Adding crushed rock to farmland pulls carbon out of the air | Hacker News Reader

Adding crushed rock to farmland pulls carbon out of the air

ucdavis.edu

272 pointsgeox278 comments

> Previous studies have estimated this “enhanced” rock weathering could store 215 billion tons of carbon dioxide over the next 75 years if spread across croplands globally.

This is an average rate of 2.8 Billion tons of CO2 per year. We currently emit over 35 Billion tons of CO2 every year so this could potentially offset about 8% of global emissions. Obviously not enough to get us to net zero but that is very significant in my opinion.

I'm not certain how the economics of this solution would work. Is it easy to source, produce, and distribute this crushed volcanic rock? Would farmers get carbon credits for doing so? Or direct subsidies paid for by taxes on net-positive CO2 generating industries (which ironically is a lot of Ag itself)?

Let's not forget the massive CO2 generated by mining, processing, and transporting crushed rock.

I used to work on SAG (semiautonomous grind) mills for fine grind on copper-bearing ore. Grinding rock is incredibly energy inefficient. I would suspect this entire process is carbon-positive despite the atmospheric capture.

It seems we will do anything to avoid the obvious - we need to reduce energy use and transition to green generation.

I don't know why you have to "suspect," when you can read the linked papers or any others...

"A life cycle assessment (LCA) about the potential of basaltic rocks for enhanced weathering and soil carbonation (Section 5.1.) found transportation (related to the distance between the quarry and the place of application) as the major process negatively affecting CO2 sequestration, whereas grinding had less effects on the CO2 budget, which could however be related to the relative coarseness (<5 mm) of the particles."

A lot of companies doing this use fines or waste material, but it can still be done efficiently.

One thing you seem to be missing coming from the copper world is that the ore for copper is very low percentage of copper and has a maybe 3:1 stripping ratio, so you need to mine and grind and use 300-400 tonnes to get 1 tonne of copper out.

With ultramafic and mafic rocks, you can have huge continuous bodies of these minerals, with very high usage and efficient ratio. One tonne of olivine removes more than 1 tonne of resultant carbon based on its Mg cation content.

Transport is electrifying and so is the grid that powers those vehicles, therefore in the long run you can assume these will become more and more efficient.

Potential and costs of carbon dioxide removal by enhanced weathering of rocks https://iopscience.iop.org/article/10.1088/1748-9326/aaa9c4

Environmental life cycle assessment of CO2 sequestration through enhanced weathering of olivine https://legacy.projectvesta.org/wp-content/uploads/2019/06/E...

The reason I "suspect" is because I've seen so many papers and sources that do not include the total cost. Or they choose a very particular process that reduces their carbon output. This is true especially of minerals that have a high place value (aggregates, etc)

>Grinding rock is incredibly energy inefficient. I would suspect this entire process is carbon-positive despite the atmospheric capture.

Grinding the olivine to this study's grain size of 83 microns[0] will consume roughly ~14 kWh/tonne[1]. One tonne of olivine absorbs about 1.25 tonne of CO2, so that's 11 kWh/tonne for grinding, which is indeed likely to be the majority energy consumer.

Clearly the solution is... build roads from olivine! :D Collectively, roadways are "naturally" subject to a huge amount of mechanical weathering, which currently mostly just generates asphalt microplastics.

No doubt the cost/geotechnics doesn't work out, but it's an amusing thought nonetheless. Maybe it could even be made workable, somehow...

[0] https://iopscience.iop.org/article/10.1088/2515-7620/acfd89/...

[1] https://worksinprogress.co/issue/olivine-weathering/

> Grinding the olivine to this study's grain size of 83 microns[0] will consume roughly ~14 kWh/tonne[1]. One tonne of olivine absorbs about 1.25 tonne of CO2, so that's 11 kWh/tonne for grinding

11kWh per tonne of CO2 sequestered is 2 orders of magnitude less energy per tonne than other DAC methods [1]. Assuming it is scalable (i.e. there is enough open land near the olivine deposits), then it is far cheaper.

1. https://www.mcc-berlin.net/en/news/information/information-d...

The "gotcha" is that at 83 microns, this study showed only 0.15% of the theoretical CO2 capacity absorbed in the first year. Worse, the authors expect this rate to taper significantly in the second and subsequent years.

This is why most EW proposals specify a smaller grain size, but that also has the effect of dramatically increasing the grinding energy required. See [1] (included again below) for a more complete and nuanced discussion of these tradeoffs.

[1] https://worksinprogress.co/issue/olivine-weathering/

I think the second "gotcha" is that even at 83 microns, that particle size is likely unsafe. That's about the size of gypsum dust used in drywall and you can't cut or sand or do anything without PPE for long without serious health consequences. Make it any smaller and it'll be well into the asbestos size range, which would probably be carcinogenic based on the mechanical damage it causes alone (a lot of nanoparticles are toxic for this reason). That's safe in a controlled industrial environment with everyone using fitted respirators but spread out on fields exposed to wind, near residential areas? Dumping that much fine dust everywhere would probably create a similar hazard to the dried out beds of the Great Salt Lake or the Salton Sea or Blackrock Desert* except everywhere there is farmland.

It'd have to be combined with a binder to form much larger particle sizes so that the natural weathering safely exposes the olivine slowly over decades. I suspect that once one does the math on the whole lifecycle, it's net carbon positive only after decades if it is to be done safely.

* People who have been to Burning Man can testify to just how much trouble dust that small causes, not to mention the frequent dust storms with zero visibility.

> I think the second "gotcha" is that even at 83 microns, that particle size is likely unsafe.

It’s a bit dark, but wouldn’t a death toll improve the situation from an emissions perspective?

If you execute all the staff at every power plant in the world and then keep executing the subsequent replacement cohorts, every power plant would have to shut down and we would dramatically reduce global CO2 production. Similarly, if you position machine guns at major roads and keep shooting every car that comes through, you will eventually reduce the environmental toll of driving cars.

> The "gotcha" is that at 83 microns, this study showed only 0.15% of the theoretical CO2 capacity absorbed in the first year

According to the study [1] (and the article), that's because the experiment was purposely conducted in a dry climate (inland northern CA) and during a drought to determine a lower bound on the CO2 absorption capacity. More well suited (wetter) climates are expected to result in more CO2 absorption.

"Given that climate change impacts such as heatwaves and droughts are already widespread, knowledge of the robustness of enhanced weathering under extreme conditions is essential to understanding its future efficacy. Here we show that enhanced weathering maintains modest carbon dioxide (CO2) removal in a multi-acre field trial under an extreme drought in California, one of the largest agricultural producers globally."

1. https://iopscience.iop.org/article/10.1088/2515-7620/acfd89

Showing yet again that there is no free lunch, and we continue to eat the earth's future with abandon.

Seems like US average is 0.855 pounds of CO2 emissions per kWh so this process looks like a significant win. Also grinding a ton of rocks doesn't use much energy if its just 14 kwh...

https://www.eia.gov/tools/faqs/faq.php?id=74&t=11

Hard to follow all the units, but, just for grinding, using these numbers:

grinding: ~14 kWh/tonne olivine

absorption: 1.25 tonne of CO2 per tonne of olivine

emissions: 0.855 lbs CO2 / kWh

emissions: 5.4 kg CO2 per 1.25 tonne CO2 (1250 kg) absorbed

> emissions: 0.855 lbs CO2 / kWh

Why do there have to be CO2 emissions?

There don't. The problem is a lack of remote industrial equipment that are EVs powered by renewable electricity sources rather than diesel fuel.

That's not really that much of a problem to be honest.

If this is to be an industrial mining scale operation that goes in with a 600 million tonne per annum target (similar scale to iron ore for steel mining operations) then the company building out the capital assets will setup EV's and solar on the grounds of both economy and PR.

You can see this with Rio Tinto Iron, Fortescue Metals, etc.

You could solar power it, or whatnot. I was just trying to contextualize the numbers others had written.

> Clearly the solution is... build roads from olivine! :D Collectively, roadways are "naturally" subject to a huge amount of mechanical weathering, which currently mostly just generates asphalt microplastics.

Nah, asphalt microparticles are in the end just very viscose oil and rock dust from the filler. The microplastics from roads come from tire wear and brake dust.

>asphalt microparticles are in the end just very viscose oil

Bitumen is still a plastic. In fact there are also increasing efforts to use post-consumer recycled plastic as an additive.

Microplastics from road transport mainly come from tire dust, but also include road markings[0] (which are plastic mixed with glass microbeads), bitumen from asphalt[1], and yes a bit of brake dust.

[0] https://resourcelab.dk/plastics/pollution/oceans/2018/10/11/...

[1] https://www.sciencedirect.com/science/article/pii/S004896972...

Or let oceans do some of the work: https://www.withouthotair.com/c31/page_246.shtml

> Clearly the solution is... build roads from olivine! :D

Haha. I'm glad you didn't include "solar" or "freakin'". ;D

> It seems we will do anything to avoid the obvious - we need to reduce energy use and transition to green generation.

The idea behind carbon capture projects is this: for years, we have been given warnings that "if we cut all emissions now, we will still be okay", to "if we cut all emissions now, it won't be too bad", and now we're at the stage where even if we meet our emission targets, things are still going to be bad.

If we want to avert disaster, we now need not only to cut emissions, but ALSO to actively remove carbon from the atmosphere. So, these projects are here to try and fill that unfortunate new need, because just cutting emissions will no longer... cut it.

Sure, but where does the energy come from to actively remove? Because that's usually the point, the energy creation created more than the removal removed.

It'll depend on the specific project in question (there are quite a few methods under investigation), but for enhanced weathering (the type under discussion), I found some articles in a quick search that suggest the energy cost of grinding and transporting the rocks is significantly smaller than the carbon removed by the programme, e.g. https://www.researchgate.net/publication/322664372_Potential...

Arbitrage it from places where green energy is cheap or free. For example, iceland has pretty much 100% renewable energy sources. Already it has an extensive aluminum industry because energy there is cheap, and aluminum is energy-intensive to use it.

So, in theory, if you use green energy to produce a carbon-offset product, it's still a useful product.

The aluminum smelter in iceland is a former ALCOA smelter from Rockdale TX. They ship the ore in from outside.

Let's not pretend mining bauxite ore is 100% renewable.

Maybe, you now have to produce that aluminum somewhere else.

Surplus energy from wind farms over land with the right kind of rock.

Anything you can’t shove into the grid grinds rock.

It's about scalability of any particular process minimizing net $/t (which includes kWh/t).

energy is not important. reducing carbon in atmosphere is more important then energy consumption. a lot of energy just escape to space every day.

In theory, you might be right. But in practice the biggest investors (and boosters) in carbon capture are oil and gas companies — and for them it’s a way to continue business as usual (i.e., continue to increase carbon output) while hand waving about some future CC project that will make this all ok.

