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Inventor of Low Tech Fridge Wins Award 369

juju2112 writes "Mohammed Bah Abba of Nigeria won a Rolex award for his pot-in-pot invention. Here's how it works. You take a smaller pot and put it inside a larger pot. Fill the space in between them with wet sand, and cover the top with a wet cloth. When the water evaporates, it pulls the heat out with it, making the inside cold. It's a natural, cheap, easy-to-make refrigerator."
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Inventor of Low Tech Fridge Wins Award

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  • keeping beer cool (Score:5, Interesting)

    by phelix_da_kat ( 714601 ) on Monday April 05, 2004 @06:03AM (#8767364)
    Remember at school/university when we use the same principle to keep our beer cold.

    Grab a clean sock, soak in water, wring out, cover teh can of beer and leave on the window sill.. LOL

    • by Rosco P. Coltrane ( 209368 ) on Monday April 05, 2004 @06:13AM (#8767415)
      Remember at school/university when we use the same principle to keep our beer cold.

      Well of course it's obvious, and everybody knows the trick, but this is a perfect example of how some people can be taken by the most outrageous nigerian scams. This time it was the Rolex award judges. Perhaps they expect 20M to be wired from some bank account in Nigeria or something...
      • by Anonymous Coward on Monday April 05, 2004 @06:25AM (#8767452)
        Happily it turns out that the joke is on the "inventor" since it wasn't really the "Rolex award judges", but a cheap knock-off panel of judges from Thailand.
        • by PhotoBoy ( 684898 ) on Monday April 05, 2004 @09:06AM (#8768139)
          Dear Sir,

          Please kindly permit me to express myself to you. My name is Mohammed Bah Abba from Nigeria. I recently won money from Rolex watch company that mandated me to search for good and reliable company/individual person who can assist me to safe keep some amount of US$100,000 dollars. This fund is paid into a fixed deposit account with coded secret account number and my coded name in a bank in Europe.

          Now, I am wanted by the NIGERIAN SCAMMERS who have mandated that all my assets, bank account home and abroad be confisicated to pay for their email fraud schemes.

          I need trust worthy investor who can go to bank in europe to receive money either through the transfer system for certified draft in his or her name to redeposit this money in your country for good investment. If you can handle this process myself or my attorney to have meeting with you anywhere in europe to go to the bank with legal letter of administration to change beneficiary to your name as investment proxy and investor to our family investments.

          This is very confidential handling if you can be able to handle it with us, I have mapped 20% for you and new fridge that not need electricity. You should contact me urgently on my email:

          This is 100% risk free and demands absolute secret and confidentially.

          If you are being good to good I pray we succeed. respond urgently.

          Mohammed Bah Abba
    • I once held two weeks' technical training in a hotel for a major UK field service company. All the students (45) stayed in the hotel too and they were all around 17-20 years old - some had not stayed away from home before!

      As you can imagine, there were some rather late night parties and although the hotel staff had cleared out the room mini-bars as requested by the FS company, the students had sufficient intelligence to stock up from the local spermarket.

      One night, however, 'Labatts Ice' bottled beer was
    • by stu_coates ( 156061 ) * on Monday April 05, 2004 @07:40AM (#8767679)

      This is obviously untrue.... have you ever heard of a student with a clean sock? ;-)

    • Re:keeping beer cool (Score:5, Informative)

      by Monsieur Canard ( 766354 ) on Monday April 05, 2004 @08:51AM (#8768043)
      We homebrewers have used this trick for a long time too.

      If you're making a lager, you are supposed to keep it at a relatively cool temperature for an extended period of time while it ... well, lagers.

      If you're not fortunate enough to have an extra fridge (with appropriate temperature regulator), or be living in a cold climate with a cool garage/basement, you can use this technique to keep it fairly cool.

      Just put your carboy (or other fermenter) in a tub with a couple inches of water in it and wrap the vessel in a towel (my favorite was a thick Bugs Bunny terrycloth) with the bottom edge of the towel in the water. Just water your beer every couple of days and you're good to go.
      • There is a timesaving trick that avoids this palarver entirely but produces an almost identical product. Simply empty out the keg and piss into it until full. Carbonate as required. Then go down the pub for a pint of bitter. Job done.


