Once captured, CO2 has to go somewhere, and where it goes has to be secure. “The good thing about basaltic rock is it’s so easy to explain,” Wurzbacher observed. “If someone asks you, ‘Hey, but is it really safe?’ the answer is very simple: within two years it’s stone, one kilometer underground. Period.” Suitable underground storage sites aren’t rare, but they aren’t common, either, meaning that, should large-scale capture plants ever be built, they’ll either have to be located in places with the right geology or the CO2 will have to be shipped long distances.
