Study finds room to store CO2 underground

March 19, 2012
Using tiny glass beads, the researchers simulated the way liquified carbon dioxide would spread through salty water in the pores of deep rock formations. Image: Michael Szulczewski, of the Juanes Research Group, MIT

A new study by researchers at MIT shows that there is enough capacity in deep saline aquifers in the United States to store at least a century's worth of carbon dioxide emissions from the nation's coal-fired powerplants. Though questions remain about the economics of systems to capture and store such gases, this study addresses a major issue that has overshadowed such proposals.

The MIT team's analysis — led by Ruben Juanes, the ARCO Associate Professor in Energy Studies in the Department of Civil and Environmental Engineering, and part of the doctoral thesis work of graduate students Christopher MacMinn PhD '12 and Michael Szulczewski — is published this week in the Proceedings of the National Academy of Sciences.

Coal-burning powerplants account for about 40 percent of worldwide carbon emissions, so climate change "will not be addressed unless we address from coal plants," Juanes says. "We should do many different things" such as developing new, cleaner alternatives, he says, "but one thing that's not going away is coal," because it's such a cheap and widely available source of power.

Efforts to curb greenhouse have largely focused on the search for practical, economical sources of clean energy, such as wind or solar power. But human emissions are now so vast that many analysts think it's unlikely that these technologies alone can solve the problem. Some have proposed systems for capturing emissions — mostly from the burning of fossil fuels — then compressing and storing the waste in deep geological formations. This approach is known as carbon capture and storage, or CCS.

One of the most promising places to store the gas is in deep saline aquifers: those more than half a mile below the surface, far below the freshwater sources used for human consumption and agriculture. But estimates of the capacity of such formations in the have ranged from enough to store just a few years' worth of coal-plant emissions up to many thousands of years' worth.

The reason for the huge disparity in estimates is twofold. First, because deep saline have no commercial value, there has been little exploration to determine their extent. Second, the fluid dynamics of how concentrated, liquefied carbon dioxide would spread through such formations is very complex and hard to model. Most analyses have simply estimated the overall volume of the formations, without considering the dynamics of how the CO2 would infiltrate them.

The MIT team modeled how the carbon dioxide would percolate through the rock, accounting not only for the ultimate capacity of the formations but the rate of injection that could be sustained over time. "The key is capturing the essential physics of the problem," Szulczewski says, "but simplifying it enough so it could be applied to the entire country." That meant looking at the details of trapping mechanisms in the porous rock at a scale of microns, then applying that understanding to formations that span hundreds of miles.

"We started with the full complicated set of equations for the fluid flow, and then simplified it," MacMinn says. Other estimates have tended to oversimplify the problem, "missing some of the nuances of the physics," he says. While this analysis focused on the United States, MacMinn says similar storage capacities likely exist around the world.

Howard Herzog, a senior research engineer with the MIT Energy Initiative and a co-author of the PNAS paper, says this study "demonstrates that the rate of injection of CO2 into a reservoir is a critical parameter in making storage estimates."

When liquefied carbon dioxide is dissolved in salty water, the resulting fluid is denser than either of the constituents, so it naturally sinks. It's a slow process, but "once the carbon dioxide is dissolved, you've won the game," Juanes says, because the dense, heavy mixture would almost certainly never escape back to the atmosphere.

While this study did not address the cost of CCS systems, many analysts have concluded that they could add 15 to 30 percent to the cost of coal-generated electricity, and would not be viable unless a carbon tax or a limit on carbon emissions was put in place.

While uncertainties remain, "I really think CCS has a role to play," Juanes says. "It's not an ultimate salvation, it's a bridge, but it may be essential because it can really address the emissions from and natural gas."

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1.4 / 5 (9) Mar 19, 2012
This should make the CO2 AGWites happy. But what about the particulate matter from coal burning? I think all that soot is far more dangerous to human and animal health.

1.5 / 5 (15) Mar 19, 2012
This research is paid for by YOUR money, money that you could be buying food with. It is the university equivalent of a man digging a ditch and a man following right behind him filling it back in. THIS is the reason that the US is in the poor shape it is in. People are getting paid to do nothing useful for society.
5 / 5 (8) Mar 19, 2012
So, MR166, present *your* plan for handling all the excess CO2. (You do have one, we must suppose, that will work at least as well and cost significantly less ... and if so, why has nothing been done so far to announce it, much less implement it?)
1.4 / 5 (11) Mar 19, 2012
CO2 is a harmless trace gas that contributes very little to today's warming or lack there of. It makes more sense to sequester belly lint!
3 / 5 (26) Mar 20, 2012
It must be nice to be smarter than the scientists at MIT.

I for one am glad for the fantastic new method of sequestering belly lint. Doh!

