"Planting" Rocks In Farms, Along With Emissions Reductions, Could Help Meet Key IPCC Carbon Removal

[OKIsItJustMe]

“Planting” Rocks In Farms, Along With Emissions Reductions, Could Help Meet Key IPCC Carbon Removal Goal

Adding Crushed Volcanic Rocks To Agricultural Fields Can Both Improve The Soil And Suck Down Carbon Dioxide. Doing So In The Hot, Humid Tropics Would Be Most Efficient, A New Study Finds

14 August 2023

Key points:

• Enhanced rock weathering makes use of a natural geologic process to store carbon long term
• Applying 10 tons of basalt dust per hectare of crop land globally could sequester up to 217 gigatons of carbon dioxide in 75 years, above the IPCC’s lower threshold of carbon dioxide removal needed to reach climate goals, along with emissions reductions
• Farms in the tropics have the biggest and fastest return on investment

WASHINGTON — Farmers around the world could help the planet reach a key carbon removal goal set by the Intergovernmental Panel on Climate Change (IPCC) by mixing crushed volcanic rocks into their fields, a new study reports. The study also highlights wet, warm tropics as the most promising locations for this climate intervention strategy.

The study provides one of the first global estimates of the potential carbon dioxide drawdown from basalt application on agricultural fields worldwide. It was published in Earth’s Future, AGU’s journal for interdisciplinary research on the past, present and future of our planet and its inhabitants.

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E360 DIGEST
AUGUST 15, 2023
Spreading Rock Dust on Farmland Has Potential to Draw Down Huge Sums of Carbon Dioxide

Adding volcanic rock dust to cropland could help the world reach a key carbon removal goal, a new study finds.

Rain absorbs carbon dioxide from the air as it falls, and it reacts with rocks on the ground to lock away that carbon. To speed this process, scientists have proposed spreading crushed volcanic rock on farmland. The new study is among the first to model the effect of this strategy, called enhanced rock weathering, at scale.

A simulation of more than 900 croplands spanning an area nearly the size of Australia suggests that enhanced rock weathering could scrub some 64 billion tons of carbon dioxide from the atmosphere by the end of this century.

The world currently produces around 37 billion tons of carbon dioxide yearly. To keep warming to 1.5 degrees C, the stated goal of the Paris Agreement, countries must not only slash emissions, but also remove at least 100 billion tons of carbon dioxide from the atmosphere.

Spreading rock dust across all of world’s croplands for the rest of this century, the study suggests, would draw down 215 billion tons of carbon dioxide. The findings were published in the journal Earth’s Future.

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[orthoclad]

1. "Passive" drawdown methods appeal to me

It would take large amounts of energy to separate, concentrate, and pipe CO2 by industrial processes - not to mention finding a good stable place to put it. We have little or no experience yet with underground storage. It could escape, or cause chemical reactions with deep rock. Has anybody studied the reaction of deep CO2 storage with fault lines? Will it increase earthquake risk, like the injection of fracking fluid does?

What I call "passive" methods like geochemical weathering and photosynthesis are the planet's own processes to moderate CO2. It would take considerable energy to mill and transport the basalt, but once it place it would use natural chemical reactions to draw down the carbon. Will it form stable minerals when reacting with basalt?

There could be energy savings if we could mill the basalt and leave it in place where it outcrops if our only goal is to draw down carbon. Using it as fertilizer would increase crop yield. We should model equations for in-place and distributed weathering to get the best return on energy expenditure.

[OKIsItJustMe]

2. "Finding a good stable place to put it" appears not to be the challenge some feared

If you put it in the right place for just a couple of years, it turns to stone!

https://www.carbfix.com/scientific-papers

[orthoclad]

4. Hmm.

"Carbon dioxide storage through mineral carbonation"
https://www.nature.com/articles/s43017-019-0011-8
from your link.

