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Aluminum formate Al(HCOO)3: Earth-abundant, scalable, & material for CO2 capture (science.org)
122 points by westurner on Nov 7, 2022 | hide | past | favorite | 99 comments



If I read this correctly, this is mostly aimed at the smoke-stacks of fossil fuel plants. Great for reducing their harm before we phase them out, and valuable especially if it is cheap enough to actually be plausible. Cheap here matter more than perfect, since the problem of emitting CO2 from fossil fuel plants is better (but more slowly) solved by phasing out fossil fuel.

But how does this work for scrubbing CO2 from general atmosphere, is it anywhere close to an option? Once we have 'solved' the problem of no longer emitting CO2, we will almost certainly still have way more CO2 in the atmosphere than we want. Does this new scrubber material make it feasible to reduce the CO2 from the atmosphere, or will it be more economical to deal with the symptoms of high CO2 levels?


>Does this new scrubber material make it feasible to reduce the CO2 from the atmosphere, or will it be more economical to deal with the symptoms of high CO2 levels?

The low tech solution for scrubbing C02 from the atmosphere is to get more plants absorbing it and prevent the plant decomposition back to CO2 or even worse to methane. Some of the agricultural waste may be just buried in the fields helping to build the organic matter in the soil, but it would be hard to avoid any CH4 emissions doing it. Just check any landfill with buried organic matter and some sipping in water. One can try to use pyrolysis and get charcoal. This would not be 100% emissions free (CO, CO2, CH4 etc.).

The main problem with the above is that collecting wood/straw/etc. transporting and then processing it also requires energy, at least on land. Converting the millions of agro machines to run on batteries or hydrogen would not be carbon neutral either.

Supposedly if we fertilize patches of the oceans the dead algae will nicely sink to the bottom not to be release CO2 for centuries.


My favourite solution to this is to use some of the pyrolysis products as fuel - if you burn and release 20% of the carbon captured by the plants to power the process of burying the remaining 80% the process is still carbon negative overall, and you have a nice to use hydrocarbon fuel that can more-or-less slot into existing machinery.

The biggest problem is the scale of it - to make a significant dent in global co2 you need to be pyrolysing a lot of wood - getting towards entire-earth scale managed forests.


I also think that compared to some pie or at times mirror in the sky terra engineering projects "plants for the rescue" look more realistic at this point.

>The biggest problem is the scale of it - to make a significant dent in global co2 you need to be pyrolysing a lot of wood

The giant scale and use of land is one thing. But increasingly in many places the limiting factor be it for agriculture or forest or biomass plantations is water. While forests and vegetation have more than just a sponge effect, we should keep in mind that a scorched dry forest or a field burns easily. One may look at it as +/- net zero (what burns was absorbed by the plants we planted), it may be safer to go for high biomass yielding plants we can cut preferably more than 1x a year. In the case of fire only the carbon absorbed in the last say half a year would be released. And nasty plants such as Arundo can re-sprout after the fire. Or in a case of a prolonged drought given the right equipment one can just cut it down and get rid of the danger.

*Edit*: cut one "While" too many


Stupid idea of mine: can we start burying our paper rather than recyling it? It means every sheet of paper requires cutting down more trees, and hence putting more trees (indirectly) into the ground. If you then re-plant those trees you capture more carbon.

I presume the paper doesn't add enough to create soil and just rots.


But paper is pretty effectively recycled and trees aren't the only input - transport, water, and heat at the plant.


>But paper is pretty effectively recycled and trees aren't the only input - transport, water, and heat at the plant. Exactly. Moreover 1ha of Arundo produces 20-50t or more dry mass per year packed in 100mx100m area. Granted, not harvested at 0% humidity, less dense than paper. Collecting 50t of recycled paper from the containers in the city probably needs more energy for transport.


This is actually the logic for just burying plastic: it doesn't degrade on any important timescale. Acts as a carbon sink, and keeps it out of everything. Winning all around.


Not if you got the plastic using fossil fuels and extra energy. Which is the case for most of the non-degradable plastic. Add to it that we are nowhere close to replace various types of plastics with materials obtained from non-fossil fuels.

Obtained from cellulose https://en.wikipedia.org/wiki/Cellulose_acetate does decompose fairly quickly in the soil.


There isn't enough arable land and fresh water to meaningfully address climate change in the time necessary. Algae farming with sea water might be a good alternative if we could address disposing the the algae without emissions.


This is the critical flaw in betting mostly on trees to remove CO2 from the atmosphere.

To get to the now-unlikely target of +1.5°C by 2100, the need is on the order of 6 billion tons of CO2 to remove each year by 2050[1]. A mature tree can capture only around 22 kg a year[2], so removing 6 billion tons would require planting 270 billion trees each year. To get a sense of the magnitude of the effort, there are an estimated 3 trillion trees on Earth today; we'd need to plant just as many in only 11 years.

[1] https://www.mckinsey.com/capabilities/sustainability/our-ins...

[2] https://www.eea.europa.eu/articles/forests-health-and-climat...


270B trees @22kg/year, right?

