4. Carbon Dioxide Emissions

Today there are over 50 large CCS projects worldwide capturing and storing over 200 million tonnes of CO2 per year from sources such as steel mills, cement plants and coal/gas power stations.

CO2 is separated chemically from other gases in a smokestack before being transported through pipelines to storage sites, compressed, and then injected underground into deep geological formations such as oil/natural gas reservoirs or saline aquifers.

CO2 can be trapped in rocks through various means. One effective mechanism is structural trapping, in which rock layers and faults around a storage site act as seals to keep its CO2 trapped there permanently. For example, in the Zero Carbon Humber project in the UK they use an underground salty aquifer known as Endurance to store their CO2. Other projects utilize low porosity formations with high permeability that provide ideal environments for long-term CO2 isolation.