Author Topic: Rocket propellant from seawater and sunlight  (Read 5795 times)

Offline Ludus

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Rocket propellant from seawater and sunlight
« on: 03/31/2013 05:22 PM »
http://bravenewclimate.com/2013/01/16/zero-emission-synfuel-from-seawater/#more-6020

I'm curious how practical it would be for Canaveral or other major space launch sites to produce rocket propellant on site in a zero net carbon method.

I'd think Spacex and a lot if other players including DOD would be interested in this if the costs long term were not much greater than conventional sources.

The notion is that seawater can be used as a source of hydrogen and carbon for Fisher-Tropsch http://en.wikipedia.org/wiki/Fischer–Tropsch_process.

Seawater has 200x the density of carbon dioxide as the atmosphere and interacts with it so carbon extracted from seawater is equivalent to taking it out of the air and hydrocarbon fuels made in this way are zero net carbon producing.

In the ordinary version of this for say Naval jet fuel, the oxygen produced would just be vented. In the space launch version obviously the oxygen also has a use.

The process ought to be able to produce a synthetic RP-1 equivalent. This is a question for anybody with a real understanding of rocket fuels and engines. What issues would there be? As I understand it, the spec for RP-1 calls for a very low sulfur variant which would be an excellent fit for a synthetic that could easily be zero sulfur. Are there other problems?

IIRC the process should have no trouble producing pure methane or pure hydrogen from and earlier process stage than kerosene.

As far as the electricity to run it, it seems like there would be a couple good fits. First it matches well practically and politically with PV solar on site. Canaveral is sunny, on the sea and has a lot of open space for safety and security that might be used for pv arrays. Beyond that, this use would be a good match for long term deals with power utilities to level demand. Propellant synthesis could soak up excess electric production in low demand periods matching both intermittant sources like renewables and greater base load like nuclear. The synthesis could change it's power draw to productively use power the grid doesn't need.

If the system had more capacity than was needed for rockets, it could switch to jet fuel grade production.

I think there is real interest in the military in developing this kind of tech given the enormous costs they have of providing lots of fuel in exotic locations.

Since rocket fuel is already premium priced it would be a closer match to the higher costs of a new synthesis technology.

Critiques?

Offline Jim

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Re: Rocket propellant from seawater and sunlight
« Reply #1 on: 03/31/2013 05:27 PM »
Canaveral is sunny, on the sea and has a lot of open space for safety and security that might be used for pv arrays.

No, not really.  It is a wildlife refuge which is not compatible with array farms.

Offline Jim

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Re: Rocket propellant from seawater and sunlight
« Reply #2 on: 03/31/2013 05:31 PM »
I'd think Spacex and a lot if other players including DOD would be interested in this if the costs long term were not much greater than conventional sources.


Not really.  The amount they use is insignificant and would not support the expense of building a dedicated plant.

And why is Spacex singled out?

Offline RocketmanUS

Re: Rocket propellant from seawater and sunlight
« Reply #3 on: 03/31/2013 05:58 PM »
Power source can be miles away. So could use solar cells and/or wind.
Takes energy to make these power sources, that most likely will produce CO2 and other by products.
Note, we need CO2 for the life cycle here on Earth.

Propellants from sea water would be LH2 and LOX. Possible CH4 if there is an economical source of CO2.

Must cost less than to bring the propellants in from another source.
There will need to be a high enough demand to justify putting in such a system.

If extra CH4 were to be made as it is the main part of natural gas it could be sold to the local market for natural gas use.
« Last Edit: 03/31/2013 06:46 PM by RocketmanUS »
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Offline Hyperion5

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Re: Rocket propellant from seawater and sunlight
« Reply #4 on: 03/31/2013 06:00 PM »
I'd think Spacex and a lot if other players including DOD would be interested in this if the costs long term were not much greater than conventional sources.


Not really.  The amount they use is insignificant and would not support the expense of building a dedicated plant.

And why is Spacex singled out?

He's just following the general rule of NSF, which basically is that the longer a conversation goes on at this site, the chance of Spacex appearing in that conversation approaches 100%. 

Offline blazotron

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Re: Rocket propellant from seawater and sunlight
« Reply #5 on: 03/31/2013 06:18 PM »
I'd think Spacex and a lot if other players including DOD would be interested in this if the costs long term were not much greater than conventional sources.


Not really.  The amount they use is insignificant and would not support the expense of building a dedicated plant.

