Direct Air Capture 9

[1503-44]

Direct Air Capture

 

[moltenmetal]

The very same thing that makes CO2 a valuable product of energy producing reactions like combustion (low Gibbs free energy), makes it a terrible feedstock for processes to make anything like a FUEL.

Nature does this because it must, and because we're awash in sunlight. And after a billion years of evolution, it's managed to get this to 2% efficiency in terms of joules of carbohydrate energy per joule of light energy incident on the leaves.

As to whether or not direct air capture makes sense:

1) To capture a tonne of CO2 from the atmosphere at 416 ppm, requires moving 1600 tonnes of air, bare minimum, through your absorber. Why would you needlessly do that, when you could instead capture from a cement kiln's calciner output at 400,000 ppm CO2?

2) You patch the hole in the hull before bailing does any good

3) If you have energy over here in excess to run a direct air capture unit, and you are burning fossils over there for energy, the best solution is to connect the two with a WIRE, not with some lugubrious carbon recycler

Direct air capture plus water plus electricity back to fuels is the equivalent of gluing Humpty Dumpty back together again after deliberately throwing him off the thermodynamic wall.

 

[1503-44]

What you say makes complete sense. Compounds resulting from combustion have a low remaining energy state and, if your goal is to capture CO2 for economic purposes, that would be much more favourable to do where high concentrations and some symbiotic relationship exist with an adjacent process or end use. IMO the authors are considering that those possibilities have been exhausted, stack cleanup has become the norm and their only purpose is to actually clean up residual atmospheric CO2 at far lower concentrations and without any additional economic benefits from reformulation or recycling the CO2 so captured. Since we are not doing that yet, it is helpful to look at existing stack cleanup projects to try to determine if their actual capital and running costs would be relevant to situations where atmospheric cleaning alone is the primary objective and to investigate other potential uses of CO2 that havent made it into the spotlight so far. Unfortunately there dont seem to be many.

 

[rb1957]

"In the Netherland they pump the CO2 into greenhouses to increase growth rates." True, higher CO2 improves plant growth ... but makes me wonder where they get this CO2 from ? produce by chemical reaction and add to atmosphere, or remove for atmosphere (probably more expensive to do) and return to atmoshpere ?

another day in paradise, or is paradise one day closer ?

 

[EdStainless]

MM, agree with you all the way.
In the Netherlands they take the CO2 rich stream from some other process, they don't make it just for this.
There are only a handful of commercial uses of CO2; for well injection, as CO2 for carbonation, as a foaming agent, or as feed to make solid carbinates. It is really just a matter of being able to offset some of the operation expenses.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[JoshPlumSE]

Costs more than burning up the Earth.
How is that possible.
Given the alternative, seems to be cheap at twice the price.

One of the things I think we sometimes fail to acknowledge is that there is a difference between KNOWN economic costs and projected / estimated economic costs. Look at it this way, who's the more valuable NFL quarterback, Jimmy Garoppolo (an imperfect, but known commodity) or Trey Lance (a projection of a draft choice based on his college production).

What I mean by this is we can compare costs or efficiency of EXISTING means of energy production relatively easily. Coal power plants cost a certain number of dollars per kilowatt generated and generate a certain amount of CO2 per kilowatt. Compare that with Combined Cycle Gas turbines, nuclear, hydro-electric, wind or solar. This becomes a VERY accurate measure of the relative efficiency of these technology. It's much easier and more reliable to make decisions about penalizing or funding based on this really good quality data.

Now, when we start projecting experimental technologies (like the kind listed in this article), it's a lot more unknown. So, when projections are sky high, I take it as a reflection of the unknown. It might be that high, it might come down. Hard to tell. Either way, I'd think it would be really important to compare the relative cost efficiency to existing technologies for reducing atmospheric carbon.... like planting / re-planting trees, bushes or other such natural means of pulling CO2 out of the atmosphere.

Lastly, the idea of comparing a relatively unknown technology like this method of carbon capture to the even more unknown projected economic cost of a similarly projected rise in temperature seems like comparing unicorns farts to dragon breath. I joke, but the uncertainty of such a comparison is so high it makes the comparison very silly.

 

[JoshPlumSE]

To be clear, I think Global Warming is real and that atmospheric CO2 is a major contributor. I just think we should deal with it as a question of energy economic policy rather than treating it as an existential threat to the future of earth or our species.

 

[rb1957]

geeze, people have been (figuratively) stoned for saying less !

another day in paradise, or is paradise one day closer ?

 

[1503-44]

"I just think we should deal with it as a question of energy economic policy "

OK. If it doesn't work one way, then hopefully we can make it work in another.
You have some ideas about how to do that as part of energy economic policy?

 

[JoshPlumSE]

You have some ideas about how to do that as part of energy economic policy?

