Shell Game or Innovative Solution?
Alvia Gaskill
mongabay.com
July 21, 2008
Shell Oil is funding a project that seeks to test the potential of adding lime to seawater as a cost-effective way to fight global warming by sequestering large amounts of carbon dioxide in the world's oceans, reports Chemistry & Industry magazine.
Adding lime (calcium hydroxide) to seawater increases its alkalinity, thereby increasing the ocean's capacity to absorb CO2 and reducing its tendency to the greenhouse gas back into the atmosphere. The process could also help counter acid acidification, which biologists say is increasingly a threat to marine life, including coral reefs and plankton.
While the concept has been discussed for years, it has been believed to be too expensive to be carried out on a scale necessary to affect ocean chemistry. Now Tim Kruger, a management consultant at Corven, a London-based firm, think he has figured out a way to make the idea economical by locating in regions that are rich with limestone and have substantial energy resources that are too remote to exploit for commercial purposes.
"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," said Kruger. [How much solar radiation the location of the limestone receives is irrelevant.]
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'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,' he explained.
Shell is funding an economic feasibility study of the concept, which is detailed at www.cquestrate.com.. Like other oil companies facing a future with caps on greenhouse gas emissions, Shell is increasingly keen on technologies that can reduce its carbon footprint.
"We think it's a promising idea," says Shell's Gilles Bertherin, a coordinator on the project, which is being developed in an "open source" manner. "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."
The project isn't the first to try to exploit the capacity of the oceans — the planet's largest carbon sink — to sequester CO2 from the atmosphere. Earlier this year Planktos, a California-based firm, attempted to conduct a large-scale iron-fertilization experiment in the equatorial Pacific. It argued that artificial iron fertilization would trigger massive blooms of phytoplankton that would absorb carbon dioxide from the atmosphere and help fight global warming. The firm would then sell the carbon credits to individuals and companies looking to offset their greenhouse gas emissions. But the scheme was widely opposed by environmental groups who said it could harm marine life. Some scientists — including researchers at Stanford and Oregon State Universities — said that any bloom of phytoplankton induced by Planktos would be accompanied by a bloom in bacteria as phytoplankton die. These bacteria may produce gases--like nitrous oxide, a powerful greenhouse gas--that counteract the effects of carbon sequestration by phytoplankton. Further, bacterial decay consumes oxygen, which alters water chemistry.
In any case, Planktos failed to attract sufficient funding to conduct its experiments. Investors were apparently put off by criticism of its plan, which relied on the use of foreign vessels to skirt the U.S. Ocean Dumping Act.
High levels of carbon dioxide in the atmosphere are causing climate change. We have an idea which we think is able to tackle this issue.
We know that it works in theory – we need to understand how we can make it work in practice.
We are developing this project in an open source way, so that we can draw as widely as possible on the expertise required to transform this idea from concept to reality.
Alvia Gaskill
Alvia Gaskill
A dash of lime...for CO2 reduction?
Yes, that's what scientists are proposing in today's issue of Chemistry & Industry, journal of Society of Chemical Industry. A dash of lime in seawater has the potential to dramatically reverse CO2 accumulation in the atmosphere, they say. Of course, they don't mean the green citrus that we squeeze in our cups and glasses but lime from limestone.
Oil major Shell seems to be pretty impressed with the idea and is funding further research 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."
The way it works is-adding lime to seawater increases alkalinity, enhancing seawater's ability to absorb CO2 from atmosphere and reducing the tendency to release it back again. The idea has been around for some time but didn't seem feasible due to the expense of getting lime from limestone, which also releases large amounts of CO2 released in the process.
Now, a management consultant at a UK firm Corven, says it can be made workable by locating it in regions that that have a combination of low-cost "stranded" energy that are often not economically viable for regular use -- such as flared natural gas or solar energy in deserts -- and that are also rich in limestone. This combination, it is argued, can make calcination (a method using heat to drive off carbon dioxide from limestone to obtain lime) possible on site.
Some researchers in the field say the idea is "certainly worth thinking through carefully"; others might call it preposterous. But the scientific world is full of such ideas.
Way back in 1989, oceanographer John Martin published an astounding theory of ‘iron fertilization' in Nature and famously said: "Give me half a tanker of iron and I'll give you the next ice age."