In general, to be scalable and cheap, CCS needs to be mostly passive activities relying on biology and large surface areas. This would then usually involve farmlands, forests, or oceans. (Not necessarily trees because they lack automatic sequestration.)

> It seems we will do anything to avoid the obvious - we need to reduce energy use and transition to green generation.

Most of the world is doing just that.

It's much, much easier said than done.

It's pretty easily done too. It's just that it's not a very fun thing to do. Like eating vegetables. It's pretty easily done but that doesn't mean everyone does it.

That's a very rich world perspective.

Fossil fuels have - at the same time as the pollution - caused a huge improvement of living standards. A substantial part of the human population tripling in size comes from that, and huge number of people would die if fossil fuels magically disappeared.

In the limit almost all people die in both extremes (if we stop all fossil fuel use today and if we don't limit fossil fuel use at all).

There is middleground that saves most of people. We're not doing that because we value our comfort now more than other people's lives later.

Living standards increases right the way to extinction. Ultimate tragedy of the commons.

> Fossil fuels have - at the same time as the pollution - caused a huge improvement of living standards.

And before that we used Whale oil, which we got through a global slaughter of whales and we nearly drove them to extinction. Then it was time to move on.

There's a huge difference between migrating off something because there's something objectively better (oil is cleaner and cheaper compared to whale oil), and migrating off something for environmental reasons. The former doesn't require any sacrifices and will happen voluntarily. The same can't be said for the latter.

what do you mean by oil is cleaner? Whale oil is food, while petrochemicals are a poison

It's a rich world perspective to buy new cars every couple years, including electric cars which massively frontload the emissions borne of those cars, or to go home every night and stream 1080p video into your living room for hours on end while serving up gigs of photos and video to your phone through Instagram and TikTok. Datacenters are something like 20% of all energy consumption.

In many parts of the world, even places you've heard of, people walk or bike everywhere they need to go and spend their free time sitting around chatting with neighbors.

No one's arguing to delete fossil fuels, but it makes sense to minimize usage to freight and public transit.

> Datacenters are something like 20% of all energy consumption.

Do you have a source for that? It didn't sound right and my quick Googling suggests that it's off by around a factor of 20 or more. (Some put datacenters as low as 1% of total electricity consumption, which is a subset of all energy consumption.)

It was admittedly hearsay. My research says it's about 2% of energy use in the US and 1% of electricity use worldwide with remarkable constancy in electricity demands due to storage and computing efficiency gains. Thanks for the reality check.

The richest 1% is responsible for 49% of lifestyle emissions. The poorest 50% are responsible for just 10% of emissions. It's really disingenuous to act like most of our CO2 emissions are being spent lifting people out of poverty rather than on luxuries like meat consumption or fast fashion. https://journals.sagepub.com/doi/abs/10.1177/001391651771068...

> "The richest 1% is responsible for 49% of lifestyle emissions. [...] luxuries like meat consumption or fast fashion"

How many megatons of meat do you think Musk eats a month? Does Bezos put a billion burgers into his belly? The vast majority of meat is consumed by people in that bottom 99%. For that matter, how many fast-fashion trendy patterned stockings do you think these men wear? It's really disingenuous to act like you're against luxuries for the 1% and then use meat and cheap clothing as your examples of great evils to be eliminated. Who would be sacrificing if large scale production of these cheap goods were banned? Not the 1%. What you are proposing is not to tear down the 1%, but to suppress the standard of living for the 99%.

Maybe you just chose bad examples by accident though, do you have any proposals that would actually limit emissions from the 1% instead of capping the quality of life for the other 99%?

It's in the pattern of consumption. Obviously Elon Musk can't eat orders of magnitude more beef than the rest of us, but in 2017 he announced that the boring tunnel would dig a tunnel directly to his house. Now I don't know if he ever did that, but it's not particularly far fetched for someone with his resources to do. For arguments sake, the emissions of such a tunnel would be ludicrous when you calculate on a per person basis. Then you have emissions associated with luxury yachts, helicopter rides, private jets, etc. on top of elevated normal consumption (i.e. able to travel more often via normal means, while occasionally also taking the jet for a spin).

The very wealthy are able to afford to not go through the same public channels as the rest of us, and so their emissions don't get amortized over vast numbers of users. This is on top of the fact that they can already consume more anyway, which is to say, I have one car, but the very wealthy might collect them (buying new! another thing I've never done), and just the process of manufacturing a new car releases more CO2 than I could produce in several years of driving.

He’s not taking about the richest 1% of Americans.

Even if he was your examples are disingenuous. Musk and Bezos aren’t representative of even the richest 1% of Americans.

I knew this was coming, all Americans are the global 1% right? Did I even say anything about America? Regardless...

Get a napkin and sanity check yourself. 1% of 8 billion people is 80 million. There are 330 million people in America. If all of the global 1% are in America and not also in Europe and Asia, which is obvious bullshit, then only 24% of Americans are in that 1% and the remaining 76% are in the lower 99%.

And do you really think only Americans eat meat and wear cheap clothing? Get real.

Could you please stop posting unsubstantive comments and flamebait? You've unfortunately been doing it repeatedly. It's not what this site is for, and destroys what it is for. We end up having to ban accounts that keep doing it, and we've already had to warn you more than once:

https://news.ycombinator.com/item?id=37708114 (Sept 2023)

https://news.ycombinator.com/item?id=36792165 (July 2023)

If you wouldn't mind reviewing https://news.ycombinator.com/newsguidelines.html and taking the intended spirit of the site more to heart, we'd be grateful.

What are you even talking about? The person you replied to didn’t say Americans. Were you trying to use Bezos and Musk as representative of the top 1% of the worldwide population? That’s even worse.

I'm telling you that meat eating and fast fashion are not "global 1% issues". You are the one who brought up Americans, not me or the other guy. Meat eating isn't a 1% thing whether you're looking at the global 1% or the American 1%; meat is consumed by almost everybody in the lower 99% no matter which way you slice it.

Your link doesn't work. I'm getting "The requested article is not currently available on this site."

Also the studies I've seen to this effect use a questionable form of attribution when it comes to the "1%". Specifically they include emissions from companies that they invest in.

Most people's lives suck and the only thing that they have going for them is consumerism. So it's reasonable that they are unwilling to give up consumerism.

Therefore, the hard part is changing the structure of society so that people's lives don't suck.

The solution there is the same thing: living in harmony with nature. It's carbon-neutral or -negative and very fun and fulfilling.

Very fun, up to the point you get ill and start wishing industrial society still existed to manufacture modern medicines.

Why not both?

In some cases micro-gassifier rocket heater/stoves (just because you can make one out of mud doesn't mean it's not high technology!) & coppicing and pollarding will make more sense. In other cases clean atomic power and induction heaters/stoves will be the way to go.

Some times willow bark tea, and sometimes morphine.

This is as realistic as peace in the Middle East by getting both sides to sit on a beach and sing kumbya

I mean, we will eventually live in harmony with Nature one way or another. Shall we cooperate consciously in the process of life and evolution, or let everything crash and burn and hope the survivors do better next time?

Are you implying that living a life without fun is easy?

Maybe I should have rephrased it. There are fun ways to live a life without emitting a bunch of carbon just as there are tasty ways to cook vegetables. It's just that people don't want to and more importantly, governments don't want to.

I used to live in LA, spend tons of money on my car, not be able to do things because they were on the wrong side of the 405, and eat tons of low quality meat. Now I live in the Netherlands, bike or take the train everywhere, and occasionally eat high quality meat. My emissions are much, much, much lower here. I'm tired of being told how great my quality of life would be with cheaper gas and a bigger house.

So, it's easy, but people don't want to do it because... they're evil?

It’s multipolar trap/ coordination problem. The costs of carbon emissions are diffuse and borne by everyone, while the costs of changing your behavior are mostly borne by you. It’s just a sad fact of life, and to solve it the only feasible way is to change the rules to making decarbonizing cheaper than continuing to use fossil fuels.

This has nothing to do with what the parent and grandparent comment was talking about, which is that carbon emissions can somehow be made without sacrificing lifestyle quality. Your comment implicitly admit that sacrifices have to be made.

Vegetables are delicious if you cook them right.

Maybe the solutions we have on how to cut on emissions is canned.

Exactly. There is little-or-no desire to eliminate animal agriculture despite the obvious data that it is killing us as much as FF private vehicles. There are many luxuries and senses of entitlements that cannot be curtailed politically short of authoritarian decree.

There's no profit in saving the planet.

Dig deep enough into any initiative that claims to be doing that and you'll find that it has far reaching consequences that negate whatever positive impact it has on the planet, and dealing with them would reduce profits.

Not true. True green technologies are already profit drivers. EVs, solar, wind, heat pumps... are becoming so cheap and efficient that not switching for industrial use (and often personal) costs more.

For heating use only, heat pumps are more expensive than natural gas in my area (MA, with ~$0.25/kWh electricity and $0.85/therm gas supply plus ~$1.13/therm delivery).

I tried to make a heat pump make sense for heating here. I couldn't make it economically pencil out. I hope I'm around and I hope the economics are different in 20 years when it comes time to replace the heat source in my house again.

That's not (automatically) true.

If you change the rules of the game, you change the winning strategies. By extension, you're changing which industries may be in competition with each other (or end up being completely obsolete), and which companies may end up having an advantage. If you ban (say) natural gas water heating, the losers will be gas supplier companies, perhaps all the peripheral industry dedicated to creating gas pipes and fittings, the pipe fitters, companies that specialize / have IP around efficient gas heat exchangers, etc.

On the other hand, the winners may now be companies that have IP / manufacturing capabilities for heat-pump technology, electricity producers, copper mines (increased load on the grid), etc etc.

Each rule change may have a net positive or negative on the greater economy in general both in the near term and far term.

In my example, heat pump water heaters are $$$ compared with conventional ones and would increase the demand on electricity (increasing its price). These hit people's pocket books, and reduce discretionary income to spend on other stuff.

On the other hand, the significant increases in complexity might result in a higher-skilled workforce requirement (with increased wages), fewer deaths due to carbon monoxide / gas explosions, fewer nitrous oxide related illnesses (decrease in healthcare costs), and maybe a hundred other knock-on effects.

There absolutely could be (profit I mean), if we taxed fossil fuels enough.

> There's no profit in saving the planet.

Why does this sound like a suicide cult?

Because it sort of is, I guess.

Capitalism by itself won't allow us to change course.

I think the lesson is that must accept the inevitable - worldwide energy usage will continue to increase, especially as the third world modernizes, and the only way to manage this increase in a low carbon manner is to accept that nuclear along with renewables will play an integral part in this green transition.

