The Idea

This is a brief description of the idea. If you prefer we also have a detailed description and a slideshow presentation on the process for you to see.

The idea works like this:

  • First, you heat limestone to a very high temperature, until it breaks down into lime and carbon dioxide.
  • Then you put the lime into the sea, where it reacts with carbon dioxide dissolved in the seawater.

The important point is that when you put lime into seawater it absorbs almost twice as much carbon dioxide as is produced by the breaking down of the limestone in the first place.

This has the effect of reducing the amount of carbon dioxide in the atmosphere. It also helps to prevent ocean acidification, another problem caused by the increase in the amount of carbon dioxide in the atmosphere.

If done on a large enough scale it would be possible to reduce carbon dioxide levels back to what they were before the Industrial Revolution.

The first step of the process – breaking down limestone into lime and carbon dioxide – seems counterintuitive as it uses a lot of energy and actually produces carbon dioxide. But this carbon dioxide can either be safely stored away or used to help grow crops in very dry areas. You can find out more about this here.

One of the questions I often get asked is: if this is so simple why hasn’t it been done before? The idea has been around for a number of years. It was first suggested by Haroon Kheshgi in 1995, but it was considered uneconomic as the process uses a large amount of energy. What we are interested in doing is using stranded energy to drive the process.

Stranded energy is energy that is remotely located, so it is not economically viable to exploit. For example, in a desert there is plenty of energy available, but it would cost too much to transfer the energy to where anyone wants it, so it never gets used. So, paradoxically, in a desert energy is abundant and cheap, but worthless. This process can use that stranded energy.

We couldn’t have got this far without the help of a large number of people who have been extremely generous with their time and expertise. We are developing this project in an open source way, so, if you are interested to help, please get involved.


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76 people have left a comment

Xeno says: July 21st, 2008

My worry is would too much lime concentration in one spot create an environmental issue for aquatic life or potentially for weather patterns; as air currents are affected by ocean currents, what affect will this have on ocean currents, temperatures, etc?

Tim Kruger says: July 21st, 2008


You are right to point out that adding too much lime in one place would be harmful. One of the things we will be researching is how widely we would have to distribute the lime in order for it to have a beneficial effect (by restoring ocean pH back to what it was before ocean acidification) rather than having a detrimental effect (which is what would happen if there was too marked an increase in pH in any one location).

Only once we are fully convinced that this process would have a beneficial effect would we proceed

Naren says: July 21st, 2008

Have any calculations been done to estimate how much lime would need to be produced and added to seawater to neutralize our current CO2 production?

Tom says: July 21st, 2008

You idiots. Unless you have a block of lime the size of a small moon up the same ass you pulled this idea from I don’t see how you expect to change ocean chemistry, not to mention deal with the unintended consequences of doing so.

Here’s a novel idea. Instead of wasting time on an idea that falls just short of satire, how about we develop tech that negates the need for putting CO2 into the atmosphere in the first place, instead of jacking up the environment even more with poorly thought out global experiments.

How about an open source fuel cell with integrated solar hydrogen generator? Ready, set…GO!

Sebeticus says: July 21st, 2008

“First, you heat limestone to a very high temperature, until it breaks down into lime and carbon dioxide.”

What do you do with the C02 created when you produce the lime? What’s the net difference of the amount of C02 you produce and the amount absorbed by the lime when you dump it in the ocean?

Jorge Gonzalez says: July 21st, 2008

I thought that the oceans are already taking up to much CO2, which is killing the corals which feed the ocean. Adding more CO2 to the oceans would definitely finish killing the coral. Remember fish get their oxygen from the water and adding more CO2 would probably kill them as well. This should be tested in small scale but I believe our oceans can bearely handle the CO2 that is currently being absorbed. I really think this is a bad idea, and oviously you can make a profit by selling the carbon credits to huge polluters. I would say only way to get the CO2 out of the air is either using the Japanese patented reaction that uses CO2 and releases O2 similar to photosynthesis, factories can act as forests and remove the carbon from our atmosphere which has taken the planet millions of years to absorb yet we have managed to reverse this work in a few hundred years.

Ken says: July 21st, 2008

Naren, here are some back of the envelope calculations:

From CaCO3 we get CaO and CO2. CaO is a slightly heavier molecule than CO2, such that for every 100 grams of limestone, you’ll get roughly 54 grams of quicklime.

If they’re saying that CaO absorbs twice as much CO2 in the seawater than is used to produce it, then 100 grams of quicklime will absorb roughly 92 grams of CO2 from the seawater, causing a net change of 46 grams (since 46 grams of CO2 were produced during calcination). Note that this is a minimum, since they can sequester some of the CO2 released during calcination as they mention.

A quick google search yields an estimate of 290 ppmv for pre-industrial carbon dioxide levels. Wikipedia states that the dry air mass of the atmosphere is roughly 5.1352 ±0.0003×10^18 kg. Of this, about 3*10^15kg is CO2 (based on Wikipedia’s listing of .0384% CO2 in the atmosphere). So there is about 3000 trillion kg of CO2 in the atmosphere. If we want to get that to 290ppmv instead of 384ppmv, we’ll need to sequester about a quarter of the CO2 in the atmosphere, or about 750 trillion kg.

This would require about 1627 trillion kg of quicklime to accomplish. You’d need about 3000 trillion kg of limestone to accomplish this. The density of limestone is about 2000kg/m^3, so you’d need about 1500 cubic kilometers (a LOT) of limestone. Australia’s Nullarbor Plain is estimated to have 10000 cubic kilometers of limestone, so this has about 9 times more than we’d actually need.

Economy of scale would reduce costs for extraction and processing of that much lime. I don’t think it is a question of can we do it, but rather how much it will cost, whether we’re sure that it will work, and how long it will take to accomplish.

