US DOE funds nuclear-coupled carbon capture studies.

[NNadir]

A little over a year ago, I discussed a paper over in the Science forum here on the electrochemical reduction of molten carbonates to elemental carbon: Electrolysis of Lithium-Free Molten Carbonates

It wasn't as sexy as talking about Elon Musk, his rocket ships, his space trash or his car trash, but what can one expect these days?

Not much, of course. We're at 421 ppm of the dangerous fossil fuel waste carbon dioxide in the planetary atmosphere this week.

Wind turbines. Solar cells.

Rah.

Rah.

Rah.

That worked well, didn't it, at a cost of trillions of dollars? Didn't it?

421 ppm.

I think quite a bit of paths to direct air capture of carbon dioxide that may be taken by the generation we screwed with all our wishful thinking, denial, and anti-this, anti-that rhetoric.

In order to reduce the carbon in carbon dioxide to the element, all of the energy that put it in the atmosphere must be produced again, and on top of that, all of the entropy associated with its dilution into the atmosphere will also need to be over come. That is not going to be easy.

The US DOE seems, or people in it, have recognized that this can only be done with clean energy, and quietly, under President Biden, it's acting on reality independent of popular nonsense:

USA funds nuclear-coupled carbon capture studies.

Excerpts:

The US Department of Energy (DOE) has awarded nearly USD5 million to two separate cost-shared projects that aim to study the use of direct air capture (DAC) technology at nuclear power plants. The studies - one led by Constellation at its Byron plant, and the other led by Battelle Memorial Institute at Southern Company's Farley plant - ultimately aim to leverage the plants' carbon-free energy to remove CO2 from ambient air.

Constellation and its project partners have been selected to receive USD2.5 million of DOE funding, with non-DOE funding of USD625,000 for a total of USD3.125 million, to examine the technical and commercial viability of a DAC and sequestration system developed by Carbon Engineering, co-located with the two-unit Byron pressurised water reactor plant in Illinois. Constellation's partners in the project are 1PointFive Inc, Worley Group Inc, Carbon Engineering Ltd, Pacific Northwest National Laboratory and the University of Illinois Urbana-Champaign.

The study will involve the use of Carbon Engineering's DAC technology, licensed to 1PointFive, within plant operations at Byron and its twin 495-foot-tall (150 metres) hyperbolic cooling towers. A chemical solution would be added to water flowing through the main condenser on the non-nuclear side of the plant. After travelling through the condenser, the water would travel out to the cooling towers, where CO2 in the air will attach itself to the chemical solution and become captured and sequestered.

The project could capture 250,000 tons of CO2 every year, using waste heat from the nuclear power plant to increase the overall energy efficiency of the CO2 removal process. According to DOE, the CO2 captured during the study will be transported by pipeline to an underground geological formation in Illinois for dedicated and permanent storage. However, CO2 sequestered in this way could potentially be used in net-zero-emission industrial processes ranging from creating sustainable aviation fuel to supplying CO2 to the beverage industry, and the study will also focus on the potential for a nuclear plant to become the centre of a carbon capture hub, partnering the DAC technology with storage of CO2...

This isn't a very elegant process by any stretch; I can think of many better, but none quite as workable with the existing nuclear fleet.

Dumping carbon dioxide is a bad idea. Reducing it to useful products is a better idea.

It's nice to see some thinking going on in the government agency once led by nuclear advocate Steven Chu.

This falls into the category of too little, too late but it's a start.

[eppur_se_muova]

1. "A chemical solution ... " Umm, which one ?

I have seen proposals to entrap CO2 using calcium hydroxide solution, which is made from limestone by heating it (in gas-fired furnaces, no doubt) to over 840 C to drive off ... CO2. Every molecule of CO2 absorbed by the solution at one end of the process is matched by one produced at the other, plus a whole lot of CO2 produced by those furnaces. I actually thought at one point people wouldn't be so stupid as to fail to see that. BUT, in fact, they can make money by selling the process (at least to investors) anyway, so that's what they do.

This is what the DAC process does:

Process Description
Our process comprises two connected chemical loops (Figure 1). The first loop captures CO2 from the atmosphere using an aqueous solution with ionic concentrations of roughly 1.0 M OH−, 0.5 M CO32−, and 2.0 M K+. In the second loop, CO32− is precipitated by reaction with Ca2+ to form CaCO3 while the Ca2+ is replenished by dissolution of Ca(OH)2. The CaCO3 is calcined to liberate CO2 producing CaO, which is hydrated or “slaked” to produce Ca(OH)2.

https://www.cell.com/joule/fulltext/S2542-4351(18)30225-3

So they're recycling the calcium internally in this case, just using a lot of energy to do it.

At the very least, they need to find a carbonate, or probably bicarbonate, which can be decomposed less endothermically. I suspect some transition metal carbonates, such as manganese carbonate, may fit the bill, but haven't researched it thoroughly. Even Ca(HCO3)2 decomposes below the temperature of boiling water, and amine carbonates might be even better.

The emphasis in the OP is on using well-established processes to reach the goal of CO2 removal, and provide a cost estimate for doing so. But less-established processes may offer enough advantages to justify the cost of development. The energy cost estimates for the DAC process could then represent an upper bound.

[hunter]

2. Ultimately we have to put all the carbon we've dumped into the atmosphere back into the ground.

Making synthetic coal and carbonates from atmospheric carbon dioxide and burying them will be a tax on all our heavy industry.

Or maybe we'll just say "fuck it" and let billions of people suffer and die.

Human nature being what it is, the very wealthy will find no refuge.

The meek shall survive, if only because there are so many of them.