The CO2 is injected into porous basalt, which is covered by a deep impermeable cap of sediment on the ocean floor, where it dissolves in water. Then it binds with dissolved basalt minerals such as calcium, magnesium and iron silicates to transform into carbonate rock that can’t escape the seabed reservoir, Moran said.
There is enough sub-ocean basalt worldwide to potentially sequester 250,000 gigatons of CO2, said Tutolo.
“It’s not pie in the sky,” she said.