Propane on Mars - (Quick, go tell Hank Hill!)

C M Edwards · 2002-06-04 10:50:08

I have some questions about Robert Zubrin?s experiment on in situ propellant production, and I was wondering if someone could help me find the answers.

I know that the experiment successfully produced methane using a Sabatier reactor fed with carbon dioxide from a very low pressure reservoir (?Mars-like? conditions). However, does anyone know if the apparatus was able to actually liquefy and store its product as cryogenic methane? Much was made of the fact that the Sabatier process is so simple, and indeed it is, but liquefying methane is relatively complex and energy intensive compared to rectifying natural gas.

Also, if he did liquefy it, what do he and his cohorts propose to do with the liquid petroleum byproducts? The Sabatier process is not a ?clean? reaction. It produces propane and butane as well as trace amounts of other hydrocarbons. In an industrial setting, these are generally removed by condensation and sold as LPG (Liquid Petroleum Gas or ?Propane?). A Sabatier reactor making 60T of methane on Mars will produce almost a ton of LPG as a byproduct.

Complete lack of discussion of LPG in The Case for Mars makes me suspect that the famous In Situ Propellant experiment wasn?t taken to a logical completion with the production of cryogenic methane.

I?m also curious to know if it wouldn?t be less energy intensive to instead recycle the methane produced in the Sabatier reactor for more complete production of LPG and use that as fuel for the ERV instead of methane. The chemical synthesis would be somewhat more energy intensive, but liquefying the propellant would be several times less so because the boiling point of LPG is so much higher than that of methane.

CME

Phobos · 2002-06-04 13:40:35

Would these byproducts be in quantities that would make
them truly useable or an issue on such a small scale as the first landing? I have no idea, but if propane comes out of the reaction that means I can take my propane camp stove to Mars. That'd be cool.

Shaun Barrett · 2002-06-04 19:46:19

A very good point, C M .
I'm pretty sure the automated methane production experiment wasn't taken to its obvious conclusion: Cryogenic storage.
Maybe Dr. Zubrin just assumes that power from the nuclear reactor will be used to maintain a miniaturised cryogenic facility to keep the gases liquid(? ) Easier said than done, I suppose?!
You've certainly got me thinking, now. If Bob Zubrin is serious about Mars Direct, and I'm sure he is, a demonstration of the entire production AND STORAGE process is surely a necessity.
???

C.COMMARMOND (FR) · 2002-08-28 12:49:57

Hi,

For information, because methane (CH4) becomes liquid at -161.5?C, night temperature on some places on Mars could be low enough or nearly to liquify it. The problem of LPG in the sabatier reaction could be not a problem because all these gas will become liquid before methane, this mean that they could be easily separated during the cooling (in fact they will become solid, and methane will probably stay gaseous).

ethylene C2H4 -103,7
ethane C2H6 - 88,5
propylene C3H6 - 47,7
propane C3Hv8 - 42
iso-butane C4H10 - 11,7
butane C4H8 - 6,2
butane C4H10 - 0,5

From this mix, we can do fuel from a ground vehicle which could use them by first heating them before burn them with LO2 (or i think it better H2O2).

So you can see that the storage will be probably easy to acheave at low energetic cost.

I spoke before about H2O2 because it presents advantage to not need cryogenic process and it is known as a good comburant for rockets. The draw back of it is that it is corrosive, but I think we could keep oxygen at standard temperature and pressure (about 10 bars) and make H2O2 just before the flight.

From all this i think all the related problems are small enough to consider the sabatier conversion as solved (at our level at least).

CC

Phobos · 2002-08-28 21:02:14

For information, because methane (CH4) becomes liquid at -161.5?C, night temperature on some places on Mars could be low enough or nearly to liquify it. The problem of LPG in the sabatier reaction could be not a problem because all these gas will become liquid before methane, this mean that they could be easily separated during the cooling (in fact they will become solid, and methane will probably stay gaseous).

I imagine if we run into problems with chemicals becoming undesirable states of matter we could just heat up the tanks a little bit, maybe install a thermostat to regulate the temperature.

