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Nuclear fusion to heat a body of water yes, this is a sci-fi question.

  1. May 16, 2012 #1
    I'm not as smart as many of you, nor is this something I've looked into deeply. I say that not only to excuse my stupidity, but also to appear modest and hopefully likeable/helpable. And I say that (as well as this) not only to appear honest, but also to begin with a little humor.

    I've recently been thinking about writing a very silly, but conceivably realistic, sci-fi story which relies on a specific conceit: a city built around a nuclear fusion reactor in the Long Island Sound. The idea is to use the reactor's waste heat to warm a large part of the Sound, mimicking the waters of the Caribbean around several man-made beaches. Is this in any way possible? Is it practical? How could the environmental impact of temperature change be minimized?
     
    Last edited by a moderator: May 16, 2012
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  3. May 16, 2012 #2

    jim hardy

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    go for it.

    Actually power plants do put out quite a bit of waste heat. I worked at one in Florida. In wintertime the wildlife loved the warm water. Fishing was great right where it came out. Some of our other plants had manatees enjoying their warm water. But in summertime the wildlife went back to cooler environs.

    So in wintertime draw your cooling water from well offshore and release it into the sound. The critters will thank you.
    In summertime reverse the flow so warm water from shallow sound gets pumped out to sea and cooler water comes in from near-shore to replace it. The critters will like that, too. So will the people for the sound will stay cleaner.

    Truth is stranger than fiction:
    http://news.google.com/newspapers?n...FhYAAAAIBAJ&sjid=6vkDAAAAIBAJ&pg=2244,1019488
     
    Last edited: May 16, 2012
  4. May 17, 2012 #3

    Ryan_m_b

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    Nothing practically wrong with it. Few points to consider: why fusion and how much water are we talking? To heat 1 litre of water by 10 degrees takes 10kj. The waters around the Caribbean are ~30 degrees, not sure how cold the waters at Long Island Sound are but you may be looking at 20-30kj per litre. Then depending on the flow rate you've got to figure out how many joules per second (watts) it's going to take to heat the water as it comes in and to maintain it at its current temperature. Finally perhaps take into account the ecological effects and the cost of this project. I don't know anything about the ecology of LIS but you're most likely to heavily disrupt local wildlife and probably have to introduce new species (which will have a knock on effect elsewhere). Of course you could just build a dome that extends a few 100m out to sea and back onto land that filters the water in and heats it making an Eden project like biome.

    Of course you said you want to do a silly story so can take or leave those points :smile: depends on how hard you want your SF to be.
     
  5. May 17, 2012 #4
    Why the long island sound? There is water going in and out with the tides twice a day, and each time you loose a huge amount of heat=energy. You'd be much better off with a closed body of water such as a great lake.

    One environmental impact to consider is that hot water will evaporate much more than cold (or possibly frozen over) water, so you will get lots of humidity in the air and much more rain and snow downwind. Kind of a mega-lake effect.

    BTW, such a thing exists on a small scale, the Blue Lagoon in Iceland is fed with waste water from a geothermal power station.

    http://en.wikipedia.org/wiki/Blue_Lagoon_(geothermal_spa)

    The power needed to heat such a huge body of water as the LI sound or a great lake fully justifies the use of fusion instead of fission. For a nice SF touch, locate the whole plant underwater.

    You need Lithium (Li) to make Tritium for the fusion fuel. That can (must?) be extracted from sea water. So a suitably modern SF plant would do that in one go, extracting it directly from the stream it heats.

    To "limit" the ecological impact, you would have to limit the loss of hot water into the surrounding sea. You need to do this anyways to limit the power needed to maintain a nice spa temperature.

    Another thing to consider is the impact in migrating birds and fish/cetaceans.
     
  6. May 17, 2012 #5

    Ryan_m_b

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    Simple idea that came to mind; build a large sea wall like in a marina or harbour with a gate to control water in and out and heat that. It will still take an extraordinary amount of energy to heat (1 hectare with average depth of 2.5 metres will take at least 500GJ to heat from 10 - 30 degrees) but it will save you energy in terms of water flowing away.
     
  7. May 17, 2012 #6
  8. May 17, 2012 #7

    Ryan_m_b

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    Indeed. I wasn't trying to suggest an insurmountable amount of energy merely that it's large, costly and in reality the number is going to be higher to deal with energy waste, cooling of the water, flow of water etc. Also 1 hactare is quite small considering the scale the OP seems to be talking about.

    It's obviously possible but the question becomes why on Earth anyone would want to invest so many resources on it.
     
  9. May 17, 2012 #8

    jim hardy

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    we warmed around two million gpm by ~ 10 degF

    since it's a story , let your imagination go. Put it on Hudson Bay and raise Arctic citrus ?
    Arthur C Clarke imagined multi-mile diameter geodesic spheres that housed cities. Warming them made them lighter than air so they could cruise the globe. That sounded appealing, I guess we have remnants of the nomad in us...
     
  10. May 17, 2012 #9
    Why would anyone invest huge resources to build something as pointless as Disneyland?

    Any yes, a hectar is too small. I just put up the numbers to get things into perspective.

    Say the time for the heat to bleed out is 100000 sec = a bit more than 24h (due to water exchange, evaporation, etc). Let's also up the estimate of the energy capacity per hectare to 10 GJ - if we are thinking big, then the water will be deeper.

    Then (1 GW reactor * 100 ksec)/(10 GJ / hectare) = 10^4 hectare = (100 km long) x (1 km wide).

    That makes for a pretty nice beach with enough warm water for swimming sailing surfing. You just have to find a way to keep the clouds out.

    Such a large hot spot would create huge changes in the weather patterns. You would get constant thermics rising over the hot zone, pulling in cold air from around. The same pattern is happening at the equator, giving rise to the trade winds.

    http://en.wikipedia.org/wiki/Trade_wind

    If the SF fusion plant produces 1000x more power than the real thing, they you can heat up quite a lot of water.
     
  11. May 17, 2012 #10
    Wow, thanks a lot for all the info. To clarify, I'd like the reactor to supply energy to Greater New York with only the waste heat being used to heat the surrounding waters. Solar panels on top of everything above water would supply energy to the plant and city. Could I also harvest the light produced from the reactor?

    The Sound temperature doesn't need to match that of the Caribbean, I'd just like the surface warm enough to keep the water clear and boost tourism. The surface currently averages 20c in the summer and 3c in the winter. If it helps, the story could take place anywhere from 50 to 100 years.
     
    Last edited by a moderator: May 17, 2012
  12. May 17, 2012 #11

    jim hardy

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    See if you can find whether Indian Point measurably warms that estuary it's on.
    Might be worth a day trip - see if they have annual open house and will show you their control room simulator.
     
  13. May 17, 2012 #12
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