You cut them down each year and replant, or assume that there are no trees locking up 22kg CO2/year for more than 1 year?


Better yet: you burn the plants for energy, then sequester the conveniently high concentration CO2 from the smokestack and do with it whatever you'd think would be smart to do when burning fossiles.

About the Science article: my quick skim stumbled over the word "regenerate", which tells me it's not about some material suggested for permanently binding the carbon, but about a tool to get from smokestack-level CO2 concentrations to even higher levels?


> The low tech solution for scrubbing C02 from the atmosphere is to get more plants absorbing it and prevent the plant decomposition back to CO2 or even worse to methane.

Bring back moors. Moors can sink a shitload of CO2 - and there have been a lot of moors de-watered over the last centuries to gather peat and agricultural land.

The downside is you have to convince or pay off a lot of farmers who have farmed the former moors for just about the same timeframe.


Yes, moors would help. I remember that during some floods in Europe one of the ideas floating around was to construct large polders which will be flooded as needed. No clue if catching up flood waters that would be enough to turn such polders into carbon sink.

There was some documentary about a German farmer keeping his grasslands in a moor-like state by rising the water table lowered by drainage. This did work well for him in the times of the draught but in general if I remember correctly it did lower his income.


>Supposedly if we fertilize patches of the oceans the dead algae will nicely sink to the bottom not to be release CO2 for centuries.

This is not true. Russ George is and perhaps always will be a grifter.

https://en.m.wikipedia.org/wiki/Iron_fertilization


Uh, the experiment log on that page is actually moderately encouraging. The lesson, particularly from the EIFEX experiment, appears to be that it works great provided there's adequate silica for diatoms. No reference to Russ George required.


> if we fertilize patches of the oceans

Don't we do it already with wastewater streaming down from fields, pipes, rivers...?


Yes, it is called eutrophication and is a huge pollution problem. The dead algae that drops to the ocean floor get eaten by bacteria and through that depletes the oxygen, resulting in hypoxic dead ocean. No fish and no plants, which in turn kills biodiversity both in and outside the water.

Even if the goal was to store CO2 and we didn't care about anything else, the method has additional problems. With nothing living in dead zones except for algae, the methane gas produced by decomposing dead algaes has a high risk of rising to the surface.


The "ocean fertilization" referred to here is not with nutrients, but with iron [0]. Apparently there are glacial runoffs at Greenland which would just need to be transported to other areas of the ocean in order to capture massive amounts of CO2.

[0]: https://en.wikipedia.org/wiki/Iron_fertilization


Yes and no. Meaning: depositing fertilizer close to the shore in shallow waters causes toxic algal blooms and suffocates everything. One needs deep, cold waters so the sinking organic matter is not decomposing rapidly.

And yes, if the winds blow the Saharan dust over large oceanic surfaces algae do grow in otherwise "desert" waters and some of the generated biomass does sink deep.


One aspect these iron fertilization experiments have ignored is albedo. Leaving any sequestration on the table, and just focussing on keeping the albedo of equatorial oceans low for as long as possible has the real potential to avoid absorbing massive amounts of solar heat into the system. That doesn't solve the co2 problem, but because you can negate the feedback loop aspect of the problem, and perhaps even make natural sequestration occur faster if you lower temperature enough. One thing I haven't been able to figure out from the data from the experiments, is how long these blooms last. The tonnage of fertilizer and the size of the bloom, yes. Also, the experiments were done in eddies mostly to isolate the effects. So an open equatorial ocean experiment would be needed. Along with better local temperature monitoring. Some satellite imagery to verify albedo would be a plus. As far as ballpark numbers, if the bloom stays equatorial, you would need about 1.5e9 USD per however long a bloom lasts in order to maintain an albedo that would initiate snowball. That is scaling linearly up from the area affected by previous experiments vs their costs.


From German Wikipedia the albedo of water changes a lot with the angle. Oceans already are "dark" when hit by sunlight at +45degs angles. So it may not be that important.


Good question. I was also suspicious of the angle/framing of the paper as a smokestack capture solution. My thoughts are

1. smokestacks are a great place to start, it's thermodynamically easier, has low-hanging fruit, and can be a stepping stone to a atmospheric DAC solution.

2. I bet that the smokestack angle of the paper is due to ALF being a decent oxygen absorber. The paper made the argument that the CO2 (diameter 330pm) vs. N2 (diameter 364pm) selectivity was due to size exclusion principles. But oxygen has diameter 346pm, much closer to CO2, so it would stand to reason that oxygen would compete for CO2 binding efficiency. If you read the supplementary materials/experimental conditions, literally every experiment is done under a protective flow of 99.95% N2 gas, indicating that this compound is not to be exposed to air.


Interesting angle.

Even if this only works in smokestacks, it is hugely valuable. We will be stuck with some fossil fuel in the coming few years at least. Making those years less polluting is worthwhile.

I suppose there is a risk that people say "we can do fossil fuel a bit longer, we scrub it now", but I think that will pretty soon be a clearly untenable position.


