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Thread: I feel this belongs here

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    This has been going around the web for a while- I think it might have been posted here before. But in any case, there are lots of reasons it's not feasible. The best post about that comes from one of the best science blogs out there, Deep Sea News:

    http://deepseanews.com/2013/03/the-o...arine-plastic/

    I’m just going to come out and say it, any project that touts itself as the “World’s first realistic Ocean Clean-up Concept” is just asking to be torn apart.

    “The Ocean Cleanup” is the brainchild of a 19-year old Boyan Slat. He proposes using the oceans themselves to clean up plastic. By setting up a line of giant sifting booms across the major ocean gyres, ocean currents will push plastic into these giant traps to be collected and reused for profit. He plans to set up an array of 24 of these sifters and calculates they will clean the ocean in 5 years.


    Before I add my two cents, here’s what Miriam had to say about the idea at the Marine Debris Listserv:

    Dear all,
    I’ve tried to stop fact-checking to every cleanup scheme, but I guess it’s an addiction at this point. Also, I feel that as a community we cannot move forward with practical solutions to marine debris until we lay some of these common misconceptions to rest. These points respond Boyan Slat’s TEDx talk, but you can also see photos of his proposal here: http://www.boyanslat.com/plastic5/ and http://www.boyanslat.com/in-depth/.


    • Most zooplankton don’t survive being caught in a standard manta net, never mind being spun in a centrifuge. They might still be twitching, but they have lost a lot of their important parts, like antennae and feeding apparatus. When we want to capture live zooplankton, we use special live-collection nets and are very, very careful. For gelatinous zooplankton like salps, the only way to bring them up in good condition is to individually capture them in glass jars on SCUBA. I am highly skeptical that any significant proportion of zooplankton are viable after caught in a net and spun at 50 RPM. (though I realize that he’s not proposing to do this on a large scale.)
    • Mooring fixed “ships” in the open ocean (avg depth 4000 meters) is highly improbable for a lot of reasons. Just to pick one: I could not find data on the absolute deepest mooring in the world, but this implies that it is approximately 2,000 meters. http://www.offshore-technology.com/p...antisplatform/. So these ships would have to be moored at twice the depth of one of the deepest moorings that existed ~2007.
    • Having seen no data, I can’t really speak to the efficacy of floating booms in removing microplastic. However, Giora Proskurowski & colleagues have shown that microplastic get mixed down below the surface in fairly moderate winds. These booms would be unlikely to function in any significant wind and wave action. And the mixed layer in the open ocean can get quite deep, around 100-150 meters in the winter with storms.
    • Speaking of wind and wave actions, ships on fixed moorings and thousands of miles of booms (because the scale of this is also improbable) have the potential to create a lot more marine debris, and seem particularly hazardous to entanglement-prone marine life.
    • This isn’t even getting into issues of scale (the California Current alone is ~300 miles across), maintenance and fouling…


    I realize that Mr. Slat is a student, and have no doubt that he, and the inventors of countless other plastic cleanup schemes, have only the best of intentions. I am hoping we can work together as marine debris professionals to channel their energies into more productive directions.

    Regards,
    Miriam Goldstein

    While I can’t speak to what these booms will and will not pick up, I completely agree with her I am highly skeptical whether the design is even feasible from an ocean engineering standpoint. Here are some of the major unanswered technical questions:

    1) How does the sifter work? To be honest, I am not completely sure. The website and TED talk are completely devoid of technical details. But from what I can gather from the concept art and the talk, I think the booms have large nets underneath them that gather plastic into what I think is a oversized swimming pool leaf trap shaped like a manta ray. UPDATE: I misinterpreted the images on the website. The design as it stands now has no nets, only the initial tests had nets. Now I have to ask, what is that sheet hanging down from the booms?

    2) The booms. The claim is that only 24 sifters are need to clean the ocean and span the gyre radius, which means the booms have to be huge. Possibly 100′s of kilometer wide. Are they rigid or flexible? Are they the manta rays? How will they be kept in formation?

    3) Anchoring something that large. I am going to assume that the booms need to stay relatively taut to retain their shape and the most obvious way to do this will be with multiple anchor lines. The water depths are deep (>3000 m), horizontal surface motions needs to be small and then there is all that water pushing on what is essentially a giant paddle. That means a fairly sophisticated plan for anchoring the array will have to be developed. Having seen how large anchors are for low-tension subsurface moorings (>1000 kg), I can’t even begin to imagine what they are going to use or how that is going to be set up.

    4) Biofouling. I forsee two major biofouling issues. The first is biological growth, which can be particularly bad because all the major mechanical parts are near the surface. There is going to be growth on the mesh, on the booms, on everything submerged which can make the booms and nets heavy, dragging them underwater.

    5) The assumption of low current speeds. This is a bad assumption. While the array may not be placed in the most energetic current regime, storms and eddies can briefly induce large currents which could place a lot of stress and shear on such a large array.
    There are other links also, which are linked to at the end of the DSN post:
    http://inhabitat.com/the-fallacy-of-...cleanup-array/
    http://kumu.cc/2013/03/27/those-craz...ning-machines/

    Like most people who love the ocean I'd love to see an ocean clean up invention that can actually work. Right now it hasn't been invented, and we're all going to have to stop letting so much plastic and debris into the water. Don't use products containing tiny plastic beads (called nurdles, are often in facial and body scrubs), use canvas or other cloth bags instead of plastic at the grocery store, and dispose of them or recycle them correctly, etc... It doesn't sound like much but it's a heck of a lot better than doing nothing and the problem getting even worse.
    Last edited by deepblue; 02-11-2014 at 02:53 PM.

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    Senior Member Euro Pod Echidna's Avatar
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    Quote Originally Posted by Mermaidmechanic View Post
    thats depressing
    there is another concept, but it might be years in the making.
    scientists are developing fish robots (drones), which can search for, identify, and "devour" plastic debris.
    once their "stomach" is full, they can send a radio signal to be located and emptied.

    while that is a nifty idea, I wager it'd take billions of such drones to clean up the oceans, and it wouldn't go very fast but likely take centuries

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    It's great to see progress in the form of fixing what we broke. I hope that there will be more young inventors that come up with terrific ideas!

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    Administrator Pod of Cali malinghi's Avatar
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    I think this whole story demonstrates some really serious problems with how the public views science and technology, and how the media reports it. People want to hear about magic solutions to instantly fix challenging problems, but those rarely exist because if they did, those problems wouldn't be challenging.

    People also love the idea of some lone individual (preferably untrained in the field) beating a bunch of overeducated eggheads at their own game. It's even inspired an entire genre of internet ads about some mom who discovered a trick to whiten teeth, or some guy who's discovered how to instantly get huge muscles, or how to instantly learn a language, and now dentists/trainers/language professors/ect hate this person.

    TED partially plays into this too. I think TED is a great thing, and presenting science and technology to people in a way that's interesting and inspiring is a great thing to do. But some people have pointed out that TED talks, and TEDx talks especially, play into this idea of what science should look like and reinforces the idea of instant solutions by lone geniuses. People should understand that life isn't a movie and be supportive of the fact that most solutions require a lot of time and money and people.

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