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Comment by ajross | Hacker News Reader

> Over a year, the equipment can capture 4,000 tons of CO2

Not to be glib, and I'm no agronomy expert, but a quick google tells me that's about equivalent to a square mile of hay field. Seems like if you were serious about this problem and wanted an economical solution, buying a farm and burying the output would be more effective than throwing money at startups like this.

Articles like this are always written from a tone of "If ONLY there was some way to economically extract and concentrate carbon from the atmosphere", by journalists who then go home and tend the heirloom snap peas in their raised beds without a sense of irony. Plants do this. It's literally what makes them plants.

Now... maybe there's a stronger economic argument for technologies like this, but if there is it's not filtering into the press hits. I remain suspicious.

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The elephant in the room with these prototype systems is that they currently leverage the excess capacity of existing industrial infrastructure. The chemistry involved has unavoidably high power generation requirements because you are fighting a very steep thermodynamic gradient. At anything beyond prototype scales, the industrial infrastructure to provide the raw materials for these prototypes would need to be purpose-built at astronomical scales, including countless terawatts of power generation capacity that does not exist today.

The only scalable sequestration technology is biomass for the sole reason that it is the only method that does not require creating new power generation facilities to feed industrial chemistry plants at an unprecedented scale. Sequestering CO2 requires application of energy and mass on the same scale as the energy that was released by putting it into the atmosphere in the first place.

You can't cheat the laws of thermodynamics.

Missing a point here. GHG _over_time_ drastically adds more net energy to the earth system than is is used to create or capture them. This because they are opaque to infrared radiation that would otherwise be escaping from the earth system.

So, GHG net heating effect is proportional to the amount of heat escape they block for as long as they remain in the atmosphere.

So much this.

The only place where those technologies could make sense would be on the industry generating a lot of CO2 in a concentrated manner. Or if you are creating a Mars colony, where it could be used to control your system.

Well we do have nuclear.

A square mile is a huge chunk of land. It's nearly 640 acres. For comparison a large suburban plot is usually only 1/8th of an acre. That is to say nothing for cost of keeping the land irrigated, free of pests and running tractors and other ag equipment to harvest the hay during growing season.

We then don't take into account the most expensive part, buying the land. In Texas a 500 acre ranch already prepped for hay or other crops costs about 1-2 million dollars to buy.

Furthermore, plants aren't perfect. Many plants also respirate co2 as well as oxygen. It's not a perfect equation like in grade school.

Doesn't really matter how efficient the process is biochemically. Buried carbon is buried carbon, and the production cost of biomass is dirt cheap.

A more focused criticism would be: it's not enough for that fancy plant to work, it needs to be cheaper than a hayfield at scale to be worth it. And I'd want to see numbers showing that. Farms are not, in fact, particularly expensive relative to venture backed startups.

> A square mile is a huge chunk of land. It's nearly 640 acres.

By the way, a square mile is exactly 640 acres.

You'd need to also prevent the hay from decaying. I learned the other day that bogs are highly efficient at sequestering carbon, because they prevent decay.

I think a lot of people are unclear on the fact that plants are made of air.

Has anyone done the calculation about how much landmass with trees it would take to reverse the CO2 pollution in a reasonable time frame (<100 yrs? <50 yrs?)? It seems like the square mileage would probably be quite large and possibly encroach on land that we need to devote farming to feed the growing population. This is entirely baseless speculation, I haven't done much research into this.

Yes. Many people had done so. This is covered in details in

https://www.drawdown.org/solutions/land-use/afforestation

https://e360.yale.edu/digest/planting-1-2-trillion-trees-cou...

https://science.sciencemag.org/content/365/6448/76

and in many similar research papers.

[edit: formatting]

It looks like we're nearing peak global emissions. The growth rate seems to have slowed dramatically the last couple of years.

IFF that's the case, we've added 375 billion tones of carbon to the atmosphere. Some estimates say that 50% of carbon is removed from the atmosphere every 20 years. So if our emissions stop growing, we'll eventually reach an equilibrium not far from what it is now. Plus, don't most estimates have carbon emissions rapidly decreasing as renewables become more cost effective? I've seen some estimates as high as 70% by 2050.