Steve says: July 21st, 2008

In general, it seems like you should test the effects of CaO distribution carefully and thoroughly, in a series of controlled settings (i.e. tanks, artificial ponds, isolated lakes, land-locked barren sea) before experimenting with the only Earth we’ve got.

One specific hurdle that comes to mind is distributing the CaO in an energy-efficient manner in both time and space, so that local, unacceptable environmental harm is not caused by the severity of the pH shift. A simple, cheap, & passive time-release mechanism for CaO (like a long-duration medicine) would be a good first step, but may not entirely solve the problem of adequate mixing to avoid local pH spikes.

You could try to take advantage of processes that already interact with large, distributed areas of water, that may be presently driving away or killing sea-life. The addition of small, controlled amounts of CaO may not make them much worse than they presently are (like an inveterate, heavy smoker eschewing sunscreen, not that much more dangerous):

-International shipping lanes – commercial ships could get tax breaks to slowly, passively release CaO in a controlled manner over their voyage, in international waters; military ships could participate in passive testing and monitoring of ocean data during peacetime operations.

-Rain water on coastal metropolitan areas causing massive run-off – it would permit the dilute addition of CaO at the desired concentration with repeatable mixing.

-Much garbage is dumped directly into the ocean – perhaps some time-release CaO could be added as well, without significantly worse effects?

Ken says: July 21st, 2008

And to Tom above, you’d need about 1500 cubic kilometers of limestone, which is nearly as large as Mars’ tiny moon Deimos, so you are correct.

Trying to figure out if it is feasible to extract this much..

That link states that a modern quarry employing 140 people extracted 10 million tons (9 billion kilograms) in one year. If that is an average quarry, we’d need 333,000 of those quarries to accomplish the task in one year. If we give ourselves 50 years to do this, it would only require about 6700 such quarries. That would require close to a million workers for 50 years at a mindblowing cost.

I am thinking this is not even remotely feasible if my above calculations are correct.

Luke says: July 21st, 2008

I don’t think that what Tom says above is an entirely fair assessment, we’re not talking about turning an ocean into a public pool. The ocean already absorbs carbon from the atmosphere, just at a slower rate than we’re adding it, altering the rate of absorbing by even a very small percent would be significant, especially if also the rate that we’re adding carbon to the atmosphere is decreasing with the current advent of alternative fuel vehicles.

ron says: July 21st, 2008

My first thought was what this would do to the cost of limes and how it would affect my ability to enjoy ceviche. But I guess you’re merely proposing to tow a chunk of Australia out into the middle of the Pacific Ocean and drop it. ok….

Duke says: July 21st, 2008

Remember the neutron bomb – the Reagan-era nuke design which produces little or no long-lived radioactive fallout. Set off a number of them in the Australian limestone. The limestone would be converted to lime dust and dispersed high in the atmosphere, then fall into the world’s oceans as “alkaline rain”.

Michael says: July 21st, 2008

I hate to say it, but I’m totally with Tom above. This projects sounds suspiciously like trying to bring cane toads into Australia to fix one problem, only creating dozens more.

Sure, you can create lime at point sources of stranded energy, but you can’t just willy-nilly point-source dump a metric butt-load of lime in the oceans… And how much more CO2 would be generated just trying to transport and evenly distribute that lime in the oceans? Sounds like a logistical nightmare!

Rather than trying to deal with the symptoms of climate change, why not deal with the causes directly?

Prevention is the way to go.

Just imagine if we were to spend a trillion dollars on a clean-energy “Manhattan project”, instead of on a dirty war to secure limited Middle Eastern resources that are just going to run out one day anyway… the energy problem might already have been solved. We might already be on our way towards operating on hydrogen or some other abundant renewable.

Whatever path we choose, I do think a truly global OpenSource forum is the way to go… with a system of government, industry, or investment rewards to encourage open collaboration rather than secretive counter-productive competition…

Just my 2c.

Thumper says: July 21st, 2008

I agree with Michael, Prevention is the way to go.

So what happens after all the lime is dumped? We’ll keep pumping the same amount of crap into the atmosphere and in a few years the problem will just come back.

Jayme says: July 21st, 2008

requizitar voluntarios civil e cada um se comprometeria em comprar um saco no comercio local dispensar no mar

Ariel says: July 21st, 2008

Re Ken’s quarry calculations… the phosphate mine of Khouribga (Morocco) has some of the world’s largest excavators and, according to their website (, has a production capacity of 19 million tonnes per year.

Ray says: July 21st, 2008

This idea seems a little of center. I think a plan like this to correct the CO2 issue will cause more and possibly worse problems. In the US we have allowed the few to speak for the many for too long. We continue to burn coal because the few have managed to stop the building of nuclear power plants. Now they have us burning corn for fuel that creates more CO2 in the long run then gas. Everyone wants an electric car they can plug in at night and drive all day. Where is the power for that going to come from? The answer right now is coal. The fact is the plant is in a constant state of change. Have we caused the current warming trend maybe. For every scientist that say’s yes there is one that say’s no. Our current world structure is built on cheap powerfull energy. Until there is a solid replacement we are stuck. We are not any where near out of coal or oil. So I agree this is a good time to start changing our ways but we all need to pull together. This open source idea seem like the right track. The key is getting the word out.

Ian S says: July 22nd, 2008

There are some interesting comments on here. For example, several people have estimated that the project is not feasible. I would point out that you do not have to reduce the level of CO2 to pre-industrial levels. Reducing it to 350ppm would be adequate. If we could reduce to that level and stabilise it at that level then we would avoid the worst effects of global warming.

I think this project is worth a go, especially with a less ambitious target such as I suggest above. I think, however, that we should ALSO be doing very ambitious things to reduce our output of carbon. A Manhattan project of both reduction of carbon emissions AND reduction of carbon levels is the way to go.

