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Mineral springs: Calcium carbonate rock that forms as alkaline, calcium-rich water seeps from underground springs in Oman.
Jürg Matter
The researchers propose a carbon-sequestration strategy that would eliminate the need to transport carbon dioxide, as well as the need to heat up the rock. In this scenario, they would access rock formations in shallow ocean waters off the coast of Oman and elsewhere by drilling into them and fracturing the rock using existing oil-industry techniques. The researchers would drill two holes. Into one, they'd pump cool seawater. Rock temperature increases with depth, so as the water is pumped into the holes, it will get hotter, until it reaches nearly 185 °C. Carbon dioxide naturally dissolved in the water would then precipitate out of the solution. The hot water would eventually make its way through the fractured rock to the second drilled hole, where it would rise to the surface via convection. This seawater would quickly absorb more carbon dioxide, since shallow waters and surf mix well with the atmosphere. Because "the atmosphere transports carbon dioxide all over the world for free," Kelemen says, this approach, if deployed on a grand scale, could be used to lower worldwide levels of carbon dioxide.
This scenario would be limited by the concentration of carbon dioxide in seawater, so a cubic kilometer of rock would only sequester about a million tons of carbon dioxide a year. But since it wouldn't be necessary to transport carbon dioxide or pay to heat the rock, Kelemen says, it would be possible to work with much larger areas of rock, and thereby reach a rate of billions of tons of carbon dioxide per year.
"From a conceptual point of view, all they say makes sense," says Mazzotti. Yet questions remain about whether the methods will work in practice. For one thing, the self-sustaining reactions depend on the magnesium carbonate and other precipitates continuing to fracture the rock to expose more of it. The researchers have observed that this has happened in the geology in Oman, but it's not a given that it would continue in the scenarios that they propose. The researchers' concepts should now be complemented with large-scale tests, Mazzotti says.
The end of an ambitious carbon-capture project shows that it's hard to economically justify the technology in the absence of a carbon policy.
Despite subsidies and new projects, carbon dioxide sequestration is still a long way off.
A New Jersey plant is planning to put ocean-floor carbon sequestration to the test.
If this process is really self sustaining and could sequester more CO2 than we produce it could be very dangerous. Best to be absolutely sure what we're doing before we try it.
The researchers say that, although the reaction is self-sustaining, it's not difficult to quench. In the on-land example, carbon dioxide rich fluid must be actively pumped in to keep the reaction going (in this case, the reaction is only self-sustaining in the sense that no external source of heat is needed to maintain the optimal reaction temperature).
In the shallow waters example, a hole that can be drilled can also be plugged up. That would stop the flow of water and carbon dioxide, and again the reaction would stop.
bottom line, though, it is foolish to remove carbon arbitrarily when not even one shred of evidence shows it to be responsbile for climate change.
I thought the assignment was to come up with an alternative that doesn't substitute massive environmental disruption in one area for another kind of massive environmental disruption. How do the people of Oman feel about this solution? Fail.
Re: This doesn't scare anyone?
The water coming back up the 'second' hole would be hot, rich in magnesium carbonate, poor in dissolved CO2, and more alkaline than the surrounding sea water. That would likely disturb the marine ecology 'near' the hole, but how near? If it's just a few feet, it probably wouldn't matter. If it extended for miles, it probably would be a problem.
Ask the oceanographers for some help on this one.
It sounds like the oil and coal industry has dreamed up a scheme to continue their rape of Earth and it's residents by sweeping their s--- under the rug.
Would beat the carbon trade system
We're not junking gas cars/trucks for quite awhile. And solar gets more efficient & less expensive all the time.
Certainly worth some trials.
Would like to see map of where low depth minerals are concentrated.
Manufacturing in the United States is in trouble. That's bad news not just for the country's economy but for the future of innovation.
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boustrephon
50 Comments
Intakes
I wonder how large the intakes will have to be to accommodate the filters to avoid sucking large numbers of marine organisms into the pumps.
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