Seabed Aquifer Sequestration

Seabed aquifers are saline aquifers located under the ocean floor and are composed of basalt or sedimentary formations, which are buried under low-permeability sedimentary rocks that serve as cap-rocks.  When CO2 is injected at depths greater than 2700 m below the ocean's surface, it is pressurized to the point that it becomes denser than seawater, so it is very unlikely to escape or even reach the level of the cap-rock (Goldberg, 2009).  Some CO2 also combines with water to form CO2 hydrate, an ice-like substance which is also denser than seawater, eliminating the danger of escaped CO2 surfacing (Goldberg, 2009).



Potential Storage Sites:

(Goldberg, 2009)

Capacity Estimates:

For comparison, 28.9 Gt CO2 represents the global total for emissions in 2007 (IEA, 2009).

Cost Estimates:

(in reference to the Sleipner project)

(In reference to the Snøhvit project)


Seabed sequestration is a technology that is available now.

StatoilHydro, a Norweigan energy company, has implemented commercial-scale projects that are already storing CO2 in saline aquifers undersea.


Sleipner was the world's first full-scale carbon capture and sequestration plant.  Carbon sequestration began in the Sleipner aquifer in the North Sea in 1996.  Since then, 1 million tons of CO2 have been injected each year (Gale, 2006).  By monitoring the wells over more than a decade, scientists have been able to get some measure of the effectiveness of the trapping mechanisms present in seabed saline aquifers.  So far, no leaks have been observed, and there has been no seismic activity caused by the drilling and injection process (Bellona, 2007).


The Snøhvit petroleum production plant in the Barents Sea began sequestering carbon in April 2008.  Its annual injection rate is about 700,000 tonnes per year.  As in the Sleipner project, the injection process is being monitored constantly, and no leakages have been detected (Statoil, 2008).