Stoning Carbon
Can Climate Alchemy Save the Planet?

Carbon capture and sequestration (CCS) may be the climate tech pipe dream, and scientists just took CCS a big step forward by demonstrating a novel new way to sequester captured carbon. CCS works by taking carbon dioxide—a greenhouse gas—out of the atmosphere and somehow storing it, thereby severing the link between CO2 emissions and rising global surface temperatures. If we were able to cheaply deploy this on a commercial scale, we could puncture the rising panic over our planet’s changing climate with one technological fix. Unfortunately, CCS isn’t scaling well, and at the moment is too expensive to talk about it as a viable solution.

Besides cost and scaling, critics have also pointed to the shakiness of the second half of this two-step process: the sequestration. Up until now, most of the focus has been on storing captured CO2 underground, but that option raises worries over potential leaks. Now, as the New York Times reports, a group of scientists in Iceland has discovered that when CO2 is injected in solution into basalt rock, it mineralizes, or turns to stone:

In 2012, they pumped about 250 tons of carbon dioxide, mixed with water, about 1,500 feet down into porous basalt. The CO2 was laced with a radioactive isotope and there were other compounds in the water that helped the researchers trace its spread into the rock. […]

The scientists found that about 95 percent of the carbon dioxide was converted into calcite. And even more important, they wrote, the conversion happened relatively quickly — in less than two years. “It’s beyond all our expectations,” said Edda Aradottir, who manages the project for the utility, Reykjavik Energy. Rapid conversion of the CO2 means that a project would probably have to be monitored for a far shorter time than a more conventional sequestration site.

Now, the caveats. This was a relatively small-scale test conducted in a basalt-rich region of the world. Scaling this sequestration option up to global levels would require a lot of water (to dissolve the CO2 into) and a lot more favorable rock formations. Moreover, it’s expensive: the lead author of a study of this Medusa-like test released in the journal Nature this week said this sequestration method could cost twice as much as storing the greenhouse gas in old wells. We don’t need to tell you that doubling the cost of an already too-expensive process is moving in the wrong direction. Finally, this only addresses one half of the CCS conundrum—we would still need to develop ways to efficiently “harvest” CO2 from our planet’s atmosphere in massive quantities.

Still, this is exciting progress. Scientists have pointed out that the project is scalable if we look to our seabeds, where there’s plenty of water and basalt. Costs can come down over time as researchers and interested companies iterate and innovate new approaches to the problem. Climate change is a real and growing problem, but it isn’t one to which we need to resign ourselves. If there’s one thing our species does well, it’s solve problems, and that’s exactly what this Icelandic team has just demonstrated.

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