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Creating Water from Thin Air 348

Iphtashu Fitz writes "In order to provide the U.S. Military with water in places like Iraq, the Defense Advanced Research Projects Agency gave millions of dollars in research funding to companies like LexCarb and Sciperio to try to extract water from the air. Amazingly, a company that DARPA didn't fund, Aqua Sciences, beat them all to the punch by developing a machine that can extract up to 600 gallons of water a day from thin air even in locations like arid deserts. The 20 foot machine does this without using or producing toxic materials or byproducts. The CEO of Aqua Sciences declined to elaborate on how the machine works, but said it is based on the natural process by which salt absorbs water."
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Creating Water from Thin Air

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  • by spun ( 1352 ) <> on Friday October 06, 2006 @05:34PM (#16342119) Journal
    I recall reading an article about ancient rock mounds, where the rocks were loosely lumped with plenty of space in between. Air filtered through and encountered the cool rock faces of the interior of the mound. Water condensed on the interior rock faces and trickled out the bottom. I'll see if I can find a link.
    • Linky link (Score:5, Informative)

      by spun ( 1352 ) <> on Friday October 06, 2006 @05:49PM (#16342357) Journal
      Here we are, [] as promised. About a third of the way down the page. Ignore the Reichian weirdness, the wells were built near the ancient Byzantine city of Feodosiya. There were 13 large conical tumuli of stones, each about 10,000 feet square and 30-40 feet tall, on hilltops. Russian engineer Friedrich Zibold calculated they would each produce more than 500 gallons daily. These theories have been disputed by some archeologists (who don't seem to like it when engineers discover cool archeological stuff and make up theories about it) but the mounds do all have numerous terra-cotta pipes around the base, presumeably to collect the run off
    • It sounds more like they created a substance that uses intermolecular forces to have a high attraction to water (like salt or any other desiccant). The secret is making it so that under a specific condition these water molecules can be released again (heat, pressure, etc). Then possibly combined it with standard evaporation methods through compression and cooling (standard dehumidifier).

      So in all they probably just found, or dynamically adjust, the 'sweet spot' between the two methods to produce the mo
  • by phekno ( 719662 ) on Friday October 06, 2006 @05:35PM (#16342137)
    at my seitch.

    • by CRCulver ( 715279 ) <> on Friday October 06, 2006 @05:40PM (#16342225) Homepage
      I was thinking of Dune [] myself. Frank Herbert's notion that man could survive with such limited water supplies apparently wasn't entirely fantastical. However, IIRC no such device was used in the series. Instead, the Fremen relied on farming the naturally forming dew of the planet. Personally, after reading Kim Stanley Robinson's Mars trilogy, I wonder why Herbert never thought of having some Fremen just crash a few comets into the planet to at least provide some selected portion of it with water. Of course, that would have killed off all the sandworms.
      • ...I wonder why Herbert never thought of having some Fremen just crash a few comets into the planet to at least provide some selected portion of it with water. Of course, that would have killed off all the sandworms.

        Because the Fremen had enough trouble just bribing the Spacing Guild to keep them from putting up weather/surveillance satellites that would expose their way of life and their actual numbers? And of course killing of the sandworms in a short time would have killed off most of the Fremen as wel

        • Sorry to reply to my own post but I forgot the fact that the Spacing Guild obviously would be totally against any action endagering the spice supply.
      • Re: (Score:2, Informative)

        by pete-classic ( 75983 )
        You recall incorrectly. Windtraps.

      • by sm62704 ( 957197 )
        I was thinking of Dune myself.

        Check the masthead - we were ALL thinking of Dune.

