1/2 size, offshore Thames Sailing Barge/Garbage scow/liveaboard

Discussion in 'Sailboats' started by misanthropicexplore, Aug 1, 2018.

  1. gonzo
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    gonzo Senior Member

    Maybe watch some videos of crew working the deck on a trawler on gillneter to get an idea of the conditions. I worked on both and the gear has to be designed for it.
     
  2. OzFred
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    OzFred Senior Member

    Interesting concept, but if burning waste plastic is a viable method of disposal, why is so much plastic that is collected in recycling bins put in land fill? Surely if it’s worth $240/ton as fuel it would be being sold as fuel?

    Also, what is the environmental impact of the combustion gasses? Aren’t they far more toxic than those from coal or gas?
     
  3. misanthropicexplore
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    misanthropicexplore Junior Member

    Plastic comes in 7 varieties, labeled on the bottom of the container, usually. "Commingled 1-7" is the name for your standard, random plastic out of a recycling bin. It's worth $230 a ton mostly because of the value of the 1 and 2, which are worth between a $1000 to $1200 a ton. Commingled 3-7 usually has a negative value, as in you have to pay someone to take it, thats why it pulls down the value of commingled 1-7 so much. #4 actually has value, but not as much, nothing like 1 and 2. When plastic is getting landfilled, it's usually 3, 5,6,7 after 1 and 2 have been taken out, or 1-7 if that facility finds it cheaper to bury than sort. The capital investment to sort is pretty high, and a lot places find it more profitable (this quarter) to bury than recycle.

    There is no such thing as disposal in a closed loop system, only dispersal. Opening a new coal plant to be fueled exclusively by plastic would be a net negative. The benefit comes in when you burn commingled 3-7 instead of coal, in a facility that would have used coal. This is beneficial because, even though burning plastic absolutely produces harmful chemicals, it produces significantly less harmful chemicals per ton than coal. It also produces more heat per ton than coal. So, if your society insists on burning coal (and most do, electricity is wonderful and coal is cheap) then there is benefit to burning plastic as a substitute. The environmental impact of burning plastic in a modern controlled coal plant is less than the environmental impact of burning coal in the same plant.

    Right now, only about 0.4% of U.S. power comes from waste to energy plants, but the number is climbing faster. Conveniently, ports in California have access to good W-to-E plants.
     
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  4. OzFred
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    OzFred Senior Member

    Great information, but you didn't answer the question—maybe you don't know. I'm sure I don't.

    Do you have references for the "significantly less harmful chemicals per ton than coal" statement?
     
  5. misanthropicexplore
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    misanthropicexplore Junior Member

    "Mass transfers and chemical reaction rates are similar in coal-fired combustion and MSW combustion. However; MSW combustion has significantly lower levels of sulfur oxides, higher levels of HCl and lower levels of fly ash compared with that of coal combustion. Since HCl and HF are easier to scrub than SO2, a system designed to scrub SO2 will have no problem with these gases with respect to removal efficiency."

    https://pdfs.semanticscholar.org/1e75/d9229dbbda5e6cb04984d21fb53ae3b28c36.pdf

    Essentially, all combustion puts things in the air you would prefer not to breath (including wood). Plastic combustion puts less heavy metals, less sulfur, and less nitrogen dioxide, than coal. About the only thing it puts out more of is hydrochloric acid, which is much easier and cheaper to catch and process before it leaves the plant than the things coal puts out, so exhaust processing is cheaper.
     
  6. Peter Vella
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    Peter Vella Junior Member

    What about dioxins from burning PVC? Is this only a problem at lower temperatures?

    I don't think the Thames sailing barge is a good basis for an ocean going design. They were built to ply the coastal trade between the Thames estruary and East Anglia and were not intended for offshore work. The flat bottom allowed them to operate in the shallow waters of that coast and they could also dry out on the mud banks. By all accounts for an offshore boat you need an AVS of over 120 degrees for it to be considered safe. I doubt you can make a TSB derived design do that, and two of the principal advantages of the TSB - shoal draft, and the ability to dry out and stay upright - are not relevant in your case.
     
  7. misanthropicexplore
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    misanthropicexplore Junior Member

    Hey! A comment about the boat instead of how dumb it is to mine trash in the ocean!

    That said..PVC does produce dioxin when burned as a coal substitute. It's not that it's "good", it's that it's "better-than-coal". For as common as it is, coal combustion produces some pretty nasty stuff. Megawatt per megawatt, coal plants actually produce more environmental radioactive contamination than nuclear plants. Uranium, thorium, and radium are trace elements (much less than 1%) in coal, but unlike nuke plants where the radioactive waste stays on site, coal plant radioactive waste leaves the facility as fly ash (all facilities) and up the flue (less regulated facilites). Your risk of getting struck by lightning is about 4x higher than your risk of dying from coal plant radiation, so it's pretty academic, but it does serve to remind people that coal combustion products are surprisingly awful.

    But, I'll agree with the experts and say that an blue water Thames Barge is a stupid idea.

    I just really like the idea of a utilitarian sailing craft that could make enough to pay for it's own maintenance if you could afford to build it. To me that means it would need to be as utilitarian as possible: shallow draft, ability go up rivers, dry out on a beach, cargo capacity, monohull. It turns out that Kasten Marine has worked on something
    similar.

    50' Junk Rigged Landing Craft - LCU-J http://www.kastenmarine.com/lcu_junk_50.htm

    I know the normal way to make a boat pay for itself is chartering. Wharram has several designs that marketed as ideal for this, with the shoal draft to prove it, but I like the idea of a self sustaining heavy, steel, cargo monohull more than a self sustaining, lightweight fiberglass/ply passenger boat. Going through all the work to make and cruise in a boat just to be surrounded by more people sounds like a bad incentive.
     
  8. OzFred
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    OzFred Senior Member

    Great information, but just watched a show on burning of plastic waste in Sweden. I think the numbers were something like:
    • Cost to build plant: $500m
    • Cost to run plant: $120m pa
    • Revenue from electricity: $10m pa
    • Revenue from heating: $65m pa
    It only makes sense because the plant provides hot water for central heating of residential housing, it's turned of during the Swedish summer. In a place where heating isn't required (like where I live), the only revenue is from electricity (unless central cooling is required and makes economic sense, which is unlikely). So while the theory sounds good, in practice it just doesn't stack up.

    In regard to greenhouse gas emissions, the rub is that burning the plastic releases all the gases immediately (more or less), whereas putting it into landfill releases them over a much longer period (years?).
     
  9. JamesG123
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    JamesG123 Senior Member

    Plastics themselves don't release gasses in a landfill. Its all the decomposable ick that goes with them that does. In the fullness of time, all the buried plastics will probably revert to some more basic hydrocarbon chains. Assuming some future civilization/species does not mine them all for the rich refined materials they contain first.
     
  10. gggGuest
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    gggGuest ...

    Why would you bother to go out to sea when there are any number of estuaries full of plastic. Assuming there's even a grain of truth in the stories about a few Asian and African rivers depositing most of the oceanic plastic then your waterborne plastic collection would be much more effective and likely cost effective done by subsistence level boat people in those estuaries. However the fact that all the plastic ends up in the rivers instead of being burned does suggest your economics may be a little bit out.
     
  11. waikikin
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    waikikin Senior Member

    James...
    Surely in jest- Waterworld one of the all time best movies:cool: and an insight on the future as science fiction so oft becomes reality.

    All the best from Jeff.
     

  12. JamesG123
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    JamesG123 Senior Member

    I usually jest. And don't call me Surely.
     
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