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Carbon sequestration tl;dr outline pt 1 #EarthDay 
1. CCU (the null case) – must be used properly
2. Pumping underground – the OG, seems sketchy, ask a geophysicist
3. Mineral carbonation – seems fine with small-scales and enriched CO2 air
1/17
1. CCU (the null case) – must be used properly
2. Pumping underground – the OG, seems sketchy, ask a geophysicist
3. Mineral carbonation – seems fine with small-scales and enriched CO2 air
1/17
Carbon sequestration tl;dr outline pt 2
4. Ocean alkalinization – logistics and kinetics don’t pay off
5. Iron fertilization – Fe speciation is complicated and biology is worse so no
6. Blue carbon – minimal impact on atmospheric CO2, but AMAZING for mitigation
2/17
4. Ocean alkalinization – logistics and kinetics don’t pay off
5. Iron fertilization – Fe speciation is complicated and biology is worse so no
6. Blue carbon – minimal impact on atmospheric CO2, but AMAZING for mitigation
2/17
1. CCU
Carbon capture and utilization (typically fuels or plastics). Has capacity to hold all the CO2 we’ve released, but its not carbon negative and plastic pollution is a problem. Books can be written on it, so that’s all I’m going to say on it. 3/17
Carbon capture and utilization (typically fuels or plastics). Has capacity to hold all the CO2 we’ve released, but its not carbon negative and plastic pollution is a problem. Books can be written on it, so that’s all I’m going to say on it. 3/17
2. Pumping CO2 underground
This fills sedimentary rock with CO2. It uses similar tech as fracking. You need an impermeable capstone to keep it from diffusing out of the rock. It seems like it varies on sequestration location and could cause seismic issues. Ask a geophysicist 4/17
This fills sedimentary rock with CO2. It uses similar tech as fracking. You need an impermeable capstone to keep it from diffusing out of the rock. It seems like it varies on sequestration location and could cause seismic issues. Ask a geophysicist 4/17
3. Mineral carbonation
Here we pump aqueous CO2 into reactive rock so the CO2 forms carbonate minerals. This traps the CO2 as an inert solid. Of the geologic storage mechanisms, this one actually has pilot projects that show progress, like CarbFix. 5/17
Here we pump aqueous CO2 into reactive rock so the CO2 forms carbonate minerals. This traps the CO2 as an inert solid. Of the geologic storage mechanisms, this one actually has pilot projects that show progress, like CarbFix. 5/17
4. Ocean alkalinization
This method also uses the CO2 + minerals -> carbonates rxn, but in this case there’s an excess of minerals and low CO2. So far, the ocean has taken up ~1/2 of anthropogenic CO2, hence ocean acidification. 7/17
This method also uses the CO2 + minerals -> carbonates rxn, but in this case there’s an excess of minerals and low CO2. So far, the ocean has taken up ~1/2 of anthropogenic CO2, hence ocean acidification. 7/17
Ocean alk. pt 2
Here, we dump reactive minerals (olivine) into the ocean so dissolved CO2 can precipitate, lowering it as well raising ocean pH and buffering the ocean. It’s also called enhanced weathering. 8/17
Here, we dump reactive minerals (olivine) into the ocean so dissolved CO2 can precipitate, lowering it as well raising ocean pH and buffering the ocean. It’s also called enhanced weathering. 8/17
Ocean alk. pt 3
Unfortunately, the issue here is the reaction rate. The reaction is already slow and its rate depends on the surface area. Grinding up rocks takes up a lot of energy and this isn’t feasible either on timescale or energy required. 9/17
Unfortunately, the issue here is the reaction rate. The reaction is already slow and its rate depends on the surface area. Grinding up rocks takes up a lot of energy and this isn’t feasible either on timescale or energy required. 9/17
5. Iron fertilization
Classic chemical oceanography here. Biologic growth in the ocean is limited by specific nutrients, like in soil where we add fertilizer. When that nutrient is added, phytoplankton fix carbon as they grow 10/17
Classic chemical oceanography here. Biologic growth in the ocean is limited by specific nutrients, like in soil where we add fertilizer. When that nutrient is added, phytoplankton fix carbon as they grow 10/17
Fe fert pt. 2
All (I think?) of life needs iron (Fe), but it doesn’t need a lot. In places that are Fe-limited, a little bit can encourage a LOT of growth called a bloom. In theory, this bloom sinks down to the bottom of the ocean 11/17
All (I think?) of life needs iron (Fe), but it doesn’t need a lot. In places that are Fe-limited, a little bit can encourage a LOT of growth called a bloom. In theory, this bloom sinks down to the bottom of the ocean 11/17
Fe fert pt. 3
Two main issues: 1. Fe chemistry – Fe reacts quickly to form Fe(III) oxides, which precipitate and sink out of the sunlit water. Microbes have gotten around this by excreting organic compounds that bind Fe, keeping it dissolved. 12/17
Two main issues: 1. Fe chemistry – Fe reacts quickly to form Fe(III) oxides, which precipitate and sink out of the sunlit water. Microbes have gotten around this by excreting organic compounds that bind Fe, keeping it dissolved. 12/17
Fe fert pt. 4
Microbes therefore have also evolved to uptake Fe-organic compounds. Dumping inorg Fe isn’t an efficient use of this process. Also, biology – these phytoplankton get eaten and their CO2 released. Or, they release dimethyl sulfide, also a GHG. 13/17
Microbes therefore have also evolved to uptake Fe-organic compounds. Dumping inorg Fe isn’t an efficient use of this process. Also, biology – these phytoplankton get eaten and their CO2 released. Or, they release dimethyl sulfide, also a GHG. 13/17
Fe fert pt. 5
The nail in the coffin here is how much of the biomass makