How Seawater Might Soak Up More Carbon
Early this year, Gaurav Sant will flip a switch on a machine aboard a battered barge tied up at a dock on the Los Angeles waterfront.
If all goes as expected, a pump will suck water from the Pacific Ocean through a 3-inch-wide pipe into a metal box roughly the size of a delivery van. An electrical charge flowing through that box will spark a series of chemical reactions. The water will flow out through another pipe and back into the ocean.
To the naked eye the water will look unchanged, but there will be one crucial difference: The outflow will have less carbon dioxide.
The CO2 will instead be broken into bicarbonate molecules or trapped as an ingredient in calcium carbonate, the same material corals use to build reefs. The carbon inside them will stay out of the atmosphere for millennia—and water leaving the device, now stripped of CO2, will be able to reabsorb even more of it.
Geoengineering has moved from a fringe idea to a real, albeit controversial, possibility.
On its own the machine, along with a twin project planned in Singapore, won’t make much of a dent in the planet’s greenhouse in a year, the equivalent of the annual output from around eight of the cars plying LA’s legendary freeways. But if they work, Sant, an engineer at the University of California, Los Angeles, is thinking much, much bigger.
