“Equatic’s process works like this: first, it pumps sea water into an electrolyser, a machine that uses electricity to split water into hydrogen and oxygen, which in Equatic’s case is run on clean electricity such as wind, solar or hydro. This converts the seawater to hydrogen gas, oxygen gas, an acid stream and an alkaline slurry of calcium and magnesium-based materials. The alkaline slurry is exposed to air, pulling out CO2 and trapping it, then discharged into the sea. A last step is to neutralise the acid waste stream using rocks (in order to avoid ocean acidification) before this is discharged into the sea too.

The CO2 captured by Equatic ends up in the ocean as dissolved bicarbonate ions and solid mineral carbonates, forms in which the CO2 is immobilised for 10,000 years and billions of years respectively, the company says. ‘In electrochemical methods that convert CO2 into a stable carbon like solid carbonates, the CO2 is locked away permanently,’ agrees Chen. ‘Unless that carbonate is heated to a high temperature of around 900C (1,200K), that CO2 will not be re-released.'”

From BBC.