Carbon Nano Tube Pipeline to Space: A Revolutionary Idea

[errorist]

Pipeline To Space?

A carbon nano tube pipeline from the Equator to geo. orbit could pump massive amounts of H2 and O2 to space to be stored as rocket fuel. The pipeline would only have to be 1/4 inch diameter.

http://www.newmars.com/cgi-bin/ikon...;f=5;t=198;st=0

 

[sid_galt]

A carbon nano tube pipeline from the Equator to geo. orbit could pump massive amounts of H2 and O2 to space to be stored as rocket fuel. The pipeline would only have to be 1/4 inch diameter.

http://www.newmars.com/cgi-bin/ikon...;f=5;t=198;st=0

The link is not opening.

Besides the cost would also be massive not to mention the different amount of weather, temperature and pressure conditions the pipeline will have to go through.

 

[errorist]

Here. This one should work! The Space Elevator would also go through a lot of these same forces!

http://www.newmars.com/cgi-bin/ikonboard/ikonboard.cgi?;act=ST;f=5;t=198

 

[russ_watters]

"Massive" amounts of air through a 1/4" diameter pipe? No.

Its an interesting idea, in any case, but it still doesn't deal with the fact that it can't be built with any technology we are likely to have in the forseeable future.

 

[errorist]

I guess Carbon Nano Tubes are not far along yet? Perhaps, a 1/2 inch tube.

 

[dweav256]

Hello Errorist,
You said:

"A carbon nano tube pipeline from the Equator to geo. orbit could pump massive amounts of H2 and O2 to space to be stored as rocket fuel. The pipeline would only have to be 1/4 inch diameter."


Errorist,
WOW! If someone could develope a system that could send gases into orbit, (to be used for rocket fuel) and not send it in the traditional manner (space shuttle, etc.), that would be a huge cost saver.

I believe you are on to something here. I wonder if H2 and/or O2 is lighter than methane (I am not very learned in science, nor the element table, etc.)?

Anyway, perhaps methane could be used for a propulsion method for the H2 and O2 (if the methane is heavier than the H2/O2), in order to get it out to space. Being that the pipe is only 1/4" in diameter this would be helpful for connecting it to a methane propulsion system, which in turn could assist the gases into orbit.

This should be extremely cost effective because the propulsion system would not need much in order for it to work (for example, grease or some other lubricant).

The government would probably support this fueling method as well because it would most likely be cheaper when compared to other costly space programs of the past and present.

 

[rachmaninoff]

If we're talking about elevating gases into LEO, does it matter that orbiting spacecraft are moving at thousands of kph relative to the (stationary) pipe? How do you work around that?

 

[FredGarvin]

Gee...does anyone know where we can get a pump to overcome that head? Let's see...you have about, what...60 miles, that's 316800 ft of static head right there (assuming constant gravity which I know it's not), not to mention the pressure drop you'd encounter over the length of a Ø.250" tube, especially at a flow rate to make this all worth the while. I'll have to go and work the numbers just for kicks.

 

[errorist]

Rachmaninoff,
It would be in a Geo. orbit like the space elevator!

Here are some numbers worked out on the Idea. I think even more powerfull pumps could work thus lowering the number of them needed by ten fold.

Calculation of the amount of pumps needed
As previously mentioned the additional amount of pumps needed per length is proportion to the force of gravity. We can neglect centripetal acceleration because it is to small to make much difference. I claim this can be written mathematically as:

dN/dh=(1/k)*/(P*g/rho)/ (P_o*g_o/rho_o)^2

Where:
Quote
rho is the density of the gas on the high pressure side of the pump
P is the pressure of the gas on the high pressure side of the pump
g is the force of gravity at the pump
G is the universal gravitational constant
M_E is the mass of the earth
R is the radius of the earth
r is the distance from the center of the earth
h is altitude
N is the number of pumps.
k is the number of attenuation constants between pumps. The fraction of gas remaining is given by e^(-k)
k=1 gives 0.3679, k=5 gives 0.0067, k=10 gives 4.5400e-005
k=1 seems the most practical.