> Cheap here matter more than perfect, since the problem of emitting CO2 from fossil fuel plants is better (but more slowly) solved by phasing out fossil fuel.

The goal is to stop emitting CO2, not phasing out fossil fuels. If you can use fossil fuel without emitting CO2 (and other greenhouse gasses), then the goal is achieved.

But we also know that fossil fuels are finite and it might be worthwhile to stop using them and learn to use alternatives before we get forced to do it when the sources run dry.

For me the most tragic part of the current situation is that if we somehow destroyed our current civilisation, there would be no raw resources to support a new industrial age.


I don't think there are (economical) ways to stop emitting CO2 without phasing out fossil fuels. And like you said, regardless of CO2, fossil fuels will run out anyway.

I wonder if any new civilization could bootstrap off existing knowledge and artifacts about electricity. Wind and water based electricity don't require stupidly complicated tech to get going. You can probably mine copper from ruins rather than mines. Similarly, perhaps current stores of coal and oil could also support some systems for long enough? Heck, I could even imagine old oil wells to be 'easy' to re-open.

In any case, neither I nor my children will be around after we destroy civilization. So I care much more about avoiding the destruction than the ability to rebuild afterwards.


If we somehow destroy our current civilization, then world population will plummet from starvation, especially in the third world that isn't fertilizer-self-sufficient.

And we'll still have plenty of raw coal + recyclable metals.


We won't have any raw coal. All raw coal is hundreds of meters below ground because everything that was easily accessible was already dug.

In my country hundreds of years ago people were gathering coal lying on the ground or picking it with a shovel in small holes. When oil was first found it was basically pooling on the surface or required a very shallow hole, nothing more than a deep water well, to reach.

Not only those, but a lot of other easily available sources have already been completely used up. There might be some that are overlooked in very sparsely populated, hard to reach places like Russia, Brazil or Antarctica. But the same reason why they have not been found and exploited would be why a new attempt at civilisation will also have hard time trying to find it.


> All raw coal is hundreds of meters below ground because everything that was easily accessible was already dug.

You should probably visit Wyoming.

https://en.m.wikipedia.org/wiki/List_of_coal_mines_in_the_Un...


Scrubbing C02 is important for industrial processes other than energy production so it’s very important to get it right otherwise we can’t fabricate stuff without increasing emissions and building renewable infrastructure while adding another 3.5b people to the population is going to involve a lot of fabrication.


> aimed at the smoke-stacks of fossil fuel plants

"CO2 from dried CO2-containing gas streams"

The word "dried" is going to cause trouble. Smoke stocks have a lot of water - more water than CO2 actually.


Yeah, and in gas/oil-fired electric turbines you typically inject a whole lot of water to create more mass going through.

A power plant I worked at in the 90s tried to keep a 4:1 ratio of water to fuel oil.

It was always amusing to explain to lay-folk that we "burned more water than oil," even if it wasn't technically precise.


The article states that the major advantage of this new material is much better resistance to water. Are you saying that the levels of water described in the paper are still way below untreated flue gasses?


I don't know. I just saw the word "dried" and mentioned it. Flu gasses are majority water. Natural gas has twice as much water and co2 (by moles), and according to another poster they even inject additional water.


Trees


Trees do not reduce CO2 in long run.

For starters, humanity emits more CO2 than the combined mass of entire biosphere (every living organism, not just trees), every 10 years. Even if we were somehow able to cover all landmasses of Earth with trees (which we can't) and thus double/triple the biomass we would only set back the problem by a decade or two.

Second, trees are part of a cycle. They store the CO2 temporarily, then release it mostly back to the atmosphere -- very small part becomes soil.

Trees are not a magical solution that is somehow constantly sequestering CO2 from atmosphere. Trees store a bit of CO2 once and then it stops and can even easily be reversed (if you burn it down). New growth is necessary to keep the store at the same level, otherwise the trees will burn or die and CO2 is returned to the atmosphere.


>For starters, humanity emits more CO2 than the combined mass of entire biosphere (every living organism, not just trees), every 10 years

""" Plants and soils together currently absorb an estimated 30 percent of the CO2 emitted by human activities each year. """

https://news.stanford.edu/press/view/38728

Do you have source for your 10 years?


It is actually very simple. Everybody can check easily. You do not have to believe me.

You need two numbers:

1. Amount of carbon emitted by humanity. The easiest way to get this is to find all production of coal, nat gas and oil and convert it to carbon.

2. Amount of carbon in biomass. You can find the estimate of weight of Earth's biomass online. Then you need to multiply by a factor of how much carbon there is in biomatter on average.

All necessary numbers are readily available and not controversial.

As to how much plants use CO2 it is IRRELEVANT. The only way it would be relevant is if you also had a number on how much plants emit CO2 back to atmosphere when they burn or rot. But this is extremely difficult to measure directly.

Just as you can't figure out how much you are saving up just based on your income without knowing your expenses.

But you do not have to estimate any of the two numbers. It is enough to imagine that, given constant weight of the biomass, all carbon converted from CO2 to biomass has also roughly equivalent release back to atmosphere one way or another.


