Carbon Capture Suggestion

[Ken Fabian]

21 hours ago, StringJunky said:

Even so, we are not suggesting it is the only solution. Even if it is the one under discussion, it is plainly obvious that a multi-pronged approach is required. You using numbers as if that is the only solution to be used.

No, I'm suggesting using the numbers to decide not to waste significant effort on something with so little potential and to move on to those other solutions.

I do think actual emissions reductions - changing to low emissions energy - is our most significant and effective action, deserving the most support and investment (which is the case), but I don't recall ever saying it should be our only action.

 

11 hours ago, mistermack said:

It would help if you posted a link to verify your claim, rather than a diagram.

But would it help? Do you have any reason to think that estimate used by the Global Carbon Project for carbon sedimentation rate is wrong?

2 hours ago, mistermack said:

4 hours ago, TheVat said:

So how did that work out for the planet's biosphere?

Ok so far.   🙂

A novel use of "Ok", usually reserved for sarcasm. Should I ask you to post a link to verify your claim or provide one myself, that appears to contradict it?

This is a link to the IPCC Impacts, Adaptation and Resilience report -

https://report.ipcc.ch/ar6/wg2/IPCC_AR6_WGII_FullReport.pdf

So far -

Quote

Human-induced climate change, including more frequent and intense extreme events, has caused widespread adverse impacts and related losses and damages to nature and people, beyond natural climate variability. Some development and adaptation efforts have reduced vulnerability. Across sectors and regions the most vulnerable people and systems are observed to be disproportionately affected. The rise in weather and climate extremes has led to some irreversible impacts as natural and human systems are pushed beyond their ability to adapt. (high confidence)

And in the future -

Quote

Approximately 3.3 to 3.6 billion people live in contexts that are highly vulnerable to climate change (high confidence). A high proportion of species is vulnerable to climate change (high confidence). Human and ecosystem vulnerability are interdependent (high confidence). Current unsustainable development patterns are increasing exposure of ecosystems and people to climate hazards (high confidence).

 

 

[mistermack]

3 hours ago, Ken Fabian said:

But would it help?

So that's a no then. 

[mistermack]

23 hours ago, Ken Fabian said:

But would it help? Do you have any reason to think that estimate used by the Global Carbon Project for carbon sedimentation rate is wrong?

No link then. I have no reason to trust that estimate, or your interpretation of it, as it happens. Without proper figures, and a clear description of exactly what they mean, the diagram you posted is meaningless. 

From what I remember, the word sedimentation is ambiguous. If they are talking about the permanent sedimentation, then I wouldn't be surprised by a low figure. But that's not the whole story. When the tiny shells fall as 'snow' to the bottom, most of them get re-dissolved over a few hundred years. They don't generally get included when they quote a sedimentation figure. But from the point of view of the current carbon problem, a few hundred years sequestration is a highly desireable outcome. 

So if you want to make a claim about sedimentation rates, you need to find a reliable clear source, with context. Your diagram tells us nothing. 

[Ken Fabian]

2 hours ago, mistermack said:

I have no reason to trust that estimate, or your interpretation of it, as it happens.

You put up the suggestion it would be a way to capture emissions - you need to show that it does. Throwing the burden of proof - that carbon sedimentation is too small, the amount it needs to expand too great and it won't work - onto me isn't helping your argument.

It is your claims about carbon sedimentation that are in question, not the validity of data from The Global Carbon Project in diagram form. It is clear to me what the numbers represent and the diagram provides it's own context - the Carbon Cycle and the values of sinks and fluxes.

If those numbers should not be trusted and are wrong, you are invited to show that.

[mistermack]

38 minutes ago, Ken Fabian said:

If those numbers should not be trusted and are wrong, you are invited to show that.

No, I made no claims about numbers. So I don't need to provide links about claims I didn't make. 

You posted that cartoon and constantly quoted it as evidence of a number. If you are pushing a number, you need to explain what it means, and how it was derived. Otherwise, it's baseless. 

