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.
"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...
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/...
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
Why do there have to be CO2 emissions?
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.
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...
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.
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.
It’s a bit dark, but wouldn’t a death toll improve the situation from an emissions perspective?
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
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.
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...
Haha. I'm glad you didn't include "solar" or "freakin'". ;D
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.
So, in theory, if you use green energy to produce a carbon-offset product, it's still a useful product.
Let's not pretend mining bauxite ore is 100% renewable.
Anything you can’t shove into the grid grinds rock.
Most of the world is doing just that.
It's much, much easier said than done.
Therefore, the hard part is changing the structure of society so that people's lives don't suck.
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.
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.
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%?
Even if he was your examples are disingenuous. Musk and Bezos aren’t representative of even the richest 1% of Americans.
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.
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.
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.
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.
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.
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.
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.)
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.
Maybe the solutions we have on how to cut on emissions is canned.
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.
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.
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.
Why does this sound like a suicide cult?
Capitalism by itself won't allow us to change course.
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?
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.
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 that person is doing now. (But I'm pretty sure you knew that.)
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.
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.
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.
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.
They are really pushing the stereotype that software engineers think they are smarter at physical sciences but are actually pretty clueless.
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.
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.
It may very well make sense under those conditions.
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.
/s
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.
Instead they're interested in blocking out the sun t̶o̶ ̶m̶a̶k̶e̶ ̶f̶a̶r̶m̶i̶n̶g̶ ̶i̶n̶ ̶p̶r̶i̶v̶a̶t̶e̶ ̶g̶a̶r̶d̶e̶n̶s̶ ̶i̶m̶p̶o̶s̶s̶i̶b̶l̶e̶ limit solar heating.
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