Scientific opinions differ over whether it would be more desirable to stop burning fossil fuels than to undertake massive carbon-sequestration ventures — but if sequestration were to be favored, many think that basalt could be important. And although backers of large-scale basalt sequestration have so far explored formations in the US northwest and southeast as well as in India, many are also looking offshore, where the sea floor could accommodate CO2 emissions for centuries to come.
Carbon-sequestration research has until now tended to focus on sandstone reservoirs rather than basalt. There are two main reasons, says David Goldberg, a marine geologist at Lamont-Doherty. The oil industry is used to working with sandstone, and such formations are relatively common — making it easier to transport CO2 from a power plant or other source to a sequestration site. That might mean that sandstone is more economically viable than ocean basalt, at least in the short term. But Goldberg says that the best place to bury globally significant volumes of CO2 is offshore, where they will be safely capped by sediments and sea water.
A single formation off the US west coast, with an estimated storage volume of 685 cubic kilometers, has the potential to hold all the CO2 emissions the country produces in a century, Goldberg notes. “If we can make it work,” he says, “the oceans have a lot of advantages.”
But none of this will be cheap, says Kevin Johnson, a geochemist at the University of Hawaii in Honolulu who has worked on lab experiments with McGrail’s team. “It’s a question of social importance — and whether the climate situation gets dire enough to justify the cost.”