[mistermack]

Just to put the energy demand of such a system into perspective, pumping water upwards in such a tube would require no more power than pumping horizontally up on the surface, because the weight of the water is in balance. So for a depth of 1,000 metres, it's the energy equivalent of pumping through a 1km pipeline on level ground. 

That's not the energy guzzler that people have been making out. In fact, in the ocean, it would be more economic than on the surface, because you could use a much wider pipe for far less money.

That's because the pipe could be made of thin flexible material, as it doesn't have to support it's own weight. 

Something akin to very heavy duty rubble sack material would probable do. So you could have a tube 10m in diameter for not much money. The wider the pipe, the less friction you would have to overcome per gallon pumped.  A flexible pipe of that sort would be kept inflated by the pumping action. 

So there's no reason to assume prohibitive energy costs. There might well be practical problems, as there is with everything.

[TheVat]

If one is pumping deep water up, why not use it for an OTEC system, producing reliable clean energy?  

Ocean thermal energy conversion (OTEC) is a process or technology for producing energy by harnessing the temperature differences (thermal gradients) between ocean surface waters and deep ocean waters.

Energy from the sun heats the surface water of the ocean. In tropical regions, surface water can be much warmer than deep water. This temperature difference can be used to produce electricity...

https://www.eia.gov/energyexplained/hydropower/ocean-thermal-energy-conversion.php

[mistermack]

7 hours ago, TheVat said:

If one is pumping deep water up, why not use it for an OTEC system, producing reliable clean energy?  

That's a good point. There's no reason why that couldn't be done. You might gain a bit of heat due to conduction through the walls of the tube as the water ascends, but you probably could calculate that pretty accurately from a simple lab experiment, and anyway, once you got the thing rolling, you could measure the temperature differences you were achieving. As with friction, the warming would be lower, in proportion to the diameter of the tube, so bigger would be better.

But in principle, if you were pumping large volumes of cold water, then that's an awful lot of energy potential on tap. Potentially enough to self-power the pumping, which would be a hell of a selling point.

The problems with this scheme that I can see would be firstly, legal and political ones. What sort of legal framework is there for exploiting oceans that don't belong to any one country? And how do you restrict the fishing rights so that you can put the profits back into running it?

Also practical problems, like underwater pumping and electrical insulation. Although that's already been done with tidal power turbines, so the technology is there for that sort of thing. 

Also, what sort of problems ocean currents might pose to a 1,000 metre tube suspended in the water. But it's the sort of thing that modern engineering can do, if there is a payoff at the end of it. 

[sethoflagos]

On 4/27/2023 at 12:03 PM, studiot said:

But the thrust of my comments relates to the sheer scale of the pumping required. I note Ken Fabian has also picked this point up.

I had hoped that some of our Chem Eng members might have useful information to add here ?

Just some back of envelope stuff.

Recast the objective as the transport of a nominal 100 tpd of deep ocean dissolved iron to the surface. 

Typical deep ocean iron concentration (from here) seems to be around 0.5 nM which sets the pumping volume to a little over 40,000,000 m³/s.

While it is correct that the external water column does largely support the pumping effort, deep ocean seawater density is generally taken to be around 1050 kg/m³ as ooposed to the 1024 kg/m³ of surface waters and that 26 kg/m³ difference does give a static pressure difference of around 250,000 N/m² per 1,000 m. If upward velocity were negligibly small (really huge diameter pipe) then a 100% efficient pump would consume a minumum VdP of 1TW / 1,000 m. 

As we're already exceeding the electrical power consumption of China and haven't yet touched on friction losses, I see little purpose in pursuing this further. Tankering in liquid fertiser is a far, far more cost effective method of meeting the initial objective. Whether or not the initial objective was a good idea, I'm with @Ken Fabian (as usual).

 

[studiot]

5 hours ago, sethoflagos said:

Just some back of envelope stuff.

Recast the objective as the transport of a nominal 100 tpd of deep ocean dissolved iron to the surface. 

Typical deep ocean iron concentration (from here) seems to be around 0.5 nM which sets the pumping volume to a little over 40,000,000 m³/s.