And why is Spacex singled out?

For what it's worth, I've heard SpaceX is the largest consumer of RP-1. 

As far as whether Fischer-Tropsch fuel can be used to replace RP-1, the RP-1 spec (and even more so the RP-2 spec, which is a tighter spec that sits inside the RP-1 spec) is designed to optimize energy density, boiling point curves, and amounts of certain chemical components (such as sulfur, aromatics, and olefins) which have significant effects on combustion characteristics.  Both were designed around fuels made from particular feedstocks primarily derived from refined petroleum. 

In order to  be a drop in replacement for RP-1, the new fuel would not only need to meet the spec, but in practice closely match the typical RP-1 composition to match RP-1 performance for use on engines qualified for RP-1.  In rocket engines, replicating the exact fuel performance is a much bigger deal than other applications of non-fossil-fuels, such as biodiesel and FT fuel used in cars.  Rocket engines are typically operated in a regime where significant changes in heat production rate, evaporation rate, density, surface tension, viscosity, hydrogen content, or constituent fractions affect mixing and combustion in injectors.  Similarly, significant changes in heat capacity, density,  coking rate, and boiling point curves can effect heat rejection into regenerative cooling circuits.  Energy density also affects the performance of a rocket as a whole as a change in the density would cause the vehicle to store more or less total energy. 

Matching all these characteristics would be relatively difficult to do with synthetic fuels and would require extensive processing of the fuels.  This makes it unlikely that a drop in replacement for existing fuels is feasible. 

This is not to say that a good rocket fuel cannot be made by Fischer-Tropsch, bio-derived, or other alternative processes.  And in fact there are several efforts underway to do this.  See for instance this article which describes some testing that has been done as well as some of the challenges I alluded to above.
http://www.flightglobal.com/news/articles/biodiesel-powers-atlas-rocket-engine-321321/
However, at that point you would be better off developing a new specification, and any program that wanted to use the new fuel would qualify their vehicles specifically to operate on it (possibly alongside RP-1). 

Offline Patchouli

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Re: Rocket propellant from seawater and sunlight
« Reply #6 on: 03/31/2013 06:50 PM »


For what it's worth, I've heard SpaceX is the largest consumer of RP-1. 

As far as whether Fischer-Tropsch fuel can be used to replace RP-1, the RP-1 spec (and even more so the RP-2 spec, which is a tighter spec that sits inside the RP-1 spec) is designed to optimize energy density, boiling point curves, and amounts of certain chemical components (such as sulfur, aromatics, and olefins) which have significant effects on combustion characteristics.  Both were designed around fuels made from particular feedstocks primarily derived from refined petroleum. 

In order to  be a drop in replacement for RP-1, the new fuel would not only need to meet the spec, but in practice closely match the typical RP-1 composition to match RP-1 performance for use on engines qualified for RP-1.  In rocket engines, replicating the exact fuel performance is a much bigger deal than other applications of non-fossil-fuels, such as biodiesel and FT fuel used in cars.  Rocket engines are typically operated in a regime where significant changes in heat production rate, evaporation rate, density, surface tension, viscosity, hydrogen content, or constituent fractions affect mixing and combustion in injectors.  Similarly, significant changes in heat capacity, density,  coking rate, and boiling point curves can effect heat rejection into regenerative cooling circuits.  Energy density also affects the performance of a rocket as a whole as a change in the density would cause the vehicle to store more or less total energy. 

Matching all these characteristics would be relatively difficult to do with synthetic fuels and would require extensive processing of the fuels.  This makes it unlikely that a drop in replacement for existing fuels is feasible. 

This is not to say that a good rocket fuel cannot be made by Fischer-Tropsch, bio-derived, or other alternative processes.  And in fact there are several efforts underway to do this.  See for instance this article which describes some testing that has been done as well as some of the challenges I alluded to above.
http://www.flightglobal.com/news/articles/biodiesel-powers-atlas-rocket-engine-321321/
However, at that point you would be better off developing a new specification, and any program that wanted to use the new fuel would qualify their vehicles specifically to operate on it (possibly alongside RP-1). 


