[adrian_b]

"how the CO2 needs to be delivered":

The experiments described in the paper have used pure CO2. The conversion process is unlikely to work directly with air, because it decomposes CO2 into solid carbon partially oxidated and dioxygen.

If one of the products of the catalyzed reaction, i.e. oxygen from the air, would be present in a much larger concentration than the input substance (CO2), like in the air, the conversion reaction will either stop completely or it will be at least slowed down a lot.

So besides the costs for the energy and for renewing the silver and gallium from time to time and also for the organic solvents that might also need to be replaced from time to time, the cost of separating CO2 from the air must be added.

Nevertheless, it might still eventually be cheaper than alternative methods, as most of them also need to first separate the CO2 from the air.

In any case, much more research is needed to scale this from experiments in minute quantities to industrial dimensions.

[photochemsyn]

Preconcentration of CO2 from air makes a lot of sense as you can then do various types of industrial chemistry on a pure CO2 stream at greater efficiency. From here you can go towards either methane and long-chain fuel hydrocarbons (Sabatier, modified Fischer-Tropsch, etc) or, as in this paper, towards solid carbon forms.

Making something like graphite from pure CO2 has certain advantages as well (easier to get purity) and graphite electrodes are used in scrap steel recycling and other industries.

For comparison, see the ISS use of Sabatier reaction and some issues they had with catalyst poisoning:

https://ntrs.nasa.gov/search.jsp?R=20140002591

This indicates that power plant emissions, typically contaminated with sulfur / arsenic / mercury / nitrogen etc. , at about 10% CO2 as I recall, would be a very poor option relative to direct air capture.

As far as scaling, even existing systems (see ISS) could be scaled fairly rapidly and would be able to produce enough fuel for specialized uses, i.e. plausibly supplying SpaceX / ULA/ etc. rocket launches as a first step, then moving to supply airports with jet fuel for long-distance travel at a much larger scale.

[kortex]

It's possible this might work with de-oxygenated air. As long as the nitrogen does not react with the generated oxygen and release NOx, this could be done with an adsorption process, which is a lot cheaper and less energy than full air separation.

Even then, NOx can be mitigated. This process is fascinating in that unlike most "breakthroughs" this has a semblance of a chance of scaling.

[cletus]

A big issue with renewable energy, particularly solar and wind, is that the power output is variable and an electric grid needs a base load to operate.

Now I firmly believe the future here is ultimately space-based solar power collectors. I've seen estimates that a panel in space around Earth can generate ~7 times the power it can on Earth. This is a deep topic but generating power in space for use on Earth isn't as crazy as it may sound.

Anyway, another potential application is to use variable power output for useful purposes on-site. For example, you can extract CO2 directly from the atmosphere and with simply chemistry you can make gasoline from that. This is currently cost-prohibitive so no one does it.

At some point this may become economic, in which case the variable power output won't be an issue. You're now only interested in the total output. You also don't lose power from transmission or require the capital cost of transmission lines.

Perhaps CO2 capture is another potential such application. Either the CO2 could be processed on site with a process like this and the byproducts (pure carbon and oxygen) can be sold.

[ClumsyPilot]

"I've seen estimates that a panel in space around Earth can generate ~7 times the power it can on Earth"

Contrast it with the fact that that panel is 1,000x more expensive, and thats a net loss. We are constrained by capital cost, not lack of sunlight or anything else.

Also consider transmission losses, orbital solar collectors must convert that power into microwaves, which are made of photons, then they must be converted back into electrons on earth. That inefficiency is compounded by atmospheric water absorbing microwaves. (you are heating clouds) You have destroyed that 7x advantage.

If you can place a panel in orbit and deliver power to Earth, then you can put a million panels in Sahara Desert and relay that power anywhere on Earth. Solar panels are made of sand, we are not short on sand. If we covered 1% of uninhabitable deserts in panels, thay would produce more power than we could use, and it would be reliable.

[laserbeam]

> space-based solar power

Cute, but very much off topic. Lets have that discussion on an article about energy generation, not about carbon capture.

[GordonS]

> I've seen estimates that a panel in space around Earth can generate ~7 times the power it can on Earth

How do you get that power back down to Earth where it can be used?

[chrisweekly]

Presumably, laser beams to heat terrestrial mountains of salt. What could possibly go wrong?

/jk

Seriously, I'm curious about this too.

Edit: a quick search shows I was close: https://earthsky.org/earth/space-based-solar-energy-power-ge...

[ClumsyPilot]

If you want to place solar panels in a hostile and distant environment to triple their efficiency, we have the Sahara Desert for that.

That article does not mention inefficiency of space that microwave transmission, it is going to wreck that 7x advantage.

Also lifting a solar panel from Earth will cost more energy than it will ever generate You have to have cities and factories in space before any solar collector could even be considered.