Adding crushed rock to farmland pulls carbon out of the air

https://www.ucdavis.edu/climate/news/adding-crushed-rock-farmland-pulls-carbon-out-air

by geox • 3 years ago

272 275 3 years ago

vosper• 3 years ago

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.

jeffbee• 3 years ago

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

philipkglass6• 3 years ago

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...

hedora3• 3 years ago

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.

freeone30002• 3 years ago

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.

dgacmu• 3 years ago

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)

londons_explore3• 3 years ago

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.

jhardcastle• 3 years ago

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...

jacobgorm2• 3 years ago

The metric system is really handy for calculations like these.

deathanatos• 3 years ago

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.

hn_throwaway_99• 3 years ago

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.

DennisP• 3 years ago

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.

brianbreslin2• 3 years ago

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?

aziaziazi• 3 years ago

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

throwawayoaky• 3 years ago

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

Belopolye• 3 years ago

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?

the_sleaze92• 3 years ago

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.

vonwolfhausen6• 3 years ago

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

svara• 3 years ago

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.

ClumsyPilot4• 3 years ago

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

chris_va• 3 years ago

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).

vonwolfhausen6• 3 years ago

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.

kisamoto8• 3 years ago

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).

stronglikedan2• 3 years ago

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

matznerd6• 3 years ago

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

jeron• 3 years ago

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

Sparkyte• 3 years ago

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

UncleOxidant• 3 years ago

It should help replenish certain minerals in the soil.

tastyfreeze• 3 years ago

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.

brianbreslin2• 3 years ago

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

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

marcosdumay2• 3 years ago

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

thsksbd• 3 years ago

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

mcpackieh4• 3 years ago

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.

jlhawn• 3 years ago

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)?

reaperman• 3 years ago

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

philipkglass6• 3 years ago

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.

spankalee• 3 years ago

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?

bluGill3• 3 years ago

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.

delecti• 3 years ago

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.

PeterisP4• 3 years ago

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.

epistasis• 3 years ago

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.

mjan22640• 3 years ago

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

api• 3 years ago

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

marcosdumay2• 3 years ago

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.

vonwolfhausen6• 3 years ago

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.

chinchilla20208• 3 years ago

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.

klysm2• 3 years ago

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.

fudged71• 3 years ago

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

scythe• 3 years ago

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.

ilyt2• 3 years ago

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

BurningFrog2• 3 years ago

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.

stronglikedan2• 3 years ago

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

schiffern3• 3 years ago

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/

silentsanctuary2• 3 years ago

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.

NoMoreNicksLeft2• 3 years ago

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?

matznerd6• 3 years ago

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...

BenFranklin100• 3 years ago

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.

oldbbsnickname10• 3 years ago

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.

forgetfreeman2• 3 years ago

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.

onetimeuse92304• 3 years ago

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.

mhandley• 3 years ago

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.

matznerd6• 3 years ago

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/

supergeek• 3 years ago

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.

ben_w• 3 years ago

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

kisamoto8• 3 years ago

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.

oldbbsnickname10• 3 years ago

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...

TaylorAlexander• 3 years ago

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??

awb• 3 years ago

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.

jamescrowley2• 3 years ago

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.

rmason• 3 years ago

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.

matznerd6• 3 years ago

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...

ruiisnwn3• 3 years ago

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

oldbbsnickname10• 3 years ago

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

globular-toast• 3 years ago

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

mnky9800n• 3 years ago

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.

denton-scratch2• 3 years ago

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?

vonwolfhausen6• 3 years ago

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

kisamoto8• 3 years ago

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)?

denton-scratch2• 3 years ago

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.

danieloj• 3 years ago

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

willtemperley• 3 years ago

This has been known for a while:

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

londons_explore3• 3 years ago

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.

kisamoto8• 3 years ago

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.

londons_explore3• 3 years ago

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

the_sleaze92• 3 years ago

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?

anonymous344• 3 years ago

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

kisamoto8• 3 years ago

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.

ruiisnwn3• 3 years ago

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

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

avodonosov2• 3 years ago

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

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

vonwolfhausen6• 3 years ago

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

avodonosov2• 3 years ago

The article also mentions metabasalt

pfdietz4• 3 years ago

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.

RecycledEle• 3 years ago

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.

PeterisP4• 3 years ago

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.

robomartin5• 3 years ago

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.

djtriptych3• 3 years ago

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.

robomartin5• 3 years ago

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.

twic• 3 years ago

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

1. Rocks

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

JoshTko2• 3 years ago

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.

ericjmorey• 3 years ago

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

Willish422• 3 years ago

#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?

totetsu• 3 years ago

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

JoshTko2• 3 years ago

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.

jacobgorm2• 3 years ago

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

huytersd2• 3 years ago

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

jamescrowley2• 3 years ago

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

huytersd2• 3 years ago

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

lucb1e3• 3 years ago

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

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 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

ruiisnwn3• 3 years ago

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

CrzyLngPwd• 3 years ago

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?

AndreSobolewski3• 3 years ago

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

earth2jason• 3 years ago

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

AndreSobolewski3• 3 years ago

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.

unlikelymordant2• 3 years ago

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.

pfdietz4• 3 years ago

My concern would be nickel pollution.

luxuryballs• 3 years ago

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…

m0llusk• 3 years ago

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.

natch2• 3 years ago

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?

matznerd6• 3 years ago

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...

natch2• 3 years ago

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.

garrickvanburen• 3 years ago

How do we get it distributed across suburban backyards?

orthecreedence• 3 years ago

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

pfdietz4• 3 years ago

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

fuzztester• 3 years ago

Gabe Brown: treating the farm as an ecosystem

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

fsckboy2• 3 years ago

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?

lucb1e3• 3 years ago

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

fsckboy2• 3 years ago

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)

coding123• 3 years ago

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.

slowhand09• 3 years ago

"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?

trhway• 3 years ago

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.

hownottowrite• 3 years ago

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

vonwolfhausen6• 3 years ago

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.

SteveGreaseBoss• 3 years ago

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.

oldbbsnickname10• 3 years ago

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.

m3kw9• 3 years ago

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

8bitsrule• 3 years ago

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.

MrDresden• 3 years ago

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.

AndreSobolewski3• 3 years ago

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."

spandextwins• 3 years ago

Just plant trees.

gomijacogeo• 3 years ago

Wondering about pH and leaching mercury...

3seashells• 3 years ago

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.

Adding crushed rock to farmland pulls carbon out of the air

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