From: http://www.elmhurst.edu/~chm/vchembook/123Adensitygas.html
Methane Data
Here are some densities:
Densities of Common Elements and Compounds
(Substance Density kg/m^3)
Quote
Hydrogen gas 0.000089e3
Helium gas 0.00018e3
Air 0.00128e3
Carbon Dioxide 0.001977e3
Water 1.00e3
Methane 0.0006557e3


The calculations will be done for air. Notice that methane is lighter then air.
To find the number of pumps needed we integrate the above expression from the radius of the Earth to GEO.
N=(1/k)int(P*g/rho),/(P_o*g_o/rho_o)^2, h=0…36e9)

Not that (P_o*g_o/rho_o) is the distance over which the pressure drops by 1/e.
Quote
=1000 Pa * 9.8 m/s^2/0.00128e3 kg/m^2=7.6563e+003 m for air.

In the calculation below we will use 6.92105e3 instead of 7.6563e+003 so are integral agrees exatly at the first pump which will be at 7.6563e+003.

Which is about 7.7 km. If the pressure at the high pressure side of each side is the same the expression for N becomes
Quote
N=(1/(k*6.92105e+003))int(g/g_o, h=0…36e6)= (1/k)int(G M_E/(h+R)^2/g_o, h=0…36e6) /0.3013
= (1/k*6.92105e+003)*int(6.67e-11 * 5.98e24/h^2/9.9, h=6e6…42e6)
=(1/k)* (-6.67e-11 * 5.98e24)/(9.9*6.92105e+003)*((1/42e6)-(1/6.38e6))=1000/k

Now to get it for others we can do this trick
Quote
For hydrogen:
1000*(density of hydrogen/density of air)
= 1000*0.000089e3/0.00128e3=69.5313
For methane:
773.8850*0.0006557e3/0.00128e3=512.66


So that is 70 pumps for hydrogen, 513 pumps for methane and 1000 pumps for air. The pumps start out being spaced 7 km apart and get further apart as the altitude increases. Also note that when the pumps get further apart the tubes must get wider to keep the viscous forces the same.

 

[dweav256]

Pump?

Fred said:
"Gee...does anyone know where we can get a pump to overcome that head?"

Every country has one (or more), all that is needed is some type of lubricant for reduction of friction.

Methane, I believe, would be usefull as the propulsion gas since it is so readily available.

As for the LEO spacecraft flying by too quickly, well we would have to figure out a way for the aircraft to slow down. Personally I believe methane could be used for this as well. If the spacecraft could be turned around, and if another mathane propulsion system is implemented, I think that in a specific matter of time that the craft could be slowed to a velicity of 0 mph.

 

[LunchBox]

If you can build me a single carbon nano-tube 18000 miles long... then I've got some nice real estate to sell you.

Better yet, show me a CNT just ONE mile long.

Even better still, show me a CNT 1000 feet long.

Sorry to burst bubbles, but there are serious hurdles to overcome before we can even build multi-mile long CNTs, let alone use them for space elevators and whatnot. I'm not saying it's never going to be done... I'm just saying don't hold you breath.

Cheers...

 

[russ_watters]

Gee...does anyone know where we can get a pump to overcome that head? Let's see...you have about, what...60 miles, that's 316800 ft of static head right there (assuming constant gravity which I know it's not), not to mention the pressure drop you'd encounter over the length of a Ø.250" tube, especially at a flow rate to make this all worth the while. I'll have to go and work the numbers just for kicks.

Actually, head wouldn't be an issue if pumping hydrogen: its lighter than air, so it'll rise through the pipe without anything more than air pressure pushing behind it.

For flow-rate vs pressure drop, yeah, I'm guessing someone didn't consider friction inside the pipe when they came up with that 1/4" dia. I can't imagine getting useful flow out of anything less than a foot diameter pipe.