  • by incognitox ( 123292 ) on Monday April 05, 2004 @06:03AM (#8767365) Homepage
    For some reason, I read "pot-in-pot" as more of a smuggler's invention. Ingenious! I'll hide the _REAL_ pot inside this _FAKE_ pot, so they'll never find it!
  • rolexity (Score:5, Funny)

    by Doc Ruby ( 173196 ) on Monday April 05, 2004 @06:04AM (#8767368) Homepage Journal
    Give a man a rolex, and he's more or less late for a lifetime. Give a man a stick, and he's on time at least once a day.
  • by torpor ( 458 ) <ibisum@gm a i l . com> on Monday April 05, 2004 @06:04AM (#8767370) Homepage Journal
    i'd sure like to know how often you have to change the wet sand, in order to get 2 weeks worth of refrigeration?

    anyone got any napkin-science calculations that can give us a ballpark of whats needed? i'm sure this is a simple physics equation, only i'm certainly not qualified to work out the formula ...
    • As long as you keep it in the shade I doubt you need to rewet the sand too often. Two layers of clay (or whatever the pots are made out of) as well as a few inches of sand should insulate fairly well. If anyone has a site that lists the "R" values (insulation coefficiants) of sand and clay all you'd need to do is compare that to something like a cooler (at least to get an idea on how effective this is).

      Just like your refridgerator at home the main limitation\factor in terms of heat loss is going to be ho
      • by kfg ( 145172 ) on Monday April 05, 2004 @07:29AM (#8767645)
        The clay is wet. The sand is wet. It all has the R value of a wet paper bag, which is to say that it's "anti" insulation.

        That's the whole point. It doesn't retain cold, it creates cold. Put on a wet Tshirt on a chilly day and go outside. Get it? It works by heat loss, and thus that's what you're striving to accomplish. The exact opposite of the way you think of a cooler.

        The whole thing works by continuous evaporation. It lasts longer in the shade, but it actually gets colder quicker if you dampen the outside and give it a bit of sun.

        When the thing goes dry it has the R value of a dry paper bag, which is to say, essentially zilch. You have to keep it wet or the whole thing goes to hell, just like when that Tshirt dries out.

        And as I explain in a post above the whole thing actually works better if you use an unglazed porous outside pot. Water seeps through the pot slowly, just fast enough so that the outside always feels a liiiiittle damp, but never wet, and you get the entire surface of the outside pot as cooling area. Throw a real lid on the thing instead of the damp cloth and it'll go for quite some time before you need to add water, although just how long "some time" is is highly variable, since it depends on factors like air temperature and humidity.

        • The whole thing works by continuous evaporation. It lasts longer in the shade, but it actually gets colder quicker if you dampen the outside and give it a bit of sun.

          That's not true. If you put it in the sun, the water will evaporate faster and more energy will be transferred, that's true. But also more energy will be added to the system in the first place, and I doubt the higher evaporation will suffice to compensate for that. Even in the best case, it will exactly compensate, not overcompensate.

          Other m
  • how many wats?

    I ask because a friend of mine.. well who am I kidding, I use watercooling and this kind of thing for keeping the water cooled could be quite cool(I already use mostly open bucket evaporating, helped with 1 big fan at low speed to get rid of the heat).

    (and during summer it's expected to go to 30 celsius for fuckin weeks again and no money for AC)
    • by ColaMan ( 37550 ) on Monday April 05, 2004 @06:27AM (#8767456) Journal
      and during summer it's expected to go to 30 celsius for fuckin weeks again and no money for AC

      You poor bastard.

      Try working outside in the sun at 43 degrees on hot earthmoving equipment (with engines hot enough to melt your boots when you stand on them)

      During summer I wished for "just" 30 degree weather every day.

      (Annnnnnd I had to crawl on my stomach 5 miles to school every day! Uphill both ways! Down in the dust and the dirt and prickles and the bitey ants! And I *liked* it, because damnit, that was *good* compared to what some of the other kids went through!)
    • I already use mostly open bucket evaporating

      during summer it's expected to go to 30 celsius for fuckin weeks again and no money for AC

      You're using evaporation to cool your home? How effective is that?

      For me, the most important function of an AC is that it dries the air. I'd even use AC if it would't cool the air as well... I can stand warm weather, but it's the humidity that usually comes with it, that does me in. "Yeah man, but it's a dry heat", and all that.

      Evaporation would cool the house

      • You're using evaporation to cool your home? How effective is that?

