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Hi this is my 2nd question on the site and I hope it is intriguing to you all. My question is: How feasible is it for an organism to sustain an Aerobic lifestyle (ie. the standard oxygen cycle found in oxygen "breathing" organisms or organisms that use Aerobic respiration) by ingesting dihydrogen monoxide (Water) and then via some process electrically breaking the H2O into its hydrogen and oxygen components. Thus using the oxygen for its aerobic respiration. The specifics of this organism are up to any of you that wish to answer the question, the main answers I am seeking are the following:

  • Is this process possible in carbon based organisms?
  • Is this electrolysis process feasible as a source of oxygen for carbon based organisms?
  • Is this process present at all in the real world?
  • What is required for this electrolysis of water within an organic organism?
  • Is this process exclusively effective for multicellular organisms or single celled organisms, or could both feasibly use it?

Additional Questions

  • What are the drawbacks or potential dangers for the organism using this process?
  • What kind of environment would likely lead to this type of respiration evolving within organisms?

If people want to go all the way I'd love to hear people's ideas for organisms that utilize this respiration system and what kind of environments or planets they would likely live in. The specifics of the theoretical organisms are up to you they just have to make use of this type of electrolysis assisted aerobic respiration. Also I'd be interested to see what people think the organisms could do with the hydrogen gas that would be a byproduct of this reaction. Not to drag on too long, but I could imagine a creature that could use the hydrogen as a flame weapon with an electrical ignition, or use perhaps a ballooning creature that uses the gas as a form of buoyancy.

I wish all luck and I hope this is a worthy question.

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    $\begingroup$ Please, follow our model: one question per post. $\endgroup$
    – L.Dutch ♦
    Commented Jan 22, 2019 at 20:06
  • $\begingroup$ Welcome to Worldbuilding.SE! We're glad you could join us! When you have a moment, please click here to learn more about our culture and take our tour. SE's model is one-specific-question/one-best-answer. So many questions makes this post too broad by definition. You'll discover that focusing on one specific question will often answer several of the others automatically. If you edit your question to focus on one specific question, I'll gladly retract my too broad vote. $\endgroup$
    – JBH
    Commented Jan 23, 2019 at 15:49
  • $\begingroup$ Thank you for the suggestions, I think I will take the information provided so far and redevelop this topic into multiple questions. I am curious should I avoid posting too many questions at once, like should I space them out over time or does that not matter? $\endgroup$
    – Aceharmsway
    Commented Jan 25, 2019 at 16:07

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This definitely can happen. It is called photosynthesis.

photosynthesis

https://en.wikipedia.org/wiki/Photosynthesis

Plants take water molecules and split them as you propose. Really they are after the hydrogen - they use the hydrogen from the water to make sugar (CHO for short) from CO2. Oxygen is pulled off of both H2O and CO2 but it is not entirely a waste product. The plants use that oxygen for their aerobic respiration just as you propose. They burn the sugar that they make for energy. Plants just make more oxygen than they need and so they don't need to store it. They push it off into the atmosphere and get it back when they need it.

I wonder if back when oxygen was more scarce in the atmosphere whether photosynthesizes kept it more close at hand rather than releasing it. It would explain the evolution of oxidative metabolism - a thing that made oxygen as a waste product could use its own waste.

Considering your scenario: an organism wants to burn sugar it has found and needs oxygen to do it. Here is a good energetics primer. https://physics.weber.edu/schroeder/eee/chapter4.pdf

It takes 286 kJ of energy per mole of H2O to split H2O to the H2 and the O. For the next step we need 6 molecules of O2 and since we just get 1 atom of O off of each water, we need to split 12 molecules of water. 286 * 12 = 3432 kJ.

Now we eat! 1 mole of sugar C6H12O6 + 6 O2 -> CO2 and H2O. There we get the water back but I thought maybe the payoff from the CO2 would make it worthwhile. Nope. This reaction yields 2800 kJ which is less than we put in to make the oxygen out of water. You get more energy back from oxidizing pure carbon (coal?) but still not enough to recapture the energy you had to use to split the water.