Chemist here. Looks promising for CO2 scrubbing !

However, my instincts would keep me cautious around this chemical. The formate ion forms formic acid and eventually formaldehyde which is extremely toxic to humans. In addition, many organoaluminum compounds (i.e DIBAL) can cause serious damage (like blowing up labs... seriously). If a bunch of this stuff was in the atmosphere, it could be quite dangerous to human life.

Otherwise, I am quite interested to seeing how this could be implemented.


The compound presented here is, however, not an organoaluminum compound. Those have Al-C bonds and are indeed very reactive. Aluminum formate has the Al3+-ion coordinated only by oxygen, and will certainly not exhibit the reactivity you described.


Chemist here.

Formate does indeed act as a reducing agent under appropriate conditions, but its byproduct is typically CO2 gas, not formaldehyde (HCOO- -> CO2 + H+ + 2e-). Aldehydes are generally unstable with respect to disproproportionation and are therefore unlikely reaction products.

Organoaluminum compounds are molecules with direct Al-C bonds, whereas these are effectively normal ionic salts with some unusual unit cell structure. Conflating DiBAl with aluminum formate is akin to conflating chlorine gas with clhoride anion...


Formate ions can disproportionate:

HCO2H -> CO2 + H2

HCO2H + H2 -> HCHO + H2O

However, aluminum salts of formate are likely more stable? You usually need formic acid and heat to generate hydrogen.


also if you get trace amounts of formaldehyde out the smokestack it isn't going to last more than a few hours in the environment. every living thing produces formaldehyde


Always flue gas, never atmospheric concentrations.

We have loads of good ideas for scrubbing flue. We have no good ideas for atmospheric CO2.

420/1000000 isn't a lot of particles per million. Moving and concentrating those particles and grabbing them is going to require an _incredible amount of energy_ no matter how you swing it. People have not comprehended the scale of this challenge yet.


If the source of the flue gas is ~renewable (e.g. wood) and the energy generated is used usefully, this isn't a bad idea for carbon capture. It's much easier to capture the carbon technologically like this, and rely on broader capture (e.g. trees) to pull it out of the atmosphere. What really counts is what happens to the concentrated carbon being extracted - it needs to not go back into the atmosphere.


We have no good ideas for atmospheric CO2

https://www.projectvesta.org is the best-looking option I have seen for this.


The one I am most interested in is https://verdox.com/


direct air capture has been demonstrated by a variety of methods, including the literally oldest human industrial chemical process, lime burning. i've done the calculations, it's not such a bfd, even with lime

yes, it requires an incredible amount of energy

guess what solar panels give you


I would be very curious to see that math that you solved the problem with, given that all of the scientists in the world working on this missed your solution.


no they didn't, you did, because that's what happens when you don't read any of the existing research

quoting my comment at https://news.ycombinator.com/item?id=32198793 about the theoretical thermodynamic minimum for direct air capture,

as https://en.wikipedia.org/wiki/Direct_air_capture#Environment... explains, it is only 250 kWh/tonne CO₂, or 900 kJ/kg in SI units. To remove the ≈60 Gt/year of anthropogenic CO₂ currently being emitted and get us to carbon-neutral with direct air capture would consequently require a theoretical minimum of 1.7 terawatts, which is only about 10% of current world marketed energy consumption, and presumably about 5% of world marketed energy consumption 10 years from now. Kicking climate change into reverse would require a bit more than that, maybe double. Depending on the sorbent system, this energy can be solar thermal; it does not have to be electrical.

Existing direct air capture systems like Climeworks's do not closely approach the theoretical minimum. ...

Point source capture is of course much cheaper but it cannot get us to net negative CO₂ emissions.

(note https://news.ycombinator.com/item?id=33504318 points out a way that point source capture could conceivably get us to net negative emissions)

https://news.ycombinator.com/item?id=29327736 describes the lime approach. it uses a huge amount of energy, 1600 kWh/tonne CO2 (5700 kJ/kg CO2), much larger than the theoretical minimum above and much more than Climeworks, so the purpose of explaining it is only to demonstrate that there's no practical scalability limit to direct air capture. you don't have to ramp up your production of triethanolamine or aluminum formate or whatever the fuck. those are just a matter of optimizing the energy efficiency


None of this explains how using 10% of total human energy production (at a bare minimum, using technology that doesn't exist) isn't a "BFD", or how in the world lime burning - a process that emits CO2 - is in any way a solution.

