Out of curiosity, how long can we inject captured carbon underground for? Do we have a good estimation of the long-term ramifications?
Long term ramifications… If you store carbon for millions of years underground, eventually a future species will tap it as a fuel source.
Probably not. It’s likely carbon that is pretty much completely oxidized since OP said it was captured as a byproduct of industrial activity (after all, why would you sequester carbon that still had useful energy?) If you store fully oxidized carbon underground for millions of years, it will still be fully oxidized when it’s dug up because that carbon’s most stable state (especially in an oxygen-rich environment like Earth). The only reason fossil fuels exist is because the carbon was sequestered in a mostly reduced (aka energy-rich aka unstable) state, so you get a mess of goopy hydrocarbons after millions of years. If you try the same thing with CO2, you just get limestone.
