ESG/sustainability professionals are mired in jargon/terminology that frequently gets in our way. I’ve blogged quite a bit on the matter and today I’m doing it again. This time, I hope everyone will join me and get real about how we talk about carbon/CO2 capture and storage (CCS). The problem is when we say underground CO2 storage, we don’t actually mean “storage.”
You see, that word reflects temporary holding or accumulation with expected recovery and use in the future. Storage for future use is by definition not permanent. For instance, we use underground caverns in salt domes for natural gas storage because we expect to extract that gas and use it. However, when CO2/carbon is injected underground either in a matrix permanently binding the CO2 or into a geologic feature to which the CO2 will bind, there is no intent for that to be temporary or recovered in the future. That is actually “disposal” – discarding CO2/carbon with no plans or ability to reclaim it.
No one wants to call permanent underground CO2 “storage” what it is – disposal.
This has US regulatory underpinnings and direct implications in carbon offset criteria.
- Those conversant in US environmental regulations will be familiar with the hazardous waste rules of 40 CFR 261, originally promulgated in May 1980. A large part of my career is anchored in those rules. They set out explicit distinctions between storage, disposal, accumulation and “speculative accumulation.” Without diving into the abyss, the main differences are whether material is a waste with no use that is to be permanently discarded, a material stored short term prior to its final disposition or a material being accumulated in anticipation of commercially-viable recovery/reuse. Different management standards apply based on these determinations.
- In the carbon market, a key criterion for offsets is permanence (Sylvera has a good explanation of that here). Permanence periods – oddly – can vary. They go from 10 years to over 100 depending on the project. If CO2 is injected underground either in a matrix permanently binding the CO2 or into a geologic feature to which the CO2 will bind, it meets offset permanence criteria – but this is actually disposal. In contrast, storage is maintaining chemically stable and separate CO2 in temporary accumulation in anticipation of recovery/reuse. In sum, storage isn’t permanent – disposal is. Storage is a red flag for offset permanence criteria – disposal is not.
Storage for recovery/reuse means there is (or will be) demand for the CO2. Yet is there really a market for the volumes of CO2 for which storage opportunities are discussed? Since many CCS projects involve injecting chemically-bound CO2 underground, recovery wouldn’t be possible anyway. And so we are back to disposal.
Let’s say what we mean and mean what we say.
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