A dash of lime -- a new twist that may cut CO2 levels back to pre-industrial levels

Jul 21, 2008

Scientists say they have found a workable way of reducing CO2 levels in the atmosphere by adding lime to seawater. And they think it has the potential to dramatically reverse CO2 accumulation in the atmosphere, reports Cath O'Driscoll in SCI's Chemistry & Industry magazine published today.

Shell is so impressed with the new approach that it is funding an investigation into its economic feasibility. 'We think it's a promising idea,' says Shell's Gilles Bertherin, a coordinator on the project. 'There are potentially huge environmental benefits from addressing climate change – and adding calcium hydroxide to seawater will also mitigate the effects of ocean acidification, so it should have a positive impact on the marine environment.'

Adding lime to seawater increases alkalinity, boosting seawater's ability to absorb CO2 from air and reducing the tendency to release it back again.

However, the idea, which has been bandied about for years, was thought unworkable because of the expense of obtaining lime from limestone and the amount of CO2 released in the process.

Tim Kruger, a management consultant at London firm Corven is the brains behind the plan to resurrect the lime process. He argues that it could be made workable by locating it in regions that have a combination of low-cost 'stranded' energy considered too remote to be economically viable to exploit – like flared natural gas or solar energy in deserts – and that are rich in limestone, making it feasible for calcination to take place on site.

Kruger says: 'There are many such places – for example, Australia's Nullarbor Plain would be a prime location for this process, as it has 10 000km3 of limestone and soaks up roughly 20MJ/m2 of solar irradiation every day.'

The process of making lime generates CO2, but adding the lime to seawater absorbs almost twice as much CO2. The overall process is therefore 'carbon negative'.

'This process has the potential to reverse the accumulation of CO2 in the atmosphere. It would be possible to reduce CO2 to pre-industrial levels,' Kruger says.

And Professor Klaus Lackner, a researcher in the field from Columbia University, says: 'The theoretical CO2 balance is roughly right…it is certainly worth thinking through carefully.'

The oceans are already the world's largest carbon sink, absorbing 2bn tonnes of carbon every year. Increasing absorption ability by just a few percent could dramatically increase CO2 uptake from the atmosphere.

This project is being developed in an open source manner. To find out more, please go to www.cquestrate.com , a new website, launched today.

Source: Society of Chemical Industry

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User comments : 34

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Lord_jag
2.4 / 5 (11) Jul 21, 2008
uh huh... and what happens to sea life when we change the oceans ph?
earls
3.6 / 5 (9) Jul 21, 2008
...

"adding calcium hydroxide to seawater will also mitigate the effects of ocean acidification, so it should have a positive impact on the marine environment.'"

Lets give it a shot.
deatopmg
3.2 / 5 (14) Jul 21, 2008
as a chemist it sounds like more smoke and mirrors to me.

CaCO3 heat ---> CO2 Ca(OH)2 [lime]
Ca(OH)2 2C02 ---> Ca(HCO3)2

why not? CaCO3 CO2 ---> Ca(HCO3)2

which is the same thing w/out the initial expenditure of energy but that may not be patentable. both are really obvious to those skilled in the art.

Problem is that the pH of seawater is above 8 and Ca(HCO3)2 is below 7. AND what about the massive amounts of limestone exposed to seawater already?

therefore; more smoke and mirrors
thinking
2.5 / 5 (12) Jul 21, 2008
Someone save us from the wacky environmentalists.... they will destroy the earth trying to save it..... I though we want to stop pollution.... adding stuff to the oceans purposly sounds dangerous....
LuckyExplorer
3.5 / 5 (10) Jul 21, 2008
Nonsense?
1. According to: The process of making lime generates CO2, but adding the lime to seawater absorbs almost twice as much CO2. The overall process is therefore 'carbon negative'. -->

To absorb 1kg CO2 from fossil fuel we have to produce another kg CO2 by adding lime. --> That also means we need twice as much energy than today! Crazy!