        I wonder why Herbert never thought of having some Fremen just crash a few comets into the planet

        Because the Guild Navigators wouldn't let them; they were powerful enough to keep the Emperor from having weather satellites.
      • Re: (Score:3, Insightful)

        Why not? Well (1) they were hiding their numbers from the Padishah emperor and the Harkonnens (2) they needed all their money to bribe the spacing guild to hide their numbers (3) it was unthinkable to imperil spice production (4) waterbombing Arrakis would quickly kill off the spice and the worms (5) the guild navigators would see this quite clearly in advance, and turn against them (6) they'd lose the addictive spice, worms as transport, Shai-hulud, and the impenetrable defensive wall of the desert. Plus t
  • ...this [] when they read this article? ;-)
  • by Verteiron ( 224042 ) on Friday October 06, 2006 @05:36PM (#16342141) Homepage
    I'm sure they'll be interested.
  • Sounds like the Windtraps from Frank Herbert's Dune.

    However the article itself was about as descriptive of technology as Frank Herbert's novels. Here is a fun quote.

    "This is our secret sauce," Sher said. "Like Kentucky Fried Chicken, it tastes good, but we won't tell you what's in it."
    • Ah, the dessert planet...
    • Re: (Score:3, Funny)

      by Amouth ( 879122 )
      who wants to bet it is a water tank? that has to be "serviced" to keep running :)
    • by sm62704 ( 957197 )
      Like Kentucky Fried Chicken, it tastes good, but we won't tell you what's in it.

      That part puzzled the hell out of me. Surely they have it patented? If so, the plans are on file and public.
      • by jfengel ( 409917 )
        Recipes are usually treated as trade secrets rather than patents. If they'd patented it, everybody could do it by now, if they wanted.

        But the secret isn't a big deal. According to William Poundstone's analysis, their "seven secret herb and spices" are (1) salt (2) pepper. Which isn't entirely surprising: KFC chicken doesn't taste particularly spicy or herbaceous. You really don't need anything else for good fried chicken; it's more about technique than ingredients (a though buttermilk marinade doesn't hurt,
    • As if we won't find out if/when the units are fielded and serviced.
      The company site is short on content and as useless as the article. Blue ISO containers, meh.
  • by ShadowBlasko ( 597519 ) * <> on Friday October 06, 2006 @05:38PM (#16342177)
    Just as long as the superconductors you use on your condensors are not vulnerable to a puppeteer plague.

    If that happens its going to take a long time before Louis shows up.
  • salt absorbtion of water and distillation of the salty water?

    I guess the telling would be to see how may gallons of water it can produce while floating on a fresh water lake, and on teh salty sea.
  • by bbk ( 33798 ) on Friday October 06, 2006 @05:38PM (#16342183) Homepage
    Anyone heard of Tatooine's moisture farmers?

    I thought so.

    (sorry, it was just too obivious)

  • Why the surprise? (Score:3, Insightful)

    by Syncerus ( 213609 ) on Friday October 06, 2006 @05:38PM (#16342189)
    What, you're shocked that all the government funded plodders were out done by a Capitalist independent? Government is very poor at creation and is typically very poor at selecting future winners in the technology race. That's why government should be a consumer of technology rather than a producer of the same.
    • Re: (Score:3, Insightful)

      by geekoid ( 135745 )
      thats simply not true.
      Historically the government has been a great catalyst of techology inovation and improvements.

      Considering that this company that has allegedly done this claims no byproducts and won't let anyone know how they did it.
      color me Sceptical.

    • by sterno ( 16320 ) on Friday October 06, 2006 @06:10PM (#16342603) Homepage
      Government is very poor at creation and is typically very poor at selecting future winners in the technology race.

      See also the Internet you're using to post your comment. Oh wait, DARPA created that, nevermind.
  • Good! (Score:5, Interesting)

    by thefirelane ( 586885 ) on Friday October 06, 2006 @05:38PM (#16342193)
    So the government failed to fund a company who promised unbelievable results with no byproducts while not supplying any details? I must say, I'm actually proud of them. Glad to see tax dollars aren't being wasted on Vaporware
  • by Anonymous Coward on Friday October 06, 2006 @05:38PM (#16342199)
    Is there a button to switch it from 'water' to 'beer?'
  • This sound like a Windtrap to anyone else. I love it when something I read about in a sci-fi book 20 years ago comes to life in a practical application.

    Fear is the mind killer...
    • I love it when something I read about in a sci-fi book 20 years ago comes to life in a practical application.

