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Wave-Powered Desalination 184

Posted by kdawson
from the wanna-buy-a-duck dept.
dptalia writes, "Scientists think they've found a way to harness the energy of waves to desalinate salt water. Currently desalination is an energy-intensive process, but this new design harnesses the renewable energy of waves to produce fresh water. Many countries depend on desalinated water to support their populations, and this invention could lower the cost of water generation." Production versions of the "desalination ducks" would be about 10 meters in diameter and 20 meters long. Each would supply water for more than 20,000 people.
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Wave-Powered Desalination

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  • Wow. (Score:5, Insightful)

    by NerveGas (168686) on Wednesday November 08, 2006 @07:42AM (#16765553)
    2,000 cubic meters per day of desalinated water from each unit. That's over 350 gallons per minute. Impressive!
    • Re: (Score:2, Interesting)

      by Rudisaurus (675580)
      I thought so too. So why do they always have to find some nay-sayer -- this Nidal dude, for instance -- who has an obvious axe to grind and is therefore completely blind to the possibilities? Scale has nothing to do with it; it's cost per unit fresh water produced that matters -- and in places where energy is scarce or infrastructure is lacking, the desalination ducks sound like an awesome solution.

      Plus -- they won't plug off the way RO membranes do. :)
      • Re:Wow. (Score:5, Funny)

        by Anonymous Coward on Wednesday November 08, 2006 @07:57AM (#16765631)
        Why do they always have to find some nay-sayer -- this Nidal dude, for instance -- who has an obvious axe to grind and is therefore completely blind to the possibilities?

        I couldn't agree with you more. They keep telling me that my perpetual motion machine will never work, but I know that I have the calculations correct! And after I patent my time travel machine and my warp engine designs I'll definitely win a Nobel prize!

        I hate those people with such small minds thinking only about facts and the truth. I know how things really work, I feel it in my gut.
    • I do love Googles [google.co.uk] conversion function though. I didn't think it would work that one out OK but it did.
    • Re:Wow. (Score:5, Interesting)

      by grozzie2 (698656) on Wednesday November 08, 2006 @08:34AM (#16765805)
      It would be more impressive if it didn't require the water to be pre-heated to 100C. I think it's safe to say, pour boiling seawater into just about anything with some condenser tubes setup, and you'll get fresh water out of the condenser. It appears to be insulated with Impossiblium, you know, the stuff that'll allow it to maintain internal temperature for a month while it works, with no heat input. I'm willing to bet, read the fine print in the marketing manuals, and you will find the Mark II version will have double the production if you power it with snake oil too....

      • Re:Wow. (Score:5, Informative)

        by finity (535067) on Wednesday November 08, 2006 @09:18AM (#16766149) Homepage Journal
        The water that must be pre-heated is the "ballast" water. That water is already fresh water. The salt water doesn't have to be heated to 100 C, it's pulled to a low pressure with the ballast water, so it doesn't have to be heated as much.
        • by jfengel (409917)
          Doesn't that cool down the ballast water? So you need additional energy input to keep the fresh water at 100C, yes?
      • by drinkypoo (153816)
        The temperature doesn't have to stay constant. The fresh water in the unit is only ballast. The rocking motion is used to put the water under partial vacuum so it boils at a lower temperature. The rocking probably continually increases the vacuum so that as it cools it continues to boil/steam. As others have pointed out, the water can be heated with sunlight, which is cheap to develop and cheap to operate (free but for maintenance.)
    • by daem0n1x (748565)
      That's about 1400 litres per minute.
    • by caudron (466327)
      That's over 350 gallons per minute.

      And over a full Library of Congress every three days! Wow! That's a whole lotta got-dang water!

