The short answer is: All of it.
Scientific estimates show that the global potential for geological storage of CO₂ outweighs all greenhouse gases ever emitted since the Industrial Revolution approximately by a factor of 3.
In Iceland only, where our plant Orca is located, over 400 billion tons of CO2 could be stored. Its ideal conditions make Iceland the perfect site to start with. But it is also possible on a global scale.
On a global scale, the potential for CO2 storage is even bigger. As there exist different approaches to store CO2 underground, estimates vary considerably. For underground storage of CO2 via mineralization, the global potential has been estimated at up to 60 million gigatons. Climeworks is exploring storage options around the world, for example in Oman with the storage company 44.01.