
Why cement emissions matter for climate change (2018) - Reedx
https://www.carbonbrief.org/qa-why-cement-emissions-matter-for-climate-change
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Klapaucius
This is a place where carbon capture and storage would be a natural fit.
Seriously.

Cement is but one example of industrial processes that inherently release
large amounts of CO2 even if we were to go 100% renewable energy-wise.
Applying carbon-capture technology to cement plants would be a way to actually
bring their emissions down to zero regardless. Capturing CO2 directly from
such CO2-intensive processes would certainly give way more bang for the buck
than trying to capture CO2 out of thin air, as many seems to be placing their
hopes on these days.

And this is not theoretical. At least here in Norway, it is already being done
at one cement plant:
[https://www.norcem.no/en/CCS](https://www.norcem.no/en/CCS)

~~~
mikorym
If you combine this with the CO2 capturing aspects of concrete itself as
mentioned by other commentators, would that mean you can actually have a net
CO2 level decrease?

~~~
Klapaucius
Theoretically yes, although reasorbtion of CO2 takes a long time.

~~~
mikorym
We hedge against old buildings then. [1]

[1]
[https://upload.wikimedia.org/wikipedia/commons/d/d3/Universi...](https://upload.wikimedia.org/wikipedia/commons/d/d3/University_of_Johannesburg.jpg)
Quite the concrete jungle...

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colechristensen
This analysis seems to skip the obvious step whereby the manufacture of cement
involves expelling CO2 from limestone so that it can be mixed with water which
re-forms the same compound by absorbing CO2.

Making Lime CaCO3 (+ heat) → CaO + CO2

Making concrete CaO + CO2 (in water, from air) → CaCO3

[there are lots of other things in concrete, but the CaO/CaCO3 are the media
that glue them together into the useful composite they are]

They quote that as "half" the emissions, well those emissions are _all_
reabsorbed by the product itself. The complete reabsorption does have a long
tail, but if you expose CaO to air it will absorb CO2 all by itself.

The rest can be pretty trivially converted to renewable sources so it seems
like this is just a big pile of scaremongering nonsense.

Which is unfortunate, it is difficult being scientifically literate and
progressive being surrounded by people "on your side" who are spouting the
exact same kind of nonsense and lies as your opposition.

~~~
icegreentea2
I think its worth considering how long that long tail is:

[https://www.cement.org/for-concrete-books-
learning/concrete-...](https://www.cement.org/for-concrete-books-
learning/concrete-technology/concrete-design-production/concrete-as-a-carbon-
sink)

Taking at a look at the link above (which is published by pretty much the more
pro-cement group you can imagine), we get that carbon resorption is a thing,
that certainly there is a potential for many structures to achieve carbon
neutrality over their design lifespans, and that in the "best case", we're
talking about 100% carbon neutrality over decades. We also get that 100%
carbon resorption is not a design goal of many forms of current reinforced
concrete applications since the presence CaC03 increases rebar corrosion.

Taken at face value then, what you have is that cement currently emits 8% of
all human carbon activity, that over the timespan of decades, it may self
sequester itself to 4%, but probably somewhere in between. So even if we
trivially converted kiln sources to renewables, there's still probably a
decent chunk of carbon emitted in cement creation process that may never be
self-sequestered.

I think understanding what that final number comes out to would be pretty
useful thing to understand, and is hardly scare-mongering.

I think once we drill into our heads that we need to decarbonize, after "the
easy step" of cutting fossil fuel use, litterally every other form of
decarbonization consists of chasing down some carbon source that accounts for
the 2-5% range. There will be no low hanging fruit left.

~~~
colechristensen
I'm not very worried about the remaining carbon producers once fossil fuels
become minority energy sources.

I think the ability of the biosphere to sink carbon is underestimated as are
the _benefits_ of a higher carbon atmosphere. Most talk about anthropogenic
climate change are either denying it exists or exaggerating (usually without
much knowledge) its negative side effects. Nobody talks about the benefits of
expanding the arable land at higher latitudes or increased plant growths in
forest (and forests denser and further north). At one point during a carbon
spike the planet was more or less covered by jungle pole to pole, how's that
for biodiversity? Change is hard and people are always upset about it, but
this is a change we have already made for better or worse. There is much doom
and gloom about any change and this one will have big consequences but we need
to move past arguing about whether or not it will happen and towards how best
to respond to it (and in ways other than only desperate attempts to reverse it
completely). That doesn't mean there isn't a great benefit to capping the size
of the change or to stop the forcing, but at some point you have to accept it
and stop treating it as your doom.

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zahma
Trying to control nature will never work out in humanity's favor. That is
precisely the same hubris that has landed us in this mess. Once we surrender
to the notion that we will capitalize on nature's response to our unwieldly
use of technology, then we are only going to make matters worse. We simply do
not understand the complexity of nature and should be skeptical of perceived
benefits -- such as increased amounts of arable land -- as if that won't have
consequences.