      Tom Caudron
      http://tom.digitalelite.com/ [digitalelite.com]
    • Oh man. Yes, completely off topic, but your sig just made me snort my chicken salad on my monitor. Thanks for finally motivating me to clean it!!! :P
      • by NerveGas (168686)
        No problem. :-)

        It's actually a quote from my wife, when she was speaking to me...
        • *giggle* Same place I got mine! (well, it was my husband, but still! :))

          Ah... our loved ones, huh? Too bad they don't come with pricey Christmas Gadget Glory. :D
  • And Australias salination problems are solved.
  • cool (Score:3, Interesting)

    by joe 155 (937621) on Wednesday November 08, 2006 @07:48AM (#16765587) Journal
    This could be really useful in the UK, we are getting frightening low on water during the summer months to the point where we thought that we might have to go back to stand pipes. We would have the money to build something like this and the energy to heat the water (it needs to be pretty hot to do it) - I do wonder though if it would be practical for the very poor countries because of the requirements on the heat (although maybe solar could take care of that) and the cost of building them... I wonder if it will be prohibitavely high

    also "One unit should be able to produce around 2000 cubic metres a day", that's pretty amazing.
    • This could be really useful in the UK, we are getting frightening low on water during the summer months

      The UK? Yeah, very serious drought [news.com.au] there every summer... [bom.gov.au]

      • Re: (Score:3, Informative)

        by cloricus (691063)
        Haha yeah...How about this for frighteningly low; in early 2008 my city runs out of water. There are no backup plans and no prospects in the pipe line at the moment, due to a rather stupid population voting on our water future based on popularity (the good looking one was the dumb one) not on science, so all 100,000 residence and twice that in the near by regions will be out of water. I hear the huge storms that hit Brisbane over the last three days are only adding a weeks worth of water to their supplies
    • Re:cool (Score:4, Insightful)

      by lisaparratt (752068) on Wednesday November 08, 2006 @08:09AM (#16765693)
      Or you could just heavily fine the water companies 'til they fix their pipes, rather than letting such huge amounts of water leak away.
      • Or you could just heavily fine the water companies 'til they fix their pipes, rather than letting such huge amounts of water leak away.

        Yeah, because it's not like they'd just pass that fine onto their customers, who, as we know, have so much choice in who they buy their water from.
    • by pubjames (468013)

      Except that in the UK the news about a "drought" every year is just bullshit. The UK is drowning in fresh water compared to many countries. Did you know that the UK only uses about 10% of the fresh water available to it each year?

      I don't understand why a big fuss is made every year about this. Perhaps it is an attempt by the water companies to get tax breaks from the government or something, I don't know. But I find it a bit sad that so many people in the UK seem to swallow it every year.
      • Re: (Score:3, Interesting)

        by Fr. Teddy (171470)
        While that is strictly speaking accurate, it is of course not the full story. The vast majority of that water is in parts of the country where it is not able to be used. Perhaps a huge canal down the middle of the country might solve it - but nothing short of that would.
      • by dajak (662256)
        It's a little more complicated than that: you can't just judge the robustness of a landscape by the amount of water available. And the droughts are real.

        Here in the Netherlands we also had severe "drought problems" a few years ago, which is admittedly odd for a country largely below sea level with some of Europe's major rivers running through it, and that normally pumps sweet water out continually. Some of the symptoms: two floodings caused by failure of dehydrated dikes that were simply no longer capable o
    • The problem isn't running out of water, the problem is the economics of the privatised utilities.

      Everyone pays a flat rate for their water so there is absolutely no reason to conserve any water at all. On the utilities side, they get paid exactly the same whether half the water is leaked out of the pipes into the ground or whether it's delivered. Maintenence then simply reduces their profits.

      The solution, which will fix both problems is water meters. That way the individual household pays for every litre th
      • You guys don't have water meters? That's ... interesting. So if I use 3x as much water as you, we both pay the same amount at the end of the month?

        Seems like you don't have to be Adam Smith to figure out the way that's going to work. It's the "splitting the tab" phenomenon (when you go to a restaurant for lunch and agree to split the check evenly ... it encourages people to order more expensive stuff than each other and thus screw everyone else).