How to cut CO2 levels? Put the lime in the ocean, you nut « Foster Grant’s babbling again … says: July 22nd, 2008

[…] Apparently adding lime to seawater increases its alkalinity, which increases seawater’s ability to absorb CO2 from the air and reducing its tendency to release CO2 back into the air. The process is supposedly “carbon negative” — processing the lime generates CO2 but adding the lime to seawater is supposed to absorb almost twice as much CO2. The people behind the project have a page where they explain their idea. […]

bruced says: July 22nd, 2008

Hey you lot The Nullarbor Plain is an Australian icon and if you want to blow up an area of limestone with or without nukes, look for one in your own backyard, wherever you are. But seriously, note that the ocean is not a well-stirred laboratory beaker. Go study some marine chemistry and try to understand what kinetics is all about.
In the end the only answer to CO2 pollution will be to stop polluting. We must reduce our burning of fossil fuels and replace by renewables and stop these idiotic schemes to solve one type of pollution by another. Schemes such as the one proposed here, sulfate aerosols in the upper atmosphere and even CO2 geosequestration (sub-surface pollution) are all just another type of pollution.

Richard says: July 22nd, 2008

No comment on the overall strategic emphasis on “fixing” the problem of burning fossil fuels by removing CO2 versus lowering emissions in the first place, but I would say that if 1 million employees working for the next 50 years could fix the problem for 6 billion (or whatever the population is) people and save the earth it’s a no brainer. Comment above indicates that this would be excessive. That is less than 2 tenths of a percent of the population of the earth and less than the unemployment on the books in the US at any given time. You have to keep the scale in mind when thinking about earth size problems. This would amount to an immaterial tax on fossil fuels. No doubt the distribution cost is underestimated here – it ain’t going to be that easy, but if it were then that cost is a rounding error in global GDP and I’d go for it.

R. A. Wilson says: July 22nd, 2008

Sounds like distributing the calcium hydroxide would difficult to do safely.

According to Wikipedia, an overexposure to calcium hydroxide can have life threatening effects:

* Difficulty in breathing
* Internal bleeding
* Hypotension
* Skeletal muscle paralysis, interference with actin-myosin system.
* An increase in blood pH, which is damaging to the internal organs.
* Calcium Hydroxide is also a cancer suspect agent.

Dumping carcinogens into the Ocean to solve global warming might be a tough sell.

max says: July 22nd, 2008

Chemically the proposed scheme works IF the added lime does not precipiate as calciumcarbonate. If this happen, then limestone is produced, sinks to the bottom of the sea and the effect is zero (guess where all the limestone is comming from?).
So added lime binds CO2:
Ca0 + 2 CO2 + 2 H20 = Ca2+ + 2 HCO3- + H20
But if the solubilty product of calciumcarbonate is exceeded then limestone precipitates and the effect is nill:
Ca2+ + 2 HCO3- = CaCO3(s) + CO2 + H20

So, IF this condition is fullfilled (can be calculated easily by any student with aquatic chemistry) and the solubility product will not be exceeded then WHY PRODUCE LIME (CaO) in the first place. Just add powerdered limestone (CaCO3) directly into the sea. It will dissolve and have the same effect, except you do not need to pump all the energy in to produce lime.

Then two of the carbondioxid treatments are so stupid it is simply not worth dealing with (hint its not option 1 or 2). Hint option 3: If you not suggesting a perpetuum mobile, then where’s the energy coming from for the process. Hint option 4: Biomass is never a sink for CO2, it’s just a very short term storage – especially if you talk algea. So focus on option 2: there’s lots of money to make if you succeed!!!

Ken says: July 22nd, 2008

Lots of comments since my calculations post. To address some:

Duke: Neutron bombs have a rather undesirable effect called an EMP. Additionally, neutron bombs are primarily designed to kill using high energy bursts, not to create massive physical destruction. A neutron bomb would be a horrible choice for disbursing limestone into the oceans.

Ian S is on the right track: Combining a far more conservative lime approach with reduced CO2 output would be a good strategy.

Bruced: People need to quit thinking in terms of NIMBY (Not in my back yard). IF this project were economically feasible and IF it were the best solution for carbon sequestering, then frankly Australia should bite the bullet. A national icon means nothing in the face of global catastrophe.

Richard: That is 1 million workers for 50 years JUST to excavate the limestone. This doesn’t take into account processing, distribution, and a large number of other factors. It would be many, many people and countless trillions of dollars to accomplish. Regardless of whether it would have the desired effect, if it is so economically unfeasible you will never get multi-national support and funding for such a project.

Max: While you’re right that dumping too much CaO in one place would result in undissolved lime, you are very wrong about biomass never being a sink for CO2!! Think about it – the problem we’re facing results from CO2 released into the atmosphere by burning fossil fuels, which are a product mainly derived from biomass. I do agree that in many cases biomass isn’t a carbon sink, but in many cases it is.

Viktor Borashnovich says: July 22nd, 2008

I don’t know about anyone else here but I’m looking forward to the planet warming up; I live in Ulaanbaatar (inner Mongolia) and it gets a bit chilly in the winter months. Everyone breathe out and create more CO2. Danke.

A.Lizard says: July 22nd, 2008

Assuming that there’s enough sun, which seems like a reasonable assumption for AU, large scale solar furnaces can be used to reduce the limestone to lime, and the CO2 can be sequestered or chemically combined into something that will render it harmless.

The lime itself can be pelletized, the reduced surface area compared to dust should handle the time-release problem.

This needs to be tested EXTENSIVELY before dumping 1.6T kg of ANYTHING into the oceans. It would be moderately unfunny if some unknown side effect of the process turned the oceans into a worldwide dead zone. Particularly since we’d follow marine life into extinction.

