Beyond Insane - Someone Finally Did The Arithmetic On The Absurdity Of Powering Direct Air Capture Of Carbon Dioxide

[hatrack]

EDIT

But as I explain in my new report, these technologies, and all potential DAC technologies, have an Achilles Heel: The laws of thermodynamics. Regardless of the technology employed, extracting CO2 directly from the atmosphere is inherently energy-intensive. Because burning fossil fuels to power DAC facilities would reduce, or even negate, the carbon-reduction goal, DAC technologies have focused on using electricity generated from zero-emissions sources.

For example, the theoretical minimum of energy needed to meet a one billion metric ton objective would require the equivalent of 10% of all electricity generated in the U.S. in 2024. The practical energy required would be at least 30%, as no technology can be 100% efficient. Producing that much electricity would require building hundreds of new nuclear plants. If wind and solar power were relied on, it would require an area larger than the state of Florida, and hundreds of thousands of megawatts of battery storage facilities to compensate for wind’s and solar’s inherent intermittency. The cost to build the required generating capacity alone would be trillions of dollars. Building additional transmission lines and the DAC facilities themselves would cost hundreds of billions of dollars more. In total, the cost is likely to be over $400 per metric ton of CO2 removed. That’s far higher than even the most recent estimates of the social cost of carbon, which supposedly measures the damages to the climate from each additional ton of CO2 emitted.

Despite the huge energy requirements, the impacts on atmospheric CO2 concentrations and global temperatures would be minuscule. The current atmospheric CO2 concentration is approximately 425 parts per million (ppm). Removing one billion metric tons of CO2 would reduce the concentration by only 1/10 of 1 ppm and, based on the Intergovernmental Panel on Climate Change's climate sensitivity estimates, by 0.003 °C. That’s about 40 times less than the assumed margin of error in measuring global temperatures. Even if billions of metric tons of CO2 were captured and sequestered annually, the impact on world temperatures by the year 2100 would be too small to have any noticeable impact on the climate.

Finally, storing CO2 underground poses environmental and health risks because it could escape, as in Cameroon in the 1980s, when Lake Nyos “burped” several hundred thousand tons of CO2, leading to the deaths of 1,700 people and thousands of cattle. It would be unreasonable to assume that, after sequestering billions of tonnes of CO2 underground, similar events could not take place.

EDIT

https://www.realclearenergy.org/articles/2026/02/12/another_climate_pipe_dream_capturing_carbon_out_of_thin_air_1164302.html

[UpInArms]

1. Ergo

The rollback of environmental protections and regulations

[NNadir]

2. I briefly scanned Dr. Less's "report." Everyone knows that removing CO2 from the atmosphere requires energy, but...

...his negative survey misses a lot of points and is nowhere near comprehensive.

First of all, it is widely recognized that seawater, on a volumetric level contains far more CO₂ than does air, moreover in multiple chemical forms, solvated carbon dioxide being one, bicarbonate another, and carbonate as a third, depending on pH. (While the ocean is being acidified, it is still relatively basic.

Dr. Heather Willauer has demonstrated on a pilot scale, using ion selective membranes that let carbon dioxide species pass through the membrane of an electrolytic cell, she can generate hydrogen and carbon dioxide, which, using the FT synthesis to make jet fuel at sea in nuclear powered aircraft carriers, perhaps making this form of war mongering carbon neutral. The cost of jet fuel produced in this way is around $6.00/gallon, close to California gas prices last I was there, and lower than the true cost at some US Naval bases around the world.

Other opportunities present themselves, by using processes already in place, wherever air compression is required. (For various reasons connected with air purification as a side product, I have suggested to my son, Brayton cycles where air is the working fluid on a powerplant. Under these conditions, I propose aqueous solutions of group one or group two metals, preferably radioactive where the carbon would be removed in the compression stage, and continuously precipitated with group 2 oxides (hydroxides in aqueous phases).

It is important that the laws of thermodynamics definitely apply in these conditions, but they can be managed in such away that the carbon dioxide is removed using heat energy that might have been rejected to the environment without being captured as exergy. Most modern nuclear plants are Rankine cycle devices, and thus have roughly 33% to 34% thermodynamic efficiency. This is an outgrowth that original designers of the nuclear plants we now use considered the heat from nuclear reactions to nearly identical to the heat used by coal. (It is also true that materials science was poor in designs that worked other ways: Some Brayton type reactors have operated commercially, however with limited success. The point is that via process intensification we can utilize some of the 67% of wasted exergy for other purposes, a process that I might add, would reduce demand for cooling water.

To my son I preach process intensification via stepped heat transfer to a point which may induce nausea in him.

As for the article. It is not really helpful, since the focus is very narrow. I can assure that the world expert in DAC, Dr. Christopher Jones at Georgia Tech is unlikely to shut his lab on reading this limited overview.

As for where to put the carbon dioxide removed, it can either be recycled, as recommended by Nobel Laureate George Olah 15 years ago, shortly before his death, or be utilized in materials setting.

Anthropogenic Chemical Carbon Cycle for a Sustainable Future George A. Olah, G. K. Surya Prakash, and Alain Goeppert Journal of the American Chemical Society 2011 133 (33), 12881-12898

The thermodynamics of producing these materials once the thermodynamics has been expended to remove from water or air, will involve recovering all of the energy put out when combustion put them there; but again, increasing the thermal efficiency of nuclear plants to around 70% or slightly more, which strikes me as feasible, makes the reduction of carbon dioxide for materials, polymers, and portable fuels where necessary, feasible.

Air capture to greenwash dangerous fossil fuels, like sequestration to greenwash fossil fuels, and like hydrogen to greenwash fossil fuels is a very dubious idea. However, in a world free of fossil fuel energy - an outcome only feasible with nuclear energy - we may be able to slowly restore the atmosphere.

[hunter]

3. Many people in the United States are perversely proud of their scientific illiteracy.

Say the word "thermodynamics" and you might as well be speaking the devil's tongue. Those who are selling absurd carbon capture schemes to politicians and the general public are counting on that ignorance.

If we are truly concerned about increasing accumulations of carbon dioxide in our atmosphere we have to quit burning fossil fuels. (If you find yourself stuck in a hole quit digging!)

Then we can start thinking about capturing carbon dioxide from the atmosphere or ocean and converting it to forms that will stay put indefinitely. That will take energy and a lot of it -- more energy than human civilization has already utilized by burning fossil fuels.

In effect we'll be turning atmospheric carbon dioxide back into materials that can be fossilized -- carbon, carbonate minerals, etc..