He believed if iron was sprinkled on the anemic zones of the oceans (20% of the world's waters lack nutrient for plant life and are called "high nutrient/low chlorophyll" zones) they would cause marine plants (phtoyplanktons) to bloom and soak up CO2. Martin believed that HNLC zones worldwide could lock up to billions of tons of CO2.
He died a few months before his planned expedition to test this theory but researchers have since carried out at least half a dozen such experiments, including IronEx I and IronEx II, and have reported noticeable plant growth on water surface.
The idea's audacity, of course, halted it and now there's a resurgence of sorts. Who knows what the future of CO2 control holds?
David Schnare
approach may be very helpful near coral reefs, especially in that it
may also help cool the waters being addressed, the more problematic
issue for reefs at this point.
d.
John Latham
A possible alternative method of cooling the waters around coral reefs
is the cloud albedo enhancement scheme that Steve Salter, Phil Rasch
and I (with others) are working on. Although the primary goal of this
work is directed towards global temperature stabilisation - which is
yielding encouraging results - it is also possibly applicable to more
localised issues, like the the coral reef one, or the cooling of the
waters in which hurricanes spawn, thus reducing their energy.
All Best, John.
David Schnare
nwo...@as.arizona.edu
Limestone is calcium carbonate. So
to make quicklime CaO or slaked lime
Ca(OH)2, one first heats limestone to
drive off CO2 into the atmosphere.
If then the lime is put into the ocean to
take up the CO2 there, (by way of
bicarbonate), all that is happening is
that the CO2 is getting shuffled, being
put into the atmosphere in making lime,
and being taken out again in the ocean.
There is no net CO2 subtraction.
Or have I missed something?
Nick Woolf
> --
> David W. Schnare
> Center for Environmental Stewardship
>
> >
>
Tim Kruger
When you heat one mol of calcium carbonate you generate one mol of CO2
and one mol of lime (calcium oxide). Then you react the lime with
water to produce calcium hydroxide.
When you put that mol of calcium hydroxide into seawater it reacts
with two mols of carbon dioxide dissolved in the seawater to produce
calcium bicarbonate solution. The difference is that you start with
calcium carbonate (CaCO3) and end up with calcium bicarbonate
(Ca(HCO3)2).
I hope that makes sense. Have a look at the website for more details
Tim Kruger
On 21 Jul, 16:55, nwo...@as.arizona.edu wrote:
> Please explain!
> Limestone is calcium carbonate. So
> to make quicklime CaO or slaked lime
> Ca(OH)2, one first heats limestone to
> drive off CO2 into the atmosphere.
>
> If then the lime is put into the ocean to
> take up the CO2 there, (by way of
> bicarbonate), all that is happening is
> that the CO2 is getting shuffled, being
> put into the atmosphere in making lime,
> and being taken out again in the ocean.
> There is no net CO2 subtraction.
>
> Or have I missed something?
>
> Nick Woolf
>
>
>
> > Good point!
>
> > Cheers,
> > d.
>
>
> >> Hello David,
>
> >> A possible alternative method of cooling the waters around coral reefs
> >> is
> >> the cloud albedo enhancement scheme that Steve Salter, Phil Rasch and I
> >> (with others) are working on. Although the primary goal of this work is
> >> directed towards global temperature stabilisation - which is yielding
> >> encouraging results - it is also possibly applicable to more localised
> >> issues, like the the coral reef one, or the cooling of the waters in
> >> which
> >> hurricanes spawn, thus reducing their energy.
>
> >> All Best, John.
>
>
> >>> If the cost implications can be made small enough, the proposed
> >>> approach may be very helpful near coral reefs, especially in that it
> >>> may also help cool the waters being addressed, the more problematic
> >>> issue for reefs at this point.
>
> >>> d.
>
> > --
> > David W. Schnare
>
> - Show quoted text -
Stephen Salter
It might be still be worth doing if you fear acidity in sea water more
than CO2 in air and if the diffusion of CO2 back to the sea was fairly
slow. It would be better if your lime factory was close to an input
point for a carbon sequestration well.
From school chemistry of 55 years ago the molecular weight of calcium
carbonate is 80 and calcium oxide is 36 while carbon is 12 so we have
to move lots more more material than we do now from coal mines. We
cannot dump it all into one place in the sea so there is a second
material distribution distribution task even if the lime production was
free. Can we put numbers on distances and energy ratios and compare
them with using the solar input for making cement rather than whatever
they use now?
