Admittedly, before reading the actual paper I was a little uneasy about the latest paper in PNAS by Goldberg et al. The paper describes a deep-sea basalt formation that would allow for storage of anthropogenic carbon dioxide. The area is the Juan de Fuca plate of the Oregon and Washington Coasts. The authors suggest that the area
provides unique and significant advantages over other potential geological storage options, including (i) vast reservoir capacities sufficient to accommodate centuries-long U.S. production of fossil fuel CO2 at locations within pipeline distances to populated areas and CO2 sources along the U.S. west coast; (ii) sufficiently closed water-rock circulation pathways for the chemical reaction of CO2 with basalt to produce stable and nontoxic (Ca2+, Mg2+, Fe2+)CO3 infilling minerals, and (iii) significant risk reduction for post-injection leakage by geological, gravitational, and hydrate-trapping mechanisms.
The new proposed site is a 78,000 square kilometer part of the ocean floor 2500m down. Under 200m of basalt the plan would be to pump as much as 150 years of the U.S CO2 production. Will it work? At current the technology still needs work but the proximity to shore makes the Juan de Fuca at least semi feasible. However, we are still looking at 5-10 year time frame at the minimum. The chemical process between basalts and CO2 convert it into a solid benign chalk material. The scientists here even mapped out specific areas that they say are isolated from earthquakes, hydrothermal vents or other factors that might upset the system. Unreacting CO2 would not rise up through the formation and even if it did the formation is capped with clay sediments.
The environmental impacts are harder to assess but if CO2 escapes during the injection process there could be significant local mortality. The nearby Juan de Fuca ridge is a active volcanic spot lined with many hydrothermal vents and their associated communities. Are there unforseen impacts of to these systems? How geologically stable is the site actually? Is this potential for local impact worth the removal of 150 years of CO2 from the atmosphere? Are we trading one habitat or organism for another?
Hard questions to answer. Of course I don’t feel these are faults of the study or the author. However you can see why I feel uneasy. But there is more…
First it seems that the move is into the deep. We ran out fish…go to the deep! We need oil…get it from the deep! What do we do will all this rubbish…put it in the deep! Where can we get precious metals…from the deep! Where do we put all of our excess carbon dioxide we generate…into the deep! All of these share one thing in common as solutions, besides relying upon the deep sea, they don’t actually address the cause of any of the problems…overfishing, overpopulation, reliance on fossil fuels, pollution, etc. It is easier it seems to put a band aid on the issue than to address the issue itself.
Goldberg, D.S., Takahashi, T., Slagle, A.L. (2008). Carbon dioxide sequestration in deep-sea basalt. Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0804397105