        I generally don't have a whole lot good to say about my munici
  • by MarsBar (6605) <[geoff] [at] [geoff.dj]> on Wednesday November 08, 2006 @07:48AM (#16765595) Homepage
    The inventor's name is Stephen Salter. Heh.
  • Why not solar? (Score:2, Interesting)

    by jonadab (583620)
    I've often wondered why solar power isn't harnessed to distill seawater. It ought to be a simple matter to hook up a glass-topped insulated-on-the-bottom pyramid or somesuch with an inlet that lets seawater in (and the concentrated result back out for that matter) whenever a larger-than-average wave passes, set it up so the seawater passes over a metal plate, add some mirrors and/or lenses to heat the thing enough to create some steam, and pipe the steam out the top and over to a shaded receptacle with a n
    • Re: (Score:3, Informative)

      by will_die (586523)
      They are called solar stills [serve.com].
      While easy in design they are rather expensive, require huge areas of land to produce sizable quantities of water and weather dependant. Also you cannot have moving water since it needs time to heat up so that steam is produced
      • Actually, I happened to see one design of solar still the other day, that was touted as both cheap and small.

        The design used something pretty close to a solar panel: a flat white plastic surface, with a thick, dark-tinted, glass panel. Between the plastic back of the panel and the glass, the inventor put a black felt surface, on top of a black plastic sheet. The felt that was wetted by a plastic tube in which (very) small holes had been punched to create a drip.

        The felt, the plastic sheet and the glass pane
        • An inflatable, sponge based still. The base of the unit is 10cm thick black polyeurethane sponge the glass is simply clear inflatable tubing.. Instead of land, you float it out on the sea. hmm, it occurs that I should patent this.
        • The design used something pretty close to a solar panel: a flat white plastic surface, with a thick, dark-tinted, glass panel. Between the plastic back of the panel and the glass, the inventor put a black felt surface, on top of a black plastic sheet.

          You do realize that there is more to a solar panel than just coloring some glass black, don't you? I'll assume you do, and that there is some actual way (other than mere appearance) in which this remotely resembles a photovoltaic cell array, and ask you what

          • Re: (Score:3, Informative)

            by Noryungi (70322)
            Yes, I know there is more to a solar panel than painting a piece of glass black. Happy? ;-)

            However, let me point out that there are two types of solar panels out there: photovoltaics [wikipedia.org] and thermal solar [solarserver.de]. The design I was talking about is, of course, a "thermal solar" type of panel, that does not generate electricity (that's a photovoltaics) but that uses the heat radiated by the sun.

            Of course, someone out there is going to say: "Aha! But thermal solar can also be used to generate electricity", to which I repl
    • by salec (791463)
      Actually, the sun has already done its part - the air above the sea surface and on the shore is humid because of evaporation. Now, all you have to do is to cool a surface which is not reachable neither by sunlight, nor by seawater and to collect condensed water. A simple long, vertical, floating, white or reflective-colored metal flask could do that (as long as the sea is cooler then the air above - otherwise, a metal panel up in the air would do the trick).
    • I've often wondered why solar power isn't harnessed to distill seawater.

      It turns out that it isn't an easy problem to solve but there is a physicist sponsored by rotary international that is on the job with a good design (I'm sick and it's late so I can't remember even a name). With a source of reasonably hot water that does not have to be clean it can go from a trickle suitable for a village to turning out clean water in industrial quantities - even if the source is full of salt, heavy metals or bacteria

  • by Rogerborg (306625) on Wednesday November 08, 2006 @08:07AM (#16765669) Homepage
    All floating platforms are subject to damage or loss during storms. You don't want interruptions in your fresh water supply, ever, and you especially don't want to lose it after a big storm, exactly when you need it most. This looks like a good idea in theory, but you don't base risk management on best case scenarios.
    • Presumably... (Score:3, Insightful)

      by turbosaab (526476)
      A sensible installation would accompany the floating platforms with a large reservoir to act as a buffer and prevent such interruptions.
      • Re: (Score:3, Interesting)

        by Threni (635302)
        Perhaps you could pull them a few metres underwater during a storm?
        • Or even... (Score:4, Insightful)

          by stomv (80392) on Wednesday November 08, 2006 @09:12AM (#16766071) Homepage
          have a spare one or two on land, ready to deploy? This is a good idea anyway, since one of the ducks could fail for any other reason, leaving people thirsty. If you lose a duck to a storm, you replace it with one stored on land.