Robert Merkel says: July 22nd, 2008

Ken: you don’t have to do one mega-project. Nor does this approach have to be the *only* one used to reduce greenhouse gas levels.

Furthermore, even if it takes ten million people, when you compare it to the total workforce of the developed and middle-income world, it’s small beer. There are 752 million workers in China alone.

Philip Witham says: July 22nd, 2008

Interesting, and please, folks, read and understand all the information on this website before posting ignorant criticism using points that are already answered in detail.

One comment, firstly, reversing ocean acidification is a critical goal that needs to be accomplished in less time than it will take to turn around the world carbon balance. It’s also probably a more feasable shorter-term goal for this project. We need to save coral reefs and the rest of the marine ecosystem soon, not in 50 years.

A question I have is, what is the sensitivity of the ocean uptake of CO2 to the change in ocean pH? To put that another way, were the ocean pH restored to pre-industrial levels, what would be the change in the rate of CO2 absorption from the atmosphere? How many more GigiTons carbon would be absorbed by the ocean? If this number is low, the project cannot achieve the goal of lowering the atmospheric CO2. (The oceans currently absorb about 3Gt C/Yr from the atmosphere).

How to distribute lime evenly, and where it is needed, is a big research question for the project, it looks like. Major river mouths come to mind. The Misissippi discharges 16,200 m³/s of water. That’s 510 Gigatons of water per year. Half a dozen others around the world larger than that. The Amazon discharges ten times that.

Some comments were to the effect of “It’s too big, we can’t quarry that much!”, well, the US mines1.5 Gigatons of limestone per year. Some limestone goes to concrete production, which is why concrete production produces 7-10% of CO2 emissions worldwide. Most of that is outside the US, so there must be much more than 1.5Gt already miined per year. Limestone mining is apparently moving under ground (room-and-pillar mines), and so you can have your nullabor plane and mine it at the same time. Sounds like a good place for sequestered liquid CO2, also. :-)

Philip Witham says: July 22nd, 2008

Another, similar concept:

Ranjan says: July 22nd, 2008

It may be a good idea to try this out in a small sea water body and see the results, before spending more time and money on this. The testing ought to be done first in an artificial environment and if successful, only then perhaps in a small natural lagoon, because this would allow in-situ test of effect on marine life.

Grasyop says: July 22nd, 2008

Max is right: what you’re doing is roughly that:
CaCO3 + H20 + energy -> Ca(OH)2 + C02 -> CaCO3 + H20 + (lost) energy

You won’t absorb twice as much carbon as is produced.

Matthew Gress says: July 22nd, 2008

I think that prevention is going to do a lot, but I agree with David Deutch (wait for it – in that if someone has been punched in the nose, the science of medicine does not consist of teaching someone to avoid punches.

This particular remediation process may not be a good way to fix the problem along with the other 2 legs of the stool (prevention and learning to live at the higher temps), but the problem of climate change was, as Deutch points out, probably already a disaster in the 1970s when the best environmental scientists were going on about the impending ice age.

Do the studies and have the world scientific community take their best shot at the results (if positive, obivously).

We have to fix what we messed up, and learning to fix it in the atmosphere of cooperation and optimistic skepticism seems most conducive to solutions.

Stone Tablet:
Problems are solvable.
Problems are inevitable.

Dave says: July 22nd, 2008

I for one applaud anyone willing to suggest these kinds of ideas, and risk themselves to open criticism – all for the good of humanity.
The more people who share such ideas, only increases our choices, and hopefully chances of making the correct descisions.

Jose Gutiérrez says: July 22nd, 2008

Me parece interesante esta propuesta, pero sin ser cientifico me surge la duda ¿de qué si hay mayor acumulación de CO2 en los oceános, esto no afectaría lavida marítima?, espero que quienes hayan estoesta propuesta tengan una respuesta a tal inquietud.

Steve C. says: July 22nd, 2008

How about this for an unintended consequence? What happens to the phytoplankton in the water that has it’s CO2 scavenged? It is marine plant life that inhales CO2 and exhales O2. So if you put all that lime in the water it will eliminate most of the CO2 the phytoplankton require to live. I suspect there is a significant likely hood that it will destroy the foundation of the ocean food chain. And for what? To fix a nonexistent problem? Remember, CO2 is a naturally occurring atmospheric gas. And by the way, CO2 has never before driven climate, it has always been the other way around. Just ask any geologist.

James Clements says: July 22nd, 2008

This may have already occurred naturally several times over geologic times. As mountains are uplifted minerals are exposed that combine with carbon dioxide (in rain water). This forms carbonate compounds and reduces the amount of atmospheric carbon dioxide.
Since increased water acidity is a byproduct of air pollution adding lime would act to return things to “normal”, unless we over do it.
If this works it can only be considered an emergency stop-gap measure; there will be a limit on how much lime can be added to the oceans before damage starts to occur.
You can Google “Appalachians ice age” and “Himalayas ice age” or go to

Dirac says: July 22nd, 2008

Distribution and Dispersal:

Here is a suggestion which is only a drop in the bucket, but could help solve another issue. Marine biology is being cross contaminated by the ballast requirements of large ships. Taking on water in one region and releasing it in another. If you treated the ballast with a high concentration of lime it would kill the organisms that threaten contamination. Then when you release the ballast slowly the lime has already been disolved into a high concentration liguid. Of course existing tanks may not be able to survive long with lime, but its just an idea that would help solve yet another problem.

Hugh says: July 23rd, 2008


Nice to know that everyone thinks our iconic land can be ripped to pieces so the US and other large polluters can continue in their ways of wrecking the climate for everyone else. Sounds like a repeat of the Bush approach of “lets dump all our nuclear waste in Australia, they won’t mind taking our poison after all it will only last for half a million years.