While it is correct that the external water column does largely support the pumping effort, deep ocean seawater density is generally taken to be around 1050 kg/m³ as ooposed to the 1024 kg/m³ of surface waters and that 26 kg/m³ difference does give a static pressure difference of around 250,000 N/m² per 1,000 m. If upward velocity were negligibly small (really huge diameter pipe) then a 100% efficient pump would consume a minumum VdP of 1TW / 1,000 m. 

As we're already exceeding the electrical power consumption of China and haven't yet touched on friction losses, I see little purpose in pursuing this further. Tankering in liquid fertiser is a far, far more cost effective method of meeting the initial objective. Whether or not the initial objective was a good idea, I'm with @Ken Fabian (as usual).

 

Thanks for looking into it and the knowledgeable answer. +1

[sethoflagos]

4 hours ago, studiot said:

Thanks for looking into it and the knowledgeable answer. +1

Before anyone looks too closely at it, I should point out that while 2.5 bar/km is a reasonable order of magnitude estimate for pipeline pressure losses, the rationale I gave for the figure is a bit of a nonsense. 

Oops your kind rep just disappeared, so I guess someone has just woken up. 

[mistermack]

12 hours ago, sethoflagos said:

deep ocean seawater density is generally taken to be around 1050 kg/m³ 

Link?

[sethoflagos]

39 minutes ago, mistermack said:

Link?

Here

[mistermack]

39 minutes ago, sethoflagos said:

Here

That's different to what you said. "can reach" is not "generally taken to be" .

The depths under discussion here don't have anything approaching that kind of density. And in any case, any part of the raised density due to high pressure would be lost as the water rises up the tube. You haven't thought it through. 

Yes, there will be a slight density difference in the top 1000m due to temperature difference but below that, it's insignificant.  https://www.windows2universe.org/earth/Water/density.html 

In any case, if you had followed the link given by TheVat, you would read about the OTEC experimental installation in Hawaii, there they ran a unit generating electricity by pumping up sea water from the deep, and the planned next phase here :  https://nelha.hawaii.gov/    No mention of gigantic pumping costs there.

Quote : " Three sets of pipelines deliver cold deep sea water from up to 3,000 ft. depth as well as warm pristine surface seawater. Current equipment and pipeline infrastructure is capable of pumping up to 100,000 gallons per minute of seawater throughout the 900-acre technology park. " 

[sethoflagos]

1 hour ago, mistermack said:

Yes, there will be a slight density difference in the top 1000m due to temperature difference but below that, it's insignificant.  https://www.windows2universe.org/earth/Water/density.html 

 

Whoever constructed this chart has assumed water to be incompressible. Many people do.

However, the bulk modulus of water is not infinite, it is 2.2 GPa. The over pressure due to 4,000 metres of seawater is around 2% of the bulk modulus so consequently the density at this depth is around 2% higher. So I guess that's the basis of the 1,050 kg/m³ figure and clearly the cartoon presented is significantly inaccurate.

But that's all by the by. 

Something has to persuade the flow to spread out horizontally at the top of the 7 km diameter pipe, and that's a flat topped mound of water oto 25 metres high. This provides the potential energy necessary to source a 10 metre deep, 20 m/s horizontal outflow at the pipe circumference.

Hence the 2.5 bar/1000m and 1TW estimates still stand.   

 

 

 

.

2 hours ago, mistermack said:

Quote : " Three sets of pipelines deliver cold deep sea water from up to 3,000 ft. depth as well as warm pristine surface seawater. Current equipment and pipeline infrastructure is capable of pumping up to 100,000 gallons per minute of seawater throughout the 900-acre technology park. " 

6.3 m³/s vs 40,000,000 m³/s

Didn't someone mention a bit of a scale disconnect earlier in the thread?

[mistermack]

1 hour ago, sethoflagos said:

Didn't someone mention a bit of a scale disconnect earlier in the thread?

Yes. Wan't it the same person who has described part of their own post as " a bit of a nonsense. "

It doesn't fill me with confidence. And that was the same person who has failed to substantiate their claim that "deep ocean seawater density is generally taken to be around 1050 kg/m³ as ooposed to the 1024 kg/m³ of surface waters ". 

