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yawaworht-a-sti-sey t1_jdd87yb wrote

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

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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