A Comparison of Two Approaches to Direct Air Capture of CO2.

[NNadir]

As it's open sourced, available for anyone to read, I will simply provide a linkto refer to, and make a brief comment on, this paper: On Comparing Packed Beds and Monoliths for CO2 Capture from Air Through Experiments, Theory, and Modeling Valentina Stampi-Bombelli, Alba Storione, Quirin Grossmann, and Marco Mazzotti Industrial & Engineering Chemistry Research 2024 63 (26), 11637-11653.

It's a nice mathematical approach to evaluating the merits of two approaches to two proposed methods of direct air capture.

Direct air capture, like all carbon capture, requires energy, the more dilute the stream, the more energy is required to overcome the entropy of mixing. Thus, in a situation in which CO₂ is being dumped into the air, as with the continuing use of dangerous fossil fuels, it is self defeating by definition. It is a thermodynamic loser.

On the other hand, in a situation in which sustainable clean energy is available - of which there is one, and only one form, nuclear energy - direct air capture might be of help restore the planet from the present conditions of extreme global heating, now observed worldwide. It strikes me as being at the edge of feasibility, albeit only in conditions of process intensification, in which heat is managed in a heat network, flowing from very high temperatures to ambient temperatures. For this to work, the situation would need to be a CCU, "carbon capture and utilization, not CCS, carbon capture and "storage." In this case, CCU, carbon dioxide would be utilized for all material purposes - chemical and structural - now provided by petroleum or coal sources.

This paper refers to two approaches for direct air capture. I'm not truly enamored of either approach, although coupled to Brayton cycles using air as the working fluid (as in a jet engine) with nuclear heat, they might have application.

I personally prefer chemical alkali carbonate formation, again in an air Brayton approach, preferably with radioactive cesium hydroxide, although it is, owing to secular equilibrium effects, unlikely, that we would ever manage to accumulate enough fission products, even in an ideal nuclear powered world, to do anything other than make a small dent in the currently observed disaster of extreme global heating. Rubidium and potassium hydroxides which are not very radioactive, even sodium hydroxide, would also work.

Just a note...

[lostnfound]

1. Recommending even though

Even though I’m not a fan of nuclear power, I’m a huge fan of science and i appreciate your commentary and explanation and the link very much.
Rock on, DU, for containing such a great variety of ways to learn.

[niyad]

2. I second that!

[NNadir]

3. Thanks, but I am completely incapable of understanding why anyone would NOT be a fan of nuclear energy.

It's our last best hope, although the fossil fuel industry, which is killing the planet, has managed to rachet up, via "but her emails" type selective attention, its demonization. It is the fossil fuel industry that is killing people, and indeed the planet.

Nuclear energy need not be without risk to be vastly superior to everything else. It only needs to be vastly superior to everything else, which it is.

To me, fear of nuclear energy is just evidence that propaganda is very powerful. I personally regard antinuclear rhetoric as the exact and precise equivalent of antivax thinking, which involves elevating rare negative events over the vast benefits.

[lostnfound]

4. I worked in power plants. Greed runs everything. I'm old and have my sympathies.

I understand well why you support it. You don’t need to know why this old woman has her doubts. I respect your take on it.

[NNadir]

5. I work in the pharmaceutical industry. One sees a lot of ethically challenging issues there, but, we are in the...

...business of saving human lives overall.

During the early days of the AIDS crisis, if someone screwed up, even with the best intentions, people died. If someone screwed up because they were out all night partying to celebrate making a lot of money, people died. Overall, though we, our industry, saved human lives.

Ordinary people, and famous people - Magic Johnson comes to mind - are alive today because of our work.

If one is old - and I am - in my opinion, one is naive if one believes that all processes are infused with an overwhelming sense of decency and the will to do the right thing.

It should be obvious that the disaster of extreme global heating we are now observing was not disconnected with greed in the energy industry in connection with fossil fuels. I would also note that there were and are hard working and generally decent people who work or worked in coal plants who do not want their plants to shut because their livelihood depends on the plant staying open. These are hard choices to make; do good for humanity as a whole, or keep food on one's own table, a roof over one's own children's head.

I worked on AIDS drugs; I worked on cancer drugs; I worked on drugs to make old men get an erection; I worked on drugs to make bald men grow hair. I objected ethically to the use of resources in the latter two cases, but I was keeping a roof over my family's head, food on the table.

I repeat and add: Nuclear energy need not be without risk, neither does it need to be practiced only by people of high ethical standards, to be better than everything else. It only needs to be better than everything else, this, on a vast scale, being the case.

Any high technology will involve injury to some individuals; the question is whether on balance it makes, on the grand scale, life more livable, and gives us the opportunity to do the great and wonderful humans can and sometimes do accomplish.

Nuclear reactors have failed, and may fail again. We have observed the consequences of these failures. To my mind these consequences are trivial in comparison to a planet on fire because of extreme weather driven by extreme global heating, although, as a nuclear advocate, I have been engaged in the tiresome exercise of listening to badly educated people, people incapable of making simple comparisons, whine and chant insipidly about Fukushima and Chernobyl.

On a scale that matters, they are both relatively unimportant events; their repeat being subject to address by improved engineering.

But let's cut to the chase:

Which killed more people in Ukraine, Chernobyl, or the Russian weaponry funded by German antinukes buying coal, oil and gas from Vladimir Putin? A former German Chancellor has been paid over a million dollars a year, for well over a decade, to work for Putin's Gazprom.

Nuclear energy saves lives, and to the extent it has been permitted to do so against the elevation of fear and ignorance, it has slowed, but not been permitted, to repeat, by appeals to fear and ignorance, to stop, the destruction of the planetary atmosphere.

Pushker Kharecha and his colleague, the famous climate scientist Jim Hansen have done the numbers:

Prevented Mortality and Greenhouse Gas Emissions from Historical and Projected Nuclear Power (Pushker A. Kharecha* and James E. Hansen Environ. Sci. Technol., 2013, 47 (9), pp 4889–4895).

As of 2013, nuclear power had prevented about a year's worth of the dumping of the dangerous fossil fuel waste carbon dioxide directly into the planetary atmosphere. We'd be well beyond 430 ppm concentrations of CO₂ if it hadn't done so. As it is, during my roughly 20 year tenure at DU, listening all the time to the whining of antinukes, the concentration has risen by about 50 ppm.

Week beginning on September 22, 2024: 421.71 ppm
Weekly value from 1 year ago: 418.28 ppm
Weekly value from 10 years ago: 395.47 ppm
Last updated: September 28, 2024

Weekly average CO2 at Mauna Loa (It was 427.98 ppm in April; the annual concentrations are sinusoidal imposed on a quadratic axis.)

The Disastrous 2024 CO2 Data Recorded at Mauna Loa: Yet Another Update.

People lie, to themselves and each other, but numbers don't lie.

Human beings have many flaws. Greed is one, I suppose, but to my mind not nearly as egregious as fear and ignorance.

Thanks for your comment.