I have absolutely "read the research", spent months in training and worked in the industry, which is why I found your claim that you've solved it and that it's not a big deal to be so ridiculous.


direct air capture normally requires cycling a sorbent, as you would know if you had worked in the industry as anything other than a janitor. you heat it up, it emits CO2 (hopefully into your underground caverns or wherever the fuck you're sequestering the stuff), you cool it back down, and it starts absorbing CO2 (for example, from the atmosphere). that's the same way scrubber systems like diethanolamine, triethanolamine, and zeolites work. calcium carbonate/calcium oxide/calcium hydroxide is one such cycle, just a particularly energy-hungry and slow one. conceivably there might be other approaches that don't rely on thermal cycling (pressure cycling, some kind of electrochemical thing) but afaik nobody has demonstrated one. they won't repeal the fundamental entropic limit anyway so they'll only be marginally better than existing thermal-cycling systems, we can't expect an order of magnitude improvement

using 70 percent as much, or even several times more, energy than the humans currently produce is not a bfd because the amount of solar energy reaching earth is five orders of magnitude greater than current world marketed energy consumption. historically that was irrelevant because burning coal was cheaper than solar panels. now solar panels are cheaper and it's just a matter of scaling up production, which will happen unless people somehow run out of economically profitable ways to use energy. see my notes from 2008 at https://dercuano.github.io/notes/solar-economics.html for details

i note a total absence of any quantitative arguments in your comments thus far; instead they rely on handwaving and gee-whiz pop science claims of incredibleness and authority


You edited your comment after I posted, but it doesn't matter, you haven't talked about the topic at hand: atmospheric CO2, a pollutant that makes up 0.04% of the air.

All of your calculations assume an infinite stream of pure CO2 - which is why sorbent based DAC work great for flue gas. Making that work with atmospheric CO2 requires tremendous pretreatment, which is hard and expensive and not something that can be handwaved away. It is the fundamental problem.


no, that is not correct; all of the calculations i have made and cited assume 400 ppm atmospheric air, not pure co2. it wouldn't even be coherent to talk about a theoretical thermodynamic minimum energy requirement to capture co2 from pure co2, which is the '10% of total human energy production' you're talking about upthread

rather than handwaving it away i linked to the calculation of what that theoretical minimum is, provided my own calculation of a trivially feasible and scalable approach that takes less than seven times as much energy as that, and mentioned climeworks, which is one of several companies doing direct air capture today for less energy than that (but obviously more than the theoretical minimum)


I don't see where you're solving this problem. How do you move the air? How do you remove the water? How do you concentrate the CO2?


if you don't know anything about how atmospheric CO2 scrubbers work i suggest reading https://en.wikipedia.org/wiki/Direct_air_capture and some of its 45 references

the top of the article has a flow diagram of a lye-catalyzed version of the lime process i was describing, a chemistry that has been used in submarines, anesthesia, and scuba diving for about a century

https://en.wikipedia.org/wiki/Carbon_dioxide_scrubber has a nice overview of the different process chemistries commonly used


Bro, you have not answered the question. How do you move and prepare the air? Think about the volume and weight of the gas that needs to be moved. See what adding fans and pretreatment does to your napkin science project and tell me how many times the total GDP of the world it costs.

There is a reason why all of science is searching for new methods for DAC right now - because what you're suggesting doesn't work at the cost and scale we need.


fans use an obviously insignificant amount of energy compared to burning lime (as you'd know if you'd ever done a process engineering calculation involving fans), air pretreatment is unnecessary for the methods i'm talking about (as i already explained), and 'all of science is searching for new methods for DAC' is the sort of nonsense that suggests you've never met a scientist in your life

the issue has only ever been that clean energy has historically been too expensive for terraforming. new methods for DAC may be economically important in a hypothetical competitive DAC market, and knocking off 50 percent or even 5 percent of the energy cost would mean a significant reduction in the absolute resources required, but they aren't going to improve on the minimum energy thermodynamically required, which is inherent to the 400ppm concentration

what's changed is that now we have a cheap source of carbon-free energy that scales to five orders of magnitude more energy than we need for this

ten years ago we didn't; without that the problem was basically unsolvable

now it's not


Alright, man, good luck. I didn't see a single answer about how you're going to physically move and prepare 5 quadrillion tons of air or why that's not necessary, but I'll sleep tight knowing that you've cracked it.

Everybody else who's reading this, maybe look up what all of the proposed DAC plants in the world look like, notice they're pretty much just a gigantic wall of fans, and think about why that might be. It's because DAC requires moving a shit-ton of air, because 400ppm isn't a lot of parts per million, and that matters.


https://www.wolframalpha.com/input?i=1.7terawatt+years tells me " ≈ 4.7 × yearly electric energy production of all nuclear power plants ( ≈ 3.2×10^15 h W )"

Or 14.9 trillion kilowatt hours, which at plausible retail prices of £0.10/kWh is approximately one and a half trillion pounds. Now, who's going to pay for that?


