
Is Capturing Carbon from the Air Practical? - mrfusion
http://www.technologyreview.com/news/531346/can-sucking-co2-out-of-the-atmosphere-really-work/
======
startupfounder
“Once capturing carbon from the air is profitable, people acting in their own
self-interest will make it happen,” says Chichilnisky.

This is the key to the entire article.

The conversation shouldn't be around the practicality of capturing carbon from
the air, the conversation should be what is the most profitable way to reduce
carbon in our air either through not putting it in the air in the first place
or removing it cheaply after the fact.

This demands a more robust marketplace beyond CO2 for soda and oil wells.

"The idea is to first sell carbon dioxide to niche markets, such as oil-well
recovery, to eventually create bigger ones, like using catalysts to make fuels
in processes that are driven by solar energy."

~~~
danielweber
I'm a bit worried that, because of weird locally-smart but globally-dumb
incentives, we might see people consuming 1 KWh to capture a unit of CO2, but
the generation of 1 KWh puts more than 1 unit of CO2 into the atmosphere.

I'd like to see the numbers.

 _EDIT_ :

The worst coal emits 2.18 pounds of CO2 per KWh.[1] As little as 917Kwh of
energy puts a ton of CO2 into the air.

They say that can do it for "$15 to $50 a ton". How much of that is energy
costs? $50 buys 500KWh, so even if you used coal to operate it, it would net
remove carbon from the air.

I'd still like to see a plant using nuclear energy to change CO2 into fossil
fuel, though.

[1]
[http://www.eia.gov/tools/faqs/faq.cfm?id=74&t=11](http://www.eia.gov/tools/faqs/faq.cfm?id=74&t=11)

~~~
ChuckMcM
That would be an effective way to arbitrage the cost of carbon which isn't
externalized on the power plant. However I don't think it would come to that.
I'm surprised the SRI effort isn't recovering the CO2 (they claim to be
venting it). After all if they really do think they can get $100 a ton for it
and make it at $50 a ton, that would at least offset some of their research
costs.

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tokenadult
This statement from the article cautions us that the economic incentives
(which are also reasonably well described in the article) so far aren't
promoting technical fixes like the one proposed by the inventors: "None of the
world’s thousands of coal plants have been outfitted for full-scale capture of
their carbon pollution. And if it isn’t economical for use in power plants,
with their concentrated source of carbon dioxide, the prospects of capturing
it out of the air seem dim to many experts. 'There’s really little chance that
you could capture CO2 from ambient air more cheaply than from a coal plant,
where the flue gas is 300 times more concentrated,' says Robert Socolow,
director of the Princeton Environment Institute and co-director of the
university’s carbon mitigation initiative."

When I hear about plans to capture CO2, I wonder immediately about whether
those plans will help enough if other gases (for example, methane) play a
significant role in greenhouse effects. We may have to sequester more than one
gas, in more than one way, to role back the accumulation of greenhouse gases
already in the atmosphere, if that is considered a desirable worldwide goal.

~~~
mrfusion
That's true, I've heard that methane is much worse than CO2. I wonder if
methane can be pull out of the air?

~~~
chriswarbo
Since methane is worse than CO2, it's actually better WRT the greenhouse
effect to burn it and produce CO2 + water. Water's also a potent greenhouse
effect contributor, but the atmosphere's already saturated with it, so the
excess will just rain back down.

Here's an interesting site found through Google:

[http://www.bbc.co.uk/climate/evidence/methane.shtml](http://www.bbc.co.uk/climate/evidence/methane.shtml)

~~~
mrfusion
Wouldn't extra water vapor end up as clouds and reflect sunlight away from
earth?

~~~
Klapaucius
The atmosphere water content is self-regulating, since it works as a cycle
(water evaporating, condensing and raining down, with the atmospheric content
mainly regulated by how much vapor the air can hold). Not so with CO2. There
is no similar "excess" threshold for CO2 after which it would "rain down".

------
mrfusion
How about the idea of building a giant "freezer" in the coldest part of
Antarctica and sublimating the CO2 out of the air? Some places already hit
that temperature naturally [1]

[1]
[http://news.nationalgeographic.com/news/2013/12/131210-colde...](http://news.nationalgeographic.com/news/2013/12/131210-coldest-
place-on-earth-antarctica-science/)

~~~
maxerickson
It isn't a high enough proportion of the atmosphere to be an effective
strategy (also, you mean precipitate out of the air; sublimation is the
process where a solid becomes a gas).

We talked about it before:

[https://news.ycombinator.com/item?id=7174246](https://news.ycombinator.com/item?id=7174246)

I linked this article, which discusses somebody actually testing the partial
pressure explanation in a lab freezer capable of maintaining those low
temperatures:

[http://wattsupwiththat.com/2009/06/13/results-lab-
experiment...](http://wattsupwiththat.com/2009/06/13/results-lab-experiment-
regarding-co2-snow-in-antarctica-at-113%C2%B0f-80-5%C2%B0c-not-possible/)

~~~
mrfusion
Wow, you're right. We already had this conversation :-)

Ok, so let's assume you're right about this. According to that chart, at a
partial pressure of 0.0004 atmospheres the precipitation temperature would be
around -140C. And nature is still doing a lot of the work of getting us to
that point at -93C.

So the question becomes is cooling air from -93C to -140C an efficient means
to capture CO2?

------
oe
It surprising how little plans for fixing global warming are discussed. Most
of the discussion deals with preventing global warming by reducing carbon
dioxide emissions, which is of course something we need to do.