      You won't be so chipper when you are drinking your recycled urine and feces through a straw in 2026.
  • hm (Score:5, Informative)

    by inKubus ( 199753 ) on Friday October 06, 2006 @05:42PM (#16342251) Homepage Journal
    Sounds like they probably use a hydroscopic [] compound such as calcium chloride [] and then you some type of ion replacement to recover the water (precipitate calcium metal and some other non-soluable salt, such as Fe(III)Cl.

    • Re:hm (Score:4, Funny)

      by hchaos ( 683337 ) on Friday October 06, 2006 @05:50PM (#16342379)
      Sounds like they probably use a hydroscopic compound such as calcium chloride and then you some type of ion replacement to recover the water (precipitate calcium metal and some other non-soluable salt, such as Fe(III)Cl.
      Quick! To the Patent Office! That'll teach them to keep their methods secret.
    • Ok, but then wouldn't they have to keep resupplying chemicals to the machine at 1/1200th the volume of the water extracted? Or am I reading those articles wrong?

      Seems to me, the key word would be SUSTAINABLE- a solar powered refridgeration radiator would be more sustainable.
    • Re:hm (Score:5, Informative)

      by c4miles ( 249464 ) on Friday October 06, 2006 @05:53PM (#16342403) Homepage
      The word you're looking for is Hygroscopic. From the article you linked to:

      The similar sounding but unrelated word hydroscopic is sometimes used in error for hygroscopic. A hydroscope is an optical device used for making observations deep under water.

      A related word, deliquescent, refers to substances so hygroscopic they will dissolve themselves using water absorbed from the air.
    • It sucks the moisture out of the air, then you heat it up and evaporate the water, leaving the salts behind to be reused.

      The great thing about is, all you need is a heat source. You can either burn fuel, or use waste heat coming off a turbine, or even use solar energy -- you need temperatures above boiling, but not too much higher.

      This is the same stuff they use for solar-powered heat pumps, except there they use a closed loop system, and evaporate the water at low pressure to get air conditioning.

    • Re:hm (Score:5, Informative)

      by Big Bob the Finder ( 714285 ) * on Friday October 06, 2006 @06:22PM (#16342723) Homepage Journal
      Calcium bromide (CaBr2) is slightly more hygroscopic, absorbing moisture down to 16% RH (Handbook of Chemistry and Physics); it's also a hexahydrate- it sponges up a lot of moisture. Right below that is lithium chloride, which continues to absorb down to 11% RH.

      Most likely it's a system where prilled or powdered salt is tumbled through dry air to absorb moisture; it's then roasted to release the moisture, captured under reduced pressure to reduce the amount of energy required, and returned to its anhydrous state. It'll be clumpy and chunky, so it'll have to be re-ground into a fine powder before reuse.

      The $.30 a gallon is probably largely from the amount required in the removal of the water from the hydrate; distillation of water runs ~$.25 a gallon (assuming no recycling of the waste heat from condensation to pre-heat water going into the boiler) at $.10/kwh. Using gasoline or diesel would be considerably more expensive- thus the reduced pressure.

      Distilled water from air- not too shabby. I've thought about trying the same here in the desert (where it's routinely ~10% RH in Phoenix), but it's just not worth it.

  • Uncle Owen! (Score:5, Funny)

    by norminator ( 784674 ) on Friday October 06, 2006 @05:43PM (#16342261)
    What I really need is a droid that understands the binary language of moisture vaporators.
    • Actually, what I really need is a quicker brain so I won't have to google for the quote, taking valuable time, allowing a dozen other slashdotters to post the same lame joke. Sorry everybody.
    • Why sir! My very first job was programming binary load lifters - very similar to your vaporators in most respects...
  • by quarrel ( 194077 ) on Friday October 06, 2006 @05:44PM (#16342285)
    Asked to clarify how it worked, the CEO noted- "Just add water, and in a few minutes it'll be ready!".