It’s not much on a global scale, given the nature of the problem it would be solving. And if it works we have a nice little renewable power infrastructure as a byproduct

The real problem is people and our near inability to coordinate at that scale


agreed, or even, as demonstrated in parts of this thread, people's inability to come to an agreement on widely-known facts that conflict with their ego defense


I know I’m not the right person to assess the validity, but if there were some consensus among those who are I’d support the expense.


i'm not sure what to recommend. https://pubs.rsc.org/en/content/articlehtml/2022/ee/d1ee0352... is recent, open access, and seems to be well written, but i haven't finished reading it. it includes, among other things, a process flow diagram with theoretical numbers for the calcium loop which gives slightly lower numbers than my own calculations i linked upthread

i did read https://doi.org/10.1016/j.isci.2022.103990 which is also recent and open access. it is very poorly written and contains a lot of embarrassing factual errors; however, it has a number of specific and hopefully correct numbers about energy costs lifted from other publications which are hopefully more trustworthy. on the gripping hand, none of them that i've tracked down so far report operational energy consumption numbers from an actually built large-scale dac plant

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2982422 is an earlier (02016) survey paper that i also haven't read in detail yet, though it looks good

none of these papers incorporate the awareness that energy costs have just gone through the first big drop in a century and a half, perhaps because that future is not yet widely distributed


sounds about right, though presumably you wouldn't be paying retail if you're setting up shop to terraform the earth. numerous recent ppas provide much lower (wholesale) prices than that; see https://emp.lbl.gov/pv-ppa-prices and https://www.greentechmedia.com/articles/read/merchant-income..., which have numerous prices below £0.02/kWh.

and, as i said, you can probably use solar thermal for sorbent regeneration

note, though, that the number you're using is the theoretical minimum energy used. existing practical technologies, as i said, consume several times more energy than that. it is unlikely that we will ever closely approach this theoretical efficiency

there is indeed a real difficulty in the current human incentive structure where everybody hopes someone else will fix the problem so they don't have to bear the cost themselves. but that's not a question of engineering infeasibility due to resource limits; that's a question of politics


Yes we do, they don't work in all climates, but we do have a quite well-working approach:

Step 1: base-resistand swamp cooler structured packing. Step 2: NaOH or KOH solution in water, at equilibrium with air (temperature& humidity). Step 3: blow air sideways while running liquid down via gravity. Step 4: regenerate liquid via salt metathesis reaction on column packed with Ca(OH)2. Step 5: dry-distill the CO2 out of the CaCO3 in a lime kiln (carbon capture for those is easier than for a gas turbine, as they exhaust like around iirc 3~5x as much C02 for each oxygen you feed in, assuming you fuel both with the usual methane). Step 6: inject the captured CO2 into old gas/oil formations.

Of course this would be better if you combine it with already-needed air handling, for example in central forced air HVAC installations where adjusting the concentration of the lye in step 2 through adding water or vacuum-distilling allows it to humidify/dehumidify the air and where the liquid/air contact can also easily do the heat exchanger task (that strongly basic water shouldn't support growth of any harmful micrograms, I think (for KOH it would typically be half the molarity of a saturated solution, for NaOH more like 80~90%)).

They use similar scrubbing but in dry columns (Ca(OH)2 beads soaked with NaOH solution, then left to drip and packed into canisters) for anesthesia rebreathers to scrub a patient's exhaled CO2, and similar lime/lye cycling in paper Mills (Kraft process; green liquor (sodium carbonate + sodium sulfite) to white liquor (sodium hydroxide+ sodium sulfite) recausticizing).

Assuming negligible cost of the initial wet air scrubbing (via fusing the air handling with HVAC and in the process even providing extra-low-CO2 air), assuming a methane-fired lime kiln, this overall prices should be able to compensates for around 2~4x as much fossil fuel burn in, say, vehicles, than the burn/consumption of the DAC plant.

And much of the process is quite amenable to using solar electricity (with about a day's worth of storage, but part might be able to use thermal storage in rock piles for pre-heating the kiln gas feed), especially as nothing really requires the lime kiln to work in the winter.


How do trees do it, then?


One adult tree captures 25kg per year. One transatlantic flight releases 500kg per passenger. Twenty trees, per person, per flight. Get serious.

IPCC projections for a "good" scenario still depend on magical BECCS processes that don't yet exist., not flue scrubbing, which I think if anything will be away to keep coal plants online for _longer_.

It's still valuable science, but don't get excited until there are major, major advancements in non-flue DAC/CCS.


You're failing to put things in perspective. There are 500 trees on earth for each human being. That would mean they can absorb 12500 kg per year.

Also, tree are NOT the largest natural CO2 sink, oceans absorb more.

Overall, the biosphere absorbs about 50% of total human emissions (25% by land plants and 25% by oceans). I think that once we drop the CO2 emissions enough, the nature will quickly scrub it out of the air, we don't need to get negative ourselves, just drop close to zero and nature should balance itself pretty quick.


It's a carbon _cycle_. We've spent a hundreds of years adding new carbon to that cycle as fast as our technology will allow, which is now very fast. It will remain in the cycle unless we sequester it back into the ground. Plants (for the most part) aren't CO2 limited, they're nitrogen limited.

The climate also isn't something that will just snap happily back into place. We're in a local minima. If we climb up this hill, we won't like what we find in the next valley.


Oceans absorbing CO2 results in acidification which is already harming the oceanic life cycle. We really want to tilt the balance away from the oceans, because the consequences of a dead ocean are dire.


There is nothing magical about BECCS.

At the power plant it is a matter of putting together technology that already exists. All of the elements such as amine strippers, pyrolysis, oxy-fuel combustion, etc. have been around since the 1970s. The literature has a "stopped clock" appearance in that people have talked about these things in the context of "clean coal" and biofuels for a long time without anything being built.