>It seems we will do anything to avoid the obvious - we need to reduce energy use and transitio

I'm not sure how this is supposed to be obvious. It's using vague language that makes it sound as if this is a trivial lifestyle change. "reduce energy use" at the rate you're hinting at strongly means things like:

* Eat less food, and worse food * Wear worse clothes longer, perhaps until they fall apart * Live in smaller, cramped housing that is colder in the winter and hotter in the summer * Go fewer places, but not just as a tourist, also for practical needs, limiting the job opportunities of many * Have less entertainment * Use less water, the bulk of which for any given person is used for hygiene

Now that I have done the actual work of making it obvious what you suggest, are you still saying we need to do those things, and if you aren't saying that, just where do you imagine energy can be reduced?

I don't agree with most of those bullet points. Some of them don't follow at all, but in every category there is at least a 90th percentile change we could make that wouldn't be some terrible imposition. It boils down to class war: the people who would have to make the most sacrifice are the people who are already using way more than their fair share. So for each of your points where you use words like "less" and "worse", we must ask:

Less than, worse than? First world people eat entirely too much, and unhealthily. Not hard to imagine diets better for humans and the ecosystem. Hell, 1.5 billion people are already vegetarian and doing fine. People will complain about eating less steak but it's a first world problem.

Worse than? Durable clothes are better for the environment, and classier. Disposable "fast fashion", made of plastic and sewn by quasi-slaves in sweatshops is the real problem. People will complain about losing a dopamine button but it's a first world problem.

Smaller than? It's completely possible to improve thermal efficiency without altering size. Maybe, if you live in a sprawling poorly insulated McMansion, you should invest in better insulation - or a better house - instead of powering through by burning energy. Apartment blocks are already far more efficient for climate control (square/cube law), so it's squarely a rich person's problem.

Fewer places than? Are people taking jet airplanes to work every day? Yeah, they should probably stop that. People taking the train are probably in the clear. This isn't even a first world problem, it's a superrich problem. Of course they'll complain...

What "entertainment"? This doesn't follow at all. "Entertainment" isn't a particularly energy-hungry category. Maybe if you're entertained by mining bitcoin? The most entertaining thing I own, besides my laptop, is a Synthstrom Deluge Groovebox, which runs for 9 hours on a single 18650 lithium cell.

Water: Another one that doesn't follow. I suspect the bulk of water for a given person is actually agricultural, so see point 1. But as important as it is to preserve freshwater ecosystems, I don't see the direct bearing on energy consumption. Most municipal water comes from reservoirs, not desalination.

>Less than, worse than? First world people eat entirely too much, and unhealthily. Not hard to imagine diets better for humans and the ecosystem. Hell, 1.5 billion people are already vegetarian and doing fine. People will complain about eating less steak but it's a first world problem.

That might be true, but people also know they're eating too much and unhealthily, yet they continue doing so. Clearly getting them to stop requires much more effort and sacrifice than you make it out to be.

>People will complain about losing a dopamine button but it's a first world problem.

So you admit that it's actually worse? You're just hand waving it away by inserting your own value judgement.

>Smaller than? It's completely possible to improve thermal efficiency without altering size. Maybe, if you live in a sprawling poorly insulated McMansion, you should invest in better insulation - or a better house - instead of powering through by burning energy. Apartment blocks are already far more efficient for climate control (square/cube law), so it's squarely a rich person's problem.

See above.

>Fewer places than? Are people taking jet airplanes to work every day? Yeah, they should probably stop that. People taking the train are probably in the clear. This isn't even a first world problem, it's a superrich problem. Of course they'll complain...

You're ignoring going to far away places for tourism, visiting friend and family across the country, and going to the Costco on the other side of town.

> Less than, worse than?

Less than/worse than that person is doing now. (But I'm pretty sure you knew that.)

> What "entertainment"? This doesn't follow at all. "Entertainment" isn't a particularly energy-hungry category.

You're disingenuous, or naive. One's as bad as the other.

This isn't 400 BC. When anyone here wants to be entertained, they don't ride the donkey cart down to the stone amphitheater and watch a play in torchlight (and you probably wouldn't allow the torches either, too many particulates).

For any sort of entertainment anyone might conceive, there is a manufactured good involved.

> Less than, worse than? First world people eat entirely too much, and unhealthily. Not hard to imagine diets better for humans and the ecosystem.

We're engineers here. It doesn't work like that. One parameter of the other, and we already heard you say which one you'd pick.

> Worse than? Durable clothes are better for the environment,

But they won't be durable. They'll just get worn out, but you'll wear it anyway because you can't get it replaced. As it was centuries ago. When someone dies, they'll fight over the clothes, they'll be that precious again. At least if you have your way.

>Fewer places than? Are people taking jet airplanes to work every day?

Those people are connected. It's the guy who drives a shitbeater car that you're worried about.

All of my bullet points follow. They're just shining the poorest possible light on your political agenda.

* less consumption of manufactured goods * less travel, both of humans and freight * high density housing instead of SFHs

That can significantly reduce CO2 in the short term. Sure you won't be able to buy as many widgets on Amazon - but we won't be on hackernews discussing silly carbon capture methods to make marginal gains that will never feasibly happen on a global scale.

>I would suspect this entire process is carbon-positive despite the atmospheric capture.

Consider the napkin math. One mole of MgSiO3 reacts with one mole of CO2 to give MgCO3 + SiO2. The embodied energy in CO2 from C + O2 is 393 kJ/mol. One mole of MgSiO3 weighs 100 grams (almost exactly) and has a specific heat of roughly 1 kJ/kg-K. That works out to roughly the amount of energy required to heat the olivine by 3930 Kelvins, although this is well beyond the point at which specific heat becomes nonlinear and would most likely melt the sample.

Since it is uncommon for rocks to melt when grinding we can conclude that the embodied energy in the carbon absorbed is way larger than the energy required to grind the material. The inefficiency of electric generation certainly comes into play but even if we use a factor of 1/5 we still find a temperature rise of 786 Kelvin which would be extremely damaging to equipment if it actually occurred, and the actual temperature rise is probably less than 100 Kelvin. This still gives a comfortable margin of inefficiency for the carbonation process. And we have assumed that all of the energy is coming from inefficient coal-burning plants, which are in reality a minority of the global energy mix.

Consequently, we can conclude unequivocally that olivine grinding absorbs more carbon than it emits even under relatively pessimistic assumptions, and dramatically more carbon than it emits under realistic assumptions. While the energy of grinding is large, the embodied energy of CO2 is very large — this is why carbonaceous fuels became popular.

There are downsides to the process — most obviously but with a distant horizon, sequestration of carbon in this manner is precisely the process expected to eventually destroy the biosphere by carbon starvation in a few hundred million years, and using olivine to stop global warming is slightly accelerating the inevitable doom of all life on Earth. Also, it takes up a lot of space and costs a lot of money. And inevitable doom. But you know, priorities.

I am talking about the actual milling of the olivine. Chemistry has nothing to do with it.

There will be specific curves for the ore they are grinding. They will look something like this. https://www.researchgate.net/publication/43497937_Milling_cu...

Obviously this is not related to olivine, so we would need to call around to get the appropriate ones. This isn't like computer work where you can just google it.

You're probably looking for the fracture energy -- the energy required to create a fracture with a unit surface area.

Take the grain size you're looking to end up with, compute the surface area and mass, combine it with the fracture energy, and you should have a pretty decent estimate for the energy required to grind a particular substance to a particular size.

Your energy math, or its explanation, is incorrect. the embodied energy in CO2 is irrelevant - the comparison is of products and reactants, of which 'C' and 'O2' are neither.

Right. I was wondering why they are doing are chemical reactions on what should be a milling/grinding curve.

They are really pushing the stereotype that software engineers think they are smarter at physical sciences but are actually pretty clueless.

The US has a very high imprisonment rate. How 'bout we create lots more laws that specify sentences of hard labor... breaking up olivine ?

> Grinding rock is incredibly energy inefficient.

Fortunately, there is a relatively cheap way of producing that energy with solar or wind installations. Your rock grinding machine can actually improve electrical grid by using excess energy and being a first candidate to be turned off in case of electricity shortage.

Another way of looking at this is that a rock grinding machine is a way to convert excess renewable electricity into oil. By converting renewable electricity into sequestered carbon you can allow amount of oil being used for net zero carbon footprint.

Yes, it costs more (but not as much as some people think -- excess energy is actually much cheaper and in some cases can have negative value). We kinda now there isn't going to be a solution that will be as cheap as what we have been doing up to this point.

what about using rock that's already being crushed for processes like that? Still have the transport but may as well use the ground stuff for something.

We are talking about adding it to farmland so we really care about yields and safety.

Possibly. I am not familiar with the sort of basalt they are using here.

It may very well make sense under those conditions.

Olivine is in ready supply as a by-product from the mining industry. There are piles of it laying around (which don't have the same effect as spreading it out) although they do need to be transported to projects.

By-product is the word I was looking for. Hopefully there isn’t a need for primary production

Clinker manufacturing for cement and concrete is amongst the worst offenders. This can be made greener with closed-loop production and CCS, and there are already efforts nearing or at commercial production with it.

Or reduce cement consumption by building with wood, which carbon negative

Once they're there, they keep doing their thing for years, so maybe only carbon-positive for a limited time.

Do you think gravity-assisted rock crushing could be feasible?

Yes, drop a large enough rock from, say, orbital height and there might be zero carbon emissions going forward.

For a rock to extinguish all life on and in Earth from an orbital drop it would have to be quite large. I suppose Jupiter would be big enough.

Just human life would do, not all life. But just a drop wouldn't have the relative speed of most asteroid impacts.

You just invented block cave mining https://www.e-education.psu.edu/geog000/node/911

It's been in use for a long time and is great for fragmenting large rocks and boulders. It does still need grind after the main fragmentation is done.

SAG Mills use the same concept to grind rock to a finer level. Most of the abrasion is rock-on-rock inside the mill.

To use gravity, you only have two options:

1. Knock things down that are already high up and hope they break at the bottom. Or,

2. Haul things up and then knock them down.

#1 only works in an extremely limited number of cases and gets exhausted quickly. #2 spends more energy hauling up than it gains.

As long as it's not a Sisyphean task.

"Join my asteroid bombardment startup...."

There's the obvious thing everyone's trying to avoid: reduce energy usage, and then there's the obvious thing everyone's REALLY trying to avoid: cut global population by 2/3.

Isn’t it what we had 5g with Covid sponsored by WEF for?

I'll belief the likes of Davos and the WEF have anything in mind but tearing down any remainig class mobility, restricting people from moving to wherever the grass is greener and reintroducing a 21st century style of slavery, when they start pushing for a ban on private combustion powered megayachts, private jets and an upper powerlimit for pool heaters.

Instead they're interested in blocking out the sun t̶o̶ ̶m̶a̶k̶e̶ ̶f̶a̶r̶m̶i̶n̶g̶ ̶i̶n̶ ̶p̶r̶i̶v̶a̶t̶e̶ ̶g̶a̶r̶d̶e̶n̶s̶ ̶i̶m̶p̶o̶s̶s̶i̶b̶l̶e̶ limit solar heating.