I could take this more seriously if the US offered to provide 50% of the Limestone from some iconic park ( eg Yellowstone or the grand Canyon – not that I know the mineral composition of these iconic parks). This would be a reasonable implementation of the polluter pays principle.

How about this dumb suggestion – lets spend the money on creating less carbon dioxide in the first palce. The McKinsey Country cost curves would suggest that we can get to the first 30-40% with a positive wealth creation outcome.

Phil. says: July 23rd, 2008

The chemistry of this system is seriously flawed and will not work. The only way that CO2 can be sequestrated by this method is if Calcium Carbonate is precipitated, at most then an equal amount of CO2 can be sequestrated as is created in the calcining process. Calcium bicarbonate will not precipitate out so the idea that more than one mole of CO2 being sequestrated is false. This is elementary HS solution chemistry. The ocean is already supersaturated with respect to Calcium but precipitation is inhibited by Magnesium, in the appropriate conditions additional Ca will lead to CaCO3 precipitation but that won’t do any good as shown above.

bruced says: July 23rd, 2008

Yeh, Hugh, I pointed this out yesterday. Australia, despite obviously what is believed in other places, is a sophisticated country with LAWS to protect the environment, indigenous lands and also the soon to be introduced carbon tax. But lets also consider what the Nullarbor (Eucla Basin) tells us about the ocean and high levels of atmospheric CO2. The response I got was that Aust must be sacrificed for the greater good. Seems some people think the only answer to a problem is to invade and bomb the sh*t out of another country! Seems they learn nothing from history. To solve a problem you must look at the cause.
But enough ranting, think science. The main bodies of the Eucla Basin are marine carbonate units laid down in the Late Eocene and Miocene. That is when CO2 concentrations in the atmosphere went to >1500 ppm. I believe the carbonates of the Murray Basin (eg Mt Gambier) are of similar age, indicating the marine life reacts to higher temps and pCO2 to produce greater deposits of CaCO3. So if you artificially increase the oceanic HCO3 concentration, probably all that will happen is that there will be increased CaCO3 production and you are right back where you started. Sorry but I consider this a pretty wacky idea.

links for 2008-07-23 says: July 23rd, 2008

[…] Cquestrate : The Idea (tags: climate water co2 carbon warming lime) […]

David Bradley says: July 23rd, 2008

Seeing as you mention Australia, perhaps it’s pertinent to remind readers of one particular case of humanity’s attempts to control the environment that went badly wrong – the cane toad.

I suspect that the tonnages involved are going to be so huge that this project really will never work, especially as shipping all that lime from the desert to the sea will release its own CO2, but even if we could try, there are bound to be enormous unforeseen environmental effects of dumping this material into the oceans on a significant scale.

The idea of using even “stranded” energy to release CO2 from limestone, ship the limestone to the oceans, where it will apparently absorb dissolved CO2, has to be fundamentally flawed. It would be simpler and more efficient to develop energy pipelines that could tap into those stranded energy sources directly.

There are lots of these kinds of macroscale engineering ideas being bandied about, but historically (iron seeding, nitrogen control) none has proved viable.

I’ll be covering this topic in the August issue of Intute Spotlight, if readers are interested in following up –


Not Savvy says: July 23rd, 2008

This idea sounds interesting and may very well work. We Homo sapiens are generally a dirty critter and any strategy that will mitigate our leavings is welcome. Does having this option permit us to use fossil fuels without concern for the leavings? Would it not be more appropriate to spend the time, money and energy developing sustainable infrastructure as opposed to attacking the fire by throwing chemical retardants on it? Historically, Homo sapiens’ efforts to impose solutions on nature have been less than effective and have had unanticipated consequences.

Pierre Jones-Savard says: July 23rd, 2008

Good en of day , i have the following équation for you :

CO2 +4(H2) give CH4 + 2(H2O) (équatio 1)

with mixture of zinc oxyde,cupper and chrome as catalist.
with the méthane we can get H2 and CO, this can led to the Fischer-Tropsch proceeding :

CH4 +(1/2)O2 give 2(H2) + CO (équation 2)

(2n+1)H2 + nCO give CnH2n+2 +nH2O (équation 3)

with iron and cobalt as catalist.

jkdoherty says: July 24th, 2008

United States annual coal production has run well above 1000 million tons per year, with some mines in the State of Wyoming producing better than 90 million tons. I think they could produce more if the market demand were there. No doubt the limestone does not mine like coal, but one might suspect that if the rewards were right the good lads from the Black Thunder mine could do make a good start at it. jkd

Paul H says: July 24th, 2008

I read as far as Tom’s comments on 21 July. Agree with Tom. This would have to rate as the stupidest wastes of time I’ve seen recently.

Paul H says: July 24th, 2008

Please excuse this silly explanatory note. My post just now should have read: “The idea that we can economically adjust the pH of the world’s oceans would have to rate as among the stupidest wastes of time I have seen recently.”

Lidia LoPinto says: July 24th, 2008

To Ken:

I like the back of the envelop calculations. Did you check all your decimal points. I think we will need to grind up all of Australia really.

The question is where is the energy going to come short term for such a process. Rather, we are not dealing with a static situation, this is a non steady state process. Carbon dioxide is being replenished as soon as we used it up. We can’t even fuel the world now. Where is the coal or oil going to come from to heat up this much lime, and Solar panels are not the ticket.

I have an idea, why don’t we dentotate a nice Nuke in the area, create a lot of radiactive lime and then with another explosion simply have it fall into the ocean creating a huge cloud of radioactiev gases…

Ohhh I forgot about the coral. Humm. Back to the drawing board.

I know, instead of trying to grind up an Autralian plain, we could start grinding up New Jersey.

I think the Chinese built a huge damm that can be seen from space. What did all that concrete do to the alkalinity of the ocean as those waters reached their destination?

