CO₂ is stored safely deep underground, mainly offshore, but also onshore where appropriate. It is permanently stored between 1 – 3km down below the seabed or Earth’s surface.
CO₂ storage sites are carefully chosen to ensure the highest confidence in permanent storage and there is rigorous site characterisation, and ongoing monitoring and verification procedures in place to check the behaviour of the CO₂ and it ensure the stays safely stored. These assessments and procedures are required by CCUS regulations before a project is allowed to proceed.
Many of the potential storage site opportunities are large saline aquifers or depleted oil and gas fields which are well understood and have already stored gas and CO₂ naturally for millions of years.