  • sucking all the moisture out of the environment will have no impact on the eco system, right?
    • Well, it's excreted back into the environment within a few hours,, I don't think it will.
    • Re: (Score:2, Insightful)

      by kfg ( 145172 ) *
      sucking all the moisture out of the environment will have no impact on the eco system, right?

      Pretty much, since you pretty much put it right back in. That's why you need so much of it in the desert. And why there's so little eco system there to damage.

      How much water gets used up when you flush a toilet? That's right. None. There's no water shortage, it's a question of purity and distribution, not quantity.

    • by erice ( 13380 ) on Friday October 06, 2006 @06:45PM (#16342997) Homepage
      It's only an issue if water is permanently removed from the environment, which it generally won't be. Water was in the air and in a few hours, it is back again.

      This is actually much better than trucking in water from afar or pulling it out of deep wells. In that case, you are altering the environment. Water not previously in the environment is being added.
  • by cowscows ( 103644 ) on Friday October 06, 2006 @05:46PM (#16342317) Journal
    If this technology really works as well as is advertised, how bout the government does something with it a bit more productive than sending a bunch to the army? Like maybe buying thousands of these things and shipping them to many of the different places in the world where a lack access to fresh water is one of the most pressing health concerns of millions of people.

    It's good that our soldiers are out in the middle east doing their jobs, and they deserve fresh water too. But seeing the general anger towards the US that's prevelant in so much of the world right now, actually helping people with something like this would generate tremendous good will. It'd probably be a lot cheaper than our wars are as well.
    • by synth7 ( 311220 ) on Friday October 06, 2006 @06:02PM (#16342521) Homepage
      Who is going to provide the guards for these condensers, because you know that the local warlords and privileged will abscond with them as another source of wealth and power. There's more than just buying the equipment, there is maintenance and policing, just to name the obvious manpower needs.
    • Re: (Score:3, Insightful)

      by couchslug ( 175151 )
      Giving people free stuff does not address ideological conflict.
      If an ideological opponent gave ME free stuff in hope that I could be bribed, I'd thank the nice man and then use it against him.
      If someone to whom I was indifferent gave me free stuff, I would thank the nice man and then question their motive.
  • ...just add water, and you've got water! That reminded me of the original Space Quest. The survival kit you get in that game has a can of dehydrated water. Although if you actually examine the can, it says it contains hydrogen, which becomes water when mixed with air. Since the game was intended more or less as comedy, they didn't take into account that hydrogen + oxygen = water is a rather exothermic reaction, it burns hot and releases a lot of heat, and the water that is produced is produced as steam.
  • Finally... (Score:5, Funny)

    by Mantrid42 ( 972953 ) on Friday October 06, 2006 @05:49PM (#16342363)
    Some good Vaporware!
  • Reusable Jokes (Score:2, Insightful)

    by zulater ( 635326 )
    Now I just need a droid that understands the binary language of moisture vaporators. Oh sorry, I thought every comment was supposed to have that joke in it.
  • Everybody is thinking about Dune, so here's what a stillsuit does. []

    By the way, download the full game with speech (legal abandonware) at []
  • not surprising (Score:2, Informative)

    by z3d4r ( 598419 )
    this is coming from an australian company, seeing as australia is both the most arid continent and largest desert island in the world.
    • Re: (Score:3, Informative)

      Actually, if we're going by humidity as an indicator of available water, Antartica's far more desert-like. It's also bigger.
  • The DARPA funded companies did not have the same motivation as the other one. It is in their best interest to keep making slow progress and asking for more money everytime they have a little breakthrough. The successful company had no such money train. It was in their best interest to actually PRODUCE RESULTS in order to patent, market, and sell the technolohy. Funny how that works huh?

  • has posted anything about moisture vaporators.
  • To make this work and be cost effective in reality these things have to continue to be cheap to run. A few things the article doesn't mention are:
    1. Does it require electricity, if so how much?
    2. Do the chemicals used in the condensation need to be replenished? If so, how often, how much potable water can be generated per load of chemicals, what is the cost of the chemicals?
  • by Shadowlore ( 10860 ) on Friday October 06, 2006 @06:04PM (#16342537) Journal
    Question1 L How inept are the congressional people in Washington DC?

