The Potential of Titan: Igniting Methane Oceans for Photosynthesis

[bennyschmidt]

If a methane-filled planet or moon like Titan was pulled toward a star, as the methane warmed and became gaseous, would it be possible to ignite it, converting the methane oceans to H2O with a CO2 atmosphere, which could in turn cause photosynthesis to naturally occur?

If it's possible, it would be the ultimate battle between good and greed -- would we use our technology to turn methane worlds we discover into living, breathing planets, or would we use it to harvest the fuel for profits and then leave?

PS My first post here!

 

[Bandersnatch]

Hi bennyschmidt, welcome to PF

Where would you get the oxygen to burn all that methane from?

 

[bennyschmidt]

Hi bennyschmidt, welcome to PF

Where would you get the oxygen to burn all that methane from?

Thanks for the response. As far as I understand, there is already some oxygen on Titan, at least in the form of ice and ammonia under the surface near the poles. If there was enough oxygen to ignite even one small area, the byproduct would be more water and CO2, which makes more oxygen available to fuel more combustion. It's also possible that with a small amount of water, electrolysis from lightning storms in the newly created CO2 atmosphere could release O2 molecules directly from the water, which would quickly turn the planet into a mostly flammable, hellish world.

But the idea is that for a very long time it burns and burns, producing more and more CO2 and H2O until eventually there is so much more water than methane, and also the methane has become so gaseous from the increased heat that it escapes anyway, leaving only lots and lots of water (oceans) and CO2 (atmosphere) left behind -- the environmental conditions needed for photosynthesis.

Maybe if it gets too close to the star, like the distance Venus is from the sun, the water too escapes as a gas (evaporates from the heat), and you're left with just a hot CO2 world. But if it gets close enough to the star, but not too close, like in the case of the earth, you end up with oceans, a greenhouse effect, and life.

 

[bennyschmidt]

Is bumping threads allowed on this forum? I'm hoping someone can answer the question without relying on "where does the oxygen come from" (because there is oxygen in the form of other chemicals on Titan)?

 

[Bandersnatch]

I'm sorry my answer is not to your liking.

But the fact remains, you still need free oxygen to burn stuff, and there is none on Titan. Neither is there any oxygen ice.
Water ice and carbon oxides help just as much as they do on Earth - that is, they're fire retardants. Methane won't burn in ammonia either. Unless you've got some process that will first release the oxygen from whatever molecule its bound in, you get no fire.

I'm not sure what else it is you want to hear. Perhaps restating the question would help.

You don't need to burn methane to get water on Titan, though. It's got plenty in the ocean/ice layer under its surface.

Bumping is fine, by the way.

 

[Nugatory]

Is bumping threads allowed on this forum?

From the forum rules:

Do not "bump" one of your threads to the top of a forum's thread list by posting a basically empty message to it, until at least 24 hours have passed since the latest post in the thread; and then do it only once per thread.

The membership here is spread across all 24 time zones, so if you don't wait at least one full revolution of the planet, you've bumped before everyone has even had a chance to see your post.

 

[bennyschmidt]

Well, the reason I wasn't happy with your answer is because it's not really accurate. The point of the thought experiment is not to see if it's possible to light water or ammonia on fire... it's to see if it's possible to convert planetary chemicals on Titan into more useful chemicals in order to jumpstart photosynthesis.

• "Titan also has a presence of organic molecules that contain carbon and hydrogen, and that often include oxygen and other elements similar to what is found in Earth's atmosphere and that are essential for life."

• "Evidence also indicates the presence of liquid water and ammonia under the surface, which are delivered to the surface by volcanic activity".

Sources:
• http://www.space.com/15257-titan-saturn-largest-moon-facts-discovery-sdcmp.html
• http://en.wikipedia.org/wiki/Colonization_of_Titan

 

[rootone]

The Oxygen existing on Titan is in the form of water ice and CO2.
These are the products obtained when burning methane.
In order to set the Oxygen free in order to burn more methane you would have to apply a vast amount of energy,
and when you do burn it, the same amount of energy you put in gets released again, and you are back with H20 and CO2 again.
Nothing gained.