~~~
colechristensen
_Never_? An enormous part of civilization is exactly wrestling for control of
nature and succeeding. From prairie nomads to mega-cities our direction is
clearly one of increasing control. The whole issue is about humans changing
the climate. We already have incredible control of many complex systems, the
planet's climate is just another system.

It will take an incredible amount of resources to control but there should be
no doubt as to if, only when. The earth is our garden, we have only to put
ourselves to the task to make it bloom. The blocking point is our intentions
and efforts not the possibility. You can't be burning down the Amazon for a
quick dollar and trying to maintain the climate at the same time. We're so
focused on arguing about whether or not we're having an effect and panicking
about what that will be that we're not really trying at all to gain any
control.

True the climate is not a trained dog, it will not act on command, it is not a
linear system that we can put one PID controller on and be done with it. It is
complex, it has feedback system on top of feedback system, some negative, some
positive, it's chaotic. None of that means we can't make it do what we want.

We just have to focus and not spend our time on the stupidity that drives our
everyday political process.

~~~
TeMPOraL
The problem of taking control over complex systems the size of climate isn't
about knowledge or technology; it's a coordination problem. We could be having
climate jumping through hoops on command today, _if_ we could coordinate at
global scale instead of competing and sacrificing long-term benefits for next
quarter rewards.

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cagenut
the article mentions cement is 8% of GHG emissions in text, but if you'd like
a good visual on that: [https://ourworldindata.org/grapher/co2-by-
source](https://ourworldindata.org/grapher/co2-by-source)

~~~
pottertheotter
What an interesting link. Fun to explore how the graph changes between
countries or regions. It's interesting that the % from cement is relatively
small in the US.

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Merrill
If cars go electric and there is less demand for gas, oil refineries will
produce less asphalt as a byproduct of oil refining. Demand for cement will go
up to pave streets for electric cars to run on.

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einpoklum
The article claims implicitly, through the chart, that capture of the CO_2
produced or of the Carbon in it can only reduce emissions by about 10-15%.
That is not true. One can definitely bind most of the emitted CO_2. It may
make production more costly, and perhaps require larger facilities, but it's
definitely possible.

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legulere
What's missing from this article is a discussion of rebar. Steel rebar is
pretty heavy and rusts easily. With alternative materials you can get longer-
lasting structures, that also need to use less concrete.

~~~
rapnie
I really like the idea of using cross laminated timber (CLT) as a full
replacement for concrete. It is a radical switch to use wood entirely, even
for high-rise buildings, but it is possible, has many benefits, and a good
environmental footprint.

[https://axaxl.com/fast-fast-forward/articles/benefits-and-
ri...](https://axaxl.com/fast-fast-forward/articles/benefits-and-risks-of-
building-with-cross-laminated-timber)

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hinkley
There were some studies in using fly ash to reduce the carbon footprint of
cement, but it was never clear to me how you avoid point source emissions of
fly ash. Isn’t it difficult to handle?

They mention fly ash as a resource but don’t cover anything other than that it
will also become scarce.

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ijiiijji1
Actually, the most important part is clinker manufacturing which then leads to
Portland cement that leads to concrete. If manufacturing occurred in a sealed
chamber and adding a step that consumes or captures carbon emissions would be
a logical improvement considering it is a nontrivial amount of GHG emissions.

Lime is a close second, but not as important when compared to the energy needs
and chemical processes involved in clinker manufacturing.

