Experiments on the ocean sequestration
of fossil fuel CO₂

Peter Brewer, Ph.D.
Monterey Bay Aquarium Research Institute

Wednesday, July 1, 1998
3:30 p.m.—Pacific Forum

The recent adoption of the Kyoto Protocol to the United Nations Framework Convention on Climate Change has accelerated interest in means of disposal, or sequestration, of fossil fuel CO₂. We already dispose of fossil fuel CO₂ in the ocean, in the amount of some two billion tons per year. The problem is that we put it in the air first, and then allow the global air-sea gas exchange process to take its measured course. The slowness of the air-sea exchange process leads to the accumulation of atmospheric CO₂ and the radiative forcing towards a warmer climate.

For several years there has been engineering interest in direct deep-ocean injection of CO₂ to ameliorate the impact on climate, and many quite speculative papers have been written. The focus has been on the use of CO₂ hydrates as a "permanent" means of disposal. Major international organizations have endorsed this strategy (see http://www.ieagreen.org.uk).

We have carried out the first series of direct ocean-injection experiments to evaluate this process. At depths greater than about 3,000m, the compressibility of CO₂ is such that the density of CO₂ becomes greater than seawater, and the experiment becomes gravitationally stable. We have used the research vessel Western Flyer and remotely operated vehicle Tiburon to execute this novel deep experiment. The phase behavior found is astonishing, unpredicted, dynamic, and dramatic, and leads to important new insights into this widely discussed phenomenon.

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