A 12" pipe with a fairly generous pressure drop of .05" w.g. per 100 feet (I design HVAC ductwork for a living...) is good for 480 cubic feet per minute. At 22,000 miles to geostationary orbit, that's a total pressure drop of 4840' w.g. or about 2000psi.

Now, of course, since hydrogen is compressible, pumping it at 2000psi will add a pump-head issue...

And then, of course, is construction difficulty...

And hey - welcome aboard: you sound like an engineer...?

Errorist, I didn't put much effort into trying to understand that equation, but it looks suspiciously like gibberish. I don't see anything having to do with friction or flow rate, for example.

 

[FredGarvin]

Thanks for the welcome, Russ. Nice place you got here.

Yes. I am an engineer.

Even if the delta P could be overcome, there's always the question of how would multiple pump stations be built at various altitudes? Pump station number 1 (on the ground) would be a piece of cake (theoretically). It's pump stations 2 and up that have me wondering...how does one build a pumping station 7 km straight up?

 

[errorist]

It would be lowered from Geo.orbit from above. Just like a pump that has gone bad in a well it would have to be lowed down to the Earth from above after repairs have been made or initial installation.

 

[hitssquad]

head wouldn't be an issue if pumping hydrogen: its lighter than air, so it'll rise through the pipe without anything more than air pressure pushing behind it.

Through most of the 30,000 mile pipe, the hydrogen would be at a higher pressure than that of the surrounding atmosphere. That might make it be rather heavy and exert more than 14.7 PSI of pressure at the elevator base on Earth.

And, if this is rocket fuel, why would you be pumping it as a gas instead of as a liquid?

 

[errorist]

If the nano tube material can handle the stresses then a liquid could also be possible.

 

[LunchBox]

I think we're neglecting the major issue here... CNTs cannot be made of the length you are specifying, errorist.

Providing that they could, how many would you need to string side by side in order to build this pipe?

Run a quick hoop stress analysis on the kind of maximum pressure you would see at any point in this pipe and you will quickly see it is a daunting task. You would need to run CNTs circumferentially around this pipe in order for it to contain even the smallest of pressures. Think of it this way, you can't build a barrel out of parallel lengths of fishing line.

If a sky hook/space elevator type structure could be built, it would be much more economical to package the fuel on good 'ol terra firma and then run it up in tanks than to build a really, really, REALLY long pipe... especially since you wouldn't be running the pump 24/365.

Look, I'm not saying it's impossible... it is just so impractical and uneconomical that it is almost useless.

Cheers...

 

[hitssquad]

If a sky hook/space elevator type structure could be built, it would be much more economical to package the fuel on good 'ol terra firma and then run it up in tanks than to build a really, really, REALLY long pipe...

The space elevator needs a really long cable. Why not make it hollow? Airplanes need wings. We make them hollow and seal them so they can serve double duty as fuel tanks.

especially since you wouldn't be running the pump 24/365.

With the exception of shutdowns for repairs and scheduled maintenance, the Alaskan pipeline runs 24/365.

 

[FredGarvin]

It would be lowered from Geo.orbit from above. Just like a pump that has gone bad in a well it would have to be lowed down to the Earth from above after repairs have been made or initial installation.

That doesn't make a whole lot of sense to me. If I am understanding this correctly, you're saying that the tube would also not only have to support itself and withstand any loads imposed on it by the environment, but it would also have to support the pumps, valving and services as well? Also, it would be flexible to winch in and out from space?

Honestly, it's a good brainstorming session to try to alleviate the issues with the expense of Earth based launches, but it is anything but realistic. We haven't even begun to discuss what the environmental folks would have to say about having a huge pipeline dangling through the atmosphere.

 

[russ_watters]

Through most of the 30,000 mile pipe, the hydrogen would be at a higher pressure than that of the surrounding atmosphere. That might make it be rather heavy and exert more than 14.7 PSI of pressure at the elevator base on Earth.

Yes, it was a developing idea and didn't go back and rewrite the beginning when I reached a different conclusion at the end (I think its useful to show the whole thought process).