I have an idea, how about planting a tree in Autralia. How much CO2 does a tree generate? we could pump water using solar pumps from deep in the land, and transform the area into a forest, and make up for all the forests we got rid of over the millenium.

We could use solar pumps go bring up water in the desserts around the world and plant forests.

That’s an idea? Anyone?

Pierre Jones-Savard says: July 24th, 2008

Congratulation Tom for your solar hydrogen générator ,because if we do hydrogen with solar énergy,
then we can do hydrocarbon with hydrogen and CO2 as i have wrote in my last comment.
We can get C02 from calcaire and for reduce cost for calcination , i suggest to take the hot gaz CO2
émitted for heat the calcaire poder before introduce it in the cooker .
The lime CaO can catch CO2 from air or from water.
We can get CO2 also elsewhere and now we have not need coal or pétroleum.
Notice that the source of my first équation in my last comment come from a French encyclopédia:
Encyclopédie Francaise Larousse # 2 , page 619 ,second column in bottom.
Notice also that i have many idéa for hydrogen générator.

Tim Kruger says: July 24th, 2008

I’d just like to clear up that I haven’t got it in for the Nullabor Plain. There is no intention of performing this process in only one location. Given that the lime would need to be delivered over a very wide area it would make sense to have numerous sites where this process could take place dotted around the world. The reason I mentioned the Nullarbor Plain is to demonstrate that there is sufficient limestone available for this process.

Lidia LoPinto says: July 25th, 2008

Tim, I am sorry but liming the ocean is just not a good idea from the chemical engineering point of view.
Seriously, to heat up the lime you need energy. The calculations I sow do not account for the inefficiency of the process, the cost of mining and transporting the oil or coal.

This is a brute force approach to undo millenia worth of damage. We have to keep in mind that this global warming is partly a naturall occurrence, part of the ice age cycle, and partly (or short term) man made.

But, people believe that the damage happend in the last century as a result of burning fossil fuels. Archelogists, bible students and ancient historians agree that areas in the middle east, for example, where wet. That ancient civilizations like egyptians and Romans did their share of serious deforestation. More recently, take a look at how much of our United States has been deforested. Add this to the huge acreage of bad lands, and soil erosion as a result of irresponsible farming practices, and the disappearance of the grasslands, well, we have a lot of carbon dioxide liberated by these processes.

It is said that when the forests of Lebanon were cut down to make ships for the Romans, they never grew back. Take a look at what is happening with the forests in Brazil.

This and other factors are the root cause of global climate change. No amount of lime in the ocean will reverse all of this.

Only an ecological sound plan to restore the forests to their original condition and to irrigate desserts can restore the balance. Trees can soak up more carbon dioxide the lime, because the wood is made of cellulose. It captures the CO2 not temporarily as lime will, but for years and years.

We need huge expanses of dessert land irrigated with solar pumps that can keep working unattended for years. It is said that beneath the Sahara dessert, there are ample supplies of fresh water. And, solar desalinators can create the rest. Once forests are established, rain will start forming.

But, by irrigating desserts that were created by man’s irresponsible practices you will also bring economic growth. The forests can be farmed. Areas surrounding these areas can be farmed as well.

We have a huge number of human beings at starvation level today becaues there is no fresh water. The water will become scarcer as more land becomes dessert. Already we have continuous wars in Iraq and the middle east. Most of the disputes are due to lack of resources, primarily water.

It is interesting that the Iraqui war began at the merging of the Tigris and Euphratis rivers, the ancient location of the Garden of Eden. Could this be a message that those lands were fertile and wet then, and that we are now really living the consequences of our irresponsibility towards our earth?

I say restore the forests at this point, because putting lime in the ocean is a temporary brute force solution that will not bring balance, but unanticipated ecological problems.

Philip says: July 25th, 2008

An alternative idea, energetically favored. | The Undercover Economist | Carbon negativity says: July 25th, 2008

[…] met a fellow called Tim Kruger this week, who was keen to tell me about his idea for a process to suck carbon dioxide out of the atmosphere. (NB: Kruger and I both used to work for Shell, and Shell has also provided some seed money to […]

Tim Kruger says: July 25th, 2008

The idea that Philip links to in his post (“Electrochemical Acceleration of Chemical Weathering …” K.Z. House et al) is an interesting one. The process they describe works by using electrolysis to split seawater, which generates hydrogen and chlorine, which can then be reacted together to produce hydrochloric acid. This hydrochloric acid is then used to react with minerals such as olivines. Meanwhile in the sea the removal of the hydrogen and chlorine increases the pH, increasing the capacity of the ocean to act as a carbon sink in the same way that Cquestrate’s idea works.

House’s idea requires 100-400kJ per mol of CO2 captured. This equates to 2.3-9.1GJ per tonne of CO2 sequestered. In comparison the energy for Cquestrate’s process is estimated at approximately 3GJ per tonne of CO2 sequestered. So roughly similar amounts of energy. The big difference is going to be the cost – electrical energy is much more expensive than heat energy.

Pierre Jones-Savard says: July 25th, 2008

Please Philip ,compare your idéa to those of Ernest Solvay proceedind ,it is the following :

2CaCO3 + heat ——–>2CaO + 2CO2 (équation 1)

2NH3 + 2H2O + 2CO2 ———->2NH4(HCO3) (équation 2)

2NH4(HCO3) +2NaCl ————>2NaHCO3 + 2NH4Cl (équation3)

2NH4Cl + CaO ————->2NH3 + Ca(Cl)2 + H2O (équation 4)

Notice that NH4Cl is NH3(HCl)
I hope you see your HCl and here it réact with lime CaO instead of your silicate,and notice also
that there is a CaO in rest instead of your NaOH that give NaHCO3 after absorb a CO2 and H2O.
As the Tim Krugger comment électrical énergy is most expensive that heat.

