We have a new paper out on how to use rocks to pull #CO2 out of the air and stabilize it as...rocks.
TL;DR: Surface rocks in Japan could remove 7.6 Gt-CO2/y at 1.5 GJ/t-CO2.
It's open access, so send it to your mother. I know I did.
A thread.
iopscience.iop.org/article/10.108…
TL;DR: Surface rocks in Japan could remove 7.6 Gt-CO2/y at 1.5 GJ/t-CO2.
It's open access, so send it to your mother. I know I did.
A thread.
iopscience.iop.org/article/10.108…
1/n
We started with a map of all the surface rocks in Japan (~158,000 entries) including the depth of the formations. We narrowed it down to rocks with high Mg or Ca content. We then removed all populated areas, protected ecosystems, etc. to make a map of potential sites.
We started with a map of all the surface rocks in Japan (~158,000 entries) including the depth of the formations. We narrowed it down to rocks with high Mg or Ca content. We then removed all populated areas, protected ecosystems, etc. to make a map of potential sites.
2/n
...this leads to a potential #CDR of 15,591 Gt-CO2...so more than we need for #2DS.
But, most of that rock is volcanic (amorphous).
Previously we found that amorphous compounds react >1,000X slower than equivalent crystalline compounds.
Shameless plug:
sciencedirect.com/science/articl…
...this leads to a potential #CDR of 15,591 Gt-CO2...so more than we need for #2DS.
But, most of that rock is volcanic (amorphous).
Previously we found that amorphous compounds react >1,000X slower than equivalent crystalline compounds.
Shameless plug:
sciencedirect.com/science/articl…
3/n
So we focused on crystalline rocks, which reduces the #carbonremoval to 1,525 Gt-CO2.
But still, this is just potential.
With what equipment would you realize this potential?
What are the CO2 emissions from mining? operating the system? removing vegetation and soil?
So we focused on crystalline rocks, which reduces the #carbonremoval to 1,525 Gt-CO2.
But still, this is just potential.
With what equipment would you realize this potential?
What are the CO2 emissions from mining? operating the system? removing vegetation and soil?
4/n
In any #DAC system you need to move a lot of air to get sufficient CO2.
The problem with using rocks is the reaction rate is slow.
So you need a system with large airflow & a high gas-solid surface area. To any engineer this spells pressure drop > large energy consumption.
In any #DAC system you need to move a lot of air to get sufficient CO2.
The problem with using rocks is the reaction rate is slow.
So you need a system with large airflow & a high gas-solid surface area. To any engineer this spells pressure drop > large energy consumption.
5/n
We get around this problem by thinly spreading finely ground rocks on trays in a tiered greenhouse.
If you're thinking, 'huh?', check out the picture. Thanks to @kellysmellfunny for bringing our vision to life!
We get around this problem by thinly spreading finely ground rocks on trays in a tiered greenhouse.
If you're thinking, 'huh?', check out the picture. Thanks to @kellysmellfunny for bringing our vision to life!
6/n
We designed the fans, tiers, degree of grinding, etc. using available technology (e.g., vertical roller mills and induced draft centrifugal fans) and standard engineering practice (e.g., Cordier diagrams, surface mining standards).
In short, this process is achievable today.
We designed the fans, tiers, degree of grinding, etc. using available technology (e.g., vertical roller mills and induced draft centrifugal fans) and standard engineering practice (e.g., Cordier diagrams, surface mining standards).
In short, this process is achievable today.
7/n
We calculated the CO2 mineralization extent based on mineral-specific empirical data at ambient conditions. For most minerals, even when ground to several micrometers, the mineralization reaction is only 40-70% complete after 1 year.
We calculated the CO2 mineralization extent based on mineral-specific empirical data at ambient conditions. For most minerals, even when ground to several micrometers, the mineralization reaction is only 40-70% complete after 1 year.
8/n
CO2 emissions from vegetation loss and soil removal were small compared to to CO2 mineralization. But, it will always be better to apply such disruptive processes to land that has already been degraded through other human activity.
CO2 emissions from vegetation loss and soil removal were small compared to to CO2 mineralization. But, it will always be better to apply such disruptive processes to land that has already been degraded through other human activity.
9/n
CO2 emissions from the materials production for the greenhouse, grinders, fans, etc. was similarly small, even when including the short lifetime of mining equipment.
Note that we assumed battery-powered mining equipment which is already being offered by major manufacturers.
CO2 emissions from the materials production for the greenhouse, grinders, fans, etc. was similarly small, even when including the short lifetime of mining equipment.
Note that we assumed battery-powered mining equipment which is already being offered by major manufacturers.
10/n
CO2 from operations was based on the emissions from the production of solar PV and lithium ion batteries used to power the system.
Side note, there is enough space on the rooftop of the greenhouse to power the full system with solar PV.
CO2 from operations was based on the emissions from the production of solar PV and lithium ion batteries used to power the system.
Side note, there is enough space on the rooftop of the greenhouse to power the full system with solar PV.
11/n
Based on the design, ~2m of rock depth could be mined and put in the greenhouse per year.
This & the net CO2 calc leads to the rule of thumb:
~1 km2 --> ~1 Mt-CO2/y of CO2 removal.
Also, most formations are >250 m deep, so you have a facility that can operate >100 years.
Based on the design, ~2m of rock depth could be mined and put in the greenhouse per year.
This & the net CO2 calc leads to the rule of thumb:
~1 km2 --> ~1 Mt-CO2/y of CO2 removal.
Also, most formations are >250 m deep, so you have a facility that can operate >100 years.
12/n
Across Japan, there is 7.6 Gt-CO2/y of negative emissions capacity using existing technology from the #Mining sector.
BTW, Japan has a long history of digging up gigatonnes of rock...they use it for land reclamation, which is one idea for what to do with mineralized CO2.
Across Japan, there is 7.6 Gt-CO2/y of negative emissions capacity using existing technology from the #Mining sector.
BTW, Japan has a long history of digging up gigatonnes of rock...they use it for land reclamation, which is one idea for what to do with mineralized CO2.
13/n
So, if you're a country with a #NetZero target and you want a low-tech #CDR method that brings a lot of jobs, and has a smaller footprint than #BECCS, I'd look into direct air mineralization. I mean, it's grinding rocks... literally the oldest technology.
So, if you're a country with a #NetZero target and you want a low-tech #CDR method that brings a lot of jobs, and has a smaller footprint than #BECCS, I'd look into direct air mineralization. I mean, it's grinding rocks... literally the oldest technology.
n/n
shameless spamming of parties interested(?) in gigatonne-scale NETs using rocks and existing technology.
@stripe, @RogerAines, @jwilceclab, @TDixonGHG, @Peters_Glen, @GreenOlivine, @ianmalcolmpower, @arejaygraham, @PeterBrannen1, @Dypingite
shameless spamming of parties interested(?) in gigatonne-scale NETs using rocks and existing technology.
@stripe, @RogerAines, @jwilceclab, @TDixonGHG, @Peters_Glen, @GreenOlivine, @ianmalcolmpower, @arejaygraham, @PeterBrannen1, @Dypingite
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