There are two problems with it.

One of them is that any kind of carbon capture is expensive and competes directly with a power plant (maybe the same power plant) without the CCS equipment. To win that competition, the operator of the power plant either needs to be fined for emitting CO₂ or has to be paid for capturing it, to the tune of $50-$100 per tonne.

Another is that the ecological accounting for biofuels is frequently not favorable. When you consider water consumption, effects of land use, and the effects of inputs, many biofuel schemes (such as Ethanol from corn in the US) seem to be a net negative.

The cheapest BECCS scheme is to capture CO₂ from the alcohol fermentation process, this has been implemented with great success

https://bioenergyinternational.com/adm-starts-commercial-sca...

Ethanol from sugarcane in Brazil is much better from an ecological and economic perspective and it would cost something like $30 a tonne to capture CO₂ and inject it into a saline aquifer but politically it seems impossible given that most international bodies think that the real problem in Brazil is deforestation and that somehow promoting agriculture in Brazil is going to cause deforestation despite the fact that the Ethanol industry is mostly around São Paulo and nowhere near the rainforest.

In principle there might be some agreement that Brazil gets credits for BECCS and also gets credits for protecting the rainforest but the latter is somewhat nonsensical in that there is a mismatch in time between processes that emit CO₂ (say you spend 5 hours on a plane) and the need to protect a forest forever to sequester a finite amount of CO₂.


> but politically it seems impossible given that most international bodies think that the real problem in Brazil is deforestation and that somehow promoting agriculture in Brazil is going to cause deforestation despite the fact that the Ethanol industry is mostly around São Paulo and nowhere near the rainforest.

It's not like Bolsonaro's term hasn't proven that deforestation is a massive problem. No one is trusting Brazil on a geopolitical stage at all, particularly as it looks like Lula is heading off in a lame-duck term against parliament and regional governors being dominated by Bolsonaro allies, who are bought off by Big Ag.


It was that way before Bolsonaro and will be that way after Bolsonaro.

Ever since

https://en.wikipedia.org/wiki/Corn_Laws

agriculture has been the most contentious issue in world trade and it is the reason why the World Trade Organization has been deadlocked since 1999. A while back Brazil asked the question: "What industries can we lead the world in?" and one of the answers was meatpacking so they got behind

https://en.wikipedia.org/wiki/JBS_S.A.

That is, JBS is to Brazil what Boeing or Apple Computer are to the US and it is by no means anomalous that it has a great deal of political influence.

When we tell them what to do with their land they react the same way we'd react if they said "It's unfair that we have to pay royalties for software like Microsoft Windows and Hollywood Movies, not to mention GMO seeds".

Most of the people in the US I talk to who rightly want to see a stop to deforestation in the Amazon are ignorant about agriculture in Brazil (e.g. they think that JBS is backwards, not the fiercely competitive corporation it is) and ignorant about agriculture in general and not particularly understanding of the process by which deforestation happens in Brazil.

It doesn't help that many questions are not well understood such as the relationship between land use in the area south of the Amazon and local climate changes that could cause the rainforest to recess northward.

There could be some compromise but so long as developed country NGOs are speaking to Brazilians in a patronizing way it isn't going to happen.


Why is sugarcane in Brazil any better than corn in the US? If they use petrochemical fertilizer, the problem is the same.

You cannot sequester a ton of CO2 for $30/tn anywhere in the world right now. You can't even do it for five times that. If what you say were true, I'd be able to clean up after my own existence right now, which I can't do. I can only buy scammy "credits" and "offsets".


See https://biowesleyan.wordpress.com/first-generation-biofuels/...

The advantage of corn over other crops is that it flourishes in the presence of nitrogen fertilizer. Sugarcane is not so hungry.

The cost of capturing fermentation CO₂ is low because fermentation CO₂ is almost pure with very little nitrogen in it. Thus almost all of the cost is the cost of compressing the CO₂, pumping it, and injecting it underground which is about $30 a tonne. Even a few percent of nitrogen will cause the CO₂ to misbehave while pumping, so capturing CO₂ from a combustion stream requires some kind of separation which historically has been an aniline stripper or something like the rectisol process, but maybe it will be aluminum formate or something else in the future. The aniline stripper costs about $50 a tonne.

The trouble with capturing fermentation CO₂ is that it is not scalable. There is a certain amount of it produced and it isn't enough to "save the Earth" but it is a low hanging fruit and it would help in the process in validating sequestration, as there are all kinds of questions about the permanence and safety of saline aquifer injection. (Don't get me started about the CarbFix water sequestration project...)

As for why you can't buy any good carbon credits it is the proliferation of junk carbon credits at low prices that keeps good ones off the market. Another problem is that many schemes are using the CO₂ to produce more oil

https://www.reuters.com/article/us-usa-energy-carbon-capture...

which on one hand is a real market for the CO₂ (in Texas you can drill and get CO₂ in some places and since the 1980s they will pump it sideways and use it for enhanced oil recovery) but doing so seems to be more problem than solution and it ties the project economically to the up-and-down cycles of the oil industry.