I can tell you that what I linked wasn't the only refutation of that claim, it was typical of several. And in any case, the phrase "deep ocean seawater" has a very wide spread of meanings, so it was a meaningless claim in the first place. 

Here's another page on density, since you think you know better than the first one : Roger Williams UNI   

and from that site : 

 

In any case, you don't appear to have understood my point about the density of compressed water falling, as it rises in the tube, judging by the way you continue to bang on about compression raising the density.

All in all, I have more faith in what Universities choose to display on the subject, than someone who describes some of his own "envelope" posting as nonsense, minutes after writing it.

And the Hawaiian project is an experiment, you appear to have missed that as well. 

[Ken Fabian]

The deep water nutrients this is intended to bring back to the surface are the ones that are potentially headed for sedimentation, if not the sediments themselves, something I missed before; ironic that doing it would reduce ocean carbon sedimentation.

As for pumping (and using that last graph of Mistemack's) - I make a rough estimate of 5 kg per cubic metre averaged over a 1,000m lift. A 10ft/3m diameter pipe, 7 cubic metres and 0.035 metric tons per metre, so 35 tons lifted 1,000m for 7,000 cubic metres delivered to the surface. That sounds like a lot of water but for this purpose, maybe not that much.

There will be pressure on the pipe walls, progressively more the deeper it goes - weight of water column plus additional pressure for making the flow. Can't use suction pumps without thicker walled pipes, it needs positive pressure (mentioned earlier in thread), either pump at base or possibly pumping water down a second pipe to provide positive pressure and flow - like some deep borehole pumps do?

As a thought experiment it was good of @mistermack to post the thread, but I think we can dismiss the potential for carbon capture adn there is a lot of preliminary research needed to establish benefits to fishery productivity - and what wider ecosystem impacts it may have.

I suspect it will need extremely large flow to be significant for fisheries but I don't know.

[sethoflagos]

2 hours ago, mistermack said:

Yes. Wan't it the same person who has described part of their own post as " a bit of a nonsense. "

No, it was made before I posted to this thread.

I'm a little curious.

Why are you spending so much time and effort trying to establish that something that I'd previously and voluntarily described as 'a bit of nonsense' was actually a bit of nonsense?  

 

[mistermack]

10 hours ago, Ken Fabian said:

I make a rough estimate

If you don't show your working in detail, then you're just asking to accept your guesswork. It's a pointless exercise. On the other hand, I've pointed to the real-life experimental unit in Hawaii that pumped cold deep ocean water continuously for six years, generating electricity from it, as linked by TheVat. And the new project, for a unit massively increased in size and capacity. If the economics of pumping for that project are not prohibitive, then I'm saying it's safe to assume that what I'm suggesting isn't out of the question either. 

In Hawaii, the only benefit they derive is electrical power and possibly some fresh water. I'm saying you can perform exactly the same process, and create a brand new fishery, and take carbon out of the system for hundreds of years. As well as creating electricity. And you can also make fresh water as a bi-product of that, using one of the methods. See the links.

The big question is how long does the fertilisation of the surface water persist? If it's decades, then it's a no brainer. If it's several years, then probably its well worth it. If it's months, then maybe not. You would have to perform a trial, to get some real idea. Or maybe you could track the effect of natural upwellings by satellite etc. and model it.

10 hours ago, sethoflagos said:

I'm a little curious.

Not curious enough to try to defend your hand-waved claims with links and numbers. 

[sethoflagos]

3 hours ago, mistermack said:

Not curious enough to try to defend your hand-waved claims with links and numbers. 

I gave the links. You're just pretending I didn't. 

However, there seems little point in insisting on 3-digit accuracy when your OP proposal fails to meet its objective by such a phenomenal number of orders of magnitude. Orders of magnitude estimates are all that is necessary here.

