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Itsumishi t1_jd9p1xi wrote

Reply to comment by gobblox38 in An Arizona plant will pull CO2 from the air and trap it in concrete by captainquirk

It also sounds like the vast bulk of the CO2 reduction comes not from the capture of carbon from the air, but changing the chemical composition of the concrete (using significantly less cement). The downside to their approach is the concrete must be baked on site.

Not to say this is a bad approach, there are plenty of uses for precast concrete, but it also makes this process useless for any concrete which needs to be poured in-situ and allowed to cure (eg footpaths, building slabs, etc.).

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yawaworht-a-sti-sey t1_jdb7vrp wrote

It's absolutely a bad approach.

We already have a method of installing CO2 extracting plants that have:

  1. A higher yield in building materials
  2. Produce building material with higher carbon storage capacity
  3. Can pull CO2 out of the air without supplying any power
  4. Require no construction to install

These incredible high efficiency CO2 extracting plants are called trees. Every penny they spent on this plant would have been more productively spent on literal plants.

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Itsumishi t1_jdbdqkj wrote

Do you really think we can replace concrete with timber in all construction?

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AaronDoggers t1_jdbecc1 wrote

If looking at this as purely a way to store CO2 from the atmosphere, trees are a going to be much simpler and cheaper

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Itsumishi t1_jdboy4i wrote

And as a method to significantly reduce the carbon intensity of concrete, the most widely used building material on earth?

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yawaworht-a-sti-sey t1_jdd87yb wrote

Carbon neutrality doesn't require every technology to be low carbon so long as you offset the carbon you produce.

Every extra dollar you spend on low carbon concrete would have been better spent buying normal concrete and using the savings to plant trees.

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Itsumishi t1_jdf0n6z wrote

I strongly disagree.

Firstly, I suspect you vastly underestimate how carbon intensive concrete is. We absolutely need to figure out how to drastically reduce the carbon intensity of concrete and/or drastically reduce how much we use of it (almost certainly both). But even if we drastically reduce how much we use its naive to think we can stop using it.

Secondly, carbon offsets can help slow climate change but it can't solve it. Planting trees is great. We should absolutely be reforesting everywhere we can. But a forest is only a useful carbon sink until it gets cut down, or burns in a forest fire at which point almost all the carbon stored in it is released back into the atmosphere. Forests are part of the natural atmospheric carbon lifecycle that is in constant fluctuation.

The idea that we can burn fossil fuels that hold carbon that has been stored in a stable condition for millions of years and offset it by planting a forest which then may be cut down or burnt out in 100 years or a 1000 years is deeply flawed.

But still we need to do it because we need to buy as much time as possible.

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yawaworht-a-sti-sey t1_jdfgtri wrote

I think you overestimate how expensive low-carbon concrete is and how much carbon it actually takes to make.

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Itsumishi t1_jdfjx2p wrote

I'll assume you meant "underestimate" regarding the expense, and on that I'd just say new technologies are always expensive. The point of pilots projects etc will be to find methods which can be made cost-effective.

On the "how much carbon it actually takes to make" comment... well its not low-carbon if it takes lots of carbon - so that doesn't make any sense.

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yawaworht-a-sti-sey t1_jdgsohi wrote

I meant overestimate how much carbon it removes and underestimate how much it costs to remove carbon from the air.

And its not a new technology that can be improved with iteration - CO2 always takes energy to remove and its other ingredients always take energy to create.

Until we get essentially carbon free and cheap energy there's no excuse to waste it on low carbon concrete when we can use those resources more efficiently elsewhere.

If you're going to waste energy on physically removin CO2 from the air then you're best bet is giving China and India free solar panels rather than using solar panels to remove CO2 to put in concrete

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yawaworht-a-sti-sey t1_jdd8iid wrote

I never said we stop using concrete, just that you will reduce carbon in the atmosphere more effectively if you use normal concrete and cheaply plant trees instead of using more expensive low carbon concrete. As an added bonus you get more building material too.

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ncc74656m t1_jdcxa5p wrote

The one thing I can say though is that if they are doing it to sequester carbon from their processes, it might actually be more beneficial than simply planting trees and hoping for the best, especially when the plant in question is located in desert areas.

It depends on how efficient the process is though, because if it's only partial capture, or the concrete suffers in some manner requiring more replacement, etc, then it might not be. But really, we are pretty well way beyond the point of being able to tree our way out of this. We need active sequestration methods and potential active decarbonization of the atmosphere now, and likely still then some weather modification like solar screening via reflective gases or particulate in the atmosphere.