"Most ongoing CCS projects inject CO2 into sedimentary basins and require an impermeable cap rock to prevent the CO2 from migrating to the surface. Alternatively, captured carbon can be stored through injection into reactive rocks (such as mafic or ultramafic lithologies), provoking CO2 mineralization and, thereby, permanently fixing carbon with negligible risk of return to the atmosphere. Although in situ mineralization offers a large potential volume for carbon storage in formations such as basalts and peridotites (both onshore and offshore), its large-scale implementation remains little explored beyond laboratory-based and field-based experiments. "

Mafic and ultramafic rocks tend to be very deep. Large-scale geochemical reactions from injecting gigatons of carbonic acid (CO2 + water) into deep rock are untested; I speculate that this could alter seismic behavior near fault lines and subduction zones. For instance, if the altered rock is more brittle than the native rock, fault lines could release and cause earthquakes. There will be no take-backs of mistakes, as with most geoengineering projects. But we'll likely use the promise of geoengineering as a reason to delay giving up emissions.

There is much quicker feedback from surface application of crushed basalt.

[OKIsItJustMe]

6. Yes, I saw the paper

Just like “reinjection” of “fracking water,” pumping pressurized carbonated water underground “near fault lines and subduction zones” might be expected to produce seismic activity.

Care should be taken in selecting injection sites:

MIT News: A new approach to preventing human-induced earthquakes

Applied in the field, a new model reduced quakes from oil and gas processes; could help manage seismic events from carbon sequestration.

Jennifer Chu | MIT News Office
Publication Date: July 28, 2021

When humans pump large volumes of fluid into the ground, they can set off potentially damaging earthquakes, depending on the underlying geology. This has been the case in certain oil- and gas-producing regions, where wastewater, often mixed with oil, is disposed of by injecting it back into the ground — a process that has triggered sizable seismic events in recent years.

Now MIT researchers, working with an interdisciplinary team of scientists from industry and academia, have developed a method to manage such human-induced seismicity, and have demonstrated that the technique successfully reduced the number of earthquakes occurring in an active oil field.

Their results, appearing today in Nature, could help mitigate earthquakes caused by the oil and gas industry, not just from the injection of wastewater produced with oil, but also that produced from hydraulic fracturing, or “fracking.” The team’s approach could also help prevent quakes from other human activities, such as the filling of water reservoirs and aquifers, and the sequestration of carbon dioxide in deep geologic formations.

“Triggered seismicity is a problem that goes way beyond producing oil,” says study lead author Bradford Hager, the Cecil and Ida Green Professor of Earth Sciences in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “This is a huge problem for society that will have to be confronted if we are to safely inject carbon dioxide into the subsurface. We demonstrated the kind of study that will be necessary for doing this.”

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[orthoclad]

7. Keep this in mind:

who's going to do the work of selecting sites and pumping the stuff underground? Exxon?

If we leave it up to "the market", they'll take every shortcut possible and cheat constantly, in order to maximize that quarterly profit report.

[OKIsItJustMe]

8. Then I guess we shouldn't leave it to them.

The key here (to my mind) is that unlike the visions of some vast cavern holding pressurized CO₂ for an indefinite period of time, it needs to be held in porous rock for a couple of years.

A “leak” would not be catastrophic.

[orthoclad]

9. We need centuries, not years.

Dr. Susan Solomon, of ozone hole fame, published a peer-reviewed paper estimating that if we stopped all CO2 emissions immediately, it would take 1,000 years for the concentration to fall to pre-capitalism levels. And she said that when the concentration was still below 400 ppm, iirc. We're looking at geologic, not biologic, time-scales, to make industrial carbon capture worthwhile.

A leak of captured carbon would be exactly as catastrophic as the emission of that carbon, with the added energy cost of capturing, compressing, and pumping the carbon.

No, we can't leave it up to industry to run the cleanup. They'll just get rich fucking it up. Since they're socializing the cost of cleanup, then society should be the boss. We'll have to have a team of geo-scientists who don't kowtow to corporations select deep, non-permeable deposits of mafic and ultramafic rock.