2. We today know that the ocean cannot absorb as much CO2 as we would like without risk for the ecology. -->
This is not a solution! This is just - stupid how we men are - shifting one problem to another, without knowledge about the sequences!
Fritz
2.1 / 5 (11) Jul 21, 2008
I think when we really begin to burn up -- which I suspect isn't that far away -- we will be desparate to try anything. This sounds like a desparate measure.
Ebrads
3.6 / 5 (13) Jul 21, 2008
I'll reserve my judgment until I see more information, but my gut says it's a bad idea.
MikeB
2.3 / 5 (19) Jul 21, 2008
The climate crisis isn't really about CO2 anyway. It is about controlling you and collecting more money from you. So anything that might really help will be vetoed by Gore and his companions.
That's why nuclear is also a very very bad thing.
ShadowRam
3.6 / 5 (9) Jul 21, 2008
This is a very idiotic idea...
Lets not fix things by adding...

Lets fix things by taking away whats causing the problem...
Mercury_01
2.9 / 5 (14) Jul 21, 2008
This is all pure bologna anyway. Ive tried this experiment countless times in my own home. C02 levels remained the same in 100% of all rum and cokes after adding lime.
orlandorr
2.5 / 5 (8) Jul 21, 2008
Mmmm... I have a bad feeling about this idea :/
mattytheory
3 / 5 (7) Jul 21, 2008
^I agree.

It is obvious, from how we "solve problems" historically, that there are going to be unforeseen consequences from this action. In the past, we shift problems from one thing to another, and, in the process, tend to make things much worse overall. The ocean is a major driving factor of the food chain and the global environment. If we are going to mess around with it, then we had better understand EXACTLY what it is we are changing and what the consequences of those changes could be. We are already in a time of environmental distress and any miscalculation could severely exacerbate existing problems. No half-assing this, for I believe that the (possibly immediate) future of life on this planet depends heavily on our actions now.

I think ShadowRam has it right: "This is a very idiotic idea... Lets not fix things by adding... Lets fix things by taking away whats causing the problem..."
vlam67
2.2 / 5 (6) Jul 21, 2008
IN a nutshell, they are proposing a CO2 transfer mechanism from the air to the ocean. Gosh, as if the problem of acidifying the ocean and its consequences are not bad enough as it already is...And when the balance is tipped, marine life is going to hell, then the acidic soup under the heat input from the sun will release the CO2 back again...for a mega greenhouse effect!
dbren
1.9 / 5 (13) Jul 21, 2008
I'm still waiting for Gore to propose banning pop and beer.
drmaxx
3.3 / 5 (6) Jul 21, 2008
This just might work IF the lime added does not precipiate as calciumcarbonate (limestone!). So either
* the water is acidic enough to keep the limestone soluble, then you also can add powdered limestone and it will dissolve with the same effect = no energy input needed
OR
* the water is not acidic enough to keep the calciumcarbonate above the solubilityproduct then you precipitate limestone.

So something is fishy about the proposition and these people obviously have no clue about aqatic chemistry!
CWFlink
2.1 / 5 (7) Jul 22, 2008
"So something is fishy about the proposition and these people obviously have no clue about aqatic chemistry!"

...so they are perfectly qualified to become leaders of the world and earn a Nobel Prize!

When will we learn that there is a big difference between being able to spot a mess and being able to clean it up ????

P.S. ...anyone notice that if we had not done such a great job cleaning up particulate pollution the increased cloud cover would have compensated for the higher CO2 levels by reflecting more of the sun's radiation back into space???? This lime (lame?) solution would NOT be the first time our intervention resulted in unfortunate unintended consequences.
jeffsaunders
1.3 / 5 (6) Jul 22, 2008
OK lets hope someone involved in this project / concept / idea reads our reactions to the idea expressed in these comments.

Mad scientists it seems are NOT just the product of horror stories - they seem to be REAL.

Lets hope that the idea gets added to the other ideas including the ones that include tying a rope to South America and dragging it back across the Atlantic and joining it up with Africa.
nealjking
4.3 / 5 (7) Jul 22, 2008
Well, I'm not good in chemistry, so I won't comment on the technical details.

However, according to Hansen, we're already above the 350 ppm of CO2 that he thinks is dangerous. If that's right, we have to go carbon-negative eventually. How do we do that? Turn everything into forests again?