Good article. Well written, and covers the subject.

5 / 5 (5) Mar 20, 2012
Burning coal will not stop until the coal is gone, because the driving force for economic development of industrializing nations will not stop. CO2 emissions will not be curbed until the direct, immediate economic cost of continued emission is greater than the cost of sequestration and storage.
1.4 / 5 (9) Mar 20, 2012
Burning coal shouldn't stop until all the alternative energy sources are in place and working efficiently, cleanly and inexpensively. Coal provides the energy to run your fridge and washing machine, and your TV and cpu. If burning coal for energy ceases too soon, be ready to discontinue your use of electricity unless you have access to alternative energy. Best thing for now is to insist that the coal companies filter their soot and gas emissions immediately if not sooner.
Attend your electricity provider's meetings and tell them in no uncertain terms, that you are concerned about those soot and gas emissions from the coal-fired furnaces that boil the water to produce steam that turns the turbines which produce electricity. Talk up and bring as much information with you to prove your point. Be forceful and they will listen. Make sure those filters are installed and changed on a regular basis.
3.9 / 5 (7) Mar 20, 2012
Another coal company shill. This one tries to deflect the argument to particulates and filters.I hope you are paid well for your services. A soul is not cheap, Rich Guy.
4.5 / 5 (4) Mar 20, 2012
Burning coal shouldn't stop until all the alternative energy sources are in place and working efficiently, cleanly and inexpensively.
There are environmental and geopolitical risks, which pure monetary economy cannot evaluate reliably. In addition, the price of fossil fuels may not reflect the fossil fuel supplies from many reasons. The consumption of energy during mining will be simply compensated with elevated consumption of fuel at place, so that the cost of fuel will remain the same. In addition, the mining companies tend to overvalue the actual state of resources, because it enables them to increase the mining quotas and it makes them more competitive.

In such way, the price of fossil fuel at market doesn't correspond the supply and demand equilibrium, which is why it fluctuates wildly. And when the resources will get depleted, then the low prices of oil will step suddenly, which will trigger the nuclear war.
4.6 / 5 (5) Mar 20, 2012
It means, if we would consider the cost of environmental impacts of fossil fuel burning (the decline of fishing due the devastation of plankton with carbon dioxide) and the prices of oil wars (Kuwait, Iraq, Iran), then the price of fossil fuels wouldn't appear so competitive. But people tend to ignore the hidden cost of fossil fuel burning, until the most powerful group of people will profit from it. It leads to the ridiculous situations, like the many years standing ignorance of cold fusion finding.

The whole problem is, most of people understand very little the global mechanisms of their own society in which they're living. They're ignoring them in solely unconscious way in the same way like the cow ignores the stars at the meadows.
1.4 / 5 (11) Mar 20, 2012
"It must be nice to be smarter than the scientists at MIT."

Nope, they are much smarter than I am. They figured out how to milk the system and get paid for useless reasearch.

This AGW scam is doing untold harm to the respect that informed people once held for scientists. They are one step below lawyers and politicians in my book since they have become nothing but tools of a corrupt system.
1.8 / 5 (5) Mar 20, 2012
Nope, that are much smarter than I am. They figured out how to milk the system and get paid for useless research.
Of course. The ignorance of scientists is not because they're stupid, but because they're smart enough to recognize, which technology could threat them and which not. They simply do follow their profit like every other group of people in most optimal way
Of course, the simplest way how to handle the excessive carbon dioxide is not to produce it. We cannot burn all fossil fuels anyway - even at the time of cold fusion we will need the at least 30 percent of oil consumed by now for chemistry and plastic industry.
3.7 / 5 (6) Mar 20, 2012
Another coal company shill. This one tries to deflect the argument to particulates and filters.I hope you are paid well for your services. A soul is not cheap, Rich Guy.
So, if someone disagrees with you they are automatically a soul-less shill who is being paid by coal companies? Hate much?

He is simply talking about mitigating the damage until reliable alternatives are in place. I don't see the down side here, and I happen to agree. If you were to shut off the coal companies right now - millions will die before alternative sources could fill the gap. I don't consider that a viable or a humane alternative.
3.4 / 5 (5) Mar 20, 2012
At the pressures required to inject CO2 into a well (> 5.1 atmospheres) it becomes a liquid.
The project becomes the same thing as fracking except that CO2 is used instead of water.
1 / 5 (4) Mar 20, 2012

This article from 2006 makes sense. Sequestering CO2 as a liquid in the ocean. . .under the sediment.
2.3 / 5 (3) Mar 24, 2012
Everyone knows we mine CO2 in Colorado, right? Pipe it, out of the ground, to Texas, where they pump it back into the ground to push out black gold, Texas Tea.

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