        Where the fuck do you live? Around some of the places I grew up, evaporation was not only the cheapest way to cool your home, it was also the most pleasant because of the wetness you put in your air.

        For me, the most important function of an AC is that it dries the air. I'd even use AC if it would't cool the air as well... I can stand warm weather, but it's the humidity that usually comes with it, that does me in. "Yeah man, but it's a d

      • by ColaMan ( 37550 ) on Monday April 05, 2004 @07:13AM (#8767586) Journal
        Evaporative coolers such as units from bonair [] are excellent in dry, hot climates. They constantly draw in dry hot air from outside, drop it by about 10 degrees C and duct it through your house to escape through open doors and windows.

        Where I live at present (Mount Isa, Queensland), just about every house and business has at least a 6000cfm evaporative air conditioner. Humidity can often get below 30%, meaning that they work particularly well. In fact, they can theoretically cool to the dew point, which if you take note of the last 72 hr readings from Mount Isa [] can pull down to 10 degrees or so when it's dry.

        They are of course completely fucking useless for about 3 weeks of the year when it's hot and humid and you get storms in the afternoon at 35 degrees and 90% humidity. You just sweat like a pig then, or retreat to the refrigerative airconditioner you normally keep in reserve in your bedroom.
      • by Rexdude ( 747457 ) on Monday April 05, 2004 @09:22AM (#8768238)
        I live in New Delhi, India-where summer temperatures of 45C are not uncommon. We have what we call 'desert coolers', which are much better than ACs for cooling. Imagine a large metal box with a big fan on one side and straw mats on the other three-which are wetted by water drawn up from the tank below by a pump. The air sucked in by the fan evaps the water, losing heat in the process, and becoming quite cool. I have a large one at home-and I've observed the room temp drop to 22-23C when its above 40 outside. This stuff consumes about 10-20% of the power consumed by an AC-so it's quite good. (power consumption depends on the wattage of the fan, u can put as powerful a fan as you like). They are also quite cheap to make, and it's almost like a cottage industry here-every summer, local shops stock these coolers in various sizes-huge 8' high ones with industrial grade exhaust fans, to cool large areas, to dinky little 'personal coolers'.
        However, during the monsoons, or rainy weather-the humidity renders them useless, as evaporation on the straw mats reduces.
        Oh, and clay pots have been used in India too, for generations, for keeping water cool-though not in the way mentioned.
  • by Propagandhi ( 570791 ) on Monday April 05, 2004 @06:06AM (#8767380) Journal
    This same man (and invention) won an invention of the year award from time (as seen here []) in 2001. I guess it's interesting that he also won this award, but why is Rolex handing out awards years after the fact? Maybe I'm just used to the break neck pace of computer advancement, but this seems a little.. late.
  • Brilliant. (Score:4, Insightful)

    by Anonymous Coward on Monday April 05, 2004 @06:06AM (#8767383)
    Unfortunately such methods have been used in ancient Egypt 4000 years ago already.
    Prior art anyone ?
  • Pot types (Score:3, Interesting)

    by nmg196 ( 184961 ) on Monday April 05, 2004 @06:07AM (#8767387)
    Does it make much difference what the materials of the pot are? I know they used clay pots, but do they need to be glazed, unglazed etc? Would plastic pots work (it's not just the 3rd would that has a use for battery free fridges).

    I was thinking that perhaps it might work best if the external pot was slightly porus, to aid evaporation, but perhaps all the evaporation occurs at the top, so it doesn't make much difference.
    • Re:Pot types (Score:2, Insightful)

      by Fortress ( 763470 )
      Such a cooler would work with any pot material, just with different efficiencies.

      Ideally, you want the outside pot to be a good thermal insulator and the inside pot to be a good thermal conductor. That way, the heat consumed by evaporation is drawn from the contents inside rather than the outside air. Maybe a copper pot inside some sort of oversize thermos with a porous cover would be ideal...of course, such materials probably aren't available cheaply where they're using these ;-)
    • Unglazed clay will work better due to water seeping through the pot and evaporating. It's very common to store drinking water in clay pots in India for exactly that reason (nowardays it'll be carried from the well in plastic pots)
      • by TuringTest ( 533084 ) on Monday April 05, 2004 @06:54AM (#8767540) Journal
        This has also been done in Spain for centuries. We have a traditional earthenware pitcher called "botijo" with a very characteristic design [].

