EGEE 101
Energy and the Environment

Sequestration: Part 2 - In the Ocean

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Recall the carbon cycle: The key to this issue is waiting long enough for the CO2 in the atmosphere to reach equilibrium with the CO2 in the ocean, at which point a significant quantity of CO2 will have been "removed" from the atmosphere - the problem is time. As my daughter likes to say on our road trips "it is taking too long!" That is the case here. We can not afford to wait. However, the good news is that the ocean offers significant CO2 storage capabilities (for long-term timelines).

There are 3 approaches to this process:

Fertilize the ocean

Remember how crude oil is formed? If there were more "bugs" in the ocean (phytoplankton) then as they grow and reproduce they will absorb CO2 (remember this is photosynthesis)! They will die and decay but providing there are more of them and they are self-replicating (whatever the outcome of plankton sex is) then there will be more carbon in the ocean and less CO2 in the atmosphere. This is a carbon sink (more on this later). The ocean "bugs" can also grow shells, which they obtain from the dissolved minerals in the ocean and dissolved carbon dioxide. "She sells sea shells on the sea shore!" Try saying that 4 times as quickly as you can. So the shells can also capture CO2 for long periods of time.

 Plot showing much of the worlds carbon is in the ocean.

"The ocean plays a vital dominant role in the Earth's carbon cycle. The total amount of carbon in the ocean is about 50 times greater than the amount in the atmosphere, and is exchanged with the atmosphere on a time-scale of several hundred years." Credit NASA
The equilibrium between CO2 in the atmosphere and the ocean is dominated by the ocean capacity.
Graph showing the CO2 cycle in the ocean.
Once we get CO2 into the ocean is still has a complex internal recycling that occurs.
Credit: NETL

Inject CO2 into the ocean to form hydrates

Check out the Monterey Bay Aquarium Research Institute) for more information about this topic.

 Graphic showing the cycle of cleaned, compressed carbon dioxide.
The cleaned, compressed carbon dioxide needs to be transported to deep water if you wish to form an underwater CO2 lake.
Credit: IBI
 Graphic showing the global carbon cycle.
The Global Carbon Cycle.
Credit: ILI

Inject CO2 to the bottom of the ocean to form a CO2 lake (underwater).

If you are a visual learner and would like to see liquid CO2 fill a beaker underwater (considerable depth): click on the image below to download and watch a short video.

 link to a silent video
Credit: MBARI

But there is a lot of concern about perturbing the ocean so this is not a very likely solution.