I think we'll get a faster and cheaper bang for the buck with milling basalt on the surface, while we plan the best way to bury carbon for centuries or millenia.

[OKIsItJustMe]

10. I believe you misunderstand me

If you capture the CO₂ and pump it into the right sort of stone, it will itself turn into stone in about 2 years. At that point, there is no danger of it leaking. In the meantime, if a leak did occur, it would not be the entire accumulation of gas.

This would not be one facility, but, instead, would need to be hundreds (or thousands.)
https://www.democraticunderground.com/?com=view_post&forum=1127&pid=166358

The science seems sound enough, I am skeptical about scaling and energy use…

Science: Rapid carbon mineralization for permanent disposal of anthropogenic carbon dioxide emissions

Atmospheric CO₂ can be sequestered by injecting it into basaltic rocks, providing a potentially valuable way to undo some of the damage done by fossil fuel burning. Matter et al. injected CO₂ into wells in Iceland that pass through basaltic lavas and hyaloclastites at depths between 400 and 800 m. Most of the injected CO₂ was mineralized in less than 2 years. Carbonate minerals are stable, so this approach should avoid the risk of carbon leakage.

[orthoclad]

11. Gotcha.

Still, from what the paper from your link that I cited said, they should avoid permeable layers of sedimentary rock and go with deep stable formations of carbon-reactive crystalline rock.

Some corps were talking about filling depleted oil and gas wells, tho I'd have to do some hunting for the references. That way they could turn over abandoned unsuitable wells without the cost of capping. We'd have to be alert for schemes like that.

[OKIsItJustMe]

12. Yeah, right, I don't support the "pump it into old oilfields" schemes

Worse yet, the ones which add, “and we can use it to pump more oil to the wellhead!”

[orthoclad]

13. Fracking with CO2

what could go wrong (grin)

[Hestia]

3. Isn't basalt the secret ingredient in Roman Concrete?

There is something special about the volcanic rocks that were added to ancient Roman building materials. It's why, even after earthquakes and pillaging that ancient structures are still standing - look at the aqueducts, which after being cleaned up, could still be used today - so well built and accurate on the slope degree for movement of water. The only reason the Colosseum looks the way it does is because it has been rattled with some major EQ's in the past.

[OKIsItJustMe]

5. There appears to be more to it than "secret ingredients"

MIT News: Riddle solved: Why was Roman concrete so durable?

An unexpected ancient manufacturing strategy may hold the key to designing concrete that lasts for millennia.
David L. Chandler | MIT News Office
Publication Date: January 6, 2023

The ancient Romans were masters of engineering, constructing vast networks of roads, aqueducts, ports, and massive buildings, whose remains have survived for two millennia. Many of these structures were built with concrete: Rome’s famed Pantheon, which has the world’s largest unreinforced concrete dome and was dedicated in 128 C.E., is still intact, and some ancient Roman aqueducts still deliver water to Rome today. Meanwhile, many modern concrete structures have crumbled after a few decades.

Researchers have spent decades trying to figure out the secret of this ultradurable ancient construction material, particularly in structures that endured especially harsh conditions, such as docks, sewers, and seawalls, or those constructed in seismically active locations.

Now, a team of investigators from MIT, Harvard University, and laboratories in Italy and Switzerland, has made progress in this field, discovering ancient concrete-manufacturing strategies that incorporated several key self-healing functionalities. The findings are published today in the journal Science Advances, in a paper by MIT professor of civil and environmental engineering Admir Masic, former doctoral student Linda Seymour ’14, PhD ’21, and four others.

For many years, researchers have assumed that the key to the ancient concrete’s durability was based on one ingredient: pozzolanic material such as volcanic ash from the area of Pozzuoli, on the Bay of Naples. This specific kind of ash was even shipped all across the vast Roman empire to be used in construction, and was described as a key ingredient for concrete in accounts by architects and historians at the time.

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