Chemistry may be the right answer.
menkaur
1.6 / 5 (12) Jul 22, 2008
well, now crazy co2 haters can shut up and start mixing water and lame and let everyone else live in peace. this occupation would perfectly fit their qualification anyway
by the way, if you're preferring banning all of the possible co2 sources, you probably should stop breathing... that's producing co2
MattJ
2.6 / 5 (8) Jul 22, 2008
The comments so far accomplish one thing: illustrate why humanity as a whole, is not at all likely to solve the problem before global warming destroys civilization.

So few of the comments show any understanding of the basic issues! But then again, this is to be expected, when the article itself shows no better than an elementary understanding of high school chemistry, and none at all of the "law of unintended consequences".

Come on now! We do NOT know what the effect of all this added lime will be on aquatic life. It is incredibly arrogant and presumptuous to state -- as this article did -- that it will be good.
minimegamonkeyman
2.8 / 5 (4) Jul 22, 2008
What happens when the ocean goes from high concentrations of acidic substances to high concentrations of alkaline substances? We'd have to stop adding lime... and we'd be right back where we started! This proposal constitutes a quick fix, with high potential for unintended consequences or unforeseen circumstances which would force us to give it up. The underlying problem remains the same: that we need to slow down our carbon emissions.
Plurk
4.8 / 5 (4) Jul 22, 2008
The premise of the article is to conduct a feasibility study. There is nothing wrong with investigating this emergency measure. Emphasis on 'emergency measure'. Implementing it is a whole other matter.
barakn
4.4 / 5 (9) Jul 22, 2008
The source of the smoke and mirrors appears to be deatompg.
CaCO3 heat ---> CO2 Ca(OH)2 [lime] is nonsense. It is instead
CaCO3 heat ---> CO2 CaO [quicklime] They won't bother to hydrate the quicklime because: 1. They're in a desert 2. They don't need extra weight while transporting it 3. They're going to be dumping it in water anyway.

"why not? CaCO3 CO2 ---> Ca(HCO3)2"
Because the ocean is basic, and CaCO3, a.k.a. limestone, is insoluble in a basic solution. This is also not a balanced reaction, as the source of the H is not even mentioned. There's also no valid reason to state "the pH of seawater is above 8 and Ca(HCO3)2 is below 7," apparently a reference to the pK1 of carboxylic acid, but that refers to the equilibrium between carboxylic acid and bicarbonate, whereas at the pH of seawater the main species are bicarbonate and carbonate, with a pK of 10.33, Another relevant reaction in the seawater pH range is CO2 H2O -> H HCO3-, pK 7.82.

What's really going on?
CaO H2O -> Ca2 2OH-

OH- HCO3- -> CO32- H2O

Ca2 CO32- -> CaCO3(s)
___________________________

= CaO HCO3- -> CaCO3(s) OH- (reaction 1)

Thus the added calcium precipitates out, taking one CO2 equivalent with it.

Also:

CO2(g) -> CO2(aq)

CO2(aq) H2O -> H HCO3-
____________________________

= CO2(g) H2O -> H HCO3- (reaction 2)

This is where the extra hydroxide from reaction 1 comes into play. It reacts with and removes the H from the RHS of reaction 2. This drives the equilibrium of the reaction to the right, pulling CO2 out of the air and converting it into aqueous bicarbonate.
barakn
4 / 5 (3) Jul 22, 2008
Real nice of the physorg comment system to filter out stray pluses and minuses. Makes chemical reactions really easy to read. Not.
Mercury_01
1 / 5 (1) Jul 23, 2008
This idea in only slightly better than covering the arctic ocean with billions of rolls of sea ice-inducing saran wrap.
deatopmg
5 / 5 (3) Jul 23, 2008
The source of the smoke and mirrors appears to be deatompg.
CaCO3 heat ---> CO2 Ca(OH)2 [lime] is nonsense. It is instead
CaCO3 heat ---> CO2 CaO [quicklime] They won't bother to hydrate the quicklime because: 1. They're in a desert 2. They don't need extra weight while transporting it 3. They're going to be dumping it in water anyway.