And, if this is rocket fuel, why would you be pumping it as a gas instead of as a liquid?

Well, I was going to let that go before, but now errorist brought it up...

Sending up liquid hydrogen would compound the problems exponentially (as if they aren't already daunting enough?) - first, how do you keep it a liquid in a 22,000 mile pipe? Second, its now much, much denser and requires a pipe several orders of magnitude stronger than if you're sending up a gas.

The space elevator needs a really long cable. Why not make it hollow? Airplanes need wings. We make them hollow and seal them so they can serve double duty as fuel tanks.

Airplanes have to carry their own fuel, otherwise they couldn't fly - its not the same thing. It would indeed be more efficient to carry liquid or gas up the elevator of a building (for example) than to pump it. And it just so happens that the same reasons you wouldn't do that in a building are the reasons you would do that with a space elevator: Pressure issues, heat (cryogenics), and efficiency.

But this is all still useless speculation: we're discussing how you would use something that can't be built!

 

[LunchBox]

The space elevator needs a really long cable. Why not make it hollow? Airplanes need wings. We make them hollow and seal them so they can serve double duty as fuel tanks.

Why not make it hollow? Because then it is a completely different engineering animal altogether. A skyhook needs only to support the vertical loads associated with the gravitational attraction of the planet it is located upon (as well as some minor off-axis forces). Making it hollow and running a pressurized fluid through it introduces a whole new set of problems. It now becomes a pressure vessel and must withstand additional longitudinal stresses as well as circumferential and shear stresses. The shear stresses are the REAL big showstopper, since a bundle of fibers can't support shearing. Making it hollow would only be compounding an already daunting engineering endeavor.

With the exception of shutdowns for repairs and scheduled maintenance, the Alaskan pipeline runs 24/365.

Yes, indeed. However, that is because there is a 24/365 demand for petroleum products in the US. Spacecraft are not going to be "lining up around the block... er orbit" as it were to refuel; the demand is just not there. So, if you WERE to run it all the time, you would need large tanks in orbit to collect the fuel when no spaceship was refueling. However, these large tanks would either have to be launched into orbit (which is VERY inane if you have a skyhook) or run up the skyhook (in which case wouldn't it be smarter to fill them on the ground and THEN run them up).

Again, I'm not saying it's impossible, nor am I trying to dissuade your creative thinking, it is just that this idea has a boatload of show-stoppers that makes it infeasible.

Cheers...

 

[errorist]

Also, it would be flexible to winch in and out from space?

We haven't even begun to discuss what the environmental folks would have to say about having a huge pipeline dangling through the atmosphere.

I am not saying winch the whole thing out at once but in sections like they do for deep well pumps. You can make the area where it punchs through the atmosphere a no fly zone. As for the environmentalists they would probably like such ideas because it would not pollute the atmosphere since rockets won't be used any more to get the fuel up there. Arther C Clark said about the Space Elevator they will have stopped laughing ten years after the thing is built.Same goes for the pipeline.

Think of it this way, you can't build a barrel out of parallel lengths of fishing line.
You can wrap the barrel the entire length with it though.

 

[LunchBox]

I am not saying winch the whole thing out at once but in sections like they do for deep well pumps.

Well, then it won't work. A skyhook of any sort has to have it's free end in a very narrow band of altitude in order to remain stable... you can't be raising and lowering it.

You can make the area where it punchs through the atmosphere a no fly zone.

The inside of both of the World Trade Center towers were no fly zones, but things still flew inside of them. Two words: eco-terrorists.

Arther C Clark said about the Space Elevator they will have stopped laughing ten years after the thing is built.Same goes for the pipeline.

HA HA!
Well, I don't know how many different ways to say it... If you have a skyhook, there is no need for this pipeline... none whatsoever... it is unnecessary... it is less efficient than hauling tanks of fuel up the skyhook...

...I'm out...

Cheers...