You joke and yet our power generation and transportation systems aren't the only aspects of human existence that are utterly unsustainable. We've bricked every major marine fishery on the planet and our agriculture requires non-renewable inputs and unsustainable amounts of water.

> It seems we will do anything to avoid the obvious - we need to reduce energy use and transition to green generation.

Well if you haven't noticed yet, that's the hard part and some emission is inevitable at least for near future. We won't get rid of fossil fueled planes or cargo ships anytime soon

Very significant impact. There is no silver bullet that can remove the excess emissions on it's own, however combinations of these removal methods (coupled with decarbonization of course) will be essential to addressing excess atmospheric CO₂.

Regarding economics; there is plenty of olivine rock already available as a mining by-product. Disadvantages are that it takes up to 1000 years to fully sequester however this is logarithmic with a large portion of this achievable in the first century (why they mention 75 years in this article). This can be accelerated with further grinding to increase surface area.

I would imagine that regulations for net-zero will push for carbon removals to be sold similar to carbon credits have been (as net-zero can only be achieved with removals, not credits). These could either be sold as they are created annually or pre-purchased as the mineralization is a pretty sure thing to happen.

Whether this (as in CO₂ removal, not limited to enhanced rock weathering) evolves into a public service equivalent to garbage collection or a utility like water is yet to be seen.

I would bet seaweed or phytoplankton plus floating farm rigs would readily lead to scalable CCS. A few small regions of Earth's oceans would need to be sacrificed for sequestration.

https://www.businessinsider.com/sargassum-turning-smelly-sea...

The collective will we'd need to deploy this globally would probably indicate that we also somehow magically gained the collective will to reduce emissions.

This is the problem with some of the geo-engineering approaches. We've shown that we can't really change how society and industry operate enough to reduce emissions, so what makes us think we can do the same for carbon capture? How do you actually get every farm to do this?

Don't be so down. We have solved the ozone hole problem - it will take years to heal, but we emit very little ozone destroying things anymore. Last year my local utility generated more power from wind than there was demand. People do care and are making change. Change is slow to come, and even after it happens takes a long time to make a difference, but there are signs of change and the cause is being taken care of.

Don't take that too far: there is a lot of work to do. However we have a good idea what that work is we just need to apply it.

It's big again

https://www.esa.int/Applications/Observing_the_Earth/Coperni...

But still on track to shrink? From your source (thank you for the read):

> Claus concludes, “Based on the Montreal Protocol and the decrease of anthropogenic ozone-depleting substances, scientists currently predict that the global ozone layer will reach its normal state again by around 2050.”

There was a discussion about this on the front page the other day:

https://news.ycombinator.com/item?id=37949994

If I understand correctly then the ozone hole fluctuates with the seasons but on average it's still shrinking.

Ozone hole was "just" replacing one chemical with another and changing refrigerator units a bit; CO2 emissions are orders of magnitude bigger as near-everything related to industry or standards of living emits CO2 in direct or indirect way.

My utility generated electric power via wind last year than all customers combined used. Electric cars are obviously taking over. Those are very encouraging signs since a large portion of CO2 comes from electric or transport uses. There are other uses aw well to work on, and some challenges in those areas, but things are looking very good.

The hope (and IMHO only reason) for geo-engineering approaches is that they can enable achieving a large effect with a much smaller political sacrifice than cutting people's consumption or preventing some countries from increasing their consumption to "first-world" levels, and at a smaller cost than that.

If someone finds a plausible way to reduce a major part of global greenhouse gases that costs merely, say, 10 or 100 billion, then that's something that a few major countries can do (and fund) unilaterally and doesn't need global consensus, unlike major emissions reductions which have the tragedy of commons problem where if you do that and other major emitters don't, then you've crippled your economy but haven't prevented any of the bad consequences.

The comment you replied to suggested carbon credits. That seems like a pretty obviously good answer. We're bad at forcing people to make broad changes, but nudging with money like that is often effective.

> metabasalt and olivine

Well, yes, a lot of farmers (not all, probably most) are interested on adding those to their soil and will do it if it's cheap enough.

I'm not sure we can mine, pulverize, and distribute it in a carbon-negative way. But yeah, coupled with large scale implantation of renewables and decarbonization of transportation, it may be enough to even roll climate change back a little bit.

Olivine comes from Norway, which uses hydro power. The energy in extracting and crushing is around 4kg CO2/ton. Pulverizing is around 30-50kgCO2/ton rock. Majority of transport is on water (ocean, river), which is low emissions. In the end, for every ton of rock around 850kg of CO2 are removed.

For basalt, it's around 200kg net, so the supply chains have to be shorter.

I checked my math with the DOE's experts, and it checks out.

Source for the numbers?

Sibelco's Aheim mine essentially supplies a large part of the world's olivine today. It is located in a Fjord with its own port. The transportation distance is very small.

See their website here: https://www.sibelco.com/en/150-years/aheim

"The proximity of Aheim’s mine, processing facility and shipping terminal enables Sibelco to run a highly efficient operation with minimal transport or double-handling of materials. Quarried olivine is moved via conveyor belt through a 4km tunnel to the processing plant where it is crushed, dried and screened into different grades."

When transporting mostly by ship, olivine ERW efficiency can remain >90% even with 1000+ kilometers of sea transit.

See this working paper: Environmental life cycle assessment of CO2 sequestration through enhanced weathering of olivine https://legacy.projectvesta.org/wp-content/uploads/2019/06/E...

Yes, further details would be very illuminating !

8% sounds good to me.

The required reduction in emissions is 99.9% (net), which is approximately "everything everywhere except maintaining grassland"[0] if done by reducing gross emissions; the last percentage point of a problem is usually the most difficult, so if we can get a whole 8% by making a cheap sink, that's probably for the best.

Just so long as it's in the sweet spot of "cheap enough" without crossing over into the realm of "people can make money mining the CO2 out of the air", because if that happens then the same economic pressure that means we have too much CO2 now will become one of too little CO2.

[0] https://ourworldindata.org/ghg-emissions-by-sector

I thought it worth mentioning that a startup called UNDO (https://un-do.com/) is already doing this - and have designed a carbon credit methodology with Puro.earth (https://puro.earth/accelerate/undo-enhanced-rock-weathering-...)

The crushed basalt they use is already a byproduct from quarries they partner with from what I understand.

We need to get to negative emissions in the second half of this century. From 5-10Gton/year, IIRC.

So this should not be used to offset new emissions, but thought of as a way to claw back the damage we are still creating today.

Those emitting CO2 will pay, and those capturing will receive the money.

Perhaps that's how it should be in a perfect world, but in the world we live in that isn't the case and doesn't seem likely to be the case - there are some local markets for CO2 incentives, but on the international level there's no willingness for major emitter countries to pay other countries, no evidence that (or why) this willingness might appear, and there's no global government that could make or enforce any rules unless countries opt-in; nobody can force nuclear countries to pay others.

Agree on the rest, but on none of this:

> but on the international level there's no willingness for major emitter countries to pay other countries, no evidence that (or why) this willingness might appear

Of course no one wants to pay, but courts have already begun shifting their attitude in a number of historic rulings against large emitters, and there are a ton of cases being in progress at the moment [1]. IMHO it's only a matter of time until the first court orders direct international financial damage payments, particularly to countries that threaten to be literally flooded from the map like Vanuatu [2]. For what it's worth, most Western countries already pay large sums of money to the Global South as part of general development aid.

> and there's no global government that could make or enforce any rules unless countries opt-in

The US absolutely can, like they did with anti money-laundering legislation. Everything and everyone that touches the US dollar is, in the end, accountable to the US and its will.

Besides, who would have thought that the world would eventually converge on getting rid of tax havens? To force the Swiss of all people to dismantle the holy grail of bank secrecy? Almost no one, given the absurd amounts of money at stake, and yet it happened (partially though as a consequence of the various leaks of tax evader data).

[1] https://en.wikipedia.org/wiki/Climate_change_litigation

[2] https://www.washingtonpost.com/climate-solutions/2023/03/29/...

I understand your position, however, I feel there's lots of wishful thinking there. The key issue is whether the industrialized first world countries would be forced to compensate the 'global south' for the damage of the global warming beyond anything they willingly choose to donate as part of their foreign aid budgets, and for that I strongly believe the answer is negative.

Of the examples you provide, there are a ton of cases but not a lot of judgments, and furthermore these cases are overwhelmingly against specific companies and many of them for violating obligations they have under USA law. USA permits that as long as they feel that it matches their interests (e.g. having British Petroleum pay a compensation to some USA city is a good thing) and it can and will alter the laws of this liability if they start threatening USA interests.

The Vanuatu example you state is (a) explicitly not asking for any financial damages[1], (b) the only thing that was agreed was to forward it to the ICJ; and (c) the decisions of ICJ are not binding, and USA has an explicit policy since 1986 to choose on a per-case basis whether they'll want to consider themselves under ICJ jurisdiction for that case or not, and so do other countries.

W.r.t the lack of global government - yes, you provide examples of how diplomatic and trade pressure from powerful countries can push smaller ones to concede. That doesn't work in the opposite direction - the same mechanisms can't force USA (or China) to change their policies or fund global change.

Fundamentally, USA (just as any sovereign country) doesn't legally owe Vanuatu anything beyond those obligations that they willingly take on, international law is simply about controlling adherence to a set of voluntary contracts between countries. And even for the existing conventions, international law is clear that countries can abandon them when they don't like the obligations, and that has happened many times in the past - so I'll repeat my point that any compensations will happen only if (and to the extent of) that the western governments opt-in, and as the consequences of the climate crisis increases, their willingness to do so will be even more limited by the needs of their own voters.

[1] Quoting the same washingtonpost article, "As Vanuatu gained support for the U.N. action, it was careful to try to build consensus, with its leaders saying they are not suing anyone nor seeking to create new international obligations. Instead, they say, they are seeking to clarify how preexisting international agreements apply to climate change."

Agriculture is currently massively carbon intensive and is one of the hardest modern technologies to decarbonize. It relies on fertilizer production that is currently completely reliant on fossil fuels. If this can decarbonize agriculture, that's a massive win for our chances to reach net zero carbon emissions on time.

It would more than offset global aviation, which is one of the areas where replacing fossil fuels is the most difficult.

And how much would it affect agriculture? Do the plants thrive if you do this every year?

Adding ground silicates can significantly increase agricultural productivity on various kinds of land. Here's one review article about the subject:

"Remineralizing soils? The agricultural usage of silicate rock powders: A review"

https://www.sciencedirect.com/science/article/pii/S004896972...

IIRC the soils that benefit the most include:

- Soils depleted in micronutrients

- Acidic soil

- Silica depleted soil (significant for rice farming and other silica-sensitive crops)

Most of the world's acidic and depleted soils that could benefit the most are in warm tropical regions with heavy rainfall. That's also where fresh mineral applications would weather most rapidly to draw down CO2. Unfortunately, it may also be harder (logistically and culturally) to encourage silicate applications on those soils than on the temperate climate soils of North America.