        The cooling effect has been scientifically studied. Here is this article describing it [] (Google-translated from Spanish).

        • The funny part is that the article you quote also quotes the Rolex award for the Nigerian man.

          So we all know that evaperative cooling has been around for a while, but can anyone explain if this particular application has been used? This still looks novel to me.

  • Mohammed Bah Abba of Nigeria won a Rolex award for his pot-in-pot invention

    So I expect soon he'll be creating MohamedCo and start selling rotisserie ovens on Nigerian TV?
  • The money (Score:5, Funny)

    by ExCEPTION ( 102399 ) on Monday April 05, 2004 @06:08AM (#8767392)
    I heard this guy needs someone to transfer the award money for him.
  • by WegianWarrior ( 649800 ) on Monday April 05, 2004 @06:11AM (#8767406) Journal

    ..but maybe the difference is in the execution or something? To me, it's less important that someone might have done this before than the fact that doing it now might change peoples life to the better.

    Shouldn't that be the focus of inventing new ways for doing things by the way? To improve peoples life?

  • This is 3 years old (Score:5, Informative)

    by jayrtfm ( 148260 ) <jslash.sophont@com> on Monday April 05, 2004 @06:13AM (#8767414) Homepage Journal
    Time Magazine invention of the year [] for 2001
  • by Anonymous Coward on Monday April 05, 2004 @06:16AM (#8767429)
    In other news: Man from Nigeria sells Rolex award, buys fridge.
  • by Propagandhi ( 570791 ) on Monday April 05, 2004 @06:17AM (#8767432) Journal
    I'm sure some of us geek's will be confused by this "sand" thing they're using in between the pots. This "sand" they talk about is actually just our friend silicon. Just thought I'd throw that out there to avoid some confusion.
  • Coolgardie Safe (Score:5, Informative)

    by Howzer ( 580315 ) * <> on Monday April 05, 2004 @06:18AM (#8767433) Homepage Journal
    This is by no means a new invention. Evaporation cooling has been in use in real products since the invention of the Coolgardie Safe [], a primitive fridge invented to cope with western Australia's hot, hot summer.

    But, cut the guy a break. The cool thing here is that he's done it with readily available local materials which is pretty much one of the key features for a real engineer. To paraphrase the old saw:

    Anyone can make you an evaporative cooler for $100; this guy's done it for $1.

  • by Anonymous Coward
    How about posting the link to the actual award website []?

    ...Journalism at its best...
    • The Rolex Awards website is Flash only, so don't bother going there if you don't have/want to pollute your system with that technology.

      I was hoping to find out what the criteria for the award were by going to the source, and hoping that it was for making the idea available in a way they can afford to people who need it by use of appropriate technology. Unfortunately, I was frustrated by an inappropriate use of technology on the web site. Those giving the award would do well to learn from those to whom it w

      • Here is the pdf from the award site: a ureate0 006.pdf

        This is my attempt at an excerpt:

        He began by studying management sciences at Ahmadu Bello University in the town of Zaria. Equipped with a Bachelor of Science degree in business administration, he became a lecturer at the College of Business and Management Studies at Jigawa State Polytechnic in Dutse in 1990, at the same time heading the college's Student Industrial Work Experience Scheme. When not teaching, A
  • Obviously (Score:2, Funny)

    by eclectro ( 227083 )

    If this guy got a $100,000 dollar award, then these guys [] should get a "cool" million.
  • by PsiPsiStar ( 95676 ) on Monday April 05, 2004 @06:24AM (#8767449)
    patent 454,845,474,734

    A liquid, excreted from the skin when hot, whose evaporation helps to maintain an organism within a certain temperature range as well as serving to eliminate certain waste materials from the body.

