How CCS works

Remove CO₂

CCS is a group of complementary technologies which remove carbon dioxide from fossil-fuel power plants and large-scale sources, such as energy-intensive industries (for example steel, cement and refining.) CCS can also be used on bio-based industries (called bio-CCS or BECCS) as a CO₂ negative emissions technology, whereby it actually removes carbon dioxide from the atmosphere.

Additionally, capturing and storing the CO₂ from the process in which pure hydrogen is extracted from natural gas results in a source of low-carbon hydrogen. This can be used to remove emissions from several areas such as domestic and industrial heating, heavy onshore transportation and in the maritime sector.

First: Capture

There are several different technologies for CO₂ capture at different maturity levels. In some cases, CO₂ can be an integrated part of the production process.

The cost of CO₂ capture varies from source to source depending on several factors. For example, the proportion of CO₂ that is entrained in the exhaust gas, the availability of low-cost energy/heat, and opportunities to integrate CO₂ capture in the production process. This means that some facilities are low-hanging fruit for implementing CCS.

Second: Transport

Once captured, carbon dioxide is transported by pipeline or ship to a suitable storage site. The technologies involved in transportation are similar as those used extensively for transporting food grade CO₂ and natural gas around the world.

Transportation of carbon dioxide has been carried out for over 40 years (particularly in the US for use in Enhanced Oil Recovery). Transportation of CO₂ by ships and road is part of the daily business in the food grade CO₂ market but in smaller volumes.

There are currently 7,762 km of operational carbon dioxide pipelines in the United States.

Third: Store

CO₂ can be isolated from the atmosphere by a variety of techniques. Currently, the most cost-effective technique for safely storing large volumes is to mimic nature and recycle the carbon back into the Earth’s sedimentary basins – from where humans have extracted it in the form of fossil fuels. This process is referred to as geological storage of CO₂, or just CO₂ storage.

Once carbon dioxide has been transported to a suitable location in liquid form, it is pumped into an oil or gas reservoir, which may or may not hold natural reserves of hydrocarbons or CO₂ from before. The common feature of any suitable reservoir rock is that it contains a fine network of small, interconnected pores that allow the liquid CO₂ to mingle with salt water already present underground.

These fluids remain a great distance below the surface and are separated from it by multiple layers of the kinds of impermeable, clay-rich rock which make finding oil and gas deposits so challenging.

Industrial experience of injecting CO₂ underground is widespread, ranging from Canada and the US to Brazil, Turkey, China and Hungary.