But if we agree that there's already too much CO2 in the air, why not figure
out ways to remove it or otherwise prevent further damage?

~~~
Klapaucius
The CO2 content of the exhaust from a coal-fired power plant is (fortunately)
many orders of magnitude higher than what's found in the atmosphere. It would
be much cheaper to capture it at the source. But even that is still considered
too expensive, which is part of the reason we don't see many large-scale
carbon capture and storage operations popping up.

But there are some encouraging news from Canada these days:
[http://blogs.scientificamerican.com/observations/2014/10/07/...](http://blogs.scientificamerican.com/observations/2014/10/07/clean-
coal-era-begins/)

------
ph0rque
> Is Capturing Carbon from the Air Practical?

You mean like... trees?

~~~
rosser
Unfortunately, the only way trees make money is when they're _cut down_.
Apparently, the only way we're going to embark on any sort of program to stave
off environmental catastrophe is if someone can make a buck off it — and until
then, we'll just keep doing what we're doing, consequences be damned.

Priorities, huh?

~~~
ankitml
Unfortunate is not the fact that trees make money only when they are cut down.
Unfortunate is the way we measure money value. Trees , forests and entire
natural biodiversity ecosystem gives us so much value which is not counted in
money. This
([http://www.cbd.int/incentives/teeb/](http://www.cbd.int/incentives/teeb/))
is the scientific project which aims to build a database for measuring
economic value of biodiversity.

------
rogerbinns
Capturing carbon from the air is extremely practical - plants do it using
solar power. What is this technological approach trying to achieve, versus
just using plants?

~~~
danielweber
It takes plants a long time to do that, and so far they aren't keeping up with
mankind's increased CO2 output. (Although parts of Canada are greening, so
there are negative feedback cycles in the carbon loop. Dunno how long that
would take.)

------
mrfusion
For another CO2 capture idea, how much CO2 could be captured if a billionaire
bought up all of the lumber on the market and buried it?

~~~
bduerst
That's not very sustainable.

What if we engineer nano machines that pulled CO2 out of the air, and used
sunlight to convert it to chemical energy?

These molecular machines could even use that chemical energy to self-
reproduce, or produce human-consumable foods and fibers.

------
Animats
If this can be made reasonably small, it could supply CO2 for carbonated
drinks in fast food outlets. Many fast food outlets have a CO2 fill port out
back, where the tank truck connects to refill the tanks. That's not going to
make a big dent in CO2 emissions, but it might be a viable product.

~~~
Klapaucius
Even if done at an industrial scale, it would serve no purpose from a climate
perspective. Adding CO2 to a drink does nothing to get rid of it. Once the
drink is consumed, the CO2 is right back out there. You only delay the release
into the atmosphere a tiny bit.

~~~
danielweber
Depends. What was the source of CO2 that you displaced? If they were also
capturing it as the exhaust from another industrial process, then you're
right. On the margin, though, there might be people producing CO2 just to have
the CO2.

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gregorkas
But if we build awesome factories that will gradually reduce the global CO2
levels, they will be useless when they do their job too good. :)

~~~
jgh
That's ok, we can always burn more coal.

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bkeroack
We have machines for doing this. They're called trees. Let's stop cutting them
down.

~~~
rthomas6
Trees are carbon neutral or even net emitters of carbon once they're mature,
so a better solution would be to frequently cut them down and then replant
them.

Edit: I am wrong in the case of old growth forests. After a bit of googling,
they are still net carbon capturers. But not as much as young forests.

~~~
readerrrr
They are? How?

My perspective is: most of the mass of the three comes from the air, and trees
are weighed in tonnes. When they die the carbon goes in the ground( as long as
they aren't burned ).

~~~
rthomas6
I was wrong in that old forests are net carbon emitters. They are still net
carbon absorbers, but not as much as young forests. The reason for this is
that trees also respirate, taking in O2 and emitting CO2, and this balances
the CO2 absorption of photosynthesis. Old forests are still net carbon
absorbers because trees have to repair themselves, and that matter still comes
from the air. But intuitively, the amount of carbon absorption from
maintenance vs. the amount from growing larger is much less for the former.

------
mrfusion
I wonder why he can't just sell carbon credits to fund it? Is that not a large
market?

~~~
mrfusion
I'm curious why this was down voted? I meant it as a legitimate question. I
don't know much about carbon credits but I'd imagine anyone taking CO2 out of
the atmosphere would be able to sell them?

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prestonbriggs
Plant more trees?

~~~
erikpukinskis
Trees convert co2 into cellulose, until they die and rot, releasing the co2.

------
avn2109
>> "Is Capturing Carbon from the Air Practical?"

There are already widely-available solar-powered redundant distributed systems
that do this while producing valuable outputs. Around here we call it the
forest (tm).

~~~
rthomas6
Apparently trees are carbon neutral or even net emitters of carbon once
they're mature, so this is only true for _young_ forests.

Edit: I am wrong in the case of old growth forests. After a bit of googling,
they are still net carbon capturers. For an individual tree, I'm more right.
And in both cases, young trees/forests absorb more carbon in a given span of
time than old trees/forests.

~~~
blhack
I think you're missing the point. The forest is literally stored carbon. All
of those trees, plants, animals, etc. are all made out of carbon that has been
sucked out of the air and converted into biomatter.

(Unless I'm really, really misunderstanding something)

~~~
mrfusion
Every tree born eventually dies and decays back into CO2 and worse (some
methane). I think that's what he's getting at.

~~~
snowballsteve
So if we say, stop with the corn infatuation and plant forests we would at
lease give ourselves some breathing room to figure things out for a half
century?

~~~
rthomas6
Well, how much carbon does corn absorb vs. trees?