          It ain't perfect, but it ain't bad either. Combine that with reservoirs (either big lake, or lots of 1 gallon jugs of freshwater at homes), and it's much better than the status quo.
          • by Shadowlore (10860)
            Open lakes and resevoirs are susceptible to storm damage as well. They often get quite polluted during and after large sea-based storms.

            I do agree with you in general: have backups and build a supply. The supply would be constantly "rotated" to prevent stagnation. It is interestign that detractors point to a problem that already exists as a reason against a new idea. This is yet another case of perfect being the enemy of good enough. Storms on that scale already represent major problems to places that might
    • Re: (Score:3, Informative)

      by artecco (1020333)
      I do not know what kind of platforms you reffering to, but I at least don't see any technical problems with build such plant. Within my industry (Norwegian oil&gas) we build offshore equipment and platforms, and the dimensioning of equipment are all well within what's technical achievable. Even in worst case scenarios

      So since we already dimension Oil rigs and equipment for mammoth storms, freak waves and gas explosions (happening at the same time for your pleasure), I would guess it wouldn't be a proble
      • by radtea (464814)
        So since we already dimension Oil rigs and equipment for mammoth storms, freak waves and gas explosions (happening at the same time for your pleasure), I would guess it wouldn't be a problem to build one of these...technical at least. Economical I don't know

        Oil platforms are mostly designed to either a) stand still or b) float freely. Either of these is technically much simpler than a system designed to stand mostly still but have really big moving parts. If you look at the diagram accompanying the articl
      • by inKubus (199753)
        Yeah, except that oil is quite a bit more valuable than water on the worldwide economy, which is what would build this. That may not be the case for much longer, especially with the population explosion that no one ever seems to talk about.

    • by muellerr1 (868578)
      This thing is powered by waves. Bigger storm surge waves will mean even MORE fresh water!
    • by khallow (566160)
      Given that all water delivery infrastructure is subject to loss or damage during storms or other disasters, this isn't saying that much. As mentioned elsewhere, move in a bunch of new platforms when such a disaster occurs. The only thing faster would be transporting in fresh water. I think this is acceptable risk.
  • Vitally Important (Score:3, Insightful)

    by Surasanji (938753) on Wednesday November 08, 2006 @08:07AM (#16765675) Journal
    This particular type of technology could be extremely important in countries with few water sources. Say such as much of the Middle East. Israel has a single fresh water source for the entire country, the Kinnert (Or Galilee) This same freshwater sea is the water source for a great part of Jordan. Both countries have coasts on the Red Sea- and already there are massive desalinization plants there, on the Israeli side. But, what about Egypt? All the African Countries on the coast that are still pretty dry. This particular technology could also be of great use in the first world, as someone else stated, in places like England. I'm sure they aren't the only country with a water problem.
    • The great thing about this is it's distilled water, there's no salt in it, therefore it can also be used for irrigation with out turn the ground into a salted out sterile waste-land in a couple decades.
    • by Zaatxe (939368)
      But, what about Egypt?

      What has happened to The Nile? I thought the egiptians had been using it as source of fresh water for something around 5,000 years by now...
    • by PsiPsiStar (95676)
      Israel doesn't get water from off the Golan Heights?
  • Engineer (Score:5, Informative)

    by Rostin (691447) on Wednesday November 08, 2006 @08:19AM (#16765737)
    Stephen Salter is an engineer, not a "scientist." The distinction can be blurry, but I think this is pretty clearly an example of engineering rather than science.

