Environment

MIT study finds carbon sequestration may not be as effective as expected

A recent MIT study has found that far less carbon dioxide than the ideal prediction of 90 percent may be turned into rock when sequestered (Photo: Shutterstock)
A recent MIT study has found that far less carbon dioxide than the ideal prediction of 90 percent may be turned into rock when sequestered (Photo: Shutterstock)
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A recent MIT study has found that far less carbon dioxide than the ideal prediction of 90 percent may be turned into rock when sequestered (Photo: Shutterstock)
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A recent MIT study has found that far less carbon dioxide than the ideal prediction of 90 percent may be turned into rock when sequestered (Photo: Shutterstock)

Carbon sequestration may not, according to researchers at MIT, be the panacea that some had hoped. A recent study, partially funded by the United States Department of Energy, has found that far less carbon dioxide than the ideal prediction of 90 percent may be turned into rock when sequestered. This means much might eventually escape back into the atmosphere.

Carbon sequestration is one of many possible ways to tackle climate change. Though typically sequestered in rock, other approaches such as using special polymers and even processes inspired by the sea urchin are being investigated, but geological sequestration is still the mainstay.

The University of Illinois recently celebrated reaching its goal of capturing and storing one million tons of carbon dioxide underground, but the process may not be as rock solid as thought.

"If it (CO2) turns into rock, it’s stable and will remain there permanently," says Yossi Cohen, a postdoc working on the study. "However, if it stays in its gaseous or liquid phase, it remains mobile and it can possibly return back to the atmosphere."

The findings almost contradict the central tenet of how the process works, which sounds charmingly elegant and simple. CO2 from coal fired power plants is collected (tricky in itself) and injected into rock at 7,000 feet below ground level then stored in large pockets of brine – or deep-saline aquifers – where it reacts with the liquid and turns from gas to solid. However the scientists found in their modelling of the process that very little gas may actually become solid. Though it does solidify, it only does so at the interface where the CO2 enters the brine pool. It then reacts to build a "wall" the rest of the gas cannot get through.

"The expectation was that most of the carbon dioxide would become solid mineral. Our work suggests that significantly less will precipitate," explains Cohen.

The scientists say that these predictions require further experimental studies. "There are many factors, such as the porosity and connectivity between pores in rocks, that will determine if and when carbon dioxide mineralizes," says Cohen. Once this is known there will be a better understanding of which kinds of rock formation will be best suited for the job.

The study, authored by Professor Daniel Rothman of the MIT’s Department of Earth, Atmospheric, and Planetary Sciences and Yoshi Cohen, was published this week in the Proceedings of the Royal Society A.

Source: MIT

10 comments
GeoffG
"where it reacts with the liquid and turns from gas to solid" CO2 doesn't turn in to a solid. It doesn't react with sodium chloride (brine) or water (it dissolves in water to a limited extent, forming very small quantities of carbonic acid - which is not a solid). We need some chemical evidence here! Are we talking about forming calcium carbonate here? If so, why no mention of the presence of Ca?
fenshwey
Why not crush the rock in a chamber that can collect the released carbon gas that was not turned to rock, and send it trough the process again, eventually ending up with carbon powder instead of carbon rocks (containing carbon gas).
zevulon
carbon 'sequestration' will one day be acknowledged for the fraudulent folly that it is . hopefully sooner than later. it's outrageous that people are spending money to bury carbon dioxide. ASSUMING you do believe in the greenhouse apocalypse is tomorrow, thing is; how are you going to influence people to STOP making MORE c02 when you have developed a technology to put in in the ground. all you are doing is FIRMLY cementing the possibility that a new technology (carbon sequestration) will , if successful, guaranteee that absolutely no one has an incentive to use higher priced alternative and renewable energy because they can simply bury their coal and petro-gas emissions. you have to be pretty thoughtless to miss how carbon sequestration , if succsful, discourages the emergence of renewables in our immediate future . thankfully, carbon sequestration is a fools errand and will never succeed and is just a simple waste of money like so many other boondoggles. if you want to minimize c02, you must first find a profiteeable method of incorporating c02 as a feed-stock into usable chemicals. there is a substantial amount of industrial chemistry research into this area and it is very very promising. and the beauty is that even if you don't believe in global warming , industrial c02 chemistry research is a very exciting field because as it stands , c02 is THE biggest industrial waste product disposed of on a continuous basis and SHOULD be a major concern for research. just because something is easy to throw away ( like flaring off extra methane from unprofitable wells) , doesn't mean researchers cannot and should not find a way to make it profitable.
GogogoStopSTOP
I don't need MIT to tell me the Second Law of Thermodynamics can't be violated. Q. E. D.
apprenticeearthwiz
Not as effective as expected? Nobody expected it to work, not even the purveyors of this greenwashing, diversionary nonsense. Burning stuff for energy is so 15 minutes ago.
Galane
CO2 sequestration is as much of a boondoggle as the "modified coal" scam that simply sprayed a bit of diesel fuel on it.
Dawar Saify
It's been discussed how this carbon issue was false, Green plants need carbon dioxide. But to solve the issue if there is a problem, here it is. Plant trees in the Sahara desert, terraform this to a forest. The water will come from desalination plants. The power for the desalination plants will come from solar power. All the world's carbon will be sequestered plus food could be grown to feed the malnourished, if anyone in the world cares for them now.
LordInsidious
So even more reason to not burn things to get things to go.
amazed W1
GogogostopSTOP does have a point. Just how much energy does it take to extract the carbon from the CO2? It must take at least as much energy as you get burning the carbon to CO2. Then there is the sequestration energy. Could the experts explain to this ignoramus what is actually is intended even if it isn't happening?
Anders Berg
@zevulon: "ASSUMING you do believe in the greenhouse apocalypse is tomorrow" Well, it's not like it's a religion. There's tons of solid research on the topic, where scientists worldwide after lots of debate have came to the concensus that a certain global warming is "man made". The question left is how strong the effects of this will be over time. The most important point for me in this is that though we might get lucky, there's a notable risk that the problems will be massive. So we need to decide: playing "environment russian roulette" by doing business as usual or really pushing the change to renewables. Also I find it quite cynical for us living in rich countries to decide to accept the risk, knowing that the poor guys will suffer many of the consequences, without having the economical means to counter them. E.g. the Bangladeshi government plans for up to 20 million citizens who need to be resettled by 2050 because of rising sea levels. A local environmentalist said: "(Climate change) here is a matter of life and death for the communities, for the people, for the ecosystem. In the West it is an issue of minor lifestyle changes." That is where the apocalyptic tone comes from: if you feel solidarity with humans elswhere on the planet, the apocalyptic tone is indeed apropriate.
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