Pierre Jones-Savard says: July 25th, 2008

Excuse me ,i forget to write in my last comment ,that if in the Ernest Solvay proceeding ,
the NH4Cl réact with silicate instead of lime CaO then we have 2 lime CaO in rest;
2 CaO can absorb 4 CO2 + 2H2O —–>2Ca(HCO3)2

Excuse me Tim ,your family name is Kruger(not Krugger).

Luke says: July 26th, 2008

Why not conduct some trials? Worth a shot. The solutions to climate change will surely be multi-faceted, switching from fossil fuels as well as sequestration, as Ian S suggests above. Obviously some big questions need to be answered before this project could be fully implemented. I really like the open source approach. Pity no comments from women (? – I think?) – as well as from developing countries with low Internet access.

Luke says: July 26th, 2008

Apologies, I see someone called Lidia wrote a comprehensive comment. Would still like to see more of a gender balance.

Chris Unitt » Blog Archive » Cquestrate - a crowdsourced solution to climate change says: July 29th, 2008

[…] basic premise revolves around adding lime to seawater.

Podnosh Blog » Archive » Cquestrate shifts up a gear and Chris nearly falls of his chair. says: August 21st, 2008

[…] solution which is free of intellectual property restrictions. I want to return to blogging on cquestrate partly because the idea needs as many of us as possible to talk about it in the hope that out there […]

Tom Keller says: August 27th, 2008

Now, I am no expert in chemistry, but it seems some that leaves comment are, and they question the idea about lime soaking up more co2 than released when treated with heat. Further more I am appaled about the whole : “Let spend gazillions of ressources/money on putting a band aid on the planet” instead of first stopping the actuall accident that caused, and still is causing the problems. I would say that spending enough ressources/money on getting our energy production away from adding more pollutants ( where co2 is only one of them ) would be goal number one, then when we know we have stopped the accident from making more harm, then we start treating the patient.
The coral reefs are not in a bad state, there are other corals that is taking over that likes hotter water, and fish and plantlife is doing well also, if we stop hunting them as we do now. Australia has shown the way in declaring a big part of the great coral reef a no fish zone, its helping, nature is slowly restoring itself as it has done millions of times in the past before, after volcanos, meteors, and other climate changing accidents.
I would very much like to go with the plan of restoring the tree’s and wet areas of the world, sahara as a desert was mostly made by the first farmers app 10k-15k years ago, and the romans burned the rest of the forrest to get enough land for wheat production to keep the roman empire going, lets start there with tree planting, the same goes for other deserts around the globe. A good global scheme would be : If you want to cut down a tree, you pay for planting 3 new ones.
Global shipping, what would happen if we used the modern technology we have today to build ships with sails, couldnt we transport a lot of goods that way, without the use of fossil fuels?
Trains can be run on electricity, that can be made with wind/solar/hydro/compost power, then why dont we build rails ( modern ones ) from and to every city and stop hauling billions of tonnes of goods on lorrys that smash the roads and burn humongus amounts of fossil fuels? The germans showed that you can transport goods from china to germany on rail that already exists, faster and cheaper than by boat even today. Lets pay for more tracks then and have the trains run on electricity, hey it has worked for the swiss for the past 50 years.
Roads, build a 5 meter high iron latice, and put solar cells on top, if we cover all the roads in the world with solar voltic cells, we could produce a lot of electricity and we would not be taking up more land from farming or forrests, the grid needed for sending the power could be easily attached to the latice and the need for digging would go away.
Connect the powergrid globally, then we could produce solar power where the sun is shining, and use it where its dark, no more talk about putting solar cells in space and beaming it down ( thus adding to the global warming problem ). This way we could get wind power from the coastal area’s to the hot inland places.
Build new houses that do not require warming in the winter or cooling in the summer, yes it is also a technology we already have ready, a few solar voltic cells on a roof is all that is needed for controlling the computer that controls the house heat and cool system.
No sorry, the world do not need more holes in the ground or playing with our little chemistry set, what it really lacks is will to use the technology we already have invented, and stop using the polluting technology we invented 100 years ago, just because we are too darned lazy to change our ways.

Tim Kruger says: August 27th, 2008

Tom – Thank you for your comments. While there are people who are sceptical about the chemistry, I have verified my analysis with a number of highly qualified chemists and chemical engineers who agree that the process will indeed produce a net sequestration of carbon dioxide.

You are right in saying that goal number one should be the reduction of emissions, but we need to face up to the fact that it is difficult to get people to change their behaviour. A good analogy is if you imagine that you were in charge of reducing deaths from heart disease in your country. The most effective way to spend your budget would be on persuading people to eat healthily, stop smoking and get some exercise – this would be the best way to reduce the suffering caused by heart disease at the lowest cost. But what about people who are already ill with heart disease? Do you refuse to treat them because the resources would be better spent on changing other people’s bad habits?

We are already suffering from the effects of too high carbon dioxide levels and need to address them. Prevention is better than a cure, but if you have already got the disease you need a cure. This is what we are trying to develop

Pierre Jones-Savard says: October 15th, 2008

Good end of day, i have listened the speaker Charles Tisseyre saturday 12 october 2008, he said that some coal power-station séquestre CO2 by stimulate plant greenhouse.
My idéa from it, is this: if we burn the plant of the greenhouse, then the séquestrate of CO2 in plant greenhouse is not good, but if we do CH4 with the plant of the greenhouse and we get hydrogen(H2) from the crack of CH4, and after this, we have only to send the carbon(C) get of this crack to the origin
coal power-house station.
Then the power-house station can produce more énergy with less coal et we can also produce hydrogen(H2), but the crack of CH4 need some énergy, this be équivalent to produce less hydrogen(H2), we can use this hydrogen(H2) for do hydrocarbon with CO2 that come from CaCO3, salute.

