Could a Century's Worth of Carbon Emissions Be Stored Within the Juan de Fuca Plate?
by Jeremy Elton Jacquot, Los Angeles on 07.15.08
Image from D G Brown
A new study published in the Proceedings of the National Academy of Sciences makes the case that 208-250 billion tons of carbon dioxide -- roughly equivalent to a century's worth of future emissions (122-147 years, to be exact) -- could be safely stored within the Juan de Fuca plate, reports The Guardian's Alok Jha.
The tectonic plate, which arises from the Juan de Fuca Ridge, encompasses an area of the seafloor several hundred kilometers from the coasts of Washington and Oregon. David Goldberg, a geologist at Columbia University's Lamont-Doherty Earth Observatory, believes its basalt layers could be suitable for a carbon capture and storage (CCS) project.
Image from USGS
Physical vs. geochemical trapping
In their study, Goldberg and his colleagues describe two methods by which CO2 could be stored for the long-term: physical trapping (the gas is buried under layers that have zero to low permeability) and geochemical/mineral trapping (the gas reacts with the underlying rocks to form carbonate -- a stable, solid mineral).
The team chose the Juan de Fuca site because it matched several of their ideal criteria for CCS: They are under at least 2,700 meters of water and are covered by over 200 meters of sediment. At such a depth, CO2 becomes denser than seawater and liquefies -- which means that, even if a leak were to occur, it shouldn't be able to rise up to the surface.
The risks of ocean storage
A series of difficulties could complicate the enterprise, however. According to Andy Chadwick, a CCS expert from the British Geological Survey, Goldberg and his colleagues would first need to find a suitable number of fractures in the basalt into which they could pump the CO2. These fractures, which he says will be very difficult to locate, could be connected to the seafloor or surface -- which would provide leakage pathways for the gas.
Couple that with the sheer costs and infrastructure needed to mount such an effort -- not to mention the many unknowns -- and you're left with a risky, potentially unappealing carbon-mitigation option.
Via ::The Guardian: Ocean floor could store century of US carbon emissions (news website)
More about carbon capture and storage (CCS)
::Scientists Develop Low-Cost Version of Carbon Capture and Storage
::Ev-eon Water Stores Carbon Dioxide
::Vattenfall Promises More Carbon Capture At German Coal Plants
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I'm always doubtful about CCS. I think it is dangerous to give false hope, and that it might make people think business as usual is ok. But on another level, I acknowledge that eventually we will have to do something with all our carbon dioxide- what we've already emitted, for example.
And if those projections that say wind and solar reach parity with coal in the next couple of decades hold true, a good CCS plan could be enough to hold us over until the current generation of power plants needs replacing. I don't like to bet on dreams, but occasionally dreams come true anyway.
FYI, other names for "carbonates" are limestone and chalk.
Nice photo, I have to comment! That looks like it's on the cliffs at Dallas Road in British Columbia's capital city, Victoria (on Vancouver Island). It's probably right at the foot of Howe or Linden (Cook Street would be to the right), and you're looking west, past Finlayson Point and toward the Sooke Hills.
The body of water you see is the Strait of Juan de Fuca, which lies between us (Victoria) and Port Angeles/ the Olympic Peninsula, WA, and it's most certainly part of the Juan de Fuca ridge/plate, and rather close to home for me!
It's also where Victoria still pumps its raw sewage to ... :-(
That CO2 better solidify into limestone/ carbonate if it's ever sequestered in the Juan de Fuca ridge. Otherwise, if any of it "escapes" through underground fissures and reaches the site shown in your photo, who knows what might happen if it reacted with all that crap (literally) that we've pumped into the Strait in such a cavalier fashion? Maybe nothing, but I'm thinking it has sci-fi movie potential...
Even though the CO2 migjht be sequestered OK as described in the article, carbon capture and sequesteration still seems unlikely to help us out, too expensive. As far as I know, there are still no CCS demos actually running, nor are any expected soon. The problem seems to me one mainly of bulk. Trainloads of coal are delivered to powerplants, and for every ton of carbon in the coal (and good coal is mostly carbon), you've gotta separate, move and bury more than 3.5 tons of CO2. Trainloads in, multitrainloads out (actually, probably high pressure pipelines.)...wind power sounds more attractive all the time...DB
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I believe you mean store the CO2 WITHIN the Juan de Fuca Plate, not UNDER it. It is beneath the ocean floor within the tectonic plate that the rigid, fractured basalt occurs. Beneath (or under) the Juan de Fuca Plate (or any plate for that matter) is the very viscous mantle into which we have never drilled before.
Anyone who takes a look at that first photo and says to themselves, "Hey, that looks like the perfect place to sequester a bunch of toxic waste," should get kicked.
Hard.