I remind you of those objectives: 

On 4/26/2023 at 11:47 PM, mistermack said:

Thanks. Actually, the effect of upwelling is pretty much accepted as fact. Pretty much all of the fisheries around the world are fed by natural upwelling, usually where the ocean current meets an obstruction like a land-mass, forcing colder nutrient-rich deep water upwards. Island areas like Hawaii stand out, they support a fishery in a vast empty ocean, so the principle can be studied. I remember seeing a chart of the world's productive fisheries, and it was all centered around land-masses, where upwellings occur naturally. Something like this : 

It's quite obvious even from this that there are vast areas of ocean that are desert. It's only lack of nutrient that keeps it that way....

In other words, you are seeking to duplicate the natural oceanic upwellings in the ocean 'deserts'' (which are btw underlain predominantly by abyssal plains at depths of 3,000 to 6,000 m).

As @Ken Fabian and others have informed you, the natural upwellings typically involve flows of tens of millions of cubic metres per second span tens of kilometres, and are powered by TeraWatts of solar energy.. Any proposal to duplicate them in areas where they don't occur naturally MUST have at least the same number of digits.

Your practical proposal? 

On 4/26/2023 at 1:28 PM, mistermack said:

You have a specially designed ship stationed at a very non-productive part of the ocean. ( most of the world oceans are ocean desert )

The ship controls a robotic electrical pump, on the ocean floor. The pump stirrs up sediment, and pumps it to the surface through a thin (but large diameter) polythene tube. 

When I read this, my initial impulse was to check the OP wasn't dated April 1st.

But apparently you were being serious. Do you still stand by your original proposal or not?

[mistermack]

7 hours ago, sethoflagos said:

Do you still stand by your original proposal or not?

I've stopped taking your posting seriously. You post false facts, make up stuff at will and never show where it comes from. And as you just ignore it, when errors are pointed out, I'm not wasting any more time on your posts. I don't mind disagreement, but just throwing out junk and not responding to specific points makes it not worthwhile engaging.

[sethoflagos]

I'lll take that as a 'No'

On 5/3/2023 at 1:44 AM, Ken Fabian said:

There will be pressure on the pipe walls, progressively more the deeper it goes - weight of water column plus additional pressure for making the flow. Can't use suction pumps without thicker walled pipes, it needs positive pressure (mentioned earlier in thread), either pump at base or possibly pumping water down a second pipe to provide positive pressure and flow - like some deep borehole pumps do?

One pumping method that may be worth considering is Gas Lift. By sparging compressed air perhaps 200 - 300 m below the top of the pipe via an array of nozzles, the density of the mixed fluid above is substantially reduced generating the pressure difference necessary for the desired flowrate. 

Not cheap, but it's a practical proposition. And it would help with oxygenation too. 

[exchemist]

10 hours ago, mistermack said:

I've stopped taking your posting seriously. You post false facts, make up stuff at will and never show where it comes from. And as you just ignore it, when errors are pointed out, I'm not wasting any more time on your posts. I don't mind disagreement, but just throwing out junk and not responding to specific points makes it not worthwhile engaging.

Really? My experience is that @sethoflagos is one of the more rigorous posters on this forum. While you can have legitimate disagreement on the science, It seems to me that accusing him or her of bad faith, as you are doing here, is quite a stretch, to put it politely.   

Edited May 4, 2023 by exchemist

[mistermack]

27 minutes ago, exchemist said:

Really? My experience is that @sethoflagos is one of the more rigorous posters on this forum.

I'm not interested in the person, I just don't find it productive to engage, when he starts with sweeping unsupported statements and figures, and ignores you if you get specific, when you check and find out they are wildly wrong. That's not debating. I answered his specific points, he's ignored mine. 

[exchemist]

32 minutes ago, mistermack said:

I'm not interested in the person, I just don't find it productive to engage, when he starts with sweeping unsupported statements and figures, and ignores you if you get specific, when you check and find out they are wildly wrong. That's not debating. I answered his specific points, he's ignored mine. 

On the density of seawater he seem to me to be substantially right. At 4000m depth it is typically 1.046: https://www.britannica.com/science/seawater/Density-of-seawater-and-pressure , due to the compression effect he referred to.