After a certain point adding more silicates doesn't help increase soil productivity. The one thing that I haven't found any reporting on is where the "too much" point is reached for soil amendment with crushed silicates. I have seen that yields stop increasing with ever-increasing addition of ground rock. I haven't seen a point where they go down. I would guess that there's some point where yields actually start dropping, and that would mark the upper limit for agricultural soil amendments.

Up to the point where yields keep increasing, you could expect farmers to spread crushed silicates on their fields for their own benefit, depending on the cost. In the high-application case where yields flatten out but carbon sequestration continues to increase, you'd need to pay subsidies to get higher application rates. You'd also need to pay subsidies in the lower-application-rate cases if yields increase but not enough to justify the expense on a yield basis.

If 2.8 billions tonnes isn't enough, can we just spray additional olivine powder over the surface of the ocean? Presumably it would lock up CO2 in the seawater just fine, allowing more CO2 to be absorbed by the ocean from the air.

Need very fine particles for that and its usually classed then as ocean alkalinity enhancement (OAE). A hybrid method has been proposed in the literature, to use beaches and is currently being implemented via a project I started (but which I am no longer with) that has been turned into a company called Vesta -> https://vesta.earth

Rolling stones; fast weathering of olivine in shallow seas for cost-effective CO2 capture and mitigation of global warming and ocean acidification https://esd.copernicus.org/preprints/2/551/2011/esdd-2-551-2...

https://smartstones.nl/research/publications-2/

You have to ask yourself the question why would farmers allow you to spread crushed rock on their farmland? There is no positive benefit for them. The academics didn't study the long term effects of it on the land. The land is the tool the farmers use to make their living.

Actually, this incorrect, soils naturally acidify through nutrient loss (e.g. natural minerals) and the breakdown of nitrogen fertilizers. And soil have been amended with limestone (and volcanic soils) for a very long time.

In fact, terrestrial enhanced rock weathering (ERW) was created to replace the cost of liming fields for farmers, which leads to the release of carbon. Many farmers are open to it because they need to balance their soil's ph. Which as you said, is important to farmers because the land "is the tool the farmers use to make their living" therefore, you can consider ERW/liming as the maintianence on their tool...

> if spread across croplands globally

That’s a big if! Reminds me of “the market for comics is $32 billion a year. If NFTs can capture just 1% of the market that’s $320 million per year.”

Also what are the CO2 emissions of transporting all these rocks??

No kidding. I’m struggling to think of any technology or technique that’s ubiquitous globally. Not to mention the labor and emissions required to harvest, transport and spread heavy rock across even a small percentage of fields.

Those rocks come from the mantle. You can find them in outcrops in places like Oman and Norway. Typically they get to the surface through tectonics.

Nit: Confusing units. The proper unit for this field is Gt (Gigatonnes).

We'll compensate for that by emitting more carbon. But hey, someone got a job out of spreading rocks.

Whom decided we need to reach the rediculous Net Zero target? We dont need to get anywhere near 0 to solve the problem

Enhanced Weathering, as the practice is called, has merit and is being investigated by a dozen startups. The idea of spreading Olivine (a magnesium iron silicate) or Brucite (magnesium hydroxide) or Wollastonite (calcium inosilicate) has been floated around for a while.

There are three aspects relating to its feasible application - as distinct from theoretical considerations.

1. Is the process feasible? The slow reaction rate seems to be a significant obstacle. Additionally, these minerals are rarely pure and may vary significantly in quality from source to source, leading to a QA/QC problem.

2. Can the process be scaled-up? Contrary to earlier comments, there is no wide availability of these minerals, not at the scale needed to make an impact. Moreover, the material-handling side of the issue is not well addressed. It isn't a simple question of drawing a distribution network on a diagram: it's working out the economics of the mass mining, transport, distribution and application of these materials. People are working on this, but I have not yet heard a compelling solution.

3. Are there undesirable side reactions? This is what farmers will worry about. It'll be good if these amendments increase soil fertility, but that has to be demonstrated. Do these amendments alter the physical structure of soils or reduce their capacity to retain water, especially after carbon is absorbed? Do they form concretions over time that would make soils less permeable? Does the exposure to plant exudates release contaminants in soil?

I was involve in a project at a Canadian diamond mine in which the host rock - Kimberlite - absorbed CO2. This caused a decrease in its alkaline pH and allowed small quantities of sulphides to oxidize and release contaminants. Clearly, this is the kind of undesirable outcome that must be avoided.

Lots more to say, but perhaps some EW experts will chime in.

This whole 'undesireable side reactions' thing is completely overblown for basalts. The effects to soil of volcanic ash from eruptions is quite well studied, not to mention crushed basalt is a recognised fertiliser in organic and biodynamic farming, and there have been places spreading it each year for the last 40 years (purely as a fertliser). You cant use rocks with significant sulphides or other heavy metals though, that has to be tested before spreading. Basalt is quite wide spread.

My concern would be nickel pollution.

I think this is cool from an academic perspective, but I have a very difficult time believing the energy needed to crush rock, and distribute it over fields, makes this a net benefit.

That depends on the energy source, and how much is available. If for example we convert to 100% wind/solar/battery, we'll end up with a large oversupply of zero-carbon electricity in the summer.

That is only true if we also convert to 100% w/s/b the w/s/b material sourcing, fabrication, distribution…

This may be a dumb question, but if we're collecting volcanic rock, could we not tap into geothermal energy from the volcano to get cheap energy?

It seems reasonable to assume that many places where there is easily accessible volcanic rock are also places where geothermal is possible, but the connection between rocks like basalt and volcanoes can be more temporally distant that you may be thinking.

If I go to a beach in the US Pacific North West, I can pick up basalt rocks/boulders/pebbles, but they last were in contact with an active volcano millions of years ago (approx 12mya is the usual number given locally, if memory serves)

The argument is basically that we will need extra energy to go towards carbon capture one way or the other. Energy in, carbon reduced. This may or may not be a feasible way to do that.

The energy use is surprisingly low and distances of 100-300 km can remain highly efficient, even with diesel trucks and avg grid power. By intentionally developing/utilizing crushing plants near clean energy and farmland, this can be made even more efficient.

See Potential and costs of carbon dioxide removal by enhanced weathering of rocks https://iopscience.iop.org/article/10.1088/1748-9326/aaa9c4

Environmental life cycle assessment of CO2 sequestration through enhanced weathering of olivine https://legacy.projectvesta.org/wp-content/uploads/2019/06/E...

Enhanced Weathering: An Effective and Cheap Tool to Sequester Co2 https://link.springer.com/article/10.1007/s10584-005-3485-y

We'll need to remove CO_2 from the atmosphere on a massive scale.

Both the low and intermediate IPCC scenarios, SSP1-2.6 and SSP- 2-4.5, rely on it. It will be essential to keep our planet recognizable by 2100.

Luckily the jittery/cyclic output of renewables is ideal for this. In the grand scheme of things it also solves the storage issue to a large degree, since massive overbuilding of (peak) capacity is necessary.

> Both the low and intermediate IPCC scenarios, SSP1-2.6 and SSP- 2-4.5, rely on it.

This is a huge issue that people do not understand, there is currently no plan for this CO2 removal and I was horrified when I realised that all our climate projections assume that a massive industry will just spring into existence

Liming is pretty common in agriculture already. If you need 10um particles it'll be a problem. If 100um is ok, then it's not a big deal (and transport dominates).

dunno! it's gonna be rich in iron and magnesium, which you need to grow plants anyway. I would think transportation cost would be the dominant factor but olivine is common everywhere

Hydro-powered rock crushers? Wikipedia gives an example of a waterwheel-powered machine that crushed tin ore in Cornwall in the 1800s.

Maybe mixing the crushed rock in with seeds when they’re already being planted?

More than likely using the water source to generate electricity that then powers whatever modern machinery you'd ever need is going to be significantly more efficient.

Windmills were used to crush grain too, but wind turbines are orders of magnitude better in terms of a solution.

Indeed, the largest active olivine quarry is in Norway, it's all hydro!

And then load it onto a sailing ship - carbon neutral!

I'm not kidding either.

There's already a large amount of this available and energy can be sourced from renewable supplies.

Also worth noting that life cycle assessments take into account the gray emissions produced while sequestering CO₂ so the removal should be the net CO₂ removal (although not sure if that's the case in this article).

It depends on the feedstock, and how far you truck it (last mile) but in general this is one of the most bang-for-the-buck CDR approaches, with yields of 5-10x CO2 removed vs CO2 required.

Maybe not at first, but over 75 years? Maybe so.

This study is about whether the rock weathering we’ve seen posted here before (crushed olivine etc) works in dry climates like California. The answer appears to be “yes, but more slowly”

> The study found the plots with crushed rock stored 0.15 tons of carbon dioxide per hectare (2.47 acres) during the study compared to plots without crushed rock. Though researchers expect different weathering rates in different environments, if this amount of carbon was removed across all California cropland, it would be equivalent to taking 350,000 cars off the road every year.

They don't say how much rock they added to each field, but note that the 0.15 tons of CO2 they remove is only 300 lbs. A gallon of gasoline emits 20 lbs of CO2 when burnt.

So, if they use more than 15 gallons of gasoline to mine, crush, transport and spread the rock over 2.47 acres, then this process emits more CO2 than it captures.

I think they'd need to use electric high-tonnage dump trucks and electric tractors to make this process actually capture carbon. Electric tractors are stating to become available, but I don't know of any high-tonnage electric truck manufacturers.

Remember that if you're already distributing something else (eg. fertilizer) over the field, the added money and CO2 costs of distributing this might be negligible.

You could just mix the fertilizer and the rock together at the fertilizer factory, and automatically a large chunk of the worlds farmland gets this added.

It's only negligible if the rock is a negligible amount of extra weight. Otherwise, the energy to transport will still come from somewhere & not be negligible unless all that energy is from a non-carbon fuel source (bulk transportation is nowhere near decarbonized).

The spreading is ok but the transport is high. The key thing is: how many years of weathering do you get out of one load of 47 tons (or 27t)?

The paper provides a very course estimate that what they measured over the year was only 0.15% of total weathering potential, which if we handwave a little turns into 6,000 lbs CO2 over 20 years, or 300 gallons of gas offset, which is probably a net gain. Though there are a ton of "it depends"es in there and it probably only makes sense with further electrification.

(Obviously, the weathering would go on for a lot longer than 20 years, but the unknowns get large there and I'm assuming we're mostly interested in a shorter time frame)

OK, with something something like the F-550 (on the small side for this use case, but also a reasonable choice for an ICE dump truck that's driving to/from agricultural fields), it could work:

https://www.ford.com/commercial-trucks/chassis-cab/models/f5...