In theory a fully synthetic or bio derived rocket propellant can be superior to that derived from petroleum.
You have more control over what's in it.
A good example is the Russian synthetic kerosene fuel Sintin.
Though I think the Russians used natural gas as the starting point a  Fischer-Tropsch process would just be adding one more step.
« Last Edit: 03/31/2013 06:52 PM by Patchouli »

Offline Lars_J

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Re: Rocket propellant from seawater and sunlight
« Reply #7 on: 03/31/2013 07:55 PM »
I'd think Spacex and a lot if other players including DOD would be interested in this if the costs long term were not much greater than conventional sources.


Not really.  The amount they use is insignificant and would not support the expense of building a dedicated plant.

And why is Spacex singled out?

For what it's worth, I've heard SpaceX is the largest consumer of RP-1. 

What, how could they be? ULA should use more, even if one only counts their east coast pad. That might change in the future, but ULA should use more for the immediate future.

Offline joek

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Re: Rocket propellant from seawater and sunlight
« Reply #8 on: 03/31/2013 08:04 PM »
For what it's worth, I've heard SpaceX is the largest consumer of RP-1. 
What, how could they be? ULA should use more, even if one only counts their east coast pad. That might change in the future, but ULA should use more for the immediate future.

SpaceX appears to do quite a bit of testing.  How much is that likely to contribute to consumption?

Offline Ludus

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Re: Rocket propellant from seawater and sunlight
« Reply #9 on: 03/31/2013 09:18 PM »
I'd think Spacex and a lot if other players including DOD would be interested in this if the costs long term were not much greater than conventional sources.


Not really.  The amount they use is insignificant and would not support the expense of building a dedicated plant.

And why is Spacex singled out?

Because Musk has an major public association with "green" projects. The fact that the amounts used are relatively low is what makes a project to supply them more practical.

Offline Ludus

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Re: Rocket propellant from seawater and sunlight
« Reply #10 on: 03/31/2013 09:25 PM »
I'd think Spacex and a lot if other players including DOD would be interested in this if the costs long term were not much greater than conventional sources.


Not really.  The amount they use is insignificant and would not support the expense of building a dedicated plant.

And why is Spacex singled out?

DOD's interest is not for rocket propellant, it's for jetfuel and diesel at the end of costly logistical chains...and probably would be better served by small modular reactors than solar, but the chemical plant end using the electricity is about the same.

Offline gospacex

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Re: Rocket propellant from seawater and sunlight
« Reply #11 on: 03/31/2013 09:28 PM »
http://bravenewclimate.com/2013/01/16/zero-emission-synfuel-from-seawater/#more-6020

I'm curious how practical it would be for Canaveral or other major space launch sites to produce rocket propellant on site in a zero net carbon method.

I think spaceports should launch rockets.
Fuel production should be left for petrochemical industry.

Offline Ludus

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Re: Rocket propellant from seawater and sunlight
« Reply #12 on: 04/01/2013 12:08 AM »
I should explain a bit more why I think this might be useful. When engineering oriented folk look at rocket fuel they realize it's such a tiny fraction of hydrocarbon fuel use that it's effectively meaningless as a issue with carbon and climate (aside from whether they are concerned about that at all). When most people look at rocket launches they see extravangant fuel use and consequences. Rocket fuel also popularly seems powerful and explosive when in fact the major difference from other grades of fuel is that it's better as an engine coolant and more stable.

Zero net carbon rocket propellant would have significant popular image benefits for space launches and aerospace in general. It would actually be a pilot for broader use of the technology.

Rockets that burn zero net carbon fuel...would also have a PR benefit for the image of such fuel as "potent" whether that's technically meaningful or not.

SpaceX is mentioned specifically because given the association through Musk with Tesla and Solar City, this sort of benefit may appeal to them more.

As to sources of electricity, I think the image of launch pads surrounded in the immediate area with solar arrays makes sense as an image. It's not important what fraction of power they supply. The more important source of supply would be deals for demand leveling with the local grid.

The popular image of rocket launches is of powerful machines that are extravagant wasters of energy and sources of pollution. This seeks to address that image issue and pilot technologies of broader interest at relatively low cost.

Offline QuantumG

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Re: Rocket propellant from seawater and sunlight
« Reply #13 on: 04/01/2013 12:14 AM »
How would it be net zero carbon rocket propellant?

Quote from: Ludus
Seawater has 200x the density of carbon dioxide as the atmosphere and interacts with it so carbon extracted from seawater is equivalent to taking it out of the air and hydrocarbon fuels made in this way are zero net carbon producing.