    "I was pretty blown away by the things it's able to do," Rowe said. "The fact that this technology is not tied to humidity like others are makes it an attractive alternative for military bases in the Mideast where humidity is not really an option.

    Yet further down ...
    Aqua Sciences' machines only require 14 percent humidity,

    Anybody with half a brain knows that there has to be some humidity in the air in order to extract water. Wait, that explains it. ;) Moving on.

    While it is an accomplishment to reduce the humidity requirement, it doe not eliminate it. Indeed given their claim of up to 600 gal/day I'd say that at the minimum required humidity of 14%, it is possible that they may require far more of them than is talked about. A key factor is how rapidly that output drops when the humidity levels drop. if it porduces 600 gal/day at optimum humidity levels, it may only put out say 10 gal/day. If that were the case you could not rely on this for troop support in such areas. A supplemental, sure.

    Depending on the size and maintenance requirements, as well as the phsyical inputs other than air, it may not be cost effective to use these in more arid regions. Now, places like the southern US they would be quite useful.

    What I'd like to know is the size and power requirements. Something like this could be quite useful in high-rise buildings. Pumping water to the upper levels requires a significant amount of power. If instead we could put a few of these on tops of buildings and use them to bring water down, we might see a net win in terms of supply and energy usage. Imagine places like Phoenix or Las Vegas.

    Pheonix has an average daily humidity of about 55% IIRC. Thus it would stand to reason that these units could pump out their maximum output. Depending on their size and power requirements, several of these atop an office building in Phoenix could produce several thousand gallons per building. As office buildings their water requirements might be low enough to satisfy with these units. They would have the further advantage of dehumidifying the hot air of Phoenix, thus possibly resulting in a slight cooling load reduction.

    Even small residential units could be tremendously benefited. The average person requires 125 gal/day. Thus one of these could supply the water needs (not counting grass lawns) of a family of four in Phoenix. If the house is designed with greywater and systems for landscaping purposes it is possible that one of these could fully supply the average water requirement of a family of four in Phoenix. Which leads to the question .. how much are they to acquire and operate?

    Anyone from Phoneix care to share how much you pay for water? If you've got a spouse and a pair of kids, and this unit eliminated your water usage bill (there would still be sewage), how much would it save you per year?

    40,000 of these units in Phoenix would drop the summer daily demand for water by 24Mgal/day, or 5-12% depending on the season (Summer to Winter).

    Essentially, if this proved cost effective then the more arid parts of the country might be able to make large savings on their infrastructure and supply costs. Which would be yet another miltary requested technology applied to positive civilian use.

    The next question is: does it scale up and down? Can it be scaled down to be an effective one-person supply? Do larger units demonstrate a better-than-linear increase in water production?

    Combine this with greywater systems, solar thermal heating (water and home), and appropriate landscaping and we would be a long ways toward a more sustainable system - without major changes and reductions to our standard of living.

    • by geekoid ( 135745 )
      "The fact that this technology is not tied to humidity like others..."

      like not as much humidity, not like no humidity.
    • Re: (Score:3, Informative)

      by sm62704 ( 957197 )
      Pheonix has an average daily humidity of about 55% IIRC

      You don't RC, it's more like 3%. Its 20% right now [] and they're predicting rain, which they usually don't get a whole lot of.

      The humidity is so low they don't use standard air conditioners there; they have "swamp coolers" which work by evaporating a stream of water. Very cheap and efficient where there's practically no humidity at all. At 50% humidity one wouldn't work.
    • Re: (Score:3, Insightful)

      by Shadowlore ( 10860 )
      In an attemot to answer some of my questions is the company's site and product listing. []

      Apparently they have container models that can produce 1200 gal/day. 20'x8'x8'. So a couple of these on office buildings would do niceley.