 

[bennyschmidt]

The Oxygen existing on Titan is in the form of water ice and CO2.
These are the products obtained when burning methane.
In order to set the Oxygen free in order to burn more methane you would have to apply a vast amount of energy,
and when you do burn it, the same amount of energy you put in gets released again, and you are back with H20 and CO2 again.
Nothing gained.

Thanks for the answer; it's a lot different than the previous one of "it's impossible to burn methane on Titan" --@Bandersnatch

 

[russ_watters]

Well, the reason I wasn't happy with your answer is because it's not really accurate. The point of the thought experiment is not to see if it's possible to light water or ammonia on fire... it's to see if it's possible to convert planetary chemicals on Titan into more useful chemicals in order to jumpstart photosynthesis.

I'm sorry, but your speculation that you can somehow convert the water to oxygen (for example) and then use it over and over to burn all the methane is very wrong. You should write some of the chemical formulas for the reactions out - that may help you see that by doing the same steps over and over again, you just run in place and don't burn ANY of the methane in the atmosphere.

 

[russ_watters]

Thanks for the answer; it's a lot different than the previous one of "it's impossible to burn methane on Titan" --@Bandersnatch

Actually, no, it was the same answer. "Nothing gained" means you aren't burning any of the existing methane.

 

[nasu]

If a methane-filled planet or moon like Titan was pulled toward a star, as the methane warmed and became gaseous, would it be possible to ignite it, converting the methane oceans to H2O with a CO2 atmosphere, which could in turn cause photosynthesis to naturally occur?

If it's possible, it would be the ultimate battle between good and greed -- would we use our technology to turn methane worlds we discover into living, breathing planets, or would we use it to harvest the fuel for profits and then leave?

PS My first post here!

The fuel used by people to warm up their houses during the winter. A really evil action. :)
We should freeze in the winter so that the gas company does not make any profits. The ultimate battle, yes.

 

[bennyschmidt]

The fuel used by people to warm up their houses during the winter. A really evil action. :)
We should freeze in the winter so that the gas company does not make any profits. The ultimate battle, yes.

You miss the point.

I'm sorry, but your speculation that you can somehow convert the water to oxygen (for example) and then use it over and over to burn all the methane is very wrong.

Why is it wrong? It seems to me that as long as you have methane (the fuel), you can certainly burn it over and over -- until the fuel is depleted. That's how burning fuel works.

 

[nasu]

You miss the point.

There is no point. You just imagine that there is one.

 

[Bandersnatch]

Why is it wrong? It seems to me that as long as you have methane (the fuel), you can certainly burn it over and over -- until the fuel is depleted. That's how burning fuel works.

Burning requires fuel and oxidiser.

Look at this reaction:
$$CH_4+2O_2 ->2H_2O+CO_2 + Energy$$
it takes the methane, burns it with oxygen to release energy and produce water and carbon dioxide.
Methane is freely available, but you need oxygen (four atoms per reaction). Where to get if from? Well, you could get water ice and melt it, or maybe even drill deep for some liquid water, and run an electrolysis to get
$$4H_2O + Energy -> 8H + 4O$$
So to be able to burn a molecule of methane, which nets you two molecules of water, you need to destroy four molecules of water. The end result is, you're converting water and methane into carbon dioxide and hydrogen (which then either bonds with something else or escapes into space). While I don't know the exact energy balance (somebody calculate it please?), it's also unlikely to be positive - especially once you take into account inefficiencies. Which is to say, even if you ran an engine powered by the methane burning to output electricity for electrolysis, you'd end up with a negative balance (you'd have to import energy or oxygen from elsewhere).

So once again, the proposed reaction is not going to happen. One way of seeing it is, all the methane that could ever burn on Titan had already burned.

But, since the idea was to take the moon closer to the Sun*, you could circumvent the problem of water dissociation by the simple fact that UV radiation can do it for you. You just need to get the moon close enough for the water to remain liquid on the surface.
Then you leave the moon for some millions of years, and you may very well eventually end up with all methane transformed into water and CO2 (still no global conflagration, though).
But then a lot of other things can happen in that time, including complete stripping of the atmosphere by increased solar flux due to the low gravity and lack of magnetic field.*this is by the way an idea so far out there, as far as energy requirements go, that worrying about methane being used as a fuel source is a bit silly; it's like flying rockets to Alpha Centauri to collect wood for your stove.

