CO2 is also the best substance to inject into oil fields for enhanced oil recovery. It becomes supercritical at the pressures involved in the oil bearing formations and is more effective at sweeping recoverable petroleum than water or steam. The problem is sourcing enough CO2 near a field.
It's also a very convenient way for oil and gas companies to suck all the renewable subsidy money in the name of "carbon sequestration", when the reality is they're developing new ways to get even more oil and gas out...
CO2 is indeed fungible. I simply suspect that a lot of companies are requesting government money to research and develop something that they would choose to research anyway even without government money. (because it increases oil production).
They get away with that because many governments don't have good tech advisers.
