
Scientists Discover Efficient Process to Turn CO2 into Ethanol - ff_
http://www.popularmechanics.com/science/green-tech/a23417/convert-co2-into-ethanol/
======
harshreality
> _This process has several advantages when compared to other methods of
> converting CO2 into fuel. The reaction uses common materials like copper and
> carbon, and it converts the CO2 into ethanol, which is already widely used
> as a fuel._

> _Perhaps most importantly, it works at room temperature, which means that it
> can be started and stopped easily and with little energy cost. This means
> that this conversion process could be used as temporary energy storage
> during a lull in renewable energy generation, smoothing out fluctuations in
> a renewable energy grid._

Is it too much to ask that a science journal report on science in, like,
_quantitative_ terms to support a headline? Specifically: What's the
efficiency (or how much energy is required per mole)? Estimated overall costs
compared to batteries or grain ethanol? Other available chemical processes for
capturing CO2, and their efficiency? Not reported. I have no idea what their
arbitrary cut-off for "efficient" is, but if they say they want to make it
_more_ efficient, it obviously isn't efficient enough. Actual numbers might
help to judge.

~~~
seren
The abstract of the article includes :

 _> Herein we report a common element, nanostructured catalyst for the direct
electrochemical conversion of CO2 to ethanol with high Faradaic efficiency (63
% at −1.2 V vs RHE) and high selectivity (84 %) that operates in water and at
ambient temperature and pressure._

I am not exactly sure how to understand the 63% efficiency but I assume that
this is the rate of conversion from electrical to chemical energy.

However the conclusion of the article mentions that :

 _> The overpotential (which might be lowered with the proper electrolyte, and
by separating the hydrogen production to another catalyst) probably precludes
economic viability for this catalyst, but the high selectivity for a
12-electron reaction suggests that nanostructured surfaces with multiple
reactive sites in close proximity can yield novel reaction mechanisms._

Which sounds much less optimistic that the article's headline.

~~~
benwikler
So basically: this is nice, but there's no reason yet to think that this could
be the way we slurp carbon out of the atmosphere and avert climate
catastrophe. Right? Drat.

~~~
gravypod
Well we already have a solution for that. We just need to create massive farms
on unused land. Plant enough stuff to feed the world populations of humans
with large excess and you're going to also plant enough things to scrub co2
out of the atmosphere.

~~~
bryondowd
Just curious, but my understanding is that plants are generally carbon
neutral. Any CO2 that is taken in by a plant is eventually broken back down
and released after the plant dies and is consumed or allowed to decay. Unless
you take a significant amount of that plant matter and contain it so that the
carbon can't be re-released, at best you get a static reduction of CO2
directly proportional to the increase in live plant volume.

So, no carbon scrubbing while feeding the world, but you could maybe scrub
carbon by taking massive amounts of excess crops and burying/sealing them
away. Not sure what the cost/efficiency of that would be.

~~~
adwn
You are correct: To get a net reduction of atmospheric carbon dioxide, you
need to increase total plant mass or prevent plants from decomposing/being
eaten.

As far as I know, the majority of net oxygen production happens through algae,
because they die and sink to the bottom of the ocean, permanently removing
carbon from the carbon cycle.

------
m_mueller
Something that annoys me with these articles is that such processes are
usually praised as carbon capture at the same time as it is energy storage.
Well yes, but not both at the same time. And I really doubt its effectiveness
as energy storage in the first place - why would you burn fossil fuels (with a
loss), then gather energy with renewables to capture back the CO2 (with a
loss) and then use the energy of the ethanol again (again with a loss)? Just
store the energy from the renewables in batteries.

~~~
adrianN
Batteries might be more expensive than storing energy in liquid fuels. They
have a limited number of charge cycles after all, whereas a vat of Ethanol can
be refilled forever. There is also a large number of motors available that can
burn Ethanol, but a significantly smaller number of electric vehicles.

~~~
m_mueller
1.) electric vehicles are also vastly simpler mechanically, so what you gain
with energy storage efficiency in gasoline tanks you loose with their complex
motors.

2.) if cheap energy density is the problem they want to solve, then this
process at least needs to be compared to using the land to grow plants in
order to turn them into ethanol fuel. So a comparison like "wind farm under
average conditions + ethanol farming" vs. "wind farm under average conditions
+ solar under average conditions + CO2 to ethanol process" \--> how many
Joules of kinetic energy can you produce per square kilometer of land, given
the fuel/electricity is used in the currently most efficient motors/batteries?