    This process may be, but is not necessecarily, augmented by a seperate device composed of a number of curved blades, fitted to a central hub and rotated at high speeds by an electric motor in order to create artificial air currents. some form of material support apparatus keeps the device elevated above the ground, either by providing a stand or attaching to the ceiling of the room, or by mounting the device inside some form of automotive vehicle. Also, a guard device may be used to keep sundry items from coming in contact with the blades.
  • Millk bottle cooler (Score:3, Interesting)

    by Bushcat ( 615449 ) on Monday April 05, 2004 @06:36AM (#8767483)
    When I used to leave for work at 6am and the milk arrived at 6:30am, I had "milk cooler" which was like a tall flower pot. I left it by the front door, soaking in a bucket full of water. The milkman would pop it over the bottle he delivered each morning. Neither of us got a Rolex for it, though. Maybe people who make Rolexes don't know about the bleedin' obvious. (And while we're at it, we could wonder who makes their watch movements and, indeed, watch bands. Doesn't leave Rolex with much to do.)
  • Water (Score:4, Insightful)

    by IJsqueen ( 768535 ) on Monday April 05, 2004 @06:39AM (#8767495)
    Thank god this only needs water, and they have an infinity supply of that in 3rd world countries, as we all well know.
  • I want to see something along the scale of a Solar powered ammonia-cycle ice maker (pdf) []

    Summary : Ammonia bonded to salt crystals in a closed system is driven off by the heat from a solar reflector, condensed to liquid via a coil of pipe in a drum of water and stored in pressure vessel in an insulated box. Remove the heat, and the ammonia liquid boils off and is recombined with the salt, and can freeze about 10lbs of ice in every 3-4 hour cycle.

    This has the advantage over the evaporative system in that i
  • Yada, yada, yada 419-like text here, only coming from the "CEO of Rolex".

    Actually this is a bit like some art - some dude publishes a 1000s of years old idea, and is recognised for it. So he's basically being rewarded for publishing the idea, not having it. Sort of like some art - you look at it and think, who on Earth would do that ? And then they sell it for $1000s, and then you think to yourself, "I'm an idiot", I could have done that !
  • by theolein ( 316044 ) on Monday April 05, 2004 @07:03AM (#8767564) Journal
    I'm from South Africa and I remember a visit to a friends farm about 20 years ago, where he showed me this big black metal box (about 6 feet, 180cm high) he had in his back yard which he used for storing spiced and salted dried meats (locally called Biltong, a bit like beef jerky I think). It worked on the same principle in that it was double walled with the space inbetween the wall filled with sand and a large grating on top which needed to be replenished with water every now and again. It was amazingly cool in the African summer heat.

    He had replaced the box after the one from his grandfather finally rusted to pieces after just over 75 years of continual use.

    Truckers in South Africa also used to also carry a water bag in a wet sand filled canvas bag outside their trucks to provide a constant source of cool water.

    I think the principle is probably much older than this, probably going back to the first person realising that the wind chilled him more after taking a dip in a lake that when he was dry.
  • How it works... (Score:5, Informative)

    by otter42 ( 190544 ) on Monday April 05, 2004 @07:04AM (#8767566) Homepage Journal
    Basically, the outer clay pot is porous. The water evaporates and escapes through the pores in the clay. This all happens very quickly because the air is so dry. So assuming that 1 kg of water evaporates each hour, this means about 2kJ of energy, and thus heat, is sucked from the pot. So for you non-metric heads, this means that every gallon of water equals 8,000 BTU. For reference, a typical family refigerator might use 7,700,000 BTU/yr, or 900BTU/hr.

    You'd be surprised at the massive amount of energy that a liquid-to-vapor phase change can carry away. In fact, six times more energy is needed to turn one molecule of 100C liquid water to one molecule of 100C vapor water than is needed to heat liquid water from 0 to 100C!

    Boiling, which is a similar phenomenon, is the most efficient way to transfer heat known to science.


    1. My girlfriend
    2. You
    3. ???
    4. Profit!
  • As a nerd I found this to be vital news on stuff that really matters. I'm going to power down my servers now and go and play with pots and wet sand.
  • AFAIK this kind of fridge is being used by street vendors in Africa. The outer "pot" is normally a wire basket and instead of sand they use coal, which gives a larger surface.

    Read this several years ago.
  • by MrIrwin ( 761231 ) on Monday April 05, 2004 @07:19AM (#8767612) Journal
    Thousands of years ago potters allready knew how to make pots sufficiently pourous that they would keep the water cool by sweating.
  • Hmm (Score:5, Informative)

    by ajs318 ( 655362 ) <sd_resp2.earthshod@co@uk> on Monday April 05, 2004 @07:39AM (#8767676)
    This isn't actually very different to the way an electric fridge or air conditioner works. The main difference is that in a fridge, the refrigerant is contained within a closed cycle; in this simple evaporative scheme it is lost to the surrounding air. Since it's only water, few people are likely to be bothered about that. That's why, if you have a CFC fridge and it's still working, there's no point getting rid of it ..... the CFCs are sealed up nice and tight inside it, till you scrap it {there's not much you can actually do to get rid of unwanted CFCs, except leak them into the atmosphere when nobody's looking; which is almost certainly what will happen to the CFCs in your fridge, even if you don't put a chisel through the evaporator in a defrosting accident} and making a new one uses up more energy and resources than keeping an existing one going.

