
Power plants that convert all of their CO2 emissions into carbon nanotubes - dnetesn
http://phys.org/news/2016-06-power-co2-emissions-carbon-nanotubes.html
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nneonneo
This is a cool idea, but it comes with a weird perverse incentive problem.

The authors estimate that a "CC CNF" power plant would produce $835 of
electricity and over $225,000 of nanotubes from a single metric ton of
methane. At this point, economically, this is no longer a power plant: it is a
carbon nanotube factory that has the side-effect of producing power. And if
nanotubes are so valuable, the power generation part starts to look like a
distraction: why not just pull the electricity off the grid and convert
methane/CO2/coal/oil straight into nanotubes for less cost and complexity?

So really, this doesn't seem to be about power plants, so much as a (maybe)
cheap way to make nanotubes from carbon. If we can incentivize people to make
useful products out of all that CO2 just floating in the atmosphere, then
maybe, just _maybe_, we can start fixing the mess we made.

~~~
duaneb
> If we can incentivize people to make useful products out of all that CO2
> just floating in the atmosphere, then maybe, just _maybe_, we can start
> fixing the mess we made.

Is this really a shorter path than just planting more trees, which is both
cheap and extremely low maintenance?

~~~
vkou
Trees can sequester a bounded amount of carbon from the air.

Burning fossil fuels can release an almost unbounded amount of carbon into the
air.

~~~
duaneb
> Trees can sequester a bounded amount of carbon from the air.

So plant more trees? It's a continual process. It's not like you can plant a
tree and say "Ok, I'm carbon neutral now!"

~~~
vkou
We only have so much land to plant trees on. (Which is very quickly shrinking
due to urban and agricultural pressure.)

The current amount of carbon sequestered in all of the world's forests is ~600
giga-tonnes.

If we stopped all of our carbon emissions today, and tried to roll back to
pre-industrial CO2 levels, we'd need to sequester ~270 giga-tonnes of carbon.
Losing that much agricultural land is unrealistic - expensive as they are, it
would be much less painful to switch our entire energy economy to renewables.

~~~
rosser
Many kind of trees can grow on land that's not agriculturally viable.

~~~
vkou
This is certainly true, but we are talking about absolutely staggering amounts
of land. As it stands now, ~30% of our planet's landmasses are covered in
forest. Also, some kinds of forest are much better at sequestering carbon -
specifically, the tropical rainforests that are being cut and burnt in the
tropics.

Re-forestation is part of the solution, but it's no panacea.

~~~
rosser
> _Re-forestation is part of the solution, but it 's no panacea._

I hadn't meant to suggest it was. I'm merely saying that any approach to our
carbon problem that doesn't include planting trees is inadequate.

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gus_massa
The idea of using this in power plans with natural gas may work. The global
reaction is

    
    
      CH4 + O2 --> C + 2 H2O + energy
    

I have to check the calculation, but the research paper looks legit. I'm
worried because they use a very indirect process so it's not clear for me that
the loss in the intermediate steps are small.

Also, I'd assume that if many power plants start to do this, then the
nanotubes price will drop almost to the level of soot. (Would it be much
cheaper to just make soot instead of nanotubes?) But they say that the energy
production will drop only 10%, so this may make sense with some carbon taxes.

But I really don't like that in the research article they propose to use this
in coal plants. They use a complex scheme, (with additional solar panels?),
but the global chemical reaction doesn't make sense. They start with coal that
is essentially C and the final product is nanotubes that are essentially C, so
there is very little room to extract energy.

~~~
sandworm101
Has any thought been put into the dangers of literally millions of pounds of
carbon nanotubes floating around with nothing to do? CO2 is evil, but some
people suspect carbon nanotubes could be the next asbestos if they become
widespread.

Wouldn't a substantial pile of such tubes be a serious fire hazard? Aren't
they essentially the carbon version of steel wool, ie much more flammable than
solid carbon?

~~~
DigitalJack
CO2 is not evil and by mass most of life on earth needs it to breathe.

~~~
sandworm101
Elevated CO2 from fossil carbon stores (coal/oil etc) is evil. That isn't the
same as C02 already in the biosphere.

~~~
reitanqild
Lets be precise here: The CO2 from fossil carbon stores is chemically speaking
_exactly_ like other C02.

That said, increasing the concentration might not be smart anyways, -I don't
know, at this point I'm not really sure. (I used to be very skeptic, now I'm
starting to think it might be correct and the proponents just don't get PR.)

~~~
sandworm101
>> Lets be precise here:

Do you or do you not believe in the link between the burning of fossil fuels
and climate change? If you do not, I am not going to get into a theological
debate with a believer.

~~~
reitanqild
> Do you or do you not believe in the link between the burning of fossil fuels
> and climate change?

?

It matters nothing for the chemical properties of CO2.

> If you do not, I am not going to get into a theological debate with a
> believer.

I am very much a believer, and for technical stuff I believe in experiments,
measurements etc : )

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m_mueller
> he system applies a voltage to split CO2 into oxygen gas and solid carbon
> nanofibers

Wait what? Where is the electrical energy coming from if not from bringing
solid carbon into a lower energy state by oxidising it and releasing the
energy difference as heat? If you want to reverse that process you will with
certainty have to invest _more_ energy to account for all the losses. At which
point this isn't a power plant anymore. Am I missing something here?

~~~
warrenpj
The fuel which is being burned has a higher specific energy than pure carbon,
(compare the specific energy of natural gas with coal [1]). The chemical
process is methane -> pure carbon with CO2 as an intermediate state.

Of course you're not generating as much power as just burning the methane
completely.