    The only reason I point that out is that I'm an engineer, and I'd like credit to go where it's due. :)
    • The author is an inventor [wikipedia.org] or a designer. To become an engineer he needs to take into account all the practical aspects of the implementation. Not only technical questions. Cost, producibility and serviceability should also be addressed in engineering. Once we see working implementations used in production we may call him an engineer.

      However, his invention is really interesting. And I really hope to see it in production.

      According to Wikipedia:

      The crucial and unique task of the engineer is to identify,

      • by Rostin (691447)
        That's a good point. I think what I really intended to point out is that Salter is a professor of mechanical engineering. I got a little overzealous. :)

        I only have one quibble with your criticism. I don't think we have to see a working implementation before we can call Salter an engineer. It may be the case that his device isn't practical under any real circumstances. When I worked in industry (I'm a grad student now), if we decided not to go forward with a project, we didn't say that the engineering wo
        • by Firethorn (177587)
          If nothing else, building a prototype is often needed for proof-of-concept, even if the prototype is ineconomical, you can have valid hopes that by studying the operation of a test prototype will allow you to gather the knowledge to build economical production models.

          Experimentation is usually part of the development process. Who knows, it might not be economical right now, but in the future the equations could change. Fresh water more expensive, fuel more expensive(making solar cheaper in relation), new
      • by khallow (566160)

        Let us not assassinate this term further, jetxee. You have done enough. Have you no sense of slack sir, at long last? Have you left no sense of slack?

        More seriously, I fail to see the point of making the distinction between inventing and engineering. Engineers typically operate in a narrow scope. Eg, shaving weight from a car floor mat while maintaining sufficient durability or inspecting an assembly of refinery pipes to see if they meet serviceability requirements. So inventing is just a narrow scope exa

  • Just use that Russian flaoting nuclear plant to heat the water up first...it'll work!
    • by steveo777 (183629)
      You're actually on to something there. Nuke-power produces a lot of heat. After the water is heated up, it just goes back where it came from, right? Or can you not use salt water for that? Or will people be leary about drinking water that tends to glow green, even when not in a 'glowy-cup'? Guess I got exited over nothing...
      • by cr0sh (43134)
        Actually, in most (all?) nuclear fission plants using water as a moderator, you have two closed water loops - the loop for the reactor and the loop for the steam turbine.

        The loop from the reactor circulates water around the core - the water acts as both a moderator and (partially) as a shield for (neutrons? can you tell IANANE?), as well as an absorber of the excess heat from the near-critical pile. This water is circulated in a closed loop system to a heat exchanger, which forms a part of the second loop.

  • by Ancient_Hacker (751168) on Wednesday November 08, 2006 @09:13AM (#16766083)
    If you read The Fine Article, you might notice a certain shortage of facts. Like the costs. Economics are important. You don't want to waste money on schemes that are many many times more expensive than proven methods.

    In general, it's not feasible to capture wave power. The stuff is too diffuse-- it takes too much infrastructure to capture too little energy to even pay back the cost of building the contraption.

    It doesnt matter whether you use the mechanical energy to generate electricity, desalinate water, or make tea. You can't build a wave energy capture device that's rugged enough to survicve the storm, corrosion and other hazards at a reasonable cost.

    As a starting point, let's take their (unsubstantiated) estimate of 2,000 cubic meters per day. A quick google shows that's worth about $1,000 to $3,000. Assuming the waves are active 75% of the time we could expect maybe $2,000 a day from this device. That's about $700,000 a year. Kinda impressive at first glance. But will that be enough to even pay for the gadget over time? Let's estimate, generously, that the device will last ten years. And that we can borrow money to build it at 5% interest. If it and the pipeline to shore can be built for $10 million, we need to pay at least approx $1.5 mil a year to make headway on the principal and interest. Plus the cost of staff and maintenance. We're still a factor of more than two away from breaking-even. And that's assuming no risks due to weather or unanticipated problems with new technology.