Stephen
Emeritus Professor of Engineering Design
School of Engineering and Electronics
University of Edinburgh
Mayfield Road
Edinburgh EH9 3JL
Scotland
tel +44 131 650 5704
fax +44 131 650 5702
Mobile 07795 203 195
S.Sa...@ed.ac.uk
http://www.see.ed.ac.uk/~shs
--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.
Tim Kruger
When you heat one mol of limestone (calcium carbonate) you generate
one mol of CO2 and one mol of lime (calcium oxide). When you put the
mol of calcium oxide into seawater it reacts with two mols of CO2 to
form calcium bicarbonate solution. So, you start with calcium
site.
Tim
> Limestone is calcium carbonate. So
> to make quicklime CaO or slaked lime
> Ca(OH)2, one first heats limestone to
> drive off CO2 into the atmosphere.
>
> If then the lime is put into the ocean to
> take up the CO2 there, (by way of
> bicarbonate), all that is happening is
> that the CO2 is getting shuffled, being
> put into the atmosphere in making lime,
> and being taken out again in the ocean.
> There is no net CO2 subtraction.
>
> Or have I missed something?
>
> Nick Woolf
>
>
>
> > Good point!
>
> > Cheers,
> > d.
>
>
> >> Hello David,
>
> >> A possible alternative method of cooling the waters around coral reefs
> >> is
> >> the cloud albedo enhancement scheme that Steve Salter, Phil Rasch and I
> >> (with others) are working on. Although the primary goal of this work is
> >> directed towards global temperature stabilisation - which is yielding
> >> encouraging results - it is also possibly applicable to more localised
> >> issues, like the the coral reef one, or the cooling of the waters in
> >> which
> >> hurricanes spawn, thus reducing their energy.
>
> >> All Best, John.
>
>
> >>> If the cost implications can be made small enough, the proposed
> >>> approach may be very helpful near coral reefs, especially in that it
> >>> may also help cool the waters being addressed, the more problematic
> >>> issue for reefs at this point.
>
> >>> d.
>
> > --
> > David W. Schnare
Stephen Salter
There is a special focus issue on Aerosol Cloud and Climate at
http://www.iop.org/EJ/toc/1748-9326/3/2
One paper talks about cosmic rays and cloud cover and another about corn
ethanol.
Geoengineers will appreciate the free download.
Stephen
Emeritus Professor of Engineering Design
School of Engineering and Electronics
University of Edinburgh
Mayfield Road
Edinburgh EH9 3JL
Scotland
tel +44 131 650 5704
fax +44 131 650 5702
Mobile 07795 203 195
S.Sa...@ed.ac.uk
http://www.see.ed.ac.uk/~shs
Ken Caldeira
Greg Rau and I proposed a low energy approach to neutralize carbon
acidity and store carbon in the oceans by using power plant flue gases
to dissolve limestone, placing the resulting fluids in the ocean.
McDermott technologies has estimated the parasitic load on power
plants to be 2% of energy in for well suited power plants (see
attachment). Furthermore, this approach is suitable for retrofits on
existing power plants.
Rau and I first proposed our approach in related papers in 1999 and
2000 (Rau and Caldeira, 1999, Caldeira and Rau, 2000).
The basic reaction we propose is: CO2 + CaCO3 + H2O --> Ca2+ + 2HCO3-
Cheers,
Ken
PS. The approach being promoted by Tim Kruger was first discussed in
Kheshgi (1995). The basic problem is that there is not all that much
stranded energy around so it is at best a niche opportunity.
--
===============================
Ken Caldeira
Department of Global Ecology
Carnegie Institution
260 Panama Street
Stanford, CA 94305 USA
+1 650 704 7212; fax: +1 650 462 5968
Alvia Gaskill
The cquestrate plan aims for removing dissolved CO2 from the atmosphere via
an increased diffusion gradient by locking up dissolved CO2 as bicarbonate,
while the Livermore (LLNL) plan was to dispose of power plant CO2 also via
conversion to bicarbonate.
The LLNL plan also seemed to have as part of the goal, release of the
bicarbonate at 700m or some depth guaranteed to keep it down there for
hundreds of years. According to the paper Ken attached, after 25 years,
most of the LLNL bicarbonate is still less than 1000 miles from the release
point near S. Francisco, except for some that is carried by currents into
the N. Pacific.
