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What would happen if we output massive amounts of helium?

  1. Dec 7, 2017 #1
    I read an article about a fusion reactor and how its waste product is helium and I am wondering what would happen if for whatever reason we output massive amounts of helium at a rate similar to how much CO2 we produced at our peak CO2 production? This is purely hypothetical so lets say we never decide to stop producing the helium from the reactors and it keeps going as long as we can sustain it.
     
  2. jcsd
  3. Dec 7, 2017 #2
    Well if we were creating a helium atom from fusion for each molecule of fossile fuel CO2, the actual Helium would be our least concern. The amount of power that is released in the fusion is almost 100 times greater than the solar power which Earth receives.
     
  4. Dec 7, 2017 #3

    jim mcnamara

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    https://en.wikipedia.org/wiki/Atmospheric_escape
    The article explains why large planets still have atmospheric helium and hydrogen in amounts much greater than does Earth.

    Helium and hydrogen in the atmosphere escape from Earth's atmosphere and do not come back. I have no good answer as to how much helium your question needs to "produce" before helium becomes as common as carbon dioxide and then stays at a level comparable to CO2. As an example.

    Helium is not biologically active, and scuba divers use Heliox in air tanks which is about 20% oxygen and 80% helium by weight. So as far humans are concerned the helium effect would not impact us biologically.

    Heliox is commonly used on pulmonary patients in acute care facilities:
    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4093964/

    The current amount of carbon dioxide == 2.996×1012 tonnes (units in article below).
    See for estimate: https://micpohling.wordpress.com/2007/03/30/math-how-much-co2-by-weight-in-the-atmosphere/

    This is a HUGE amount of helium. This question asks us to speculate, which is not what PF is all about. If someone has informed estimates please post them.

    But speculation is a great way to get the thread locked.
     
  5. Dec 7, 2017 #4

    Orodruin

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    First of all, the necessary production of helium through fusion would be much much less than the amount of CO2 that is produced by burning coal. On top of this, helium is an inert gas and not a greenhouse gas and it escapes the atmosphere due to its small atomic weight as already mentioned.

    The current rate of CO2 production worldwide is the peak rate so it would be more accurate not to speak in past tense here.

    It is worth mentioning that this is in order to dive deeper without the negative effects of an increased partial pressure of nitrogen. For recreational diving at moderate depths, compressed air is perfectly fine and for somewhat deeper dives a different oxygen-nitrogen (Nitrox) admixture may be preferable (generally using a mixture with less nitrogen and more oxygen). However, both oxygen and nitrogen are quite dangerous at too high partial pressures and hence the need for Heliox at larger depths, which allows you to breath a gas with the same pressure as the surroundings while maintaining a safe partial pressure of oxygen and avoids nitrogen narcosis. Helium also has a narcosis effect, but its level is at about 5% that of nitrogen. Just as nitrogen, helium can cause decompression sickness, but it leaves the bloodstream faster than nitrogen, which means you generally would need shorter decompression stops to avoid it. To go really deep, you would generally bring several tanks with different mixtures for use at different depths.
     
  6. Dec 7, 2017 #5

    jim mcnamara

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    @Orodruin - thanks for the addition. This link is where I got my information:

    http://www.lakesidepress.com/pulmonary/books/scuba/sectionl.htm
    The article repeatedly mentions recreational divers versus professionals, in that context:
    I think this is largely congruent with what you said.
     
  7. Dec 7, 2017 #6

    Orodruin

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    I would say so yes. I took my Nitrox course together with my father, sister, and brother-in-law. I am a physicist and they are all medical doctors. I felt bad for the instructor who had to tell us about the underlying physics and physiological effects of different gas mixtures ... Let's just say it was not his normal crowd.
     
  8. Dec 7, 2017 #7
    If we had too much Helium, the Earth would get too light, and we would float out of our solar system.:wideeyed:

    As others have said in regards to the biological aspects of Helium, I'd agree. Helium is considered an inert gas, and is essentially used to dilute the oxygen when diving to deeper depths. The deeper in the water you go, the higher the partial pressure of oxygen you consume and it will eventually become very toxic. The reason we don't use nitrogen at deeper depths is because, again as stated before, it also becomes toxic but in a different way. After about 130 FSW you become susceptible to nitrogen narcosis, which is basically like getting high- uncontrollable laughter, disregard for safety, and disorientation. I've experienced this in a recompression chamber when I was diving for the Navy and it was a damn good time but I wouldn't want that to happen underwater! So as far as biologically, breathing Helium in the atmosphere wouldn't be a problem as long as the oxygen concentration remained around 21% SEV (surface equivalent value).

    Makes me wonder though if we'd all be talking funny if the atmosphere was Helium instead of Nitrogen?
     
  9. Dec 7, 2017 #8
    It was one of the oddities noticed in Mote in God´s Eye. The otherwise earthlike planet had atmosphere rich in He - unexpected and unexplicable.

    The planet turned out to have had technological civilizations using fusion for a really long time

    Suppose that someone comes up with a viable solution to fuse protium into helium. Taking water from the sea, and dumping waste heat, oxygen and helium into atmosphere.
    At a rate viable for heat dissipation of Earth atmosphere, how fast would He and oxygen build up in Earth atmosphere?
     
  10. Dec 7, 2017 #9

    davenn

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    except the main disagreement

    Orodruin .....
    and Jim, your quote said .....

    so out of my own learning curiosity ... which is correct ?


    Dave
     
  11. Dec 7, 2017 #10

    Orodruin

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    I might be misremembering. I was the physics part of the correction unit in the nitrox course. The main advantage of heliox is the reduced narcosis effect, nitrogen narcosis can literally be a killer at larger depths when you start thinking that down is up ...

    Edit: Luckily, computing decompression stops yourself or looking them up in tables is largely a thing of the past. Any reasonable diving computer will do it for you nowadays and I suspect anyone diving with heliox will have a pretty good one ...
     
  12. Dec 7, 2017 #11

    davenn

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    Thanks, all good :smile:

    not having done diving ( tho I have always had an interest in learning) I only have a very basic understanding of the problems and processes assoc. with the activity

    Dave
     
  13. Dec 16, 2017 #12

    mfb

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    Let's add some numbers. The global primary energy consumption is about 6*1020 J per year. Fusing one nucleus of deuterium (D) with one nucleus of tritium (T) releases 2.2*10-12 J. If we replace all our primary energy consumption by fusion we have to fuse 2.7*1032 atoms of deuterium and tritium per year to produce the same number of hydrogen atoms. Sounds like a lot - but it actually just produces 1800 tonnes of helium. The current global helium market is 32,000 tonnes per year, so we couldn't even be a major supplier there. It also wouldn't have any measurable effect on the atmosphere.

    Global CO2 emissions are currently about 35 billion tonnes per year (~5 tonnes per person as global average, 16 tonnes per person in the US). If we want to produce 35 billion tonnes of helium per year with DT fusion, we have to release 1.2*1028 J per year. That corresponds to a power of 3.7*1020 W, or 2000 times the power we receive as sunlight. Keeping this fusion rate for a longer time would literally melt the surface of Earth and make it glow orange at a temperature of roughly 2000 K.

    It wouldn't sound funny if it would be normal.
     
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