
Engineers find neat way to turn waste carbon dioxide into useful material - geeklord
https://newsroom.unsw.edu.au/news/science-tech/engineers-find-neat-way-turn-waste-carbon-dioxide-useful-material
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bit_logic
Every time there’s a discussion about synthetic carbon fuels, there’s the same
frustrating replies. I want to reply to those with one statement: the whole
point is to use excess power from solar/wind. There’s always the same replies
pointing out how it’s more efficient to use the power directly in EV
batteries, laws of thermodynamics, and other similar things. Those completely
miss the point. Solar/wind is going exponential and we have a big problem of
storing excess power. Massive really massive amounts of batteries is one
option. But converting that into carbon fuels that work directly in existing
infrastructure and is effectively carbon neutral is a good option too. That’s
where the discussion should be, not pointless arguments about efficiency of
EVs.

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skybrian
A problem with processes based on using excess power is that they use
equipment inefficiently. If cheap power is only available for a quarter of the
time then it would take 4x as long to pay for the investment in the equipment.
Whatever scheme you set up to use excess power needs to be pretty cheap to
make it worth running only a small part of the time, or it needs to be doing
something especially valuable.

Compare to the strategy of locating somewhere that electricity is always cheap
and running all the time.

~~~
bit_logic
Solar produces only during the day, but wind is at any hour. And these days,
the idea of massive over-provisioning is being discussed to overcome the
intermittent problem since solar/wind keeps getting cheaper and cheaper. The
idea is simple, how to overcome the cloudy winter day issue? Simply overbuild
a lot of solar/wind so it can still provide enough on a winter day. Then
during summer, shutoff the excess power generation.

But what a waste of potential to do that! All that overbuilt power generation,
simply turned off during summer. Batteries don't help here, it would store it,
but then the question of what to do with it is still here.

If society goes the route of massive overbuilding solar/wind, then there's an
opportunity to do something with effectively free power during summer. But
it's ONLY during summer, so it needs to be something valuable that can also
act as a energy storage.

Carbon fuel is perfect for this. Millions of ICE cars exist and are still
being produced. Long distance airplanes will be carbon fuel based for a long
time. And so many other uses. I think another option is water. Water can also
be seen as a valuable resource that acts as energy storage. Use the excess
summer power to fill up a near empty dam with desalinated water? Sounds like a
perfect fit for regions like southern California or Arizona.

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LegitShady
>Use the excess summer power to fill up a near empty dam with desalinated
water?

Pumped storage hydroelectricity is the biggest form of power storage at the
moment, and has efficiencies around 70-80%. The losses for desalinization
(pumping through media) are ruinous compared to just pumping uphill, and
storing desalinized water means you can't use it without spending potential
power. There might be good reasons not to mix desalinization and energy
storage.

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PopeDotNinja
As I understand it, the main challenge with pumped storage is that you can't
do it everywhere. You need fairly specific geography for it, and it's a big
civil engineering project. Here's a good video on by Practical Engineering:

[https://youtu.be/66YRCjkxIcg](https://youtu.be/66YRCjkxIcg)

~~~
MaxBarraclough
Good video, thanks. It briefly mentions the idea of pumped seawater storage.
Is that really any different from using freshwater, other than location?

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LegitShady
seawater is saline, you have to be careful what you do with it because you
dont want to literally salt the earth where you are (soil remediation friggin
sucks).

seawater is also not valuable. You don't care about the water quality in the
reservoir, you just let it fall back into the sea. If it evaporates you're
losing energy but you aren't losing potable water that you sell, and it
doesn't require a connection to a water distribution main.

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credit_guy
The application doesn't really make sense the way they explain it: use CO2
from a power plant to produce syngas. If the power plant burns methane, you
might as well produce syngas straight out of methane, and short-circuit the
step where you produce CO2. From the net energy usage point of view, you are
better off (otherwise, you just found a recipe for perpetual motion).

Where this could make sense is energy storage. Say you are next to a large
solar power plant, and you want to store the excess energy produced during the
day and release it at night. Batteries are too expensive, pumped water
requires some mountains, etc. With this, you store a quantity of CO2 in some
tanks. At day you generate syngas and consume electricity, and store it in
some other tanks. At night, you burn the syngas, get some of the initial
electricity back, and store the CO2 back in its tanks.

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nine_k
This makes complete sense if you replace a power plant that produces
electricity with an industrial process that produces heat, e.g. a blast
furnace.

