> Not a surprise, since co2 is an oxide, and therefore very stable in the athmosphere. It would take a huge amount of energy to remove it,
There is an exothermic reaction that removes CO2 from the atmosphere, the formation of carbonates from weathering of silicate rocks. As this is naturally very slow, there is currently ongoing research into multiple different ways to speed it up.
>The extracted CO2 will then be piped from the collector boxes to a nearby processing facility, where it will be mixed with water and diverted to a deep underground well.
And there it will rest. Underground. Forever, presumably. The carbon dioxide captured from the Icelandic air will react with basalt rocks and begin a process of mineralization that takes several years, but it will never function as a heat-trapping atmospheric gas again.
The only use is in removing it from the atmosphere.
What they are discussing is simply an acceleration of a natural process: the carbonate-silicate cycle[1]. Silicate rocks are transformed into carbonate rocks through weathering. This captures CO2 from the atmosphere.
When carbonate rocks are transformed back into silicates through metamorphosis or magmatism the CO2 is released back into the atmosphere.
This definitely has the potentially for the long-term capture of CO2. For example in about 600 million years increased solar output will disrupt the carbonate-silicate cycle, resulting in the increased weathering of rocks and the capture of enough CO2 that C3 plants, which make up 99% of existing plant species, will no longer be able to live on earth. [2]
> If we had a source of massive CO2-free power we could extract CO2 from the atmosphere and turn it back into coal, effectively unburning all the coal and oil that we burned so far.
>We could start pulling more CO2 out of the atmosphere than we put in, and at that point we'd be pretty confident things won't get worse for the climate.
Not sure that would be terribly efficient to pull CO2 out of the atmosphere to pump through this setup.
Would be fine for many other reasons though.
I wonder how it behaves with "non clean" CO2 sources. Like say at the output of a coal fired PowerStation.
>Most of the skepticism about CO2 removal from the air is focused on "carbon sequestration and storage" or CSS, which is mitigation of emissions from fossil fuel by putting CO2 into the ground
That is false! Most of the skepticism about CO2 removal from the air is focused on the difficulty of said removal, compared with the relative ease of removing CO2 from eg power plant exhaust.
> The problem with sequestering CO2 as hydrocarbons is that you need to put a whole load of energy (embodied in the hydrogen you're combining it with) into the ground and leave it there.
If sequestering CO2, combining it with CaO to make CaCO3 (calcium carbonate) makes more sense, and is even exothermic. It's also biologically harmless and can be safely dumped, used in building materials, etc.
> he imagines [the necessary CO2] would come from power stations and other industrial processes, such as cement-making, that produce the gas in large quantities as exhaust.
IANAC, but it seems like that just exchanges one problem for another. I imagine that most, if not all, of the industrial processes that produce CO2 exhaust gases also result in other gases and particles getting into the exhaust stream, meaning that you'd have to refine/filter the exhaust from those processes to get just the CO2.
CO2 can also be sequestered by reaction with silicates to make carbonates. This process is mildly exothermic, if slow, and is how nature will draw down the CO2 we've been releasing, eventually.
Removing CO2 from the atmosphere doesn't mean unburning it. The CO2 either gets dissolved into the deep ocean, stored underground in deep aquifers, or reacted with silicates to make carbonates.
> You capture it at great cost and then you create a fuel. Which you then burn and dump in the atmosphere.
But if the need for carbon based fuels is not able to be eliminated, this is the next best thing. It is better than digging more of it out of the ground, and then burn and dump it into the air!
Nothing. It already happens in nature, but at a far smaller scale. It is not a self-renewing or runaway process. The point is to distribute the correct amount of olivine to stabilize CO2 at ~200 PPM which is close to its pre-industrial level.
> if we consume the fuel byproduct, presumably we just end up with co2 in the atmosphere?
The process would still be great news if true, as it could be a carbon-neutral source of hydrocarbon fuel for applications that are hard to electrify, like aviation.
> We could start pulling more CO2 out of the atmosphere than we put in, and at that point we'd be pretty confident things won't get worse for the climate.
How much of the atmospheric CO2 can you actually capture with stations at ground level? I assume this isn't critical since I haven't seen anyone propose a Tower of Babel of carbon capture machines, but I'm not sure why it isn't.
>If it would be carbon negative show me where it removed CO2 from the air and how it is stored now "forever".
If you read the article you'll note that they are specifically doing that in partnership with Stripe's climate program which funds startups who do, at signifgant cost, physically remove the CO2 from the air and sequester it.
> use it in chemical processes other than ones which sink the carbon into long lasting solid
There are not many chemical reactions that 'fix' CO2. The compound is pretty low energy. Kind of a analogous to 'feed' bacteria with plastics.
The Swiss start-up Climeworks [1] has a business model built around actually already is in operational mode when it comes to pumping CO2 into the ground in Iceland.
There is an exothermic reaction that removes CO2 from the atmosphere, the formation of carbonates from weathering of silicate rocks. As this is naturally very slow, there is currently ongoing research into multiple different ways to speed it up.
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