The cq plan (sorry for the acronym) has no identified depth target, but
would need to spread the liquid across the surface of the ocean in order to
ensure that a deficit in dissolved CO2 would be created. My comment earlier
about subduction and the similarity to OIF referred to the concern that the
cq outfall (assuming it is a pipeline run from the Nullarbor deposit) at a
shallow enough depth would result in much of the CO2 depleted water being
drawn down to depths that would not allow it to come into contact with
surface water for decades and that the water replacing it would not be
depleted in dissolved CO2, thus not resulting in any decrease in atmospheric
CO2.
All that will have been achieved is dissolving carbonate rocks and flushing
the resulting solution into the ocean. Over thousands of years, the impact
of this if done on a large enough scale would be to alter the equiliibrium
between the atmosphere and ocean, but on the scale of concern, the 21st
century, modeling and engineering would have to show that this would have an
almost immediate impact to be of value.
That is one potential outcome. Another is that a higher pH depleted CO2
zone will be created next to Australia and this would act as a sink for
atmospheric CO2 from that one location. How much it would remove would have
to be determined.
The earlier questions about the efficiency of the cq plan are somewhat
answered by the website. If solar energy is used to calcine the limestone
and the CO2 from calcining is emitted to the air, the net removal of CO2 if
the ocean/atmosphere process is 100% efficient over short time periods is
about 0.79 moles of CO2 (1.79 going into the ocean and 1 going back into the
air). Applying CCS technology to the calcining process would add to the
cost, but again if the energy is free, so what. I am not aware of any
attempt to apply CCS to calcining processes and what additional challenges
that would entail vs. coal fired power plant emissions. Even if it is a
pure CO2 stream, it still has to be captured and compressed.
If natural gas is used instead, the additional CO2 produced if released to
the air would reduce the efficiency by 0.3 moles to around 0.5 moles.
Again, CCS could be used to eliminate all CO2 emissions from calcining. Not
shown in the calculations is the effect of using coal, which would reduce
the efficiency even further. The cq site also proposes nuclear energy for
this purpose, but I think that one is a non starter for a lot of reasons.
The other add ons, growing plants for food and energy sources or using CO2
itself to make fuel seem rather speculative.
Tim Kruger
One of the stranded energy sources we are hoping to use is natural gas
that is currently flared off from oil production in remote locations.
Current estimates are that 150 million tonnes of methane are flared
off each year - our initial calculations are that using the process we
have put forward it would allow the sequestration of 2-2.5 billion
tonnes of CO2 each year.
Best wishes
Tim
PS We do acknowledge on the wbesite that Haroon Kheshgi was the person
who first came up with the idea of calcining lime and adding it to
seawater as a way of removing CO2 from the atmosphere
On 21 Jul, 18:29, "Ken Caldeira"
>
> http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab/
>
> Rau_et_al_Energy2007.pdf
> 652KDownload- Hide quoted text -
Tim Kruger
Thanks for your thoughts on this.
A couple of points to clear up any confusion if it didn't come
throught clearly on the website:
There is no intention of only performing the process in the Nullarbor
Plain. The purpose of mentioning the Nullarbor Plain was simply to
demonstrate that while the quantity of limestone required is huge,
there is ample limestone available around the world. So the issue of
there being a pH imbalance caused by the dumping of calcium hydroxide
in one location would not arise. We are well aware that large
localised pH increases would not only be harmful to the marine
environment, but also counterproductive as it would lead to calcium
carbonate precipitating out, which would give back the CO2 sequestered
- it is only by distributing calcium hydroxide in a very controlled
and measured way that this process works. Exactly how that would be
done is an open question, which we are hoping to answer through an
open source route.
The other point is that the CO2 released by the calcination of the
limestone will be captured as pure CO2. As I am sure you are aware,
the most expensive part of sequestering CO2 from the flue gases of a
power station is the separation out of the CO2 from the other gases -
the actual sequestration itself is relatively cheap. Thus all 1.79
mols of CO2 (less any CO2 generated by producing the heat required to
drive the calcination process, if fossil fuels are used) would be
sequestered. If methane is used (and the CO2 produced from its
combustion is not sequestered), then a net 1.5mols of CO2 will be
sequestered. For more details about this please have a look at the
videos under Energy Balance and Energy Sources under the Get Involved
tab on the website.
With regard to the other 'add-ons' as you put it, yes, they are
speculative. But I'd rather put the seed of the idea out there and see
if someone can build upon it than hide it away.
Tim
>
> >http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab/- Hide quoted text -