> CO2 is being (as in right now, yes) stored as a supercritical fluid inside saline aquifers deep under the seabed. These reservoirs are known to be leakproof s

> CO2 is being (as in right now, yes) stored as a supercritical fluid inside saline aquifers deep under the seabed. These reservoirs are known to be leakproof since they've already been holding pressurized fluids for millions of years. I simplified it a bit too much. CSS has been in use since the 1980s by the oil industry to push out more oil and natural gas from their wells. However, it is relatively small scale. I've seen proposals and demonstrations of saline aquifer projects, but I know of no currently operational such facility (and can not find it from light googling) That the chambers could store methane or oil for 100k years is promising, sure, but it doesn't end there. Co2 is a smaller atom that has an easier time moving through small cracks. CO2 mixed with water is also a mild acid that can corrode different rock types. Even if we had enough stable underground chambers, even if capturing the carbon and compressing it was free. How much could we even offset? We need a green grid first, not instead.