Carbon capture and storage, as is evident from its appellation, has three stages. At the first stage, CO₂ is separated from other components of emissions like water vapour, nitrous oxide and sulphur oxide. The gas is then transported to the storage site either, via a pipeline, by ship and by road. Since the gas occupies a large volume, it is compressed or converted into liquid to reduce storage space.

The amount of CO₂ to be stored would have to be comparable to the amount that is currently emitted in order to achieve significant results. This can only be done in deep ocean or geological reservoirs. Technological and economic aspects of storing the gas in oceans are still uncertain. More importantly, the impacts on the environment (marine or the atmosphere) have not been properly understood.

Storage of CO₂ in geological formations, on the other hand, appears to be more promising. Potential sites include depleted oil and gas fields, deep saline aquifers and unmineable coal seams. Some of these have trapped hydrocarbons in gas or liquid states for millions of years through a natural process. CO₂ is injected into these formations at high pressures and temperatures. This process decreases the volume of the gas considerably.

At depths of the geologic traps, the pressure is high enough to further compress the injected CO₂ thus ensuring storage in larger quantities.