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yawaworht-a-sti-sey t1_jddb148 wrote

Your money would be better spent giving india and china free solar cells than this pie in the sky active sequestration shit. That can wait until we actually have cheap and carbon neutral energy to throw at it.

We'd be better off just biting the bullet and going for ocean fertilization or dumping sulfur dioxide in the upper atmosphere if we're that desperate.

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ncc74656m t1_jddfchl wrote

TBH we probably already need the sulfur dioxide. But also, if we're giving away free solar, we should probably work on finishing ours here, too. But of course, we'll never do that either if our pols are still monetarily beholden to the fossil industry.

Don't get me wrong, I'm not saying this is the solution, or even a good final one. Just that it's something we probably need, and on the heavy assumption that it is being done properly and with enough efficiency, it's a step in the right direction. And of course, seeing that this is in AZ, it's quite reasonable to say it should be solar powered to boot.

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yawaworht-a-sti-sey t1_jddftg4 wrote

I think it's a waste of time and money and if we're going for pie in the sky like this we and we might as well throw the money at fusion or something instead since that might give us the energy for us to do something like this in the first place.

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ncc74656m t1_jddhb6x wrote

Fusion is probably a (very) long term solution, and tbh, unless we're also prepared to supply that to the rest of the world, it's not really a fix. Much of places like India, China, Africa, and South America require socioeconomic change too, but the catch is, most of those problems are either enabled or straight up caused by Western capitalism, and capitalism is quite happy with those results thank you much.

So, really, the best we can do is minimize what we're creating, keep planting trees as you say, and try to capture what remains.

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Itsumishi t1_jdf207v wrote

Lower carbon concrete is not remotely as much a pie in the sky proposition as fusion. Not even comparable.

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yawaworht-a-sti-sey t1_jdfgym1 wrote

we're talking about sequestering carbon from the air and storing it. Low carbon concrete isn't even carbon neutral.

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Itsumishi t1_jdflgn0 wrote

Sequestering carbon from the air is only a small element in this particular trial (and to be honest I suspect that's a journalistic error).

The bulk of carbon emissions in the manufacture of concrete come from the processes which occur during the creation of cement. There's two elements to this:

  • Current methods of creating cement involve heating limestone and clay to around 1400 degrees Celsius. Its hard to hit these temperatures without large inputs of fossil fuels.
  • The chemical process which occurs within the limestone during this baking releases A LOT of CO2. (This is the most carbon intensive bit).

So to achieve lower carbon intensity, we need new methods of producing concrete that use significantly less cement (which is how this trial aims to achieve the bulk of its CO2 reductions); and/or we can capture some of the CO2 from the limestone and embed the carbon back into the concrete.

Pulling it from the air does seem incredibly inefficient when the concentrations will be much higher in the exhaust and waste gasses than the atmosphere. This is where I think the journalistic error occurs. The article says they'll use the AirCapture technology - but I suspect they'll use that technology within a closed system - not just pulling it from the nearby atmosphere.

And yeah - it still won't be carbon neutral, but a significant reduction in a very carbon intensive process is still better than not doing it.

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yawaworht-a-sti-sey t1_jdgszyh wrote

>And yeah - it still won't be carbon neutral, but a significant reduction in a very carbon intensive process is still better than not doing it.

In the absence of superior alternatives which should always be pursued first in order of efficiency.

>Pulling it from the air does seem incredibly inefficient when the concentrations will be much higher in the exhaust and waste gasses than the atmosphere. This is where I think the journalistic error occurs. The article says they'll use the AirCapture technology - but I suspect they'll use that technology within a closed system - not just pulling it from the nearby atmosphere.

And it is incredibly inefficient but as marketing it works - the comments here are proof of it.

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gobblox38 t1_jddbxx1 wrote

Trees are a temporary reservoir that'll hold the carbon for about 50 years +/- a few decades. There's entire regions where trees are dying because the climate has changed too quickly for them to adapt.

The true natural carbon sequester is algae in a high sediment deposition area. If the algae is buried before their bodies decay or are eaten, the carbon can be captured indefinitely. This is the first step in how oil is formed.

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yawaworht-a-sti-sey t1_jddf3e9 wrote

Yeah, further up I said we're better off fertilizing the oceans or dumping sulfur dioxide in the upper atmosphere than doing this active sequestration shit when we don't have cheap abundant energy.

You might as well just give china and india free solar panels instead.

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