ideas, there's a difference here: I'm not saying just any desal ship, I am talking about a low cost implementation, that will be ON the sea (not above it, so the big aircraft-carrier type ship in the link probably won't work) and I'm talking about distilling the water (by solar heat) rather than desalinating it (which is usually done by back osmosis). And I'm talking about a modular floating unit that could be connected in parallel or sequence in order to receive larger amounts of distilled water.
-- pashute, Jun 03 2008


If not steam, how about solar cells that reduce 2(H2O) > 2H2 + O2. No need to keep the pipes heated, plus the recombination of the oxygen and hydrogen would produce not just water but clean energy too.
-- Ozone, Jun 03 2008


Sorry Ozone, because electrolysis wont work. Boiling water is easily feasable at very low cost, and simple, which is what the idea is about. Electrolysis is not low cost, and not simple :-(
-- pashute, Jun 04 2008


Some modern life rafts have a small, simplified version of this.
-- Alterother, Jun 06 2008


Although this is mildly warmed, I wouldn't dare call it baked on a large scale.

[+] for thinking big.
-- shapu, Jun 06 2008



random, halfbakery