Greenhouse Gas Can Find a Home Underground

My name is Ruben Juanes, and I’m a professor in the Department of Civil & Environmental Engineering at MIT. In my research group, we study (among other things) carbon capture and storage. Carbon capture and storage is a promising technology to reduce CO2 emissions in the atmosphere from large, stationary sources, like coal-fired & gas-fired power plants. The idea is to capture CO2 from the flue gas of these plants and then inject it into deep geologic reservoirs for long-term storage. These reservoirs are typically one to three kilometers underground, well below the freshwater aquifers used for drinking water. They are bounded above by one or several caprocks, that prevent the upward flow of CO2, back to the surface. A key question for the future of carbon capture & storage is: for how long can it stabilize CO2 emissions? To answer this question, it is essential to understand how CO2 behaves in the subsurface. We model the subsurface fluid dynamics of CO2 storage. To begin with, we model the injection of the CO2, to ensure that the injection pressure does not become too high, and fracture the caprock. We also model what happens to the CO2 after injection, to ensure that it does not travel to a potential leakage pathway, like a large fracture shown here in red. After injection, the CO2 will migrate upslope beneath the caprock, because it’s buoyant. As it migrates, the plume of CO2 will become arrested by two trapping mechanisms. One mechanism is capillary trapping. During migration, the CO2 will become immobilized into blobs by capillary forces in the wake of the plume, show as light grey in the cartoon. The photograph shows residual CO2 in a tank packed with glass beads that simulates the storage reservoir. The second trapping mechanism is solubility trapping. Since CO2 is soluble in water, the plume of CO2 will dissolve into the groundwater, shrinking as it migrates. It turns out that the water with dissolved CO2 is more dense than groundwater, and therefore dissolution will lead to an unstable configuration: a layer of dense, CO2-rich fluid, sitting over the lighter ambient groundwater. As a result, the dissolved CO2 will sink away from the plume, to the bottom of the reservoir, in a process known as convective dissolution, which we illustrate with a hi-res computer simulation. This process will greatly accelerate the dissolution rate, and together with capillary trapping, will eventually cause all of the CO2 to become completely trapped. To determine how much CO2 could be stored in the United States, we studied 20 of the largest, most promising deep saline aquifers over the country. For each saline aquifer, we calculated the maximum amount of CO2 that could be stored subject to two constraints: the ejection pressures must be low enough to avoid damaging the caprock, and the CO2 must be completely trapped before migrating to a major leakage pathway. The footprints of trapped CO2 in these saline aquifers is shown here in blue. We found that the United States can store enough CO2 to stabilize emissions at their current rate for over 100 yrs. This result suggests that with a favorable political and economic framework, carbon capture and storage can be a viable climate change mitigation option in this country for the next century.

Comments 8

  • Ohh man, can't pump all that CO2 into the crust, it'll mess with all the underground Reptilian Alien bases!

  • I'ts great to see that options like these exist. Because there will always be some CO'2 emitting powerplants. But I think that it would be much better for the environment, if we would try to shut down the coal powerplants and build nuclear powerplants if there isn't enough energy from green sources. I migh't be wrong but I think that its extremely more secure to keep Radioactive material underground than CO'2 because there much less amounts and its not a gas(or watersolution).

  • @DarkSmith91 you said it, YOU'RE WRONG! Moreover JUST TALK ABOUT WHAT YOU REALLY HAVE LEARNED AND STUDIED! Nuke wastes HAVE NOTHING to do, in matter of SHORT-TERM HAZARDS OCCURRENCES, with CO2 issues. Nothing! Unless you are some french AREVA under-covered "commenter"…

  • Why does everybody get that emotional when hearing the word radioactive ?! I know that nuclear waste is a completely different story than CO2 emission. But that doesn't mean that you can't compare them! Because both are an undesired byproduct of different powerplants and the question ist which is worse in our current situation.

  • i am thinking about what will happen after 100 years?

  •  Joseph P Trantas, Sr.   i need your help please watch pt-1 and pt-2 very important !!!!!! also dr john holdren thank you  if I have to watch one more video of all these experts talking about greenhouse gases I'm going to explode I am showing something with greenhouse gas that is 10 times bigger than their story but no one is looking at this it drives me crazy how could you talk about this without looking at my research please take the time to watch the video I posted this problem must come to the front of all conversations pertaining to climate change study especially greenhouse gases thank you     

  • What about contaminated aquitards and aquifers? What about biological activity that will die as a result? organisms won't be able to migrate upwards/downwards on the strata. They will die along the way; killing the ecosystem. This is really bad. I don't believe in these Co2
    "traps", that's just not possible- let alone depressurization and porous flow. I wonder what hydrogeologists really think about this "patch" solution. I think the background song only wants to give a "modern touch" to the overall proposal, yet these solutions will only create more problems.

  • anything harm for ecosystem ?

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