 

[FredGarvin]

"As for the environmentalists they would probably like such ideas because it would not pollute the atmosphere since rockets won't be used any more to get the fuel up there."

Environmentally, that is not the concern. The real concern would be what would happen if a puncture were to occur in the pipe line, say, in the upper atmosphere or even lower. You now have a "pipe" discharging into the open atmosphere with no hope of containing the leak in any appreciable amount of time.

One other item to consider would be the magnitudes and directions of winds at altitudes. I think you may be surprised to see just what speeds come up.

 

[hitssquad]

Arther C Clark said about the Space Elevator they will have stopped laughing ten years after the thing is built.

http://www.google.com/search?q=clarke+"after+they+stop+laughing"

 

[errorist]

Oops, Sorry, I was fourty years off.

 

[hitssquad]

Sixty years. (50 + 10 = 60)

50 . 40 . 30 . 20 . 10 . SE . 10

 

[russ_watters]

Sixty years. (50 + 10 = 60)

50 . 40 . 30 . 20 . 10 . SE . 10

And 50 years is over the "never" time horizon for science. I think you may misunderstand Clarke's point, Errorist: Scientists can't reasonably look any further away, so virtually nothing is ever predicted to be more than 50 years away (or even 30 years). Its like saying, 'I don't know when, but certainly not in my lifetime.' Fusion, for example, has been 50 years away for about the past 50 years. Spaceflight to Mars has now dropped to about a 20 year horizon, which means people think it is technically possible. Point being, when Kennedy said the US would go to the moon in 10 years, it was a real, reachable goal. It ended up being 9.5 years, and though it could have just as easily been 12, it was within the forseeable horizon. Nanotube space elevators are not.

 

[errorist]

Once out there you could compress it into liquid again no problem. Also, you could use the gas for an ion drive engine!

 

[LunchBox]

Ugh...

Once out there you could compress it into liquid again no problem. Also, you could use the gas for an ion drive engine!

No, you cannot use hydrogen as the propellant for an ion engine. You can use hydrogen as the propellant for a VASIMR (VAriable Specific Impulse Magnetoplasma Rocket).

Now...
How many ways do I have to say it? This pipeline would never be built, even if it could be. Is it a novel idea? Yes. Would it work? Probably. Is it feasible? You betcha. However, it is much less economical than using the skyhook you already need to build to haul tanks of propellant into orbit. The costs associated with building this pipeline would be so large that something like it would never be built unless transporting fuel into orbit was more economical if it was done this way. It isn't, so no agency - governmental, commercial, or private - is going to fund such a project.

It's a novel idea... but it's run it's course...

Cheers...

 

[errorist]

Any gas coild be used for an Ion drive engine.It does not have to be xenon.Btw,xenon could also be pumped up there.One other advantage it would have. It would have less of a chance of being impacted by a micro metiorite because it is so much smaller.
The sky hook has a million times the mass thus a million times the cost. This thing is but 1/4 inch Inside diameter.

 

[LunchBox]

The sky hook has a million times the mass thus a million times the cost. This thing is but 1/4 inch Inside diameter.

So all the pumping is going to be done from the surface of the Earth? Run a quick pressure analysis and see what kind of pressures that is going to require near the bottom. Then see just how many CNT layers you need to contain that via thin wall pressure vessel. Your OD may surprise you.

Cheers...

 

[errorist]

Calculation of the amount of pumps needed
As previously mentioned the additional amount of pumps needed per length is proportion to the force of gravity. We can neglect centripetal acceleration because it is to small to make much difference. I claim this can be written mathematically as:

dN/dh=(1/k)*/(P*g/rho)/ (P_o*g_o/rho_o)^2

Where:
Quote
rho is the density of the gas on the high pressure side of the pump
P is the pressure of the gas on the high pressure side of the pump
g is the force of gravity at the pump
G is the universal gravitational constant
M_E is the mass of the earth
R is the radius of the earth
r is the distance from the center of the earth
h is altitude
N is the number of pumps.
k is the number of attenuation constants between pumps. The fraction of gas remaining is given by e^(-k)
k=1 gives 0.3679, k=5 gives 0.0067, k=10 gives 4.5400e-005
k=1 seems the most practical.


