Carbon dioxide air capture

Carbon dioxide air capture or Carbon dioxide removal (CDR) is a form of carbon capture, and it part of a potential process of carbon sequestration. It removes carbon dioxide from ambient air by carbon dioxide scrubbing. It is a different approach to removing CO₂ from the stack emissions of large point sources, such as fossil fuel fired power stations. It is regarded as greenhouse gas remediation, which is a branch of geoengineering. Some commentators regard air capture as a form of carbon capture and storage, but CCS is usually used to describe capture at source rather than capture from ambient air. CDR methods are notably supported by IPCC chief Rajendra Pachauri.

Air capture is not generally seen as an attractive alternative to capture at large, point source emitters (such as power plants), as it is likely to be more efficient and cheaper to capture and store carbon dioxide from more concentrated streams. There are, however, some advantages of air capture as it removes the need for CO₂ piping to transport the gas to underground storage sites, and allows the use of renewable energy and optimal storage sites.

It is particularly effective at dealing with small point sources such as domestic heating systems and vehicle exhausts, where piping of exhaust gases is impractical.

The mitigation effectiveness of air capture is limited by societal investment, land use, and availability of geologic reservoirs. These reservoirs are estimated to be sufficient to sequester all anthropogenically generated CO₂.

Carbon Dioxide Removal Benefits

There are several benefits to using air capture:

• Capture of CO₂ from dispersed sources (e.g. cars and domestic heating systems) is possible.
• Energy required for the process can be cheaply generated renewables, as long distance transport of power is unnecessary.
• Geographic flexibility will allow the use of near optimal carbon storage geology and reduces labour costs.
• Administration and control will be easier with large, centralised facilities.
• Support industries could naturally 'cluster' around air capture plants, reducing costs.
• As a geoengineering approach, because it is a greenhouse gas remediation technique it is superior to solar radiation management techniques, as it removes CO₂ from the atmosphere and thus prevents ocean acidification. It is, however, slower acting.