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Comment by condensedcrab | Hacker News Reader

Direct air capture imo can’t escape the scaling problem - when the feedstock has CO2 at ~400 ppm the economics simply won’t work out despite various oil companies backing one off systems around the globe.

Capturing CO2 at the source (power plant, etc) would be simpler to reach economic viability but without incentives it’s dead on arrival. I believe the IRA infra bill had put a price ~$50/ton of CO2 captured.

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But we still need to remove all the excess co2 that we released into the atmosphere since the start of the industrial revolution if we want to reduce the temperature back to what it was before we started disrupting the natural state of the plane.

We and previous generations took out a loan and the payment is coming due.

Because of the framing about degrees in celcius change people are thinking in small numbers, like "oh, it's just 1.5'C over normal. oops, we missed that, well maybe we'll get it at 2.0'C. They don't realize that if we want normal we ahve to reduce the temperaure and to do that we need to take that c02 blanket off that we've been tightly wrapping around our collective bodies for decades.

And that endeavor is nearly unfathomable. Think of all the energy used by humanity since the industrial revolution and the energy we're going to be producing in the time period that we attempt to sequester the previously poduced C02. All of that needs to be accounted for.

And then there's the surplus energy roiling around in the system now, and the collapse of food webs.

I don't see how we get our way out of this in the next 50 years.

That’s true. It’s more of a policy issue that’s like carbon credits… nice on paper but a big nothing burger. Look at F1 and Porsche talking about sustainable synthetic fuels.

When you compare round trip efficiencies and economics it makes sense to just not burn the hydrocarbons to begin with.

Yes

For the atmospheric one, grow trees and algae

With ice caps melted off, just removing all the excess CO2 isn't even enough since with that reflective surface gone, more energy from sunlight stays in the atmosphere than previously when more of it was reflected back into space instead of nowadays being absorbed by the ocean.

Absolutely. People seem to think that we just need to recycle more, seal some cracks in the house with foam, install some solar panels, and buy an electric car.

They underestimate the scale of the intervention that will be required to stave off the potential end of human civilization as we know it. If we have any hope of continuing to live at something resembling the quality of life that we've grown up in it will require radical science fiction like developments.

We're going to need things like space based solar shades to regrow glaciers and icepack, advanced breeding and cloning and ecosystem engineering to reconstruct collapsing food webs, and I think the big picture thing is that we're going to need to engineer people to reduce susceptibility to addictive food and manipulative marketing.

> If we have any hope of continuing to live at something resembling the quality of life that we've grown up in

Chances are, developed countries won't be hit that hard, at least for a generation or two.

I agree, plus were would one store the CO2 ? To get back to "1980", I really doubt puling CO2 from the atmosphere will ever work.

Another concern, who will pay for maintenance ? See this for why you cannot let CO2 escape from underground storage:

https://en.wikipedia.org/wiki/Lake_Nyos_disaster

If stored near a populated area, hundreds of thousands could be kill, including all animals and insects, in a matter of minutes if the "vault" has a catastrophic failure. I would rather live near a nuclear waste site than a CO2 Site.

Well as far as storing it goes, if you can capture it, turn it into a solid and stick it in the ground.

Imagine you were growing a huge biomass that you harvest, dry out, and then store. We know how the bacteria and processes that stripped co2 from the atmosphere in the past, we just need to do that in a big way. Good thing we have places on earth that are huge and flat and growing algae won't be a problem.

And then we complement that with green energy and an attempt at net zero.

As long as leading figures either claim it's a hoax or that it's not necessary to do sth about it, none of this matters anywhere.

This is less of a technogical problem than it is a political one, I'm afraid.

Not exactly less.

It's a science fiction grade engineering problem and a historically unprecedented political problem. That's a tough mix to crack.

It's worth trying to delay the end of civilization, but reversing this is literally like putting the fire back in the Molotov.

> I would rather live near a nuclear waste site than a CO2 Site.

If it's between immediate death and a slow one of cancer, I'm not sure your choice is the obvious one.

A failure in containment at a nuclear waste storage site means danger for people on the site itself but it is easily detected by monitoring equipment and can be repaired, the waste is solid and can't spread easily. A failure in containment of a massive quantity of pressurized CO2 would be significantly more dangerous and probably a lot more likely to happen given the frequency of accidents

https://aiche.onlinelibrary.wiley.com/doi/abs/10.1002/prs.68...

https://www.youtube.com/watch?v=zkWeZ1YPI88

https://www.youtube.com/shorts/H1rWZHNWBWo

Can't we just store C and let the O2 back in the air like plants do? We could store it right where it came from, in old coal mines.

Chemical reduction of CO2 is a very hard problem since it takes a lot of energy. There's an enormous amount of research in this area. Storing it costs money, so most of the research focuses on turning the C into a useful product.

https://en.wikipedia.org/wiki/Electrochemical_reduction_of_c...

Capturing CO2 at the source will always be worse than removing the source. At the same time, capturing CO2 from the air will stay necessary until we do it.

DAC is unsustainable, and shouldn't be a primary offset mechanism. What would be more sustainable is less net emissions and using something else like oceanic biomass CCS by taking advantage of blooming kelp and/or phytoplankton and then processing it for sequestration using floating, automated harvesting rigs.

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