      They seem a bit on the large side for single-family home use. Bummer. Perhaps that would improve. These seem to have a built-in generator. If attached to grid I wonder how much smaller these would be. Perhaps multi-family structures could work out wel
    • Re: (Score:3, Insightful)

      by hankwang ( 413283 ) *
      Even small residential units could be tremendously benefited. The average person requires 125 gal/day.

      What?? Here in the Netherlands, which does not exactly have a water shortage, the water consumption for residential use is about 125 liters per day per person.[1] [] That is about 4 times less! What do you do with all that water?

  • From Aqua Sciences's website:-

    Machines may be powered by electricity or a self-contained diesel generator and are environmentally friendly due to lower energy requirements and no harmful or toxic by-products.

    So it's not, in fact, "no by products", it's "low by products". Although how Diesel emissions can be considered non-toxic is beyond me.
  • 1/4 the country was swampland before Saddam screwed that up, another quarter is snowy mountains, and two of the mideast's biggest rivers flow right through the place, although Turkey's in the process of gobbling those up.

    If the damn fools would stop blowing up their own water and power plants, they'd have plenty of water.
  • The 20 foot machine does this without using or producing toxic materials or byproducts.

    So does my AC. Not 300 gallons though, but if it were 20 feet long and used a few hundred lilowatts it might.

    Several systems on the market can create water through condensation, but the process requires a high level of humidity.

    Or a high level of wattage? TFA is completely absent on details about how it works.
  • by rampant mac ( 561036 ) on Friday October 06, 2006 @06:11PM (#16342609)
    I hang out with a SERE [] instructor and do a lot of camping / hiking / ORV riding where I'm sometimes far away from reliable potable water. He gave me some pretty cool information about how to obtain water from your surroundings:

    1) Water from plants is always drinkable. I'm talking about water from the root system, not some stagnant water you could slurp out of a recess between branches. The easiest way is to take a large trash bag, grab a cluster of branches and put the bag around them (make sure the open end of the trash bag is tightly sealed to prevent air from going into the enclosed bunch). It forces the tree to "sweat" water from its root system. After about 24 hours you can slit the bottom of the bag and drain it into a nalgene bottle. You can only do one group of branches per 24 hour period, so you need to use different trees to gather water. I tried it out when I was in Eastern Oregon (which, for all intents and purposes, is an inland desert) and averaged about 1 liter of water per 24 hours. I had 6 trash bags that I normally have in my hiking ruck, so I could feasibly harvest 6 liters per day if I was SOL somewhere.

    2) A cluster of birch trees usually means there's water underground.

    3) Any multi-celled berry (ie: raspberry) is edible.

    Anyway, I thought it was pretty cool shit, and informative. :)

  • Solar Still (Score:5, Informative)

    by David Off ( 101038 ) on Friday October 06, 2006 @06:22PM (#16342725) Homepage
    A solar still [] produces water in the desert and uses no external energy source other than sunlight (there is plent of that in the desert)
    • Re: (Score:3, Informative)

      by jamesh ( 87723 )
      In central Victoria (South Eastern Australia), we're having a bit of a drought at the moment. I was listening to talkback radio show where a woman was talking about a fairly simple device to collect dew (basically just some fine mesh with a collector down the bottom) and how it could be used to keep a few plants alive without actively watering them.

      This got me thinking though, what is the effect going to be if this sort of thing is deployed in a really large scale? Does it reduce the moisture content of the
  • by jjohn ( 2991 ) on Friday October 06, 2006 @08:02PM (#16343691) Homepage Journal
    From the article:
    "We figured out how to tap it in a very unique and proprietary way," Sher said. "We figured out how to mimic nature, using natural salt to extract water and act as a natural decontamination.

    "Think of the Dead Sea, where nothing grows around it because the salt dehydrates everything. It's kind of like that."

    All the Alton Brown [] geeks in the house should have perked up their ears when they read that. Salt is hydroscopic []; it attracts water. Sugar is also hydroscopic, but salt is much cheaper (especially if you don't need food-grade salt).

    There are two ways salt is harvested by humans: evaporation and mining.