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  • $\begingroup$ May need to find a way to make up the extra 632kJ of energy via some other biological mechanism. Would a simpler sugar other than glucose yield a better energy ration? Maybe ethane, ethylene or other simple hydrocarbons? Sorry, enthalpy equations always kicked my butt in chemistry $\endgroup$
    – sonvar
    Commented Jan 23, 2019 at 3:25
  • $\begingroup$ @sonvar - Probably acetylene would do it. Naphtha. Benzene? All calculable but it is late for me. $\endgroup$
    – Willk
    Commented Jan 23, 2019 at 3:47
  • $\begingroup$ An acetylene burning creature would be lit. $\endgroup$
    – Joe Bloggs
    Commented Jan 23, 2019 at 15:40
  • $\begingroup$ Photosynthesis has characteristics of what I'm looking for, but I want to see if there could be a possible respiration cycle outside of the norms that utilizes water as the primary reactant. Interesting to think about how efficient plants are that they can actually make use of their own "waste" products. However with photosynthesis the plant still needs CO2 to operate and I'm developing an organism that would not have to ingest gasses at all to sustain itself. Thank you for the informative answer though. $\endgroup$
    – Aceharmsway
    Commented Jan 25, 2019 at 16:19
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Certainly anything is possible, and all kinds of molecules are processed in different ways in organisms. That said, without more information about the size and lifestyle requirements of the creature in question, I'm going to use humans for reference.

OK, so I'm gonna do some napkin math. Feel free to correct me if I make any egregious errors.

An adult human breathes something like 11000 liters of air per day; about 11 m^3, or 14.2 grams. Air is composed of 20% oxygen, so we really only breathe about 3g oxygen in a day (I'll assume we use all of it). Water is 18 grams per mole, and it takes about 273kJ to dissociate 1 mole of water.

Oxygen weighs 15x more than hydrogen, so it's safe to say that for every 3.4 grams of water you dissociate, you'll get about 0.4g hydrogen and 3g oxygen. So, doing the math, that means about 51kJ to perform the dissociation.

I'm lead to believe that humans use an average of 8400kJ per day, but I don't know how much of that is spent on breathing. So I think it's fair to guess that this will occupy around 5% of the person's energy. Hydrogen gas is quite reactive, and can be used in all sorts of ways to subsidize the body's heat generation, enabling the creature to spend less energy on temperature regulation if it lives in a cold environment.

So, yeah, totally feasible. That said, your creature is going to have to make sure it consumes at least 3.4 grams of water in addition to its normal water consumption. It might make sense for this creature to be some kind of warm-blooded arctic sea-creature.(maybe?)

But to your specific quesitons:

  • Possible in carbon based life-forms? Sure.
  • Feasible? Yeah.
  • Present in real world? I don't think so.
  • What's required for this? The creature would have to generate electricity. Could be done in a number of ways (maybe ask another question, "how could an organic, carbon based pikachu generate electricity internally" or something.)
  • Multicellular vs single-celled? I only looked at multicellular organisms. Probably a good one for a separate question, after you've decided on the process.
  • Drawbacks? Electrolysis can damage tissue, so it should have some internal protection from it. Probably good to couple this with "what's required for this?"
  • What kind of environment? I don't think it's necessarily environment dependent. Depends what you use the Hydrogen for, I think.

Hope this helps with your world!

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  • $\begingroup$ Thank you for the detailed response, having read through many of the comments thus far I think I'll be splitting this topic up into multiple individual questions. I like the ideas you hit on here, yet again thank you for the response I'm gonna keep digging on this concept. $\endgroup$
    – Aceharmsway
    Commented Jan 25, 2019 at 16:24
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This would not work. Reason: Thermodynamics

The reason that organisms undergo aerobic respiration is to oxidize fuel which gives off energy. The energy released is mostly due to the energy given off in the formation of water from the oxygen from the air and the hydrogen in the fuel. However, if energy has to be spent to break the bonds through electrolysis, then the respiration is no longer going to be a net source of energy for the organism.

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  • $\begingroup$ Yeah no I get that the energy requirements to use electrolysis makes this a difficult and inefficient process. However I feel like that isn't such a closed book, I'm still looking for answers that's why I'll be reposting this topic in the form of a few variant questions, but I feel like their could be some organic mechanism or environmental process an organism could make use of that could make this electrolysis based respiration feasible. $\endgroup$
    – Aceharmsway
    Commented Jan 25, 2019 at 16:22

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