 

[Drakkith]

Why is it wrong? It seems to me that as long as you have methane (the fuel), you can certainly burn it over and over -- until the fuel is depleted. That's how burning fuel works.

As has been explained already, converting water to oxygen and hydrogen requires energy. 572,000 joules per mole of water actually. Burning one mole of methane with oxygen to produce CO₂ and water nets you 802,000 joules, but since each reaction requires four oxygen atoms, you need to produce 4 moles of oxygen atoms, which requires 4 moles of water and 4x572 kJ, or about 2,228,000 joules. So, to get enough oxygen atoms to burn with methane, you need 2.85 times the energy that the combustion process even produces. In other words, you're losing energy. A lot of energy.

 

[russ_watters]

Why is it wrong? It seems to me that as long as you have methane (the fuel), you can certainly burn it over and over -- until the fuel is depleted. That's how burning fuel works.

Its not the methane you want to use over and over, it is the oxygen. In order to use it again, you have to "unburn" it, which just leaves you back where you started. You can, for example, do this:
Step 1: Convert water and carbon dioxide to methane and oxygen.

Step 2: Burn the oxygen and methane you just created, yielding water and carbon dioxide.

Repeat forever, with the same small group of molecules, never touching the rest of the planet.

 

[russ_watters]

As has been explained already, converting water to oxygen and hydrogen requires energy. 572,000 joules per mole of water actually. Burning one mole of methane with oxygen to produce CO₂ and water nets you 802,000 joules, but since each reaction requires four oxygen atoms, you need to produce 4 moles of oxygen atoms, which requires 4 moles of water and 4x572 kJ, or about 2,228,000 joules. So, to get enough oxygen atoms to burn with methane, you need 2.85 times the energy that the combustion process even produces. In other words, you're losing energy. A lot of energy.

IMO, the energy considerations are secondary to the problem with the required chemicals not even existing on Titan to do what he wants (or, rather, reactions not being able to use the same three oxygen molecules over and over to consume the whole atmosphere). A hydrogen economy on Earth would be a net energy loser too, but it at least can be done.

 

[Ophiolite]

Benny, more than once you have mentioned your end goal is to "jump start photosynthesis". What life forms are you planning to seed Titan with to initiate and maintain this photosynthesis?

 

[bennyschmidt]

As has been explained already, converting water to oxygen and hydrogen requires energy. 572,000 joules per mole of water actually. Burning one mole of methane with oxygen to produce CO₂ and water nets you 802,000 joules, but since each reaction requires four oxygen atoms, you need to produce 4 moles of oxygen atoms, which requires 4 moles of water and 4x572 kJ, or about 2,228,000 joules. So, to get enough oxygen atoms to burn with methane, you need 2.85 times the energy that the combustion process even produces. In other words, you're losing energy. A lot of energy.

Losing energy has nothing to do with the thought experiment. I imagine that essentially terraforming a moon would have a high energy cost. I'm wondering if it's possible to do it though, not wondering if I can gain energy from it. The question is whether it's possible or not to change the chemical state of Titan by converting its methane into other chemicals.

 

[bennyschmidt]

Benny, more than once you have mentioned your end goal is to "jump start photosynthesis". What life forms are you planning to seed Titan with to initiate and maintain this photosynthesis?

Why is this relevant? I just want to know if it's possible. Who knows what types of organisms would form if the environment was habitable in some sense.

 

[bennyschmidt]

IMO, the energy considerations are secondary to the problem with the required chemicals not even existing on Titan to do what he wants (or, rather, reactions not being able to use the same three oxygen molecules over and over to consume the whole atmosphere). A hydrogen economy on Earth would be a net energy loser too, but it at least can be done.

You also missed the point like a few others... I'm not asking whether or not you can get fuel from the planet; only wondering if it's possible to convert methane into other chemicals on Titan.

