Carbon Capture and Storage (CCS) occurs when a relatively pure stream of CO2 from industrial point sources is captured, treated, transported to long-term storage locations and utilized with fossil fuels to produce low carbon energy sources.

CCS technologies involve extracting CO2 from the atmosphere and depositing it in deep geological formations such as basalts for long-term storage, complementing natural carbon storage techniques like soils and forests.

What is CCS?

Carbon Capture and Storage (CCS) technology enables polluting power plants to continue operations while helping mitigate climate change. CCS works by collecting carbon dioxide emissions at power plants before transporting them off-site for long-term storage.

Carbon dioxide can be captured before or after fossil fuel combustion using various methods, including chemical processes or physical adsorption processes (adsorption). Once captured, CO2 must then be compressed down for transport via pipelines, trucks or ships to an underground storage site where it will eventually be permanently stored within rock formations.

One such saline aquifer in the North Sea known as ‘Endurance’ can store large amounts of carbon dioxide for thousands of years; new technologies, including two-dimensional ‘ionic liquids’ are also being developed as ways of capturing and storing it.

However, CCS can be costly and currently lacks economic viability as a standalone technology. Most CCS projects worldwide are attached to oil and gas facilities which use it as a license to increase emissions rather than being implemented for decarbonisation purposes.

What happens after CO2 is captured?

Carbon capture technology (CCUS) involves collecting CO2 emissions from fossil fuel power plants before they enter the atmosphere, as opposed to “carbon removal,” which involves technologies which take CO2 directly out of the air such as forest restoration or direct air capture.

Once captured, CO2 can either be permanently stored underground in geological formations or used in products like concrete and chemicals or synthesized fuels that reemit CO2 when burned.

An alternative method would be using captured CO2 for enhanced oil recovery, increasing the amount of crude extracted from an existing oil field. As the climate impacts of using CCUS-generated CO2 depends on its source and end use, each project needs to be assessed on a lifecycle basis – using fossil-fuel-derived CO2 streams would have far greater adverse climate repercussions than using airborne CO2.

How much CO2 can be captured?

While CCUS may not be considered a zero-emission technology, it can help combat climate change by mitigating power plant and other energy intensive industry emissions.

At present, large-scale CCS projects capture and store carbon dioxide by converting it to liquid form, transporting it by pipelines (or sometimes trains), then injecting it deep underground geological formations for long term storage – typically depleted oil and gas reservoirs or coal beds.

Direct air capture (DAC), an emerging form of carbon capture and storage (CCS), removes CO2 directly from ambient air using chemical processing. DAC could form part of future NETCCS systems or be applied at existing facilities such as Texas’ NRG Petra Nova project using natural gas plants as carbon capture/EOR facilities; however, many significant barriers still prevent its widespread implementation including needing vast areas of land to grow plants that absorb CO2.

What is the cost of CCS?

Once captured, CO2 is injected underground for permanent storage, either into saline aquifers or depleted oil and gas fields. CO2 may also be stored underground coal seams if their rocks meet certain physical criteria or within geological formations such as organic shales.

CCS facilities can be costly to operate due to their need for large amounts of energy – typically drawn from steam and power circuits – for their operations, with significant amounts being consumed through internal energy use (leading to significant loss in saleable output that often goes unaccounted for). This contributes to increasing capital costs for the facility.

Carbon capture and storage technologies may not yet be economically feasible on their own; however, their development could make this feasible in future, leading to greater zero emission coal power usage as well as supporting deployment of other low carbon technologies like renewables or nuclear. This would lead to reduced Lifecycle Cost of Electricity Estimates across all forms of power production.