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Q&A October 2008

Q How do scientists get CO2 to the ocean floor and push it underground? Won’t it explode?
—Submitted by 4th through 6th grade students participating in Birch Aquarium at Scripps' Summer Learning Adventures program.

Storing CO2 underground is a lot like pumping oil or natural gas out of the ground – just in reverse. Oil companies have developed considerable technology to let them pump oil up to the surface from underground reservoirs. They have been able to reverse this process in order to pump CO2 from the surface down to the end of the pipe into an empty underground reservoir where the gas can be stored for a long time.

Sleipner Carbon dioxide extracted from gas production on Statoil's Sleipner West field in the Norwegian North Sea is stored 1,000 meters below ground instead of being released to the air. Credit: Alligator film /BUG / StatoilHydro

The reservoir, which probably is one that used to store oil or natural gas, isn't really empty – it's usually filled with sand and water, and the water gets pushed aside to make room for the CO2. Luckily carbon dioxide is safe to pump because it doesn’t burn. It’s a fairly stable gas.

SleipnerStoring CO2 underground is a lot like pumping oil or natural gas out of the ground – just in reverse. Credit: Photo: Dag Myrestrand / StatoilHydro


The trick is being sure the CO2 stays down there. Being a gas and lighter than water, carbon dioxide wants to bubble back to the surface through the sand and rock layers. The key is to find a rock layer that the CO2 can't get past because it's so dense and tight (or “impermeable,” as scientists say).

—Mark Zumberge, research geophysicist, Institute for Geophysics and Planetary Physics


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Scripps Scientists take on questions from students curious about ocean and earth sciences


Mark Zumberge

"Storing CO2 underground is a lot like pumping oil or natural gas out of the ground – it’s just in reverse." — Mark Zumberge research geophysicist, Institute for Geophysics and Planetary Physics