    • Re: (Score:3, Interesting)

      by Alcari (1017246)
      10 years, Are you kidding? You can easily build it to last 75 or hundreds of years with proper maintenance. Take the word of a civil engineer. The moving parts may be more difficult, but I doubt it. We've got movable dams that are just about zero maintenance, that have been standing there for almost 40 years now. Of course, If you put multiple installations nearby, it saves the immense cost of laying another pipeline underwater (Probably costs more then the whole facility.) Also, funding for projects like
      • >10 years, Are you kidding? You can easily build it to last 75 or hundreds of years with proper maintenance.

        That's for things in fresh water, and things that can be taken out of the water to be scraped and repainted.

        None of those things apply for a seawater desalinizer. Think of supertankers, which cost tens of millions of dollars, and only last a few decades before rust overwhelms them.

        >Take the word of a civil engineer. The moving parts may be more difficult, but I doubt it. We've got movab

    • If you read The Fine Article, you might notice a certain shortage of facts. Like the costs

      It is too early for costs. If you consider reality costs are variable based upon manufacturing techniques, materials used, supply, economies of scale, administrative costs, delays by regulatory groups and other things that are not immediately apparent even after construction of the first prototype. First you find out if it can be done - then you work out how to do it well for as little as possible based on better as

      • You can't build a wave energy capture device that's rugged enough to survicve the storm, corrosion and other hazards at a reasonable cost.

        It may be possible that is true but it is a pretty wild claim to make - what do you have to back this up? Why don't you think it is likely that the designer has considered existing structures that are built to survive for decades in waters with very powerful storms?

        Mostly because there aren't any comparable structures to compare it to. Mostly because existing structur

        • Mostly because there aren't any comparable structures to compare it to.

          Oil drilling platforms sometimes have a lot of very heavy gear in the water and winch it up or lower it down when storms approach. Would it be all that hard to have it on pylons and sink the thing? Also something that is mechanically complex to you may not be mechanically complex to a civil engineer, marine engineer, fitter, rigger etc etc. These things are not even really that big and don't have to go in deep water - they may even

    • by khallow (566160)

      It doesnt matter whether you use the mechanical energy to generate electricity, desalinate water, or make tea.

      It most certainly does matter. A key point here is that the power produced is used at the same location. This means you don't need the infrastructure for transporting electricity or other power.
    • You can't build a wave energy capture device that's rugged enough to survicve the storm, corrosion and other hazards at a reasonable cost.

      Your assertion is void without defining "reasonable cost".

      For this post all monetary terms will be in US dollars.
      Currently, the best desalination plants are running $2.5-3/1000 gallons (for seawater plants, the target market) in costs. Stated another way that is about $2.5/3.8 cubic meters.

      One of these units producing 2000m^3/day means the cost of running that unit would
  • Renewable waves? (Score:4, Insightful)

    by ScentCone (795499) on Wednesday November 08, 2006 @09:14AM (#16766093)
    the renewable energy of waves

    Come on, this is supposed to be a science/engineering summary of a science/engineering article. The term "renewable" should at least mean something. Bio-fuel crops are arguably "renewable." Waves simply are. Nobody needs to re-plant our gravitational interaction with the moon once we've harvested it. Swine waste methane is not the same as tidal activity. It's the article summary, for cryin' out loud. At least get the fundamental concepts behind the word choice straight. "Renewable" isn't the same as "something other than oil."
    • by eluusive (642298)
      Exactly what I was thinking. Do they plan to push the moon back a little closer when it gets too far away or something?
    • by ambrosen (176977)
      What do waves have to do with the movement of the moon?
      • by ScentCone (795499)
        What do waves have to do with the movement of the moon?