Well, not for removing CO2 from the atmosphere. That's not an aspect of the issue that I've thought about. However, there are a lot of ways to reduce our current production of CO2.

a) Nuclear is largely carbon free and very efficient at energy production. So, expand nuclear energy production.
b) Burning coal is much less efficient (in terms of tons of CO2 per megawatt produced). So, IMMEDIATELY switch over from coal to dramatically more efficient (but still imperfect) means of energy production like combined cycled gas turbines with
c) For "green" methods of energy production, rather than focusing on government funding for rich people to get roof top solar (which are rich people virtue signaling their environmentalism) throw that money towards the type of solar that uses steam turbine generation to produce energy. Essentially reflective mirrors that heat up the water source to create steam and generate turbines. Only in that I think this is a more promising technology though it's only efficient in locations (like the desert) where the sunlight is plentiful and land is cheap.
d) Legislate more MPG restrictions on cars / trucks to force us towards more efficient hybrid technologies. Or, even better steeply increase the tax rates on inefficient cars and throw that money towards discounts towards the most efficient ones.
e) Maybe add steep import levies on foreign generated oil is it comes from locations that don't capture the natural gas that is emitted when drilling for oil (because it's not as cost effective to capture).
f) Levies on imported trade goods that come from countries that use coal to generate their power or which don't have certain types of environmental regulations.

One of the things that we MUST do is address the fact that many of the countries with the worst CO2 production in the world currently benefit from our economic policies. Why? Because all of the environmental regulations that we impose on ourselves in the US (and even more so in Europe) merely result in the manufacture of goods shifting to far away lands that don't have these regulations. Which results in WORSE treatment of the environment and also necessitates the shipment of these goods over very long distances.

 

[1503-44]

Thanks. I wasn't sure what energy economic policy was. So its a combined energy use and economic policy.

There's food for thought there.

 

[JoshPlumSE]

Sorry, I grew up with that term Energy Economics (my father being the founding member of the International Association of Energy Economics). The idea behind the organization is that the discussion of energy issues at the time tended to be very heated politically, but involved little rational discussion of economics. Since he had a background in Government and Academia (and many contacts there) and had just started working for private industry, he felt like there needed to be a forum for these excellent minds from the various sectors to meet and exchange ideas.

That was true then when when inflation and oil prices was the big issue. I see a lot of similar issues today where CO2 emissions are the big issue. The discussion today (IMO) is mostly dominated by political actors and environmentalists (including climate scientists) helped along by allies in mass media. Unfortunately, there is very little discussion of the economics of energy. Despite the fact that there are lots of good articles published on the subject from various positions.

https://www.iaee.org/en/inside/history.aspx

 

[1503-44]

Politics has taken over science, economics, religion and just about everything else.

 

[JoshPlumSE]

I tend to agree.... But, it doesn't have to be that way. Not sure how we get away from that nationally. But, we can all do it locally and in our personal interactions.

 

[1503-44]

I send my senators semi-regular advice, but it goes in one ear and quickly echos back out. I get better responses from senators I write to in states where I used to live.

 

[DrZoidberWoop]

"The machines essentially function like giant vacuum fans that pull carbon from the air and magnetically attach it to calcium or potassium molecules, transforming the emissions into a substance that can be injected underground for permanent storage, to prevent its return to the atmosphere."

I worked on this exact subject in graduate school and 2 years into a PhD program (did not finish due to extenuating circumstance) and I say this is not a viable strategy. It's a fun idea, but the sorption levels are not high enough to make a real difference, and mining companies walk a very fine line between business and compliance with environmental regulations. They all but threw us out after our pitch meeting. haha.

Bottom line, it's "feel good" science that would end up being another Solyndra debacle.

It's the exact subject that made me cynical about academic types and their incentive structure. I definitely wrote and edited my fair share of shady money-grab proposals while in school. Tenure can be a perverse master.

 

[JoshPlumSE]

It's the exact subject that made me cynical about academic types and their incentive structure.

Yup. Similar things are true all around. The politicians push stuff not because they think they'll work, but because it helps them to raise funds for re-election or excites their base. Industry groups are rightly concerned about their own profits and how regulation will affect them.

Every group acts in their own self interests. That's not a bad thing. But, we need to do a better job of balancing the various considerations and taking real and rational action. Actions that are both scientifically and economically feasible.

 

[1503-44]

I admit I've done my fair share of laughing off PhD opinions.

 

[JoshPlumSE]

I look at the "direct air capture" technology kind of similar to how I look at Santa Barbara's desalinization plant. California is in a constantly cycle of drought / non-drought. So, when we were deep in a drought Santa Barbara built a desalination plant to convert sea water into drinking water.

It's proven technology, but it's also very expensive. The plant was built in 1991 and only operated for 5 months. Then it was de-commissioned until 2017 and now provides about 30% of the cities water supply. It deserves to be in the discussion when we are in crisis mode for water supply. Even having it run like it does now provides us with flexibility in case other things happen.

However, it alone is not a solution. Part of the solution, sure. But, the economics of desalination means that it shouldn't be looked at as a MAJOR solution to our problems.

 

[rb1957]

Oz too. Sydney built a desalination plant in the last drought ... now they're drowning (again).

another day in paradise, or is paradise one day closer ?

 

[1503-44]

It seems that they think being prepared is better than insufficient water supply during times of drought. You know what they say, when it rains, it pours. In any case, weather is certainly appearing to be getting extreme, according to your own observations, so it just could be a prudent investment. So, what are you saying? That the droughts are finished and they wasted their money? It would seem that they should look at desal plants or building a large dam. Problem with dams is that if you don't ever get rain again, you don't have any water at all.