    The idea that an evaporating liquid draws heat from its surroundings is nothing new.

    Basically, the difference between a liquid and a gas is how much the molecules are vibrating: if the vibration is weak, the molecules' affinity for each other bonds them loosely together so they follow one another around, assuming the shape of a container but occupying a definite volume. If the vibration is stronger than that attractive force, then they just fly apart, occupying the whole of the container and exerting a pressure on it. Heating, of course, makes the molecules vibrate more strongly, which is why liquids turn into gases when heated.

    If you try to force more molecules into a space, eventually they will be forced into colliding with one another often enough to form a liquid. This is what goes on in a cigarette lighter: there are just too many molecules to behave as a perfect gas, so some of them are forced together and behave as a liquid.

    Pressure, volume and {absolute -- i.e. in Kelvins, 0C = 273.15K} temperature are related by the equation: P * V = n * R * T, where n = number of moles of gas and R is the Ideal Gas Constant. No gas is truly ideal, because the assumption is that the individual molecules have neither mass nor volume; however, the relationship holds reasonably well in real life, only deviating sharply around the point where liquefaction actually occurs.

    A fridge or air conditioner has three main parts: the compressor, the condenser and the evaporator. The refrigerant gas is first compressed. Pressure goes up and volume goes down, so temperature also goes up. It is then pumped around some pipes at the back of the fridge {or in the outdoor part of the air conditioner; portable units don't have an outdoor section, so the condenser is cooled by blowing air over it and out of a window through a length of flexi-flue -- uncouple this and you've got yourself a de-humidifier} to allow it to cool down. Once the refrigerant has cooled to ambient temperature and become a liquid again, it is forced out by its own pressure through a tiny hole into a larger space {the evaporator - usually the outer jacket of the icemaking compartment of a fridge, or the coil of pipe in the indoor part of an air conditioner that gets covered with ice crystals}. Now the pressure is not sufficient to keep the refrigerant molecules together, so it becomes a gas again. Pressure goes down, volume goes up, so to satisfy the laws of physics, temperature must go down.

    The compressor's intake draws the low-pressure refrigerant out of the evaporator and the whole thing starts again. {In an air con., the whole process has to be stopped every so often to allow the accumulated ice to melt off the surface of the evaporator. Plumbed-in units have a permanent drain, portable ones have a tank which needs emptying periodically. The meltwater is pure enough to be used anywhere demineralised water is required.}

    You can also get a terracotta butter cooler which works on this principle: the inside of the tray and dome are salt-glazed, the outsides are unglazed. You soak the whole thing in water, which then evaporates slowly from the outer surface, keeping the butter usefully cold {not rock solid, but not runny either}.
  • Invention ? (Score:5, Interesting)

    by mritunjai ( 518932 ) on Monday April 05, 2004 @07:49AM (#8767718) Homepage

    I second the people posting that its around 4000 year old method.

    I'm from India and I first I read about it when I was around 10 year old (I'm 23) in a popular social magazine (called 'Dharmyuga', the most popular magazine of its time). It had schematics identical to those offered by this fellow, and yes, they mentioned it to be "very old technique". My dad still has collection of old issues of this mag and I'm sure I can fish out the article mentioning this 'invention'.

    Can't these fellows do at least a google query to verify that whatever they're offering money for is indeed an invention ??