Anyway, a tree over the course of 40 years, can sequester 1 ton of carbon. The Amazon Rain Forest has ~390 Billion trees. So, if we could plant another Amazon Rain Forest and keep our emissions where they are (or hopefully reduce them) couldn't we avoid any further warming?

I've had this idea forever, but I'm just doing the math now. If we lined every street and highway in the US with trees, that might be enough to sequester the carbon we've added (and will add before equilibrium) to the atmosphere.

There's 5.3 million miles of road in the U.S. If you spaced the trees 10 feet apart, you could plant 528 trees per side per mile, or ~1000 per mile. That means, we could plant 5.3 billion trees, or 1/75th of an Amazon Rain Forest. If you added in every country in the world (there's 64.25 million miles of paved road and probably well over 150 million miles of paved and unpaved roads), we could plant like 1/6 to 1/2 of an Amazon.

I feel like if you added in shrubs and flowers and combined the insect biomass increase, this could actually be a thing... I mean, you could also potentially bio-engineer trees for maximum sequestration & particulate absorption. And probably there's trees you could plant 3 feet apart instead of 10 that could sequester the same amount of carbon.

We could probably capture a lot of particulates from the roads as well, naturally cool cities with added shade (and make them prettier), and increase insect biomass (which has shrank like 75% in the last 27 years).

At least in the US -- Oaks, Chestnuts, and Walnuts sequester a lot of carbon per square foot. Chestnuts are native to the northeast, and Oaks are native in the west (California oaks are one of the prettiest trees IMO), and Walnuts are native in the South.

Pin Oaks don't take up much space, they grow really fast (70 feet in 28 years), and weigh literally tons. They thrive basically everywhere in the U.S. beside Arizona, Florida, and Coastal California. It also has shallow roots, which would keep it from destroying sidewalks / roads. Pair them with Hemlocks, Gold and Red Euonymus, & Climbing Hydrangea -- and our roads would be beautiful!

I dunno. It sounds crazy. But it also seems obtainable.

I'm not sure how this impacts methane, though. Unfortunately, global beef & pork production is growing quickly.

I'm not sure what your argument is. That since the technology isn't fully developed we shouldn't fund development?

This is akin to saying (in the early 1900's) "Planes can only fly short distances, are very expensive, and can't carry any serious loads. It would just be better to put this money into trucking."

The core of the argument is the cost of reversing thermodynamics at extremely large scales. We need a way to scale the application of energy to the sequestration process which is intrinsically energy intensive. Biomass sequesters CO2 from the atmosphere with almost perfect scalability because it has a built-in energy source and the sequestration "factory" largely builds itself.

The industrial chemistry infrastructure required to drive this sequestration at the same scale literally doesn't exist by several orders of magnitude. Even worse, the tremendous power generation capacity to support that industrial chemistry infrastructure also doesn't exist. We're talking global GDP levels of CapEx just to build the infrastructure that would make it possible to build sequestration infrastructure that could remove CO2 on a reasonable time frame. Biomass requires none of this investment to operate at the same scales.

These prototypes of industrial sequestration are only pricing in the OpEx and the CapEx of the facility itself. At scale, you also have to pay for the creation of the entire supply chain from scratch -- the factories, power plants, mines, logistics, etc that allow these sequestration facilities to exist at the required scale. The only way the fully burdened cost remotely makes sense is in applications where none of this infrastructure needs to be built i.e. small scale applications. For global atmospheric CO2 reduction, the fully burdened cost of sequestering CO2 via industrial processes is never going to be viable due to industrial chemistry economics.

Industrial chemistry is not embarrassingly parallelizable.

> the fully burdened cost of sequestering CO2 via industrial processes is never going to be viable due to industrial chemistry economics.

To this I fully agree. This problem isn't going to be solved by industry. I'm not sure why people are putting that on the table. There is no incentive for them (unless you put huge carbon taxes on as well). This is really a thing where we have to cut our losses and say "It is cheaper to build these now than the cost of the damage of what happens if we don't." There's no industry incentive for that. But there is huge public and governmental incentive.

I don't think you understood what was meant by "industrial chemistry", it is a type of science and engineering (basically doing chemistry at mass scale) not an interest group. The government is bound by the same laws of physics as everyone else. The industrial processes outlined in these articles are fundamentally non-scalable to the problem of meaningfully reducing atmospheric CO2, it doesn't matter who implements them. The fully burdened cost per ton of CO2 adds up to more resources than humanity has available in its entirety as a practical matter.