        The tidal movement of the oceans (the thing that allows wave-based energy stuff to work) is largely driven by the movement of the moon in its orbit around the earth. The moon tugs at the ocean, which sloshes around, rising and falling. This does not need to be "renewed" in order to continue to work.
        • by ambrosen (176977)
          Oh, I thought waves were caused by wind.
        • by imsabbel (611519)
          You are seriously mixing up tidal power with wave power generation.
          While the first really is moon-powered, the latter is, as a bastard child of the wind, solar energy at work.
          • by ScentCone (795499)
            I do understand the difference (hey, I toured a tidal generating facility in Nova Scotia, which was quite cool, I must say). But the notion that tides are not part of wave action is a little simplistic. All that sloshing around generates a lot of "impulse" type energy that results in part of how waves behave and where they appear, and in what form, and how regularly, etc.
    • by khallow (566160)
      Get used to it. "Renewable" here has the meaning that either the energy source either isn't consumed or if it is consumed, it is restored to original utility over a short period of time. So in particular fission and fusion power would not be renewable because their fuel source is not renewable. Geothermal should be partly non-renewable as well so the classification isn't particularly rigorous.
  • Hmmm (Score:3, Funny)

    by LizardKing (5245) on Wednesday November 08, 2006 @09:20AM (#16766167)

    As an added bonus, this could all be funded by selling the extracted salt to crisp companies.

    • by ajs318 (655362)
      Hah. Do you really think potato crisps won't be banned [bhf.org.uk] within the next 10 years?

      They tries to introduce healthy meals in schools, kids didn't like the food. So this [bbc.co.uk] happened. And this [bbc.co.uk]. Didn't take a crystal ball to see this [bbc.co.uk] coming, did it?

      Some or other Tart Magazine recently carried a review of 20 ready meals. They had some half-famous foreign chef award star ratings based on taste. An anonymous nutritionist gave separate advice based on levels of fat / salt / sugar. In every category, the nutrit
  • It's about time. The energy efficient, low cost derivation of safe, potable water from ocean water is one of a handful of technological achievements that is urgently needed to prevent the ongoing suffering, impoverishment and deaths of a significant percentage of people throughout our planet. Here's hoping that technology can achieve this, finally, this time.
  • How about giving some numbers? kWh required for classic desalinisation of 1 l water vs. when using a duck?
    How efficient can the insulation of the freshwater be when the central partition (in direct contact with the freshwater) acts as a heat exchanger?
  • by The evil doctor Matt (847030) on Wednesday November 08, 2006 @10:13AM (#16766875)
    desalination ducks... Wonder if they'll use the salt to make saltine quackers...
    • by kafka47 (801886)
      desalination ducks... Wonder if they'll use the salt to make saltine quackers...

      And are they water-tight?

  • But are waves truly renewable? The energy comes from somewhere. I thought tidal generators were slowing down the rotation of the Earth until it someday becomes tidal-locked with the Moon. And while there is a lot of energy tied up in the rotation of the Earth, it's hardly limitless, nor renewable.

    You think global warming is a concern now. Consider how bad it would get with 336 hour days!

  • The motion from the waves only serves to "pump" steam from heated sea-water into a condensor where the fresh-water is then pumped to shore via (apparently hollow) legs. But where does the steam come from? According to the article there is a "central section" that heats the sea water. No mention of how "wave power" plays a part in this nor is there any mention of just what, exactly, causes the sea-water to heat up. Presumably to 100C which is what the ballast water has to be "pre-heated" to in order to start
  • by cellocgw (617879) <<moc.liamg> <ta> <wgcollec>> on Wednesday November 08, 2006 @02:21PM (#16771563) Journal
    Unmentioned so far: what to do with the leftover salt. Unless you wait for 100% of the water to evaporate, you end up with highly salinized waste water. IIRC there are some desalinization plants in the Middle East or India, and significant "dead zones" in the ocean nearby. None of the indigenous aquatic life can tolerate raised salt levels.

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