 

[Bandersnatch]

If you have unlimited energy at hand to sink into the project, then sure it's possible. You could even go as far as nuclear transmutation to produce whatever elements you'd like to have in the atmosphere.

Whether it's feasible is another matter.

 

[Ophiolite]

Why is this relevant? I just want to know if it's possible. Who knows what types of organisms would form if the environment was habitable in some sense.

You appear to believe that creating an carbon dioxide atmosphere would automatically lead to the emergence of photosynthetic organisms. There are several things wrong with this idea:

• Life took millions and probably hundreds of millions of years to emerge on the Earth.
• While we do not know the initial conditions that led to that, it is reasonably certain that an atmosphere of carbon dioxide was not in itself sufficient.
• Photosynthesising organisms arrived a considerable time after the first life.

As to your question directed to Drakith, the methane could be converted to other chemicals, but not by burning and carbon dioxide would not be a sensible target compound. However, I am still not clear what the ultimate objective of this thought experiment is.

 

[russ_watters]

You also missed the point like a few others... I'm not asking whether or not you can get fuel from the planet; only wondering if it's possible to convert methane into other chemicals on Titan.

No, I didn't miss the point, you misread my post. I said - four times now - that it isn't possible. Let me try a fifth time, to explain it a different way:

Here's what you said in post #3:

As far as I understand, there is already some oxygen on Titan, at least in the form of ice and ammonia under the surface near the poles. If there was enough oxygen to ignite even one small area, the byproduct would be more water and CO2, which makes more oxygen available to fuel more combustion.

Ok, so say you have a small sample of the atmosphere of Titan, containing 100 molecules of methane (you removed all the nitrogen and hydrogen). Somewhere, you find 2 molecules of oxygen, put it in the container and ignite it. Now you have 99 molecules of methane, 1 molecule of water and 1 molecule of carbon dioxide. And you're done. You can't re-use the oxygen because your goal was to create water and CO2, and to get the oxygen back, you have to destroy (unburn) the water and CO2. You need 198 more molecules of water to achieve your goal of converting the methane to water and CO2.

Or, if you do unburn the water and CO2 and then use the oxgen to do some burning again, you'll again be left with 99 molecules of methane, 1 molecule of water and 1 molecule of carbon dioxide.

 

[russ_watters]

However, I am still not clear what the ultimate objective of this thought experiment is.

If you had a sufficient quantity of oxygen available, you might be able to terra-form Titan by igniting the atmosphere, converting all of the methane to water and carbon dioxide. The result would be an atmosphere of about 98% nitrogen and 2% carbon dioxide, with solid water ice on the surface. That's what the OP is suggesting.

...of course, it would still be freezing cold.

 

[Ophiolite]

If you had a sufficient quantity of oxygen available, you might be able to terra-form Titan by igniting the atmosphere, converting all of the methane to water and carbon dioxide. The result would be an atmosphere of about 98% nitrogen and 2% carbon dioxide, with solid water ice on the surface. That's what the OP is suggesting.

...of course, it would still be freezing cold.

I see that is one thrust of his thinking, but his introduction - from the OP - of spontaneous emergence of photosynthesisers seems bizarre.

 

[bennyschmidt]

If you have unlimited energy at hand to sink into the project, then sure it's possible.

Why does it have to be unlimited energy? Why couldn't it just be a large amount of energy? Oh because you need the idea to be crazy in order to oppose it.

 

[bennyschmidt]

I see that is one thrust of his thinking, but his introduction - from the OP - of spontaneous emergence of photosynthesisers seems bizarre.

Yeah because photosynthesis didn't spontaneously emerge on Earth right?

 

[bennyschmidt]

If you had a sufficient quantity of oxygen available, you might be able to terra-form Titan by igniting the atmosphere, converting all of the methane to water and carbon dioxide. The result would be an atmosphere of about 98% nitrogen and 2% carbon dioxide, with solid water ice on the surface. That's what the OP is suggesting.

...of course, it would still be freezing cold.

Thanks for the answer! :) Although if it was closer to the sun and had an atmosphere, or if it was possible to ignite Jupiter and turn it into a secondary sun (lol have fun with that), then it would be liquid water.