~~~
adrianN
Many people dislike growing plants for Ethanol production because they compete
for arable land that can be used to produce food. Solar and wind farms can be
built in places where agriculture is not viable.

~~~
m_mueller
well, at the end it's just sunlight, carbon, nitrogen, water, a few minerals
and a bunch of chemical reactions. I'm pretty sure you could find a biological
process to put anywhere that's also viable for solar farms, including open
water. In fact, haven't there been a bunch of papers using algae?

------
Gatsky
I don't get the point of this. We already have a self propagating machine that
can turn carbon dioxide into a useful carbon substrate that is stable over
long time periods, and is a thoroughly proven carbon sequestration technology.
It's called a tree.

~~~
weatherlight
I do agree wholeheartedly, but the problem with trees is that they die and
then they rot releasing all that carbon back into the atmosphere. It's a good
start though! It be awesome if we had some sort of technology that sequestered
carbon (where it be in the form of CO2 or wood chips, and sorted that carbon
in a solid form effectively indefinitely. for trees to be a permanent
solution, we would have to convert 50% of the land we use agriculturally to
woodlands and and then better utilize the remaining land for food production.
/shrug

~~~
ju-st
The co2 released by a dead tree is captured again by the next tree. So don't
look at single trees but at whole forests.

~~~
larvyde
Which means less atmospheric carbon that we actually want to scrub gets
captured by that 'next tree'...

------
maga
>The catalyst’s novelty lies in its nanoscale structure, consisting of copper
nanoparticles embedded in carbon spikes. This nano-texturing approach avoids
the use of expensive or rare metals such as platinum that limit the economic
viability of many catalysts.

How about large scale production of the catalyst? Do we have any idea of how
to produce efficiently a "nanoscale structure consisting of copper
nanoparticles embedded in carbon spikes" in large quantities?

~~~
acveilleux
No idea about this material in specific but a lot of nanoscale stuff is
manufactured using photo lithography, basically the same way we make micro
conductors since it's a process we understand well and we can scale (just ask
Intel.)

It sounds like this material would have good tolerance for minor imperfections
(unlike IC) so yield could be really good.

~~~
AstralStorm
The problem with this one attempt is the energy input required for it to work.
That requires major research on the cathode.

------
VT_Drew
>potentially creating a new technology to help avert climate change

>The reaction turns CO2 into ethanol, which could in turn be used to power
generators and vehicles.

I am no scientist, my question is this: wouldn't it be a zero sum game at
best? You are taking C02 out of the atmosphere, turning it into fuel, which
then is used in C02 emitting engines.

~~~
77pt77
> I am no scientist, my question is this: wouldn't it be a zero sum game at
> best?

Worse than zero sum.

~~~
VT_Drew
that is why I said _at best_

------
lvs
Except it also generates CO and methane in nontrivial amount (something like
5-10% apparently), one of which is a highly toxic pollutant and the other is a
much worse greenhouse gas than CO2.

~~~
eveningcoffee
Methane can be used as fuel, so can be converted back into energy and CO2.

CO is more troublesome as it is converted into ozone in presence of sunlight
and hydroxide ions.

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M_Grey
I used to read PopMech in the bathroom, but years ago it fell far below even
that modest standard. Today, I wouldn't wipe myself with it.

"By using common materials..." Which ones? In what arrangement? How would it
scale to the level of atmospheric scrubbing?

They mention copper and carbon later, but fail to mention if that carbon is in
the form of nanotubes, or some more easily mass-manufactured form. If you read
this article and come out of it with fewer questions than you did going in,
you're doing it wrong.

------
mrfusion
Is there a way to cheaply store ethanol long term and prevent it from turning
back into co2?

~~~
kinofcain
Barrels.

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brownbat
"Efficient" here does not imply "economic viability," which the original
article suggests is out of reach for this technique.

Should click-baity science articles be flagged on HN? I don't know.

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krylon
So, basically, we can fight Global Warming _and_ get hammered doing so? Now
that's what I call a win-win! (Seriously, though, one could do other things
with ethanol besides burning it.)

------
mrfusion
Could we run this process on Venus for terraforming?

------
bnolsen
We got moonshine, yes we do!

------
mtgx
"Great, now we can go back to using coal!" \- said coal industry supporters.

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british_india
This strikes me as a Hail Mary play by the fossil fuel industry to make us
think--for a little more profit for them--that it's okay to burn carbon.

I don't buy it.

~~~
vorotato
Most people in Tennessee don't care about burning carbon so I don't see why
they'd need a "hail mary play".

~~~
logfromblammo
I'd presume that people in Tennessee may still prefer to burn a carbon-based
fuel that does not leave behind a toxic ash slurry [0].

[0]
[https://en.wikipedia.org/wiki/Kingston_Fossil_Plant_coal_fly...](https://en.wikipedia.org/wiki/Kingston_Fossil_Plant_coal_fly_ash_slurry_spill)
[http://www.timesfreepress.com/news/local/story/2015/may/10/r...](http://www.timesfreepress.com/news/local/story/2015/may/10/reclaiming-
kingston/303447/)

