Author Topic: necessity of methane production on Mars  (Read 11385 times)

Online Semmel

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Re: necessity of methane production on Mars
« Reply #80 on: 03/02/2017 07:43 PM »
Here is a paper that might be relevant.

http://onlinelibrary.wiley.com/doi/10.1002/slct.201601169/full

Quote
Herein we report a common element, nanostructured catalyst for the direct electrochemical conversion of CO2 to ethanol with high Faradaic efficiency (63 % at −1.2 V vs RHE) and high selectivity (84 %) that operates in water and at ambient temperature and pressure. Lacking noble metals or other rare or expensive materials, the catalyst is comprised of Cu nanoparticles on a highly textured, N-doped carbon nanospike film. Electrochemical analysis and density functional theory (DFT) calculations suggest a preliminary mechanism in which active sites on the Cu nanoparticles and the carbon nanospikes work in tandem to control the electrochemical reduction of carbon monoxide dimer to alcohol.

Online dror

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Re: necessity of methane production on Mars
« Reply #81 on: 03/04/2017 04:04 PM »
Here is a paper that might be relevant.

http://onlinelibrary.wiley.com/doi/10.1002/slct.201601169/full

Quote
Herein we report a common element, nanostructured catalyst for the direct electrochemical conversion of CO2 to ethanol with high Faradaic efficiency (63 % at −1.2 V vs RHE) and high selectivity (84 %) that operates in water and at ambient temperature and pressure. Lacking noble metals or other rare or expensive materials, the catalyst is comprised of Cu nanoparticles on a highly textured, N-doped carbon nanospike film. Electrochemical analysis and density functional theory (DFT) calculations suggest a preliminary mechanism in which active sites on the Cu nanoparticles and the carbon nanospikes work in tandem to control the electrochemical reduction of carbon monoxide dimer to alcohol.

Though very interesting, it looks like procucing ethanol requires a lot of hydrogen so water ice harvesting will still be necessaryon Mars.
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Offline gospacex

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Re: necessity of methane production on Mars
« Reply #82 on: 03/04/2017 05:34 PM »

There is dry ice on Mars. Could it be easier to collect frozen CO2?

Dry ice is at the poles. Settlements and landing sites will be nearer the equator. Dry ice would need to be transported for thousands of km. Maybe feasible when there is significant industry and infrastructure. Not early.

Exactly.
If you need faster fuel generation, send a few more ITSes loaded with atmospheric fuel production plants and solar panels, and deploy those. There is no shortage of atmosphere and land there.

It's one-time expense, compared to constant hassle of digging up H2O/CO2 ices, hauling them around and purifying them.

Thankfully, at the moment Mars has very low population of bureaucrats, no zoning committees and no EPA. At least here, the weight of plant equipment will be substantially larger than the weight of paperwork needed to deploy it.
« Last Edit: 03/04/2017 05:35 PM by gospacex »

Offline lamontagne

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Re: necessity of methane production on Mars
« Reply #83 on: 03/05/2017 12:29 AM »

There is dry ice on Mars. Could it be easier to collect frozen CO2?

Dry ice is at the poles. Settlements and landing sites will be nearer the equator. Dry ice would need to be transported for thousands of km. Maybe feasible when there is significant industry and infrastructure. Not early.

Exactly.
If you need faster fuel generation, send a few more ITSes loaded with atmospheric fuel production plants and solar panels, and deploy those. There is no shortage of atmosphere and land there.

It's one-time expense, compared to constant hassle of digging up H2O/CO2 ices, hauling them around and purifying them.

Thankfully, at the moment Mars has very low population of bureaucrats, no zoning committees and no EPA. At least here, the weight of plant equipment will be substantially larger than the weight of paperwork needed to deploy it.
Isn't it really a question of energy?  The power required to compress the atmosphere into a usable liquid for separation, vs the power to transport CO2 for a long distance?
Clearly not a viable short term solution, but it would be interesting to calculate the cost of moving CO2 on a large Mars train vs the cost of compression, for example.

Offline lamontagne

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Re: necessity of methane production on Mars
« Reply #84 on: 03/05/2017 12:30 AM »
Do we need methane to produce ammonia by the Haber process for plant fertilizer, or is there a more direct way?

Offline Norm38

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Re: necessity of methane production on Mars
« Reply #85 on: 03/05/2017 12:58 AM »
Isn't it really a question of energy?  The power required to compress the atmosphere into a usable liquid for separation, vs the power to transport CO2 for a long distance?
Clearly not a viable short term solution, but it would be interesting to calculate the cost of moving CO2 on a large Mars train vs the cost of compression, for example.

Energy has to be stored to be used. Solar panels can dump their energy straight to chemical storage. But to haul
dry ice from the poles requires a lot more hardware. Meaning a lot more shipment from Earth and all that energy.  I bet compression wins out.

Offline gospacex

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Re: necessity of methane production on Mars
« Reply #86 on: 03/05/2017 04:49 PM »
Isn't it really a question of energy?  The power required to compress the atmosphere into a usable liquid for separation, vs the power to transport CO2 for a long distance?
Clearly not a viable short term solution, but it would be interesting to calculate the cost of moving CO2 on a large Mars train vs the cost of compression, for example.

And the cost of separation out dust and sand from that frozen CO2. And the cost of operating and maintaining earthmoving equipment at the ice mining site. And the cost of maintaining trains and rails. All that machinery is bound to break from time to time.