That can move 14,870 lbs (minus the weight of the driver and the dump truck bed) per trip, so it would take more than 6.7 trips to deliver rock to treat an acre. At 6.7 trips per acre it would have to use less than 44 gallons of gasoline per trip for breakeven. It should use significantly less than that for fields that are somewhat close to an appropriate quarry / rockery.

The lightning can only move 7000 lbs per trip, so it would have to make 13.5 trips per acre.

How does 6lb of gas release 20lbs of CO2?

I found this[1] link from the EPA with a number similar to yours, 8.8kg per gallon of gas, but they say it "creates" rather than "emits." I'm still struggling with this creation of mass out of thin air...

[1] https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-t...

It's because the majority of the mass of CO2 comes from the oxygen from the air used to burn the carbon. So in this case, it's quite literally creating mass out of thin air.

Specifically, the atomic mass of carbon is 12 and oxygen is 16. So for CO2, 12/44 of the mass is carbon, or about 27%. So of that 20 pounds of CO2, about 5 1/2 pounds are carbon, the other 15 pounds is oxygen sucked out of the atmosphere.

"Out of thin air" is right :-)

The CO2 contains mass from the atmospheric oxygen consumed during combustion. 12 grams of carbon becomes roughly 44 grams of carbon dioxide when it burns.

"produce" is probably a better verb than "release" in this case, for the common person to understand what's going on.

> but note that the 0.15 tons of CO2 they remove is only 300 lbs

Your point stands, but it was 600 lbs.

They quoted figure is a rate, not an absolute amount removed:

> 0.15 tons of carbon dioxide per hectare

Per hectare. They spread it over 5 acres, or roughly 2 hectares, for a total of 0.3 tons, or 600 lbs.

Depends on how high “high tonnage” is. Kennworth is offering a 680hp full-electric with a 3 hour range. Volvo offers an electric VNR with identical performance to its standard VNR. Freightliner sells the eCascadia, matching its regular Cascadia.

These vehicles would need to be charged on fully renewables or non emitting sources (like hydro) to offset this. Even if Natgas or Gas plants are much more efficient than engines, the calculation still needs to account for amortized emissions.

Yes? Obviously yes? Idk why everyone is assuming we’re going to keep dragging our feet on something that, at this point, is merely a matter of buying a few batteries and setting up a few more solar panels. Provinces have done it; heck, entire countries have done it. Switch to renewables already.

Because we're still not there yet. In the US, California's grid hits near-100% solar only around midday for an hour and then at night becomes mostly natgas, and can't handle peak demand on hotter days. If you're talking about the load of adding BEV trucks then that's adding a whole different dimension to the equation. I'd like to be optimistic about these things but we're far from it in the US.

Those are semi-trucks. You'd need to attach a compatible dump trailer to them. (Those might exist, but I don't think I've ever seen one).

They exist, its how animal manures are applied to fields. Likely this would be shipped via trains long distance and last mile with semi.

The metric system is really handy for calculations like these.

Taking only 3% of California's cars off the road seems way easier.

It is, but consider the future. We need net negative emissions to stabilize the climate because we didn't decarbonize early/fast enough to achieve this goal with emissions cuts alone. The vast majority of climate progress must come from energy system decarbonization, but active carbon dioxide removal approaches like this one will be necessary to draw down the excess atmospheric CO2 accumulated so far.

"IPCC Report: Carbon Removal is Now Required to Meet Climate Mitigation Targets"

https://www.carbon-direct.com/insights/ipcc-report-carbon-re...

Also see this IPCC fact sheet about carbon dioxide removal, which includes enhanced rock weathering (the technique under discussion here):

https://www.ipcc.ch/report/ar6/wg3/downloads/outreach/IPCC_A...

Without human actives the earth is slightly net negative. We need to be more net negative than that in the short term to fix some problems (ice melt), but we don't need that forever.

> Without human actives the earth is slightly net negative

Source? AFAIK greenhouse warming has the capacity to be a runaway effect. It's not immediately obvious that if you remove all current human carbon emissions, that temperatures would level off & start declining vs continue increasing because of the feedback loop.

The Earth slowly depletes excess atmospheric CO2 due to the geological carbon cycle of silicate weathering. This is the slow, natural counterpart of the accelerated silicate weathering discussed above. It is too slow to reverse global warming on human time scales, but it means that if anthropogenic emissions ceased Earth would reach its peak temperature in less than a thousand years (ice melting and other reactions to this change would go on for several thousands of years) and gradually decline back to the pre-industrial atmospheric CO2 and climate within about 100,000 years.

My source for this recollection is David Archer's 2009 book The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth's Climate.

Humans are currently on track for around 4 degrees of warming by 2100 assuming we hit all our current emission reduction targets (i.e. reaching net zero when governments have said they would). So removals are quite necessary.

Can anyone speak to whether this helps or hurts the fertility of the soil?

The sand and rocks in the soil is where phosphorus and trace minerals come from. Ideal soil has a combination of living carbon, dead carbon, and minerals. The fungi and bacteria breakdown the minerals along with weathering and make it available to plants. All the living carbon builds itself from the dead carbon. The dead carbon came from dead plants that pulled the carbon from the air with photosynthesis.

volcanic soil is often considered very fertile for agricultural purposes. [1]

[1] https://www.bgs.ac.uk/discovering-geology/earth-hazards/volc....

Depends on the soil. But it helps often enough that there is no lack of places.

If it were a good idea from the perspective of farmers, then farmers would already be paying to do it themselves. This isn't the case though, so you will have to pay farmers to do it.

Why does it even have to be on farmland in the first place? If it's such a great idea with no environmental downsides, then dump the crushed rock onto other land instead. Then you can dump more of it without being limited by whatever is optimal for farm yields.

Not too sure, but some plants greatly benefit from rock in soil.

It should help replenish certain minerals in the soil.

They're dumping alkalinity into the soil. What could go wrong?

Crushed anything in air or water can be bad for the environment though. In air, it is effectively PM2.5/PM10 pollution. In water, I bet it gets into fishes gills just like it gets into our lungs.

The crushed rocks in this case mineralize into stable silicates which can be beneficial as they flow down rivers into the sea. As they are alkaline they can combat ocean acidity and the minerals help crustaceans harden their shells.

Are those super finely crushed stable silicates those same ones which cause silicosis?

Good question, more research needed (on my side and perhaps in general related to this specific case).

This article is directly relevant to this question: https://carbonherald.com/silicate-to-undertake-first-ever-en...

"Climate tech startup Silicate is set to start the first-ever enhanced weathering trial in the United States. The trial will involve applying 500 metric tons of milled returned concrete to 50 hectares of farmland in Buckingham, Illinois. According to company estimates, this project has the potential to remove as much as 100 tons of carbon dioxide from the atmosphere annually."

I'm reading this a single-use carbon sequestration solution, is that not correct?

As in - you pay the carbon to crush it, ship it and spread it. Then it captures carbon exactly once, and then what do you do with it?

This has been known for a while:

https://www.nature.com/articles/s41586-020-2448-9

"crushed rock stored 0.15 tons of carbon dioxide per hectare (2.47 acres)". (.15 * 2000lb)/2.47 = 300lb/2.47 = ~121.5lbs/acre of carbon uptake. After applying 41tons/acre of olivine. How is this feasible? You ship railroad cars of volcanic rock dust, spread it on a field, and watch it take up a sandbag size amount of carbon per acre. Is it continuous or a onetime thing?

Related idea, but for oceans https://www.vesta.earth/

1. Tax companies for their portion of CO2 generation. Let costs trickle down to customers. 2. Split tax collected evenly to each citizen/perm resident via monthly check. 3. Let market figure out Co2 reduction solutions. 4. Create whistleblower process to keep carbon sequestration companies in check.

#2 seems like a ludicrous misalignment / conflict of interest. Why would I as a taxpayer/voter want CO2 emissions to decrease if I'm essentially getting a monthly bonus for their existence?

If 1-4 is implemented, gas would become a lot more expensive. Companies will switch to EV fleets, gas demand would drop, oil companies would not lobby politicians for drilling permits as new drilling would have bad ROI. Voters will to a lesser extent do what companies are doing and purchase lower carbon impact products. The hypothetical voter you speak of would only benefit if they purchase lower carbon impact products and pocket the savings from the check. However the act of purchasing the lower carbon impact product today has far more impact than a vote for a politician carbon intensive policy in the future. The incentives are aligned in that even this weird hypothetical voter will drive the adoption of lower carbon impact products long term.

Consumption taxes do still tend to have disproportionate effects on those at the bottom (https://en.wikipedia.org/wiki/Consumption_tax#Savings_effect), but there's more logic to step 2 if gas prices are increased across the board than my initial post.

That does make some sense, thanks for replying and elaborating!

Presumably if there is an option that is more C02 efficient, it would have less tax so could be cheaper. If you spend your monthly bonus on the cheaper option it’s still a net positive

That industries fight hardest against this approach tells me that it's probably the most effective and efficient approach.

The two-step plan to fix more carbon into soil:

1. Rocks

2. Ants! https://www.scientificamerican.com/article/ants-may-boost-co...

I've been enjoying this thread. I have a company that does this (Eion). We are recruiting for a data engineer role to implement the algorithms for quantifying carbon removal, if these questions are interesting to you. Touches on nearly every aspect in this thread.

in New England (and other places I assume), rocks are light enough to float.

There are many rocks under the surface of the soil, and over time they work their way upward and pop out of the ground. Every spring when the fields are being tilled for planting, these rocks get in the way and they need to be removed (for the convenience of the farmer and his plow). Today's New England forests are all 2nd or 3rd growth; the land was previously completely cleared for farmland, before the farmland of the Great Plains opened up and was found more efficient for scale farming (and not least because the human population there was smaller).

If you walk through the New England woods today, you will periodically/frequently come across old "abandoned" stone walls among the trees. Farmers built these stone walls to mark their property from the stones that were handy because they were removed from their nearby fields, where these stones had "floated" to the surface. The reason these stones are under the surface is because the grinding and bulldozing of glaciation, and then the subsequent outwashing of ice-melt carrying stones and sediment.

All of that (from memory, apologies for any mistakes) to ask: won't adding crushed rocks to farmland result in a lot of those rocks popping back out of the ground? Will plowing just keep them turned under, but even so, wouldn't the population of rocks keep increasing?