    I can see using salt to grab the moisture in the air present in the pre-dawn skies, but I don't rightly know how to make the salt give it back up. I assume they just cook the rocks and capture the steam. Salt, being a rock, can be heated lots of times before degrading.

    I imagine a process like this would produce fairly clean water.

    Give up for Food Science! Hell ya!

  • by tsotha ( 720379 ) on Friday October 06, 2006 @08:57PM (#16344061)
    This technology is actually pretty old.

    One of the problems which has dogged airships from day 1 is the inability to replace the weight of burned fuel. There's a couple ways you can deal with this problem, but none of them are ideal. Modern blimps and airships are actually heavier than air, relying on lift from engine pods to get the airship in the air. As they burn fuel they get lighter, but they're never actually "lighter than air". Early airships were much too large for this strategy especially since engine technology was far less advanced.

    The most successful airship in history, the Graf Zeppelin, used a gas called Blau Gas to power its engines. Blau Gas is just a mixture of propane and hydrogen that weighs the same as air, so when you burn it and the gas volume is replaced by air of the same weight you don't have any buoyancy problems. Graf Zeppelin used hydrogen, which is relatively cheap, for its lifting gas. If it became too light they could vent enough hydrogen to restore neutral buoyancy.

    But this scheme wasn't very efficient, from an engineering perspective. Every cubic meter of fuel was a cubic meter that couldn't be used for lift. Also, as they designed the Hindenburg they were concerned about safety, so they decided the Hindenburg would be filled with helium instead of hydrogen. Since heliem is about 10% less efficient as a lifting gas, Zeppelin engineers decided they just couldn't live with Blau Gas. Also, Blau Gas has the same safety drawbacks as hydrogen. Helium is much more expensive than hydrogen, so if the company was to be profitable there was no way they could just vent helium when the ship was too light. So if they were to use diesel fuel exclusively in the Hindenburg, they needed a way to add weight to the airship in flight.

    The solution was to remove water from the air and use it as ballast to replace the now-missing diesel fuel. The system they designed used a silica gel, the same stuff that comes in a little packet labeled "DO NOT EAT" when you buy a pair of shoes. Ambient air was blown over the gel, which is highly water absorbent. The gel was then heated using waste engine heat to produce water vapor, which was collected in a condenser. Eventually they decided to use the diesel exhaust (which is apparently very humid) instead of ambient air. This was 70 years ago.

  • by Nate Eldredge ( 133418 ) on Saturday October 07, 2006 @02:39AM (#16345741)
    I have here a copy of a book entitled "The Inventions of Daedalus", which reprints the column of the same name by David E. H. Jones from New Scientist magazine. This column would propose unusual inventions, generally based upon sound scientific principles and seeming entirely reasonable except for their total absurdity. Previous proposals include a scheme for slaughter-free meat production by harvesting reptile tails which then regenerate; a weapon called "Shattergas" causing sudden and catastrophic corrosion of militarily important metals and plastics; and an addictive birth control pill which the user would never forget to take.

    Anyway, it includes a column dated May 25, 1978 entitled "The Desert Waterer" in which "Daedalus" proposes just such a device, whereby moisture is collected from the air by means of a hygroscopic liquid. The water can then be extruded through a semi-permeable membrane if the liquid is under sufficient pressure. This can be accomplished simply by placing the liquid in a tall column; moisture enters at the top and the hydrostatic pressure at the bottom allows recovery. Daedalus then considers some convenient liquids for the purpose. Sulfuric acid is readily available in industrial quantities but would need a column 2400 meters high, which is somewhat awkward. Invert sugar syrup has a higher molecular weight and would require a column merely 720 meters high, as well as being nontoxic, and even edible in case of an emergency. Best of all, he says, is a product called "Carbowax", for which a column of only 50 meters would suffice.

    The firm in charge of this present project has a suspiciously similar name, so perhaps they have just created a better Carbowax.

    Daedalus, in the book, cites a number of cases where an invention from the column has become the subject of serious research. So this is just one more example...

When you make your mark in the world, watch out for guys with erasers. -- The Wall Street Journal