Offline lamontagne

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Re: necessity of methane production on Mars
« Reply #87 on: 03/05/2017 05:18 PM »
Isn't it really a question of energy?  The power required to compress the atmosphere into a usable liquid for separation, vs the power to transport CO2 for a long distance?
Clearly not a viable short term solution, but it would be interesting to calculate the cost of moving CO2 on a large Mars train vs the cost of compression, for example.

And the cost of separation out dust and sand from that frozen CO2. And the cost of operating and maintaining earthmoving equipment at the ice mining site. And the cost of maintaining trains and rails. All that machinery is bound to break from time to time.
As do compressors and other gas separation equipment.  And you need to separate the dust out of the atmosphere as well, and that can wear out.  I have no preference one way or the other, really.  Horizontal transportation on rails can be pretty cheap.  but the cost of the infrastructure needs to be proportional to the demand, and for a 5000 km run, at, 1 million per km?  That's a 5 billion dollars in rail...  won't be producing those levels of fuel before some time :-)

Offline Steve D

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Re: necessity of methane production on Mars
« Reply #88 on: 03/10/2017 06:40 PM »
Do we need methane to produce ammonia by the Haber process for plant fertilizer, or is there a more direct way?

Fish

Offline Steve D

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Re: necessity of methane production on Mars
« Reply #89 on: 03/10/2017 06:43 PM »
Isn't it really a question of energy?  The power required to compress the atmosphere into a usable liquid for separation, vs the power to transport CO2 for a long distance?
Clearly not a viable short term solution, but it would be interesting to calculate the cost of moving CO2 on a large Mars train vs the cost of compression, for example.

And the cost of separation out dust and sand from that frozen CO2. And the cost of operating and maintaining earthmoving equipment at the ice mining site. And the cost of maintaining trains and rails. All that machinery is bound to break from time to time.
As do compressors and other gas separation equipment.  And you need to separate the dust out of the atmosphere as well, and that can wear out.  I have no preference one way or the other, really.  Horizontal transportation on rails can be pretty cheap.  but the cost of the infrastructure needs to be proportional to the demand, and for a 5000 km run, at, 1 million per km?  That's a 5 billion dollars in rail...  won't be producing those levels of fuel before some time :-)


Why use rails? An autonomous tanker truck would work just as well.

Offline lamontagne

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Re: necessity of methane production on Mars
« Reply #90 on: 03/10/2017 08:50 PM »
Do we need methane to produce ammonia by the Haber process for plant fertilizer, or is there a more direct way?

Fish
Fish food?

Offline lamontagne

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Re: necessity of methane production on Mars
« Reply #91 on: 03/10/2017 09:07 PM »
Just how hard is it to separate out the CO2 in Mars' atmosphere anyway?

It seems clear that a frozen CO2 hauler would also be moving water, as the two seem to freeze out more or less together in the present atmosphere of Mars, as per the joined paper.

Perhaps the membrane or chemical way would be cheaper than compression, after all.



Offline Rei

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Re: necessity of methane production on Mars
« Reply #92 on: 03/10/2017 09:15 PM »
Do we need methane to produce ammonia by the Haber process for plant fertilizer, or is there a more direct way?

There are other processes (such as from cyanides and electric arcs), but not good ones. The discovery of the Haber process was really one of the great moments in chemistry - production of nitrates previously had been low volume and expensive, but the process created a way that works so well that the design of modern ammonia plants is little changed from the original days.  Three different Nobel prizes have been granted in relation to the process. The catalyst (iron/magnetite with various promoters) is easy to make and renew (indeed, at very high pressures you don't even need catalysts - the walls of the reactor themselves act as a catalyst).  There are a couple alternative modern catalysts, but no real huge leaps forward.

The main disadvantage of the Haber process is the need for high pressures. But that's pretty unavoidable, you have to shift the thermodynamic equilibrium to favour ammonia.

Now the Ostwald process, there's a lot more potential for improvement there... mainly reducing catalyst erosion and/or better catalyst recovery and/or cheaper catalysts.

ED: Wait, you said methane?  Methane isn't involved in the Haber process, hydrogen is. On Earth we make most hydrogen from methane, because that's the cheapest way here, but it's certainly not the cheapest way on Mars.
« Last Edit: 03/10/2017 09:17 PM by Rei »

Offline Rei

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Re: necessity of methane production on Mars
« Reply #93 on: 03/10/2017 09:21 PM »
Just how hard is it to separate out the CO2 in Mars' atmosphere anyway?

It seems clear that a frozen CO2 hauler would also be moving water, as the two seem to freeze out more or less together in the present atmosphere of Mars, as per the joined paper.

Perhaps the membrane or chemical way would be cheaper than compression, after all.

Mars's water vapour is so vanishingly sparse that it's generally not considered a practical feedstock vs. ground sources (for which the TRL is still very low).

As for how easy it is to separate, I'd recommend reading the design of MOXIE  :)  It gives an idea of the various complications that have to be handled.  Still, as far as feedstocks go, it's a relatively uncomplicated one. 

Offline guckyfan

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Re: necessity of methane production on Mars
« Reply #94 on: 03/10/2017 09:56 PM »
Do we need methane to produce ammonia by the Haber process for plant fertilizer, or is there a more direct way?

Fish

Fish don't produce nitrates from nitrogen. They produce it from proteins in their food. So not a source. They can help keep it in circulation.

Offline Robotbeat

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Re: necessity of methane production on Mars
« Reply #95 on: 03/11/2017 07:53 PM »
Do we need methane to produce ammonia by the Haber process for plant fertilizer, or is there a more direct way?

Fish

Fish don't produce nitrates from nitrogen. They produce it from proteins in their food. So not a source. They can help keep it in circulation.
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