Then you can grab the waste CO₂ and turn it into something useful (ultimately
liquid fuel, plastics, etc) by using the cheap solar energy, of which we often
have a surplus at daytime.

This has the downside of only operating efficiently during sunshine, or
needing a power transmission line from somewhere under sunshine currently
(e.g. during local night).

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Animats
_“We used an open flame, which burns at 2000 degrees, to create nanoparticles
of zinc oxide that can then be used to convert CO2, using electricity, into
syngas.”_

Is this a real catalyst? (That is, it doesn't get used up in the process.) Or
do they have to keep making more zinc oxide clouds to keep the process going?
The paper summary is unclear about the energy inputs to this process.

Costs $10 to read the paper.

~~~
philipkglass
It's a real catalyst. Full paper here:

[https://sci-hub.tw/10.1002/aenm.202001381](https://sci-
hub.tw/10.1002/aenm.202001381)

I don't think it will have industrial significance any time soon, though.
Catalysts and processes for the reverse water-gas shift reaction are better
developed. The hope is that electrochemical catalysts like this can combine
the electrolysis process for making H2 and the syngas production step into
one, with lower equipment costs. It's hard for me to believe that it will
overtake better established industrial processes. It's very hard to take a
maybe-better process from lab scale to industry when there's already an
established pair of processes that get to the same outcome.

My prediction: electrolyzers and catalytic processes will continue to be
optimized separately, and combining those modules will continue to be more
predictable and affordable than all-in-one electrocatalytic approaches like
this.

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elcritch
Do you have more resources regarding the current state of art for the separate
processes?

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woodandsteel
Synfuels are very important for saving the climate. Yes, we need to eventually
move all transportation to batteries, and we now have the technology to do
that with cars and increasingly with trucking.

But for ocean ships and long-range airplanes we are nowhere near ready for
that. And hydrogen fuel cells are not nearly good enough. So at least for many
years the only way to make some important forms of transportation carbon-
neutral will be synfuels

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pronoiac
This looks like the same story:
[https://www.sciencedaily.com/releases/2020/06/200610152016.h...](https://www.sciencedaily.com/releases/2020/06/200610152016.htm)

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ajuc
How are they converting CO2 into H2+CO? Where is the hydrogen coming from?

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thereisnospork
Water. In a conventional CO2 electrolyzer (electricity + CO2 -> CO + O2) where
CO2 is dissolved in water (plus salt) H2 is the standard byproduct per H2O +
electricity -> H2 + O2. The concept of CO2+H2O directly into H2 + CO is
neither novel nor useful, as dedicated green-H2 production is more efficient.

This is an example of 'meh' level work being puffed up.

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gpm
Slightly offtopic, what's the easiest way to scrub CO2 from air (e.g. in a
house) without using up consumable materials? Some form of pressure swing
absorption?

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atrus
Probably a bunch of plants.

~~~
gpm
Just in terms of numbers, you breathe out a kg of CO2 per day, you need to be
growing more than a kg of plants per day to keep up with that.

That's a _lot_ of plants.

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crimsonalucard1
Doesn't the net CO2 in the air increase?

So you harvest CO2 to into fuel. That fuel is burned and the CO2 is released
back into the air. So net difference is zero.

But to harvest the CO2 you needed to generate a high amount of heat. That's
extra CO2. So net CO2 is more.

It depends on the cost of harvesting that CO2.

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lykr0n
You can use Solar and other renewable energy to power the conversion process.
Progress is still progress.

I would much rather to pay more for net zero carbon fuel, then not do
anything.

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perl4ever
I do not understand the concept that a property of a _sum_ of a bunch of
numbers somehow applies to those components.

Whether something is net zero depends on what you are adding it to; it's not
inherent in that thing.

It's like, if you have a pile of blue things, then the pile is also blue. But
other characteristics do not work that way. If you have a pile of things that
each weigh 1 lb, then the pile does not weigh 1 lb.

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readams
If you make a hydrocarbon by taking CO2 from the air, and you use a carbon
free energy source to do it, then burning that hydrocarbon is net zero carbon.
That is, if all your hydrocarbons that you burn were made this way, then the
atmospheric carbon doesn't increase because of your activity.

It acts just like a battery.

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perl4ever
You're not telling me anything I don't know.

Look at it this way, do you believe CO2 is basically fungible in the context
of global climate change?