PaganToris · 2002-08-31 23:05:15

Well it seemsd that Hank hill would be verry up set becuse yer nt buying STRIKLAND PROPANE my choice would be to go with the Blue rihno
but naw its impossible to have propane on mars now PLUTO is a diffrent storry the eskimos use it to cook there wonderfull frost bitten fish

C M Edwards · 2006-09-14 12:01:04

Bump.

louis · 2008-03-27 18:41:06

CME -

Why are you worried about energy intensive processes. The one thing we won't be short of on Mars is energy. It will be available in abundance through ultra thin photovoltaic film. We can afford to be profligate in our energy consumption as long as we are achieving our vital objectives: energy storage, food production, heat and light for habitats, various industrial processes and - yes - rocket fuel production.

idiom · 2008-04-01 05:13:52

Bump.

Thats pretty cool. Mekanical fotosinthisis.

JoshNH4H · 2008-04-01 14:05:40

I agree. Don't they have spray-on PVC's now? Just take a can and a bunch of tin foil, and spray away if you need more power. But couldn't all of the other products be burned in the rocket engine as well? They all have similar Isp's.

Terraformer · 2008-04-05 12:21:53

Then the engine would have to handle different fuels of different masses at once, probably adding weight to the system. Pluswe'd need different tanks for the fuels, adding weight (unless we slush the Propane etc and dissolve it in the Methane?)

Propane would be a denser fuel, and if it has roughly the same ISP of Methane it has SSTO applications (my current spacecraft obsession ) Maybe Ethane? Producing one Ethane molecule from two Methane molecules would release one H2, which presumably would be recycled through the system.

Terraformer · 2008-04-05 12:34:16

Ethanes boiling point: -88.6c. (according to wikipedia). Too cold?

JoshNH4H · 2008-04-05 13:06:58

better not be. Methane's boiling point is -162 C. Hydrogen is -250 C. Oxygen is -190 C.

idiom · 2008-04-05 16:32:06

Propaane Ethane and Methane all have very low *freezing* points, just a few degrees above Oxygens boiling point. This means you can get away with a thinner bulkhead.

Terraformer · 2008-04-06 07:46:04

Could we freeze the Methane/Ethane/Propane in the LOX and have it crushed up into a fine powder? That would have the advantage of only one tank needed. I don't think the mix would spontaneusly ignite inside the tank.

JoshNH4H · 2008-04-06 15:24:32

Seems like a good idea to me.

Terraformer · 2008-04-07 04:03:06

It isn't. Check the New Fuel thread.

JoshNH4H · 2008-04-07 14:04:23

Maybe something like the H2O2/Propane idea?

Terraformer · 2008-04-08 14:25:46

I claim the rights to that idea!

The advantages of H2O2 as an Oxidiser: Non-cryogenic, and contains more Oxygen than N2O.

I wonder whether Propane could be pressurized into a liquid? Maybe it would have Single Stage To Orbit 8) applications? Something like a VentureStar, except without having to keep the fuel really really cold?

JoshNH4H · 2008-04-08 14:49:08

no, it wasn't your idea:

http://www.dunnspace.com/alternate_ssto_propellants.htm
These do show some that seem to have decent SSTO applications Specifically LOX/Cycloopropane.

Terraformer · 2008-04-09 04:29:05

I've looked at that. Butane/H2O2 seems to be a lousy fuel.

But they've investigated all fuels that are possible that don't poisen everybody. So of course they have that one.

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#1 2002-06-04 10:50:08

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#2 2002-06-04 13:40:35

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#3 2002-06-04 19:46:19

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#4 2002-08-28 12:49:57

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#5 2002-08-28 21:02:14

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#6 2002-08-31 23:05:15

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#7 2006-09-14 12:01:04

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#8 2008-03-27 18:41:06

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#9 2008-04-01 05:13:52

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#10 2008-04-01 14:05:40

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#11 2008-04-05 12:21:53

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#12 2008-04-05 12:34:16

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#13 2008-04-05 13:06:58

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#14 2008-04-05 16:32:06

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#15 2008-04-06 07:46:04

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#16 2008-04-06 15:24:32

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#17 2008-04-07 04:03:06

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#18 2008-04-07 14:04:23

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#19 2008-04-08 14:25:46

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#20 2008-04-08 14:49:08

Re: Propane on Mars - (Quick, go tell Hank Hill!)

#21 2008-04-09 04:29:05

Re: Propane on Mars - (Quick, go tell Hank Hill!)

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