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> Think about it - if these formations were not leakproof on geological scale, there wouldn't be any oil and gas for us to extract in the first place.

This is survivor bias. We only see the sites where it didn't leak too much, and extract from it. The sites that leaked, we don't hear about them (no oil to extract). In fact, a quick search shows that there are many leaking sites (both on land and under the oceans). The argument you present is a case of survivor bias, especially on the time scale of multiple millions years.

> This is survivor bias. We only see the sites where it didn't leak too much, and extract from it

…those are the sites we’re pumping the CO2 into.

"This pressurized tank is doing a great job not leaking, that means it will never leak! Let's keep filling it up, WOO!"

Strawmanning you a bit but surely you see that this line of reasoning leaves a little to be desired?

> surely you see that this line of reasoning leaves a little to be desired?

When responding to innumerate “napkin maths” and a sourceless speculation, on one hand, and a multibillion-dollar practice done by experts, on the other hand, no, not really.

I didn't make the initial post, and 'unsourced in this particular instance' doesn't mean there's no legitimate basis for OP's claims. To be clear, I'm not anti-CCS, but I have an environmental degree and based on my admittedly nonexpert opinion I agree with OP's assertion that it's not really a solution - it's a temporary measure at best.

But yeah I see your point - no multibillion dollar industry filled with experts has ever done anything ill-advised, futile, or environmentally damaging simply for profit. cough corn ethanol Can you imagine how the world would look if that were the case?

https://theicct.org/carbon-capture-and-storage-a-lot-of-eggs...

https://www.foodandwaterwatch.org/2024/09/13/leakage-at-firs...

There are a number of scientific papers that are also skeptical about the long-term viability of underground CCS strategies but they're all paywalled so I didn't link them here, but you should seek them out yourself.

> no multibillion dollar industry filled with experts has ever done anything ill-advised, futile, or environmentally damaging simply for profit

Sure, they’re scandals. Scandals have sourcing. Not supposition. Someone who assumes industry is always evil isn’t a reliable source.

I’ll note that your sources are both credible and the first in this thread.

> Think about it - if these formations were not leakproof on geological scale, there wouldn't be any oil and gas for us to extract in the first place.

Leakproof to one substance doesn't necessarily mean leakproof to another. Heavy oil is hydrophobic and a less mobile, volatile molecule than CO2. Methane otoh is lighter.

That said, CO2 capture mostly works in scenarios where you have a highly concentrated stream AND can afford the weight and energy penalty of the capture apparatus. Good on big chemical/industrial plants, refineries and maybe gas power stations, and worth doing for that reason - industrial processes are some of the hardest to replace or avoid of the big emitters. Likely useless for vehicles and aircraft.

It's very hard to feed 8Bn people without a whole lot of Haber-Bosch though, and hard to do that without methane in, CO2 out. All the more reason to cut down on wasteful uses of both food and energy.

Supercritical CO2, which behaves rather similar to a liquid, is also hydrophobic, which is why it is one of the best solvents for extracting oils from mixtures with water, being now preferred to older, gasoline-like solvents, which were hard to eliminate after extraction (if the pressure is reduced, supercritical CO2 evaporates from mixtures).

Many of these kinds of formations also house natural hydrogen for geologic time periods.

Yeah, that's not how caprocks on geological formations work. It's not a matter of pore pressure (what porous media people call hydrophobicity). It's a matter of caprocks having zero intrisic permeability.

> 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.

CO2 is not a smaller atom than CH4 or H2O, on the contrary. And CO2 injection in a saline aquifer in the Utsira formation has been ongoing since 1996, there's been hundreds of research papers on it and multiple seismic imaging studies to confirm permanent trapping.

> We need a green grid first, not instead.

We need to do all of the things at once, unfortunately. If we started investing heavily in renewables in the 1960s, maybe we would have had that luxury.