Pierre Jones-Savard says: November 14th, 2008

Good end of day, i have learn from the forumer Yves Vinet( his pseudo is vinety) that in south América
many cultivators do dark soil by use of wood coal ;
they have only to spread the wood coal before the soil tillage.
The wood coal is carbon and in soil it is stable for a long time, salute.

Juana Banana says: November 20th, 2008

Have you herad about artifical Reef construction? It requires electric energy, which can be obtained from solar energy.
Reefs bind aswell a lot of CO2 and Ca. And reefs have a several positive effects for coastal communities, such as protecting coasts from adverse weather conditions, wave impact and flooding.
For each kilogramm of CaCO3 they bind aproximatley 450 gramms of CO2.
So instead of digging up a lot of rocks and throwing them into the ocean, why not “create” living rocks directly in the ocean. Reefs will be poblated by algae, which will then use additional CO2 for biomass production.
Probably will cost a lot less and have less impacts, but is based on the same mechanism.

Small Blue Planet » Blog Archive » Geo-Engineering - Science for the End of Days says: December 1st, 2008

[…] clipped from […]

Mike McFall says: January 17th, 2009

I have a very simple scientifically based idea on how to sequester Carbon from the atmosphere.
P.h.d.s have said it will work. As a father of three children I must watch out for the welfare of my family first, therefore I am simply waiting for a solid monetary offer from a corporation before revealing my idea. With the economy the way it is I need all the financial help I can get.
This method does NOT require the introduction / use of ANY material whatsoever. This will eliminate any enviro-groups complaints about anything.

Dan Breen says: March 1st, 2009

I am a chemical engineer, my business used lime and exhaust gas CO2 to preduce precipitated calcium carbonate. I struggle with two issues with your concept.

1. Lime requires a lot of energy to drive the limestone rock to 1000 deg C to drive it from CaCO3 to CaO. This evergy is currently generated by burning oil, gas, coal or pet coke. These fuel generate a lot of CO2. Also, a major factor here will be the evergy required to deliver and distribute the lime. Have you looked to see if the total CO2 required to produce and deliver you lime will not exceed what you believe it will do?

2. In my manufacturing experience, lime must be slaked to become hydrated lime (exothermic reaction). We then pass gasses with at least 8% CO2. This goes rapidly and efficiently to back to calcium carbonate (CaCO3). The evevated pH of the slaked lime, goes down to neutral as the CO2 is introduced and Calcium carbonate forms. How stable is the HCO3 you believe will form? Why wont it go back to CaCO3 as it does in the oceans such as the areas of forming limestone near Jamaica? If that accurs the result will be one CaO to one CO2.

Cquestrate « Kirstybooth’s Blog says: March 16th, 2009

[…] carbon dioxide issues would lie with limestone? After an hour with Chris Unitt, the developer of Cquestrate’s website, the advantages and potential draw backs of this seemingly obvious project became […]

Alberto says: July 7th, 2009

Anybody thinking of the effect of lime on seafishes life cycle???

Anybody thinking of thermodynamics saying that the CO2 you will use to break limestone you won’t have lime enought to trap it all again???

…anybody with a serious scientific background checking this intox before it goes public?

So sorry ’cause many people believe in fairy tales.

Marcello Romagnoli says: July 8th, 2009

Why not plant trees? They have a lot advantages with respect the present idea
1) They can capture the CO2 present in the air and store it in a very natural way.
2) Wood can be used as renewable energy source with zero CO2 impact
3) A lot of species of trees produce food (fruit), wood.
4) They produces money
5) They can be grown also by poor countries so helping their economies.
6) If they are planted and produced money, less arson will be.
7) A forest produce tourism and animals (other accumulator of CO2)
8) …. I have other 1000 reasons

Last but not least they are nice and improve the mood.

Will Gibson says: July 9th, 2009

Just wondering if you can sell the CO2 produced when you break down the limestone to fire extinguisher manufacturers and generate some income from it to help fund it?

Alberto says: July 9th, 2009

“Just wondering if you can sell the CO2 produced when you break down the limestone to fire extinguisher manufacturers and generate some income from it to help fund it?”

It is cheaper for fire extinguisher producers to produce their own CO2 than recovering CO2 form another process.

Gerry Wolff says: July 11th, 2009

You say that you are not seeking more funding at present. But it seems to me that what is needed now is a study by a team with an appropriate range of knowledge and skills that will develop the ideas in *much more detail* and provide answers to the various questions that people will ask. That will cost money.

marco says: July 14th, 2009

Sequestrate CO2 from the air, mix it to Calcium, and bingo, you have CaCO3, calcium carbonate in solid form, stable and inert.
Please don’t play the mad scientist with the sea, our species has already done so much damage to our poor Earth..

Alberto says: July 21st, 2009

“Sequestrate CO2 from the air, mix it to Calcium, and bingo, you have CaCO3, calcium carbonate in solid form, stable and inert.”


Do you think that lime can be found in nature as a pure, ready to use Calcium lime or that you have to produce it? As you see, lime is quite reactive to CO2 and thus it is not stable…
…and where do you start from to produce Calcium lime? CaCO3!

…so, you spend X energy(or equivalent CO2, if you want) to produce a M quantity of Calcium lime (capable to trap Y<X equivalent CO2; Y<X due to process can NOT have yield 100%)…
Result is that to trap 100 grams of CO2 you will have (before that) to produce 200 due to need to produce lime.
…and I am not talking about the materials needed to build the plant where you’ll process all.

to shortly resume the scientific and engineering feasibility of such an idea as “Cquestrate” as a potential solution for CO2 atmospheric removal: BULLSHIT!

ps: Gerry, the only funds they should raise is the bill they need to pay a basic chemical thermodynamics class.

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