There’s nothing thermodynamically wrong with burning methane, releasing the water, and putting the CO2 back underground. Sequestration does not require un-oxidizing the carbon.
Though if we’re going to bury harmful waste underground, nuclear power reduces the quantity of waste by a factor of a million.
I’m not sure what you’re trying to convey here. Carbon sequestration is unarguably a way to mitigate climate change, and sequestration of CO2 is probably the most reasonable way to do so. It doesn’t need to be as a gas, as taking CO2 and exposing it to various oxides creates carbonates, which are generally very stable compounds like limestone.
The other commenter simply said carbon could be captured as CO2 and sequestered without being reduced, which is absolutely true and frankly makes much more sense from a physics/thermodynamics POV.
You guessed right - without reductions or conversion it simply becomes a ticking time bomb. Anything secure enough to capture and contain a gas reliably for millennia without maintenance will be too expensive to be practical.
There’s nothing thermodynamically wrong with burning methane, releasing the water, and putting the CO2 back underground. Sequestration does not require un-oxidizing the carbon.
Maaaaybe if the CO2 is captured at the point source of the methane burner. But if you’ve already let it disperse into the atmosphere, forget about it ever making sense to try to compensate for that huge increase in entropy by collecting and re-concentrating it.