It would be great if it could feasibly scale but there is no science that supports that notion. Any chemical engineer worth a damn can figure that out on the back of a napkin.

Scaling is hard for industrial chemistry, same as with software, and it is only weakly parallelizable. The idea that we will take one of these prototypes and scale it a million-fold (literally) while increasing efficiency by 1-2 orders of magnitude is completely implausible for well understood boring engineering reasons. And even if we could do this, the economics are barely within the realm of plausibility.

Biomass, on the other hand, has math that works out (still expensive though).

> The fully burdened cost per ton of CO2 adds up to more resources than humanity has available in its entirety as a practical matter.

What are you basing that math on?

At $100 per ton it's about 4 trillion dollars a year to capture all current emissions.

That's five percent of world GPD. And that's ignoring any attempt to reduce emissions, or to more efficiently capture carbon at power plants.

Even at the current price of $600 if we reduced emissions by half we could afford that.

And for land use, 40 billion / 1 million * 300 acres is 19k square miles, or one sixth of Nevada.

Would there be material shortages? Are all those prices fake?

The other poster is correct. The prices are complete fiction at any scale that has any impact at global levels.

The price is literally infinite at that scale as the resources do not exist.

Which resources?

Money can buy employees and manufacturing capacity. What are the things that would cost more per unit the more you buy?

Energy and raw chemicals. I think few people appreciate what the implied scales are for anything remotely resembling fast sequestration (read: this century) of atmospheric CO2.

There are finite supplies of everything. We've only every been able to do gigaton industrial chemistry when it was strongly thermodynamically favored; in this case we are trying to run it backward up a steep gradient. The chemical processes described would also require globally depleting mined chemicals that we also use to produce food.

We would need to manufacture several orders of magnitude more raw materials, including the entire upstream supply chain, than exists today. The actual scale is comparable to current global GDP for many of the proposed industrial plant solutions when scaled up. We simply don't produce the required chemicals, nor have the underlying resources to produce said chemicals, at anything remotely resembling those scales. No amount of wishful thinking will change that. I trained as a chemical engineer, I can do the math.

It isn't a problem of employees. We literally have no capacity to produce the upstream resources to feed these industrial designs at the required scale. The inputs to their process are not produced by magic. This is a fairly technical point but literally no one has offered a proposal for how the chemistry would scale to a level that would solve atmospheric CO2 this century.

It is a really hard problem. We are trying to run planetary scale thermodynamics backward. The amount of energy required is mind-boggling even in the most optimistic scenarios.

Mostly power generation. Don't quote me but I recall reading we'd need approximately a million times more power than currently produced to capture current emissions with current technologies.

Grab a factor of ten from reduced emissions and another factor of 100 from tech improvements and it's still way out of reach

We emit about 40 billion tons a year, so that would imply we need the entire world's electricity supply to capture 40 thousand tons.

This single tiny test plant is capturing 4 thousand tons.

The number you read is wrong by miles.

If we look at $100 a ton and guess that half of that is power at 10 cents a kWh, we would need 20 petawatt hours per year. Current world production is 25 petawatt hours per year.

The prototype uses the excess capacity of existing industrial infrastructures which is many, many orders of magnitude smaller than is required to meaningfully reduce atmospheric CO2. It uses chemicals that are extremely energy intensive to produce from mined minerals. Scaling the raw inputs would require massive scaling mining, energy production, logistics, etc far beyond anything that has ever been done before by a very large margin.

Their $100 per ton is extremely optimistic because it doesn't require building the upstream supply chain that can feed their processes at the required scale. It isn't like this is something that already exists, it all has to be built from scratch, is amortized into the cost per ton, and has much worse than linear scalability. I'm not sure how to accurately convey just how qualitatively inaccurate your perception of our capacity to do this at scale is.

Constructively, I'd like to see the argument that we can manufacture the potassium hydroxide at the scale required to sequester all 20th century CO2 in 20 years. The math, inputs, and capacity for the entire supply chain are public. There is much opportunity for rigor but even cursory analysis shows that it is not remotely feasible to effect CO2 sequestration this way even with heroic efforts. And that is under the most ideal of circumstances.

