Aligning on carbon capture and removal terminology
Navigating the acronyms' nuances
There seems be a lot of inconsistency with using the terms carbon capture vs. carbon dioxide removal, which leads to false generalizations about solutions that differ widely. And it is understandably confusing! All the acronyms sound similar and mean similar things, which is tough to keep track of. But the differences are critical. So, I figured I’d share some reputable definitions from American University’s Center for Carbon Removal Law & Policy, which I’ve found helpful in clearing things up:
Carbon capture: “any process for capturing carbon dioxide, whether from the atmosphere or from a smokestack or other concentrated source of carbon dioxide emissions. This term is sometimes used ambiguously to refer to carbon removal and carbon capture and sequestration, despite the important differences between those two activities.” Hence, carbon capture is defined here as an overarching term for both CDR and CCUS (that said, see below for another take).
Carbon capture and use (CCU): “the two-step process of capturing carbon dioxide and using it to make valuable products or provide valuable services. For example, carbon dioxide can be used to carbonate beverages or make synthetic fuels, cement, carbon fibers, and much more. The term is used for the use of carbon captured from the atmosphere and for the use of carbon captured from flue gas via conventional carbon capture and sequestration (CCS). CCU only counts as carbon removal in cases where the carbon dioxide is captured from the atmosphere and stored for long periods of time (e.g., in long-lived products, such as cement).” So, CCU can be CDR if the carbon is coming from the atmosphere rather than point-source.
Carbon capture and storage (CCS): “the process of capturing carbon dioxide emissions from a point-source, such as the flue of a gas-fired power plant, and injecting the captured carbon dioxide into geological reservoirs. CCS on a fossil fuel power plant reduces carbon emissions but does not remove carbon dioxide from the atmosphere. It therefore does not count as a form of carbon removal.”
Carbon Capture and Use or Sequestration (CCUS): “Carbon capture and use or sequestration (CCUS) is an umbrella term covering both carbon capture and use (CCU) and carbon capture and sequestration (CCS). It often refers to CCU or CCS associated with fossil fuels or cement, rather than to carbon removal.”
Carbon dioxide removal (CDR): “two-step process of capturing carbon dioxide (CO2) from the atmosphere and locking it away for decades or centuries in plants, soils, oceans, rocks, saline aquifers, depleted oil wells, or long-lived products like cement.”
So yes, it’s confusing. But this confusion is having an impact on the dialogue of numerous solutions, especially with Direct Air Capture (DAC). It’s not fair to group all DAC companies with all CCS companies under one “carbon capture” term, which is what continuously seems to happen. CCS companies are focused on the point-source capture of emissions, and their current/potential customers are industrial fossil fuel heavyweights. Those technologies (and the new 45Q tax credit for point source CCUS) are in some ways enabling oil and gas companies to continue burning fossil fuels and polluting, which causes obvious harms to frontline communities even if the CO2 emissions are lower.
On the other hand, many DAC companies are utilizing electricity (ideally renewable) to capture carbon dioxide from the atmosphere, and then storing it permanently (or planning to) in concrete, mineral deposits, and/or geologic reservoirs. The numerous startups and solution providers in this space, such as Heirloom and CarbonCure, are not integrated with fossil fuel companies and are not contributing to any of their respective damages.
With that in mind, some would say “carbon capture” should be thought of entirely separate from “carbon removal,” rather than an umbrella term. In this situation, carbon capture = point-source capturing, and carbon removal = atmospheric drawdown. I tend to agree with this demarcation. It’s beneficial to separate CDR from the bulk of CCUS solutions that are working with point-source emissions; not providing this clearer distinction will likely result in more of the same confusion around all the terms.
Either way, aligning on the terminology is a key step in moving the carbon removal industry forward and garnering the proper support, policy, investment, and awareness toward the best solutions. I hope to see the leaders in the CDR space continue refining and publishing their definitions so the broader industry can follow in step.
Curious if anyone uses alternative definitions or prefers other ways of marking the distinctions. If so, feel free to comment below.