From: http://www.elmhurst.edu/~chm/vchembook/123Adensitygas.html
Methane Data
Here are some densities:
Densities of Common Elements and Compounds
(Substance Density kg/m^3)
Quote
Hydrogen gas 0.000089e3
Helium gas 0.00018e3
Air 0.00128e3
Carbon Dioxide 0.001977e3
Water 1.00e3
Methane 0.0006557e3


The calculations will be done for air. Notice that methane is lighter then air.
To find the number of pumps needed we integrate the above expression from the radius of the Earth to GEO.
N=(1/k)int(P*g/rho),/(P_o*g_o/rho_o)^2, h=0…36e9)

Not that (P_o*g_o/rho_o) is the distance over which the pressure drops by 1/e.
Quote
=1000 Pa * 9.8 m/s^2/0.00128e3 kg/m^2=7.6563e+003 m for air.

In the calculation below we will use 6.92105e3 instead of 7.6563e+003 so are integral agrees exatly at the first pump which will be at 7.6563e+003.

Which is about 7.7 km. If the pressure at the high pressure side of each side is the same the expression for N becomes
Quote
N=(1/(k*6.92105e+003))int(g/g_o, h=0…36e6)= (1/k)int(G M_E/(h+R)^2/g_o, h=0…36e6) /0.3013
= (1/k*6.92105e+003)*int(6.67e-11 * 5.98e24/h^2/9.9, h=6e6…42e6)
=(1/k)* (-6.67e-11 * 5.98e24)/(9.9*6.92105e+003)*((1/42e6)-(1/6.38e6))=1000/k


Now to get it for others we can do this trick
Quote
For hydrogen:
1000*(density of hydrogen/density of air)
= 1000*0.000089e3/0.00128e3=69.5313
For methane:
773.8850*0.0006557e3/0.00128e3=512.66


So that is 70 pumps for hydrogen, 513 pumps for methane and 1000 pumps for air. The pumps start out being spaced 7 km apart and get further apart as the altitude increases. Also note that when the pumps get further apart the tubes must get wider to keep the viscous forces the same.

 

[LunchBox]

So it can't be any smaller than a skyhook, because you have "stations" hanging onto it at regular intervals. These are effectively the same as "cars" on a skyhook.

Your point that it could be smaller is now moot.

Cheers...

 

[errorist]

The pumps are even smaller and are part of the structure and the mass is still a million times less than the skyhook.

 

[FredGarvin]

That's the second time you have gone about this line of reasoning and I guess it will be a second time telling you that those calculations are incomplete to say the least. The only thing those calculations are doing is accounting for gravity. Try looking into frictional and compressibility effects.

Someone please close this thread.

 

[LunchBox]

Someone please close this thread.

I second that.

Cheers...

 

[errorist]

"Try looking into frictional and compressibility effects."

I'll look at these factors later but for now I can see for sure these pumps could also overcome these losses.

 

[LunchBox]

The pumps are even smaller and are part of the structure and the mass is still a million times less than the skyhook

What is going to power these pumps?

 

[errorist]

Perhaps,microwaves??

 

[errorist]

If you had a lot of pumps a RF wave guide would probably be the way to go to power them.

 

[brad50]

Why come to the surface harvest the atmosphere then pump to low Earth orbit, geo orbit is a anchor point. They will not get hydrogen oxygen is 1/2 of the fuel. Make a high thrust orbital tug gets its oxygen from are gas station hydrogen would come the old way. This tug would come down to suborbital levels dock with a suborbital craft boost to low orbit . Then transfer to proper orbit or a ion tug.We would not have to wait till cabin nano tubes can reach earth. Any one know how strong they are now, how far they can reach, is there any oxygen there how thick.

 

[russ_watters]

Welcome to PF. This thread is far too old to be resurrected.