> these rocks get in the way and they need to be removed [...] you will periodically/frequently come across old "abandoned" stone walls [made] from the stones that were handy because they were removed from their nearby fields

You didn't mention what size these rocks/stones are (to my non-native ears, a rock is at least several centimetres), but if you can build walls from them, I take it they're not sand-sized. If you click the link in the first paragraph of the article, leading to the source, it mentions in the introduction

> Crushed metabasalt and olivine soil amendments were used to investigate changes in soil pore water alkalinity as a proxy for bicarbonate production. The metabasalt (median grain size: 102 ± 22 μm) was selected because of its benign elemental composition and modest weathering potential (the parent volcanics includes felsic facies, yielding an overall silica content in the intermediate-to-felsic range). The olivine (median grain size: 83 ± 12 μm), in contrast, was chosen for its potential to weather rapidly

TL;DR the remains of the crushed rock they tested is measured in micrometers

ooooh, micrometers. I was thinking pebble sized. I wouldn't call it crushed, it's pulverized powder (polvare which is powder in Italian, you see it in reference to minerals in wine vineyards)

There are interesting positive/negative (it hasn’t been researched enough yet) side effects on the effects this has in raising the pH of the ocean, potentially reversing ocean acidification

Crushing rock is very energy intensive, transporting rock to farms is energy intensive. Placing rock in the soil is energy intensive. Its hard to see how this passes the B/S test.

Yep. It's easy to skip the TCO analysis to make it seem like it's "helping" in the context of a study trying to sell another study.

The Bill Gates-associated method of spraying fine lye in a hyperboloid tower seems the most effective, perhaps at a slightly higher pressure of 2-3 atm to both increase the temperature and reactivity. The lye would be produced in a closed carbon cycle process using renewable energy sources.

> 215 billion tons of carbon dioxide over the next 75 years if spread across croplands globally.

But for how long does the rock 'function' before needing to be replaced? I'm doubtful that it would work at the same rate over just a few years, let alone 75.

With the need for massive mining, transportation and application of the rock at regular intervals I wonder if it would erode what ever gains this gives us.

>The study found the plots with crushed rock stored 0.15 tons of carbon dioxide per hectare (2.47 acres) during the study compared to plots without crushed rock.

According to the article it took several months of winter. Say, even though there is less rain in the summer, it is 0.3 tons per hectare per year.

To put into perspective - trees sequester more than 6 tons of carbon dioxide per hectare per year.

There’s so much more to soil conservation. Our reliance on manmade chemicals over good stewardship of the land has resulted in so many problems.

Highly recommend looking into Louis Bromfield. A very accessible book: The Planter of Modern Life: How an Ohio Farm Boy Conquered Literary Paris, Fed the Lost Generation, and Sowed the Seeds of the Organic Food Movement

As a land owner all I can think of is; I wonder what the unforseen outcomes of this might be?

Will it turn my soil acidic? Will it kill off bacteria? Will reduce drainage or will my soil suddenly be unable to hold water? Will it harm the nematodes, will it create a nutrient imbalance that is only corrected by some monsanto/bayer patented soil amendment?

These are the same questions I raised in an earlier comment. They are pertinent.

Peculiar as to why this is pitched at farmers. Maybe there could be a question of ulterior motives.

Wouldn't it make more sense to sponge rock without crushing it? Basically drill air pipes into it, then fracture the material with rapid cooling and heating +water.

What is the risk to get silicosis caused by that rock dust?

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

Dust is never good, but olivine specifically was introduced as a foundry sand specifically because it doesn't cause silicosis (vs quartz).

Olivine is a kind of silicate where the silicon atoms are in isolated tetrahedra (with four oxygen atoms), rather than linked into large chains, sheets, or 3d lattices. This makes it weather more quickly (for CO2 absorption), but I suspect also makes it dissolve more quickly in the body.

The article also mentions metabasalt

Gabe Brown: treating the farm as an ecosystem

https://youtu.be/uUmIdq0D6-A?si=RnMka7Nnx0yZ3Tqm

Why are we even thinking of doing this? I am more than a little concerned that it may not be wise to assume the answer to biome engineering is even more biome engineering…

Before we blew past 400 ppm carbon in the atmosphere this might have made sense. Now it would probably be more accurate to phrase the implicit proposal as asserting the answer to rampant biome disruption may include some cautious biome engineering.

Are they claiming that microbes and other life forms don't just harvest the carbon (directly or indirectly) putting it right back into the air?

The CO2 storage is inorganic as bicarbonate dissolved in seawater and is considered permanent (60,000-100,000+ years). This process occurs as rocks weather and release magnesium or calcium cations. The "enhanced rock weathering" (ERW) process is all about speeding up the rate of release of these cations. Taking them out of a closed mountain not in the tropics and grinding them up, increasing their reactive surface area, speeds up the weathering process by many millions of years or more.

See: The role of soils in the regulation of ocean acidification - https://royalsocietypublishing.org/doi/full/10.1098/rstb.202...

Interesting. I don’t know enough to judge the veracity of this, but it will lead me to learn more, so thanks.

And geology is fascinating, so that’s another reason to learn more.

So I guess you end up with finely-divided carbonate.

I didn't notice any mention of how long it takes powdered basalt to weather down. Is that over a year?

I seem to be wrong about the result of basalt-weathering being carbonates.

https://en.wikipedia.org/wiki/Basalt#Weathering

It seems that basalt consists mainly of metal oxides, predominantly Fe, Ca, Mg and Al. How does carbonic acid from rain get bound into basalt, without dissolving in the next rainstorm?

(My knowledge of chemistry is restricted to "A" level, what Americans would call High School; and I've forgotten it all, because it was 40 years ago).

The article says that basalts weather down into clays, which aren't carbonates.

Can be <5 years if it is super fine (~25um) or >20 years if it is coarse (minus 3/8" fines).

To reach maximum sequestration rate I thought it was much longer than that (~95% within 30 years at 3um). Where did you get your numbers from (curious, always looking for more sources)?

In other news the Mining industry rushes to produce 3000 trillion tons of crushed rock, causing 1b cubic tons of rock dust over the world.

Typical "Assume a cow is a uniform sphere of milk one meter in diameter" proposal.

> "adding crushed VOLCANIC ROCK to cropland" ... "by crushing the rock into a FINE DUST"

Emphasis mine.

So...

  - Mine massive far-away lava fields
  - Generate massive amounts of CO2 through this process
  - Cause serious environmental damage
  - Transport what you mined 
  - Generate massive amounts of CO2 through transportation
  - Crush it into a fine dust
  - Generate massive amounts of CO2 through this process
  - Transport massive quantities again
  - Generate massive amounts of CO2 again
  - Likely need for massive amounts of chemicals as part of all of the above
  - Use a high carbon footprint process to distribute the dust
  - Use a high carbon footprint process to bury the dust to the required depth
  - Hope and pray for enough rain
  - Hope and pray you don't destroy the fields for agricultural use

Right.

And that's not even a full accounting of what the process at scale would look like. It is far more likely to add massive amounts of CO2 to the atmosphere than the opposite. Not to mention potential ecological damage across every region the project might touch, from mining to deployment.

We are not going to surface real solutions until we are willing to be honest about the full and real accounting behind proposals. Most so-called solutions barely pass basic high school science and economics tests. That's where we are. Still. I mean, we are still talking about stuff like huge fan-powered filters? Have we gone mad?

All we are doing is wasting time and money looking at false supernatural solutions to a planetary scale problem that requires real solutions.

> if this amount of carbon was removed across all California cropland, it would be equivalent to taking 350,000 cars off the road every year.

OK. Then forget volcanic dust and focus on the infrastructure and power generation required to enable a million electric cars per year. If this volcanic powder nonsense is good for 350K cars per year, well, doing THREE TIMES BETTER with electric cars is a realistic objective that isn't in fantasy-land at all and does not create the potentially horrific ecological danger of mining and spreading volcanic dust. One is realistic and attainable. The other is, at best, a dangerous fantasy.

I can imagine a geothermal-based extraction process to mine + a wind/solar transportation method. This works fine even if it takes 100x longer to transport. Can be fully robotic piloting for instance.

Bottom line I'm not sure it MUST be a C02-generating process once bootstrapped.

Also no reason we can't focus on both electric cars and this soil method.

The problem with these assumptions is that you are asking for yet-to-be-invented solutions to mining, transportation and processing problems. As a friend of mind is fond of saying, at some point we have to recognize that we took a problem from boiling a pot of water to trying to boil the ocean.

None of these proposals qualify as solutions, because they are never aligned with reality. Or, another way to put it: Reality is always far more complex than recognized by these experiments.

I suppose.

I do remember stories from undergrad engineering about the development of the first moon landing and the associated technologies. That and maybe the Manhattan Project.

In both these projects, budget was essentially unlimited, and ultimate success absolutely required planning around yet-to-be-invented technology. I see enough similarities to think something like this is possible. If, for instance, we thought seeding farmland soil reduced emissions by 99%, we'd probably do it. It's a leap of faith, but there is absolutely precedent.

> I do remember stories from undergrad engineering about the development of the first moon landing and the associated technologies.

Of course. However, in all of those cases you could go through the math in a brutally honest manner and determine that things were realistic within a certain margin of error given physics constraints.

The issue I have with every single proposal I have seen is that they are, to put it in a certain way, dishonest. It's the equivalent of "and then a miracle occurs" being reported as a real solution.

In this particular case, I would not have funded this research without first funding an initial (much lower cost) study to prove that the project meets basic physics. If, and only if, the researchers can prove the solution is actually realizable without causing damage, etc. We move to the next phase.

So, now you know it can be done without causing more damage and the numbers add-up.

Phase 2 would entail what I call a "sense of proportion" report. Again, much cheaper than funding the entire experiment.

What is that?

Before you launch into anything you need to understand what impact it might have if you succeeded at deploying it in the most optimal form imaginable. From there you grade it on a curve and try to estimate what reality might be. Is reality +/- standard distributions from the reported optimal value or worse?

The report would also have a "Comparables" section. Using language we use in the US when a home is appraised. Realtors find similar homes and look at how much they sold for to then compute the value of the home they are selling. This attempts to ensure that the home is sold for a reasonable price, not too low, not too high.

The "Comparables" report would compare the proposal to alternatives. In engineering it is always interesting to suggest new solutions to a problem. However, you always have to consider the alternatives or you risk wasting your time and money.

In this case the comparables might be what I mentioned in my original comment: One of the figures of merit they mention in the paper is CO2 reduction equivalent to removing 350K internal combustion (IC) cars from the roads. OK. Great. The question to ask, then, is: Can we achieve the same or better performance using other solutions, existing or under evaluation?

In the case of cars the obvious thing to look at is the replacement of IC cars with electrics. You have to evaluate that solution against the proposal before moving forward. Why? Because it is a real solution with real metrics we understand far better than a science experiment.

If all of the above and the comparison to known solutions shows the project might have merit within an acceptable margin of erro, and only if that is the case, then it gets funded and the required research begins.

Until all of the above passes basic math and physics, the entire thing is a big hand-wavy "and then a miracle occurs" fantasy. I am sorry to say that most of what has been proposed in this domain is nothing more than that, fantasies. Expansive fantasies that nobody ever seems to want to rigorously evaluate, as if reality didn't matter at all.

