What are Carbon Dioxide Removal (CDR) and Carbon Capture & Storage (CCS)?

This article is part of illuminem's Carbon Academy, the ultimate free and comprehensive guide on key carbon concepts

"Carbon removal" and "carbon capture" are related concepts, but they refer to slightly different processes in the context of addressing climate change. 

1. Carbon Capture & Storage (CCS): Carbon capture involves capturing carbon dioxide (CO2) emissions produced from industrial processes, power plants, or other sources before they are released into the atmosphere. The captured CO2 is then transported and usually stored underground to prevent it from contributing to climate change. Carbon capture technologies are often used to reduce the emissions from existing facilities and can be applied to various industries. 

2. Carbon Dioxide Removal (CDR): Carbon removal, on the other hand, is a broader term that encompasses various methods to remove carbon dioxide from the atmosphere, not just capturing emissions from specific sources. Carbon removal techniques include natural approaches, such as afforestation (planting trees) and reforestation, as well as technological approaches like direct air capture. These methods aim to reduce the overall concentration of CO2 in the atmosphere, mitigating the effects of climate change.

According to The State of Carbon Dioxide Removal, the most recent report on CDR, CDR must follow 2 key principles:

• The CO2 captured must come from the atmosphere, not from fossil sources
• The subsequent storage must be durable, so as not to allow CO2 to be reintroduced to the atmosphere

Carbon Capture and Storage (CCS) does not fulfill these conditions:

• CCS does not necessarily result in durable net removal of CO2 from the atmosphere
• In CCS the CO2 comes directly from fossil fuels or minerals (for example, limestone). CCS technologies serve to either recycle or store fossil CO2 emissions that would otherwise be released into the atmosphere. They thus count as an emissions reduction rather than removal since the CO2 is taken out of the atmosphere only after having been emitted. In other words, CCS does not guarantee additionality, since industries take out the CO2 they have emitted and not the CO2 that is there regardless of their emission.

Note: CCS can, however, be applied to CO2 streams generated using biomass or directly from the air, in which cases the overall process counts as CDR. In the CDR report mentioned above, authors refer to “fossil CCS”, to distinguish it from CCS as a component of CDR methods.

In summary, carbon capture specifically focuses on capturing emissions from specific sources, while carbon removal encompasses a broader set of strategies aimed at removing carbon dioxide from the atmosphere, whether emitted from human activities or occurring naturally. Both concepts are crucial components of strategies to address and mitigate climate change.

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