Maybe I'm just missing your point here, but extracting carbon from the ocean only to put it back in the atmosphere is something I'd expect the warmers wouldn't warm to.
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline Ludus

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Re: Rocket propellant from seawater and sunlight
« Reply #14 on: 04/01/2013 12:33 AM »
How would it be net zero carbon rocket propellant?

Quote from: Ludus
Seawater has 200x the density of carbon dioxide as the atmosphere and interacts with it so carbon extracted from seawater is equivalent to taking it out of the air and hydrocarbon fuels made in this way are zero net carbon producing.

Maybe I'm just missing your point here, but extracting carbon from the ocean only to put it back in the atmosphere is something I'd expect the warmers wouldn't warm to.


Zero net carbon fuels use carbon extracted from the atmosphere/ocean system and put it back when they are burned. The net effect is to neither add or subtract carbon, hence zero. Global civilization could burn an unlimited amount of hydrocarbon fuels of this sort forever without adding any more carbon to the atmosphere. Fossil sourced hydrocarbon fuels add carbon that was previously buried and out of the atmosphere/ocean.

Hydrocarbon fuels are MUCH easier to handle than hydrogen...and if the carbon component is just recycled through the atmosphere they are completely "sustainable". They cease to a source of energy and are just a storage medium like hydrogen was intended to be in visions of a "hydrogen economy". Hydrogen just turns out to be too hard to handle...plus would need a whole new infrastructure.

Offline QuantumG

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Re: Rocket propellant from seawater and sunlight
« Reply #15 on: 04/01/2013 12:38 AM »
the atmosphere/ocean.

I don't know where you're getting this idea that the atmosphere and the ocean are interchangeable, but they're not. Extracting carbon from the ocean to dump into the atmosphere is going to get you just as much flack from the people you're trying to appease as fracking for natural gas would.
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline Patchouli

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Re: Rocket propellant from seawater and sunlight
« Reply #16 on: 04/01/2013 12:52 AM »
the atmosphere/ocean.

I don't know where you're getting this idea that the atmosphere and the ocean are interchangeable, but they're not. Extracting carbon from the ocean to dump into the atmosphere is going to get you just as much flack from the people you're trying to appease as fracking for natural gas would.


The atmosphere and ocean constantly exchange gasses so taking CO2 out of the ocean would have zero net CO2 emissions.
In fact taking CO2 out of the ocean could offset ocean acidification which would be beneficial.
« Last Edit: 04/01/2013 12:52 AM by Patchouli »

Offline Ludus

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Re: Rocket propellant from seawater and sunlight
« Reply #17 on: 04/01/2013 01:21 AM »
the atmosphere/ocean.

I don't know where you're getting this idea that the atmosphere and the ocean are interchangeable, but they're not. Extracting carbon from the ocean to dump into the atmosphere is going to get you just as much flack from the people you're trying to appease as fracking for natural gas would.


Patchouli's right. The ocean/atmosphere are part of a single system as far as CO2 and extracting it from the ocean would be no different than extracting from the atmosphere...just easier cuz it's more concentrated.

Nobody concerned with CO2 and climate change would question that. Not saying they wouldn't wuestion other thngs about it, but not that.

Offline QuantumG

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Re: Rocket propellant from seawater and sunlight
« Reply #18 on: 04/01/2013 03:52 AM »
Nobody concerned with CO2 and climate change would question that.

Yes they would.

You're making a logical argument for something you already said was irrational.

Any human activity that increases CO2 levels in the atmosphere is suspect to some people. Messing with the oceans just gives them bonus points.
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline Ludus

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Re: Rocket propellant from seawater and sunlight
« Reply #19 on: 04/01/2013 04:20 AM »
Nobody concerned with CO2 and climate change would question that.

Yes they would.

You're making a logical argument for something you already said was irrational.

Any human activity that increases CO2 levels in the atmosphere is suspect to some people. Messing with the oceans just gives them bonus points.

Not quite sure what you mean. This does not increase CO2 levels in the atmosphere. I don't think it's irrational, just that the main reason it might be interesting is not it's direct impact (since space launches are a tiny fraction of fossil hydrocarbon use) but it's impact on public image and it's utility as a pilot project for broader uses of the same technology.

I think this approach in general has huge promise and it's use for rocket propellant might be an interesting choice for some of the same reasons that Tesla is better off competing with the BMW 7 series than making econoboxes. Rocket fuel is the upscale high image end of the fuel biz. To me people who criticize Tesla for not making cars for the masses don't get the point.

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