CURRENT emissions. You're forgetting the century of built up emissions.

So add an extra 50%, still affordable, cleans things up in about 35 years. If we're actively backing up in CO2 levels that rate should be acceptable.

> Biomass sequesters CO2 from the atmosphere with almost perfect scalability because it has a built-in energy source and the sequestration "factory" largely builds itself.

Wait, what? Biomass uses solar.

Yes, that was my point. Humans are not required to build vast power generation infrastructure for biomass to sequester CO2 from the atmosphere, we get it for free.

The industrial chemistry for sequestering CO2 is not that expensive in terms of mass ingredients (nothing rare or exotic), considering the scale, but it is extremely energy intensive and that is where most of the cost of sequestration comes from. If almost all of the sequestration cost is the cost of putting energy into the system then biomass has a massive cost advantage, literally orders of magnitude.

Oh, it's your mention of internal energy source that confused me, as biomass depends on external energy, just as any industrial process. And we know that an industrial process can be potentially at least just as efficient as biomass, by the virtue of same physics/chemistry.

It's more "Planes are new and unproven and if you want to ship cargo on them I'm going to want to see numbers". In fact this did eventually work, but not until FedEx came along half a century later using surplus early generation jets that no one was imagining in the early part of the century.

Someone who threw a ton of venture cash at "Air Freight Ltd." in 1913 or whatever would have lost their shirt.

Back to the point: I'm not saying this won't work. I'm saying that there are firm limits to how well it MUST work just to be better than technology that was proven out five millenia ago. That's a really high bar, and it needs numbers and not press hits.

All I'm saying is that this technology is still in its infancy. It sounded to me like you suggest we defund them and use the money for other things. I disagree with this on a number of points. 1) We need sequestration to solve climate change. 2) technologies need money to develop and get off the ground. To go from demonstration to something really useful.

We have the technology. It's called planting forests and then sinking then in the deep ocean. It works. Every other technology is much much much worse. Including this one.

Hi, do you have some source or paper on this approach? I don’t mean to dispute this but have never heard of it before and a quick query didn’t turn up any results, rather the opposite (decay processes happening on the sea floor, not sure whether / or in what amounts those release co2 again).

I don't have a source, just some napkin math. I don't know what the timescale is for plant decay in the deep ocean. Perhaps my 'it works' is optimistic.

Optimistic perhaps, but maybe not impossible ;)

I've done some further googling and found some studies on the topic, though on-land: https://cbmjournal.biomedcentral.com/articles/10.1186/1750-0... and some more from a presentation https://www.feem.it/m/events_pages/20167111127315Zeng_presen...

Though the question still remains how securely the CO2 would be stored under the ocean. Maybe with a large enough layer of rock on top it would suffice.. I suppose it's high time we started field trials on all these approaches.

My own back-of-napkin calc says that we'd need to cut about .1 to .2 % of tropical rainforests per year and remove them from the carbon cycle, not sure if that's right.

Oops, my calculation was way off (missed a kilo-prefix somewhere), we'd need to cut and store about the entire rainforest per year. So, this is obviously not possible as an all-around solution but might help with some Gigatonnes..

Just because current tech sucks doesn't mean we shouldn't keep developing it. I'm not sure why this is such a controversial idea, especially among tech savvy people.

It's controversial because we already have a decent solution and the competing ones suck for a lot of reasons that can't be developed away.

It would be as if someone started doing research on vacuum tube transistor technology today if we were having a global compute crisis and we also had limited amount of sand with which to make glass and sand was an essential resource in all sorts of other things like the food supply chain.

But that's not the situation we're in. We can't plant enough trees without destroying a lot of cities. There are in fact better places to place trees than other places, besides the fact that we can't plant enough and they don't do enough fast enough. The issue is that we currently don't have a full solution. We're close, but not all the way there.

If sinking trees is not a good enough solution, developing and improving a solution that is currently immeasurably worse and might someday be a hundred times worse is lunacy.

What impact on cities? Cities take up almost no space and are irrelevant when talking about planting forests and then sinking them in the ocean. At worst there will be more freight train noise.

Um, AirMail was a thing in the 20’s and 30’s, long before FedEx. It’s where the airline industry got its start.

To this day, airplanes carry a tiny fraction of the world’s freight. Trucking, rails and ships won.

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