    Several docs with feedback []

    • Re:Invention ? (Score:3, Informative)

      by Forgotten ( 225254 )
      The Rolex site mentions that Abba was aware of evaporative cooling through pots from his childhood growing up in a family of potmakers. The problem was that clay pot technology was being lost by these people, replaced by impermeable plastic and aluminum pots sold to them by importers. This is a pretty common pattern when you think about it - culturual colonisers replacing indigenous technologies with supposedly better stuff that's mainly just more profitable to the colonisers. When something's been done for
  • by hak1du ( 761835 ) on Monday April 05, 2004 @08:01AM (#8767766) Journal
    From Convair's web site []:

    Ambient Relative Humidity
    Temperature (&#186;F)

    -- 10% 20% 30% 40% 50% 60% 70% 80% 90%
    50 36.2 37.9 39.6 41.2 42.8 44.3 45.8 47.2 48.7
    60 42.9 45.1 47.2 49.3 51.3 53.2 55.0 56.7 58.4
    70 49.2 52.1 54.7 57.3 59.7 61.9 64.1 66.1 68.1
    80 55.3 58.9 62.2 65.2 68.1 70.7 73.3 75.6 77.8
    90 61.4 65.7 69.6 73.3 76.5 79.7 82.4 85.1 87.7
    100 67.2 72.5 77.1 81.3 85.1 88.5 91.7
    110 72.9 79.1 84.5 89.3 93.6 97.5
    120 78.7 86.0 92.2 97.5
    130 84.5 92.8 99.9
    It's nice, and it helps, but it's no refrigerator. Note that effectiveness depends on humidity.

    Evaporative cooling has been use in kitchens for millenia, although it is usually used to keep water cool (unglazed pots). For storage of more than a few hours, a cellar, solid stone building, or cave is less hassle. You easily get guaranteed 70F or below long-term storage in most regions of the world, and if you are architecturally clever, you can actually get lower-than average-long-term temperatures without any maintenance or needing to re-fill water into little jugs.
  • by PhotoGuy ( 189467 ) on Monday April 05, 2004 @09:05AM (#8768131) Homepage
    Here [] is a link to research being done using a similar approach, but more efficient evaproration (not water), and a vacuum, so it can actually produce 2kg of ice a day. (Not in production yet, due to deterioration of the system after a couple of years, but doesn't sound too far off.)
  • by 955301 ( 209856 ) on Monday April 05, 2004 @09:36AM (#8768346) Journal
    Grats to this guy for winning the recognition. But from what I understand in his culture the money he receives will just have to be doled out to his family, and his extended family, and their families, etc.

    Someone correct me if I'm wrong here, but that's part of the problem with entreprenuership in a lot of African nations. As soon as you start to get somewhere, people start crawling out of the woodwork looking for handouts as part of your family, and it's against traditions to not give the assistance to them. That's why nepotism is such a problem. If you are elected to a position of power you pretty much have to hire your relatives.

    I'm assuming this based on the following story: I dated a (great) woman for about two years who lived in Rwanda for 18 months. While there for the state department, she taught a native how to manage his small furniture business and turn a respectable profit. Once he started making enough gains to expand and have a chance at doing more than just surviving off his work (expand his shop, hire more carpenters, open a real store, etc.) she learned that his family threw some serious pressure at him to buck her advice and give the money to them.

    So he never was able to make a business to sustain his family because they didn't understand he needed to pay people working for him to bring even more in. Don't spend the seed money.

  • by Anonymous Coward on Monday April 05, 2004 @09:47AM (#8768467)
    This is not about whether or not you did the same thing in college with your beer, or whether you did something like this in 8th grade science fair, or whether the ancient Egyptians had these with ice-dispensers built in to the side. Yeesh.

    This is about how someone came up with an easily packaged low-tech device that will help millions of people. Sure, it's obvious, but he's doing something that will actually help people.

  • How cold? (Score:3, Interesting)

    by Dr. Mu ( 603661 ) on Monday April 05, 2004 @11:34AM (#8769641)
    So how cold can these things make their interiors? The article mentioned being able to keep perishables for three weeks, which seems to be on par with my fridge -- if not better! But what does that translate to in degrees Fahrenheit (or, for the rest of the world, Celsius) with, say, a dry 100-degree F ambient?
  • by blrichwine ( 263927 ) on Monday April 05, 2004 @11:47AM (#8769801)
    What is new about this is his effort. He maximized his design for over two years to get the maximum affect (prolonging the life of produce) for the least cost. Then he built two factories to produce them and distributed them to rural villagers for free (using his own money). Imagine the changes it made on a culture where food grown would only last 1-2 days once picked if it could now last a month or more!

    The real "invention" here is his efforts toward making a positive change in the villager's lifestyle. Obviously if someone is awarding $100,000 dollars there is more to it. You folks should do some more research before you nock it!! He plans to use the $100,000 to distibute the pots more widely and to increase his education efforts!

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