"why not? CaCO3 CO2 ---> Ca(HCO3)2"
Because the ocean is basic, and CaCO3, a.k.a. limestone, is insoluble in a basic solution. This is also not a balanced reaction, as the source of the H is not even mentioned. There's also no valid reason to state "the pH of seawater is above 8 and Ca(HCO3)2 is below 7," apparently a reference to the pK1 of carboxylic acid, but that refers to the equilibrium between carboxylic acid and bicarbonate, whereas at the pH of seawater the main species are bicarbonate and carbonate, with a pK of 10.33, Another relevant reaction in the seawater pH range is CO2 H2O -> H HCO3-, pK 7.82.

What's really going on?
CaO H2O -> Ca2 2OH-

OH- HCO3- -> CO32- H2O

Ca2 CO32- -> CaCO3(s)
___________________________

= CaO HCO3- -> CaCO3(s) OH- (reaction 1)

Thus the added calcium precipitates out, taking one CO2 equivalent with it.

Also:

CO2(g) -> CO2(aq)

CO2(aq) H2O -> H HCO3-
____________________________

= CO2(g) H2O -> H HCO3- (reaction 2)

This is where the extra hydroxide from reaction 1 comes into play. It reacts with and removes the H from the RHS of reaction 2. This drives the equilibrium of the reaction to the right, pulling CO2 out of the air and converting it into aqueous bicarbonate.

Thanks!
thku4grace
1 / 5 (3) Jul 26, 2008
I find it quite interesting that anyone would propose a solution to a perceived dilemma without having considered whether sunspot activity or underwater volcanoes will cooperate with this hypothetical solution.
GuruShabu
2 / 5 (4) Jul 26, 2008
Absolutely crap.
Gore's power, nuclear power money greed with nothing scientific.
The Earth is very healthy as it was and it will be.
State of fear petty politics.
And btw, talking about Earth's healthy is what "they" want us to do. The temperatures, the concentration of CO2 are NOT maximum or minimum that have not been reached in past and nare (1000s of years) in future, so why all this fuss?
$$$$$$$! and Power!
Enthalpy
1 / 5 (1) Jul 26, 2008
Converting carbonate to bicarbonates, why not. Other people suggested to convert silicates to silica and carbonates, which may need more energy.

I don't see neither why the extra step through CaO is useful. Is the direct reaction with CaCO3 too difficult? Increasing reaction surfaces looks easier to me than providing the energy to split CaCO3.

But why the hell use the Ocean for that mess? Dump the bicarbonates in the same Nullarbor plain! Anyone having seen the reaction of CaO with water would answer: do it somewhere else.

The very same bicarbonates (which are separated from the Ca ions as soon as they're dissolved) are already increasing in seawater, making it more acid (or less alkaline) and dissolving the shell of marine organisms.

O yes, I've heard bicarbonates are unstable in air and go back to carbonates and CO2, that's how stalactites form. Isn't there any better idea than an ocean to stabilize bicarbonates?
GrayMouser
not rated yet Jul 26, 2008
Some questions:
1) Wouldn't adding lime to the oceans would be polluting them?

2) Are these organic limes?
Cyril
4 / 5 (1) Jul 27, 2008
Converting carbonate to bicarbonates, why not. Other people suggested to convert silicates to silica and carbonates, which may need more energy.

O yes, I've heard bicarbonates are unstable in air and go back to carbonates and CO2, that's how stalactites form. Isn't there any better idea than an ocean to stabilize bicarbonates?


Magnesium silicates offer a promising solution, in particular olivine seems suitable. Doesn't require any energy, except that for mining, crushing and bringing it to the sea, which is quite acceptable.

http://www.google...ch?hl=nl&q=olivine sequestration&meta=

Cyril
not rated yet Jul 30, 2008
Link doesn't work, hmm! Physorg is buggy.

Just google 'olvine sequestration'
Cyril
not rated yet Aug 04, 2008
er, 'olivine sequestration'
Modernmystic
1 / 5 (1) Aug 21, 2008
A few well placed rather large bombs in the Sahara per year will solve the "problem" too....