Burying our excess atmospheric carbon dioxide might offer a way out of future climate chaos, but there are a few downsides to carbon sequestration as we know it today. One, it’s expensive. And two, it’s hard to keep a gas deep underground when it’s so much lighter than everything else around it.
Well, an engineering professor at the University of Texas at Austin thinks he might have an answer to the second objection.
Steven Bryant, who’s scheduled to give a presentation on his solution at this week’s International Conference on Greenhouse Gas Control Technologies in Washington, D.C., proposes to mix the carbon dioxide with saltwater first. The kind-of salty soda, he says, would be easier to keep buried than regular compressed carbon dioxide.
Bryant’s method goes like this: drill wells into appropriate sequestration sites under the oceans and pump out the saltwater. Then use above-ground mixing tanks to dissolve the carbon dioxide in the water before pumping the fizzy stuff back underground.
Mixed with the carbon dioxide, the newly reintroduced saltwater would be heavier and denser than regular seawater, so wouldn’t have the tendency to rise, Bryant says.
“This process has several advantages, but the most important is that it eliminates the risk of sequestered carbon dioxide escaping from the storage formation,” Bryant says. He adds that, while the procedure costs more than standard sequestration techniques, it’s not prohibitively more.
“In essence, the incremental cost can be regarded as the price of risk reduction,” he says. “This is an important consideration because all stakeholders will want the greatest assurance of secure storage for the lowest cost.”