[1] [http://www.engineeringtoolbox.com/co2-emission-fuels-
d_1085....](http://www.engineeringtoolbox.com/co2-emission-fuels-d_1085.html)

~~~
m_mueller
Thanks. So disregarding any heat losses, you get (12-7.5)/12 = 37.5% of the
stored energy. Gas power plants appear to have an efficiency of 54% [1]. I
honestly can't imagine how you could reasonably get electrical energy out of
that system.

[1]
[https://en.wikipedia.org/wiki/Combined_cycle#Efficiency_of_C...](https://en.wikipedia.org/wiki/Combined_cycle#Efficiency_of_CCGT_plants)

------
narrator
Only problem with carbon nanotubes is they are kind of toxic -- like maybe
asbestos level toxicity. So you just made your CO2 emissions problem into an
asbestos problem. Congratulations!

 _Dose-dependent mesothelioma induction by intraperitoneal administration of
multi-wall carbon nanotubes in p53 heterozygous mice_

" Here, we report a dose-response study; three groups of p53 heterozygous mice
(n = 20) were given a single intraperitoneal injection of 300 μg/mouse of μm-
MWCNT (corresponding to 1 × 108 fibers), 30 μg/mouse (1 × 107) or 3 μg/mouse
(1 × 106), respectively, and observed for up to 1 year. The cumulative
incidence of mesotheliomas was 19/20, 17/20 and 5/20, respectively." [1]

[1][http://onlinelibrary.wiley.com/doi/10.1111/j.1349-7006.2012....](http://onlinelibrary.wiley.com/doi/10.1111/j.1349-7006.2012.02318.x/full)

~~~
rosser
It's not like they're just venting CNTs out the top of the smoke stack,
instead of CO₂.

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enimodas
Weren't these nanotubes the new asbestos?

~~~
pasquinelli
yeah, that was my thought too. now we have an interesting new pollutant.

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beatpanda
Aside from the other objections raised here, this also doesn't do anything
about environmental and social impacts at the site of fossil fuel _extraction_
, which are significant. One of the benefits of transitioning away from fossil
fuels is not having to pull them out of the ground anymore.

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andrewflnr
Isn't there a problem of quality, here? Not all nanotubes are equal, I'm
guessing especially for applications like construction. Will it be difficult
to make sure the nanotubes this process creates are actually usable?

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teraformer
Grey goo, here we come!

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teslaberry
carbon capture is billions of waste JUST LIKE the synfuels fiasco of the
carter administration.

There is NO scarcity of carbon as an input in industrial processes. so
producing it through the MOST inefficient means , just like making FUEL OUT OF
ETHANOL , is not just unprofitable and dumb, but environmentally destructive
and stupid.

capturing carbon is just making it more expensive to burn more carbon based
fuel. capturing carbon means you are getting a lower EROI on the input energy.
so you are actually winding up getting a more carbon intensive energy
production as a result Albeit ----some of that carbon is going to be
'captured'. BUT this means the more carbon capture you achieve, the more
carbon intensive your energy source!!!!! moral hazard anyone?

the support for carbon capture amongst the greenies is one of the best
examples of internal inconsistency and thoughtlessness amongst the greens. the
total rejection of nuclear power on any and all terms, is the another.

but let's get on with it. consider that all this 'captured carbon' will just
be magically stored underground or somewhere else it won't escape for a 100
million years. MASSIVE VOLUMES in the atmosphere, cheaply and easily
'CAPTURED' and now of course, we assume it can all be stored perfectly. just
like nuclear waste right!?

no. that was sarcasm. c02 sequestration is the biggest joke of all. despite
the nonexistence of effective sequestration methods ( which all COST ENERGY,
and are thus more carbon intensive ) ------why not assume it already exist.

ok what then, consider that within 100 years, any given earthquake let alone
the basic erosion of nature will eventually lead to this carbon somehow coming
back to the atmosphere one way or another.

so now , the final piece of stupidity is introduced, let's take the carbon and
use it for industrial production instead of sequestering it. yes ,
PERFECT!!!!! LET'S INVENT NEW THINGS THAT DON'T EXIST AND ARE UNPROFITEABLE
EVEN IF THEY DID AND USE THE MOST EXPENSIVE THEORETICAL SOURCE OF INPUTS OF
CARBON TO MAKE THEM.

this is how sovietized economies reason, based on a goal centric output,
rejecting ALL COMMON SENSE about investment to achieve the perfect recipe for
optimal levels of destructive malinvestment.

\-----------------------

let me break it down for you liberals. the only effective way to sequester
carbon is to plant trees, or otherwise encourage nature to run her own course
(perhaps by stopping clearcutting trees to begin with) , because natures'
course naturally consumes oxygen and sequesters carbon by way of...THE CARBON
CYCLE!. seeding the ocean with iron for algea has not worked because our
science is lacking in the area. we know SO LITTLE about the ocean, including
to what extent it controls our atmosphere. YES, every year a whole new ton of
research comes out about the oceans previously unknown influences on the
atmosphere. why is this? because it is deep and huge. and so much of the ocean
has not been subject to study without physical penetration in many different
simultaneous locations ( like the worlds biggest scientific gang bang ) . Only
now are we even beginning to understand ocean currents below the surface of
the ocean ( where 99.999 percent of the ocean's water exists )

as for carbon, capturing it from smokestacks is just stupid. It is
uneconomical let alone more carbon intensive. please by all means continue to
pursue your interests in renewable energies. but stop being dumb. carbon
capture for the sake of smoke stack 'cleansing' is a cruel joke.

~~~
IIAOPSW
Maybe there's a coherent train of thought in here. But the random ALL CAPS and
unnecessary politicization ("let me break it down for you liberals") just
makes your entire comment come off as "THANKS OBAMA".