This is quite interesting, thanks for sharing. I had written off ethanol because of how gunked up it got with the American corn industry and the stupid fact that Iowa votes first in the US primary elections. Maybe there's something to this.


At about 3% efficiency, but compensating by being spread over a large fraction of the land surface.


Sunshine. Lots of it.


One thing that is suspiciously absent from the abstract is the stability of this material to O2.


I suspect that there are applications and industries that cannot fully be decarbonized. For example, steel production. So anything that can capture carbon from that (8% of global CO2 emissions, I believe) would be fantastic.


Is this something to be used for CC at power plants ? Or does it have any application to DAC ?


"Aluminum formate, Al(HCOO)3: An earth-abundant, scalable, and highly selective material for CO2 capture" (2022) https://www.science.org/doi/10.1126/sciadv.ade1473

> Abstract: A combination of gas adsorption and gas breakthrough measurements show that the metal-organic framework, Al(HCOO)3 (ALF), which can be made inexpensively from commodity chemicals, exhibits excellent CO2 adsorption capacities and outstanding CO2/N2 selectivity that enable it to remove CO2 from dried CO2-containing gas streams at elevated temperatures (323 kelvin). Notably, ALF is scalable, readily pelletized, stable to SO2 and NO, and simple to regenerate. Density functional theory calculations and in situ neutron diffraction studies reveal that the preferential adsorption of CO2 is a size-selective separation that depends on the subtle difference between the kinetic diameters of CO2 and N2. The findings are supported by additional measurements, including Fourier transform infrared spectroscopy, thermogravimetric analysis, and variable temperature powder and single-crystal x-ray diffraction.


"NIST Breakthrough: Simple Material Could Scrub Carbon Dioxide From Power Plant Smokestacks" (2022) https://scitechdaily.com/nist-breakthrough-simple-material-c... :

> [What to do with all of the captured CO2?]

>> - Generate more formic acid to capture more CO2

- Make protein powder (#Solein,). And nutrients and flavors?

- Feed algae

- Feed plants, greenhouses

- CAES Compressed Air Energy Storage

- Firefighting: https://twitter.com/westurner/status/1572664456210948104

- Make aerogels. Aerogels are useful for firefighter protective clothing, extremely lightweight insulation, extremely lightweight packing materials, aerospace; and no longer require supercritical drying to produce: https://twitter.com/westurner/status/1572662622423584770?t=A...

- Make hydrogels. Hydrogels are useful for: firefighting: https://www.google.com/search?q=hydrogel+firefighting https://twitter.com/westurner/status/1572664456210948104

- Make diamonds, buckyballs, fullerenes, graphene

- Water filtration: activated carbon, nanoporous graphene

Is there a similar process ("MOF,) for capturing Methane from flue gas? Is that before or after the CO2 capture?

- Methane is worse for Earth than CO2 FWIU. And there are many uncapped wells leaking methane, as now visible from space: https://news.ycombinator.com/item?id=33431427

- It's possible to make CBG Cleaner Burning Gasoline from methane (natural gas)

How does the #CophenHill recycling and flue capture facility currently handle CO2 and Methane capture?

- "Transforming carbon dioxide into jet fuel using an organic combustion-synthesized Fe-Mn-K catalyst." (2020) https://doi.org/10.1038/s41467-020-20214-z https://news.ycombinator.com/item?id=25559414


CO2 is a great red herring, the real cancer toxins and forever chemicals are spewed more every year while people scramble to sequester a harmless substance. In the distance, Bayer-Monsanto is laughing at all the useful idiots.


I challenge you to find a single peer-reviewed paper that states excess CO2 is not a contributing factor for anthropomorphic climate change.


Didn’t you read the Climategate mails? Academics in charge of climate journals admitted to “changing the meaning of peer review.” I’m under no obligation to listen to these communist prognosticators after an admission like that.


My dude, I used to work for Environment Canada. Climate change is real and people are causing it. I have quite literally worked with the raw data coming in from multiple sources. It paints a comprehensive picture of excess CO2 and Methane release into the atmosphere and overall less heat from the sun being radiated back into space as a result.

Also, "communist prognosticators" really? Grow up.


You used to work for a climate agitprop outlet? And you believe anthropogenic climate change is real? No shit.


I challenge you to discover Russel's teapot.


Climate change has nothing to do with cancer



why not tackle both?


Big CO2 counter propaganda has pushed the other stuff out of the limelight


Any physicist seems to say co2 is a neutral molecule which makes any carbon capture tech very energy intensive, whatever technology it uses.

Tired of money trying to greenwash lies.


That's why the smart people focus on capture from flue gases, which might be generated not only from fossil fuels but also from renewable biomass (basically the same just so much younger) and leave aside the direct air capture follies. Guess which side the process described in this article is on.


When we have CO2 capture running, will all the money from "CO2 credits" that was stolen from businesses be returned? :')


I'm not familiar with that but I assume it would actually be spend on things such as this




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