I want real solutions. I don't want us to waste time and money on fantasies, which is what we seemed to be doing. BTW, lots of money in the fantasy business these days. Maybe I should join them. It would sure be far more profitable than trying to point out the emperor has no clothes [0].

Just based on the downvotes and comments over the years on this topic, it is obvious to me, using HN as a sample of people who should be smart critical thinkers, that something is wrong. Perhaps people are so emotionally invested in the subject to forget that the very first job in science is to demand (and offer) proof of hypothesis based on the scientific method. This, among other things, requires full disclosure as well as the ability for anyone to verify and reproduce claims.

In this case, there should have been an entire section --pages-- on this report with an honest appraisal of mining, processing and delivery timelines, feasibility and consequences to the environment. Without that sort of thing it's like me showing a super efficient machine without disclosing that I am not accounting for additional energy being supplied from outside the system. Looks great. Dishonest as hell.

[0] For those who might not understand the relevance of the reference to the story by Hans Christian Andersen:

https://en.wikipedia.org/wiki/The_Emperor%27s_New_Clothes

From the article:

"Two swindlers arrive at the capital city of an emperor who spends lavishly on clothing at the expense of state matters. Posing as weavers, they offer to supply him with magnificent clothes that are invisible to those who are stupid or incompetent. The emperor hires them, and they set up looms and go to work. A succession of officials, and then the emperor himself, visit them to check their progress. Each sees that the looms are empty but pretends otherwise to avoid being thought a fool.

Finally, the weavers report that the emperor's suit is finished. They mime dressing him and he sets off in a procession before the whole city. The townsfolk uncomfortably go along with the pretense, not wanting to appear inept or stupid, until a child blurts out that the emperor is wearing nothing at all. The people then realize that everyone has been fooled. Although startled, the emperor continues the procession, walking more proudly than ever."

The basic physics is a known quantity and doesn't need to be repeated for every new study in the field. Here's a publication that contains the core insight of accelerated silicate weathering:

https://www.ipcc.ch/site/assets/uploads/2018/03/srccs_chapte...

See section 7.2.2, "Chemistry of mineral carbonation."

The carbonation of magnesium and calcium silicates is thermodynamically spontaneous but kinetically hindered. The kinetic hindrance is why an additional energy input is needed to draw down atmospheric CO2 in less than geological time: the mineral's accessible surface area must increase dramatically for fast silicate weathering. The thermodynamic spontaneity is why the additional energy input can be small compared to the original energy embodied in the fuels that generated the CO2.

You misunderstood.

You are thinking about dust-in-dirt passing physics. That is NOT the entire process. That's the very end of the process.

Maybe you are not familiar with this use of the phrase?

Elon Musk uses the “it must pass physics” phrase to basically mean that the ENTIRE THING has to obey the laws of nature, not just the last step.

Perhaps this example can clarify the concept:

If, on the other hand, we propose to use electrolysis to generate liquid hydrogen to use as fuel, the ENTIRE PROCESS has to pass physics.

It does not.

Why?

Well, it takes approximately 55 kWh of electrical energy to extract 1 kg of gaseous hydrogen from water.

Great.

However, 1 kg of gaseous hydrogen contains 40 kWh of energy.

In other words, you have to use MORE energy to extract the hydrogen than the energy it contains. This idea, at the most basic level, does not pass the physics test. It's a fantasy.

Once we add such things as the inefficiencies of generating the energy, energy transportation losses (wires, connections, transformers, etc.), the energy required to bring the water to the electrolysis plant and run it at scale, the energy required to liquify hydrogen (12 kWh per kilogram), the energy required to transport and manage liquid hydrogen, etc. Well. The entire story quickly becomes a ridiculous fantasy. You are going to expend more than 100 to 200 kWh per kg of gas to deliver 40 kWh of stored energy in liquid form.

That's what "does not pass physics" means. The entire process cannot stand up to scrutiny when all factors are considered.

So, all of this, and the steps I have not listed (for example, fuel delivery), have to pass physics as a complete proposal:

  - Mine massive far-away lava fields
  - Likely use explosives, strip mining and very large machinery
  - Burn large amounts of diesel and other fuels  
  - Generate massive amounts of CO2 through this process
  - Cause serious environmental damage
  - Transport what you mined 
  - Burn large amounts of diesel and other fuels  
  - Generate massive amounts of CO2 through transportation
  - Crush it into a fine dust
  - Consuming very large amounts of energy
  - Generate massive amounts of CO2 through this process
  - Transport massive quantities again
  - Burn large amounts of diesel and other fuels  
  - Generate massive amounts of CO2 again
  - Likely need for massive amounts of chemicals as part of all of the above
  - Use a high carbon footprint process to distribute the dust
  - Burn large amounts of diesel and other fuels  
  - Use a high carbon footprint process to bury the dust to the required depth
  - Burn large amounts of diesel and other fuels  
  - Hope and pray for enough rain
  - Hope and pray you don't destroy the fields for agricultural use
  - Etc.

What I said is that phase 1 should be about proving that the entire thing passes physics. For that stage, it is OK assume that the proposed final element passes physics (whether we know it or not). What you are trying to quantify is everything else, which, in this case, is everything before a particle of volcanic dust finds itself 30 cm deep in dirt at a farm. That's what you have to prove before the physics of that dust particle in dirt is even remotely relevant in the context of the proposal.

Using electrolysis to extract hydrogen from water is, to use your phrase "a known quantity and doesn't need to be repeated for every new study in the field". In other words, that process is real and "passes physics".
If, on the other hand, we propose to use electrolysis to generate liquid hydrogen to use as fuel, the ENTIRE PROCESS has to pass physics.
It does not.
Why?
Well, it takes approximately 55 kWh of electrical energy to extract 1 kg of gaseous hydrogen from water.
Great.
However, 1 kg of gaseous hydrogen contains 40 kWh of energy.

In other words, you have to use MORE energy to extract the hydrogen than the energy it contains. This idea, at the most basic level, does not pass the physics test. It's a fantasy.

If the creation of hydrogen fuel via water electrolysis is an example of something that "doesn't pass physics" then the idiom "doesn't pass physics" obscures more than it clarifies. There is nothing physically implausible about water electrolysis. Despite the energy losses, water electrolysis to produce hydrogen fuel may be better than the alternatives; for example, you can launch a rocket to orbit with hydrogen fuel but you can't do that with electricity. If "doesn't pass physics" is supposed to be shorthand for economic implausibility relative to alternatives, just make the economic argument instead of referring to physics.

> There is nothing physically implausible about water electrolysis.

You are getting lost in the semantics and an example I grabbed as an illustration and ignoring the message, which is simple:

Anyone can propose anything. And that's fantastic. No problem. However, at some point, it has to make sense. And it has to make sense while looking at the entire process, not just a small element of it.

There are a lot of things in life that sound fantastic, until you run a full analysis and understand that they don't really make sense, particularly at scale. This has to be the first step.

Beyond that, after that step, the project has to be compared to other proposals that can deliver similar or better results. This, again, can usually be done before launching into these projects. It's about that list of dependencies I posted in my other comment.

Why?

Because we are wasting valuable time and money on fantasies, that's why.

Making a business comparison to try to further illustrate the point. In business you have to run through top level before jumping head-first into anything at scale. You also have to run competitive analysis and decide if your proposal is actually realizable and competitive.

In my work in aerospace I have to do this all the time. We are used to conducting what's usually called "Trades Analysis". This is a document where you present and analyze, to a sufficient level, all reasonable options to solve the problem you are trying to address. This is the starting point for a discussion that usually leads to choosing the solution or approach that makes the most sense within the stated objectives and constraints.

> If "doesn't pass physics" is supposed to be shorthand for economic implausibility relative to alternatives

No. That's not it. It really is about everything else first and foremost. Before you consider economics you have to consider science. Again, for the entire process, not a small portion of it. Of course, there are cases where the economics is so obviously ridiculous that scientific analysis quickly becomes irrelevant. A ridiculous example would be something like mining materials from the moon to make common concrete on earth. We don't need to look at science to know that would be economically and ecologically ridiculous.

> for example, you can launch a rocket to orbit with hydrogen fuel

If you change the problem, you change the required analysis methodologies. Still, you have to look at the process in its entirety and in the context of comparisons to other ideas. That's why nobody launches rockets into orbit using hydrogen. It doesn't make sense when looked at from a macro perspective.

My advice:

Always take a very large step back. Try to understand and quantify the entire picture. Things have to make sense at the macro level.

Your "macro" picture is still making a number of questionable assumptions, especially the amount of CO2 that would necessarily be burned.

We're addicted to stuff that runs on fossil fuels. Keep running into ideas about how to offset that. We need to wake and stop. If there hasn't already been enough climate Narcan sprayed to wake us up by now, we'll keep dreaming until we can't. Then we will stop.

For any one that need to squeeze out that extra carbon credits

How do we get it distributed across suburban backyards?

It could be sold as a magnesium and iron supplement, to make lawns greener when those elements are in short supply.

Simple: https://cloudfront-us-east-1.images.arcpublishing.com/archet...

I thought humans spent thousands of years removing rock from dirt to create framland.

Are they trying to reverse that?

Certainly destroying the farmland and letting people starve would result in decreased carbon dioxide emissions.

It depends on the soil pH, where it's needed, crushed olivine is already used to increase crop yields (see e.g. https://modernfarmer.com/2023/09/enhanced-rock-weathering/ ) where it's close enough / cheap enough.

Bringing it everywhere where it could be useful, though, is unlikely to happen without subsidies to cover the transport costs, but the need for carbon capture might support that.

Wondering about pH and leaching mercury...

how about u just dont cut all the trees because of greed??

Not enough for what we need.

Even if we covered all the possible area we could with trees we couldn't capture enough CO₂. And that ignores the fact that climate change increases the chances of wildfires.

Whom decided we need to reach this rediculous Net Zero target?

Why not aim for minus 101 percent why we are at it

Minus is the long term goal. Net zero is purely a stepping stone on the journey there.

Just plant trees.

So ruin farmland with crushed rock? Why would you even study such things?

It can actually have benefits to the soil as a fertiliser - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10011191/

Anything bigger than a pebble is going to ruin harvesters and planters.

They’re using rock crushed to ~100 microns.

The person you're replying to posted a link which mentions in the "materials and methods" section that the particles in the study were all smaller than 2mm (and 99.6% smaller than 1mm).

To compare with your pebble, which wikipedia says is

> A pebble is a clast of rock with a particle size of 4-64 mm

If you open the article and click the only link in the first paragraph, leading to the source, it will tell you in the introduction

TL;DR scan for the digits in that quote. This stuff is measured in micrometers.

> Why would you even study such things?

Because if everyone were willing to read sources and get to understandings, we would probably not have climate problems in the first place

I doubt that. You yourself are just going along with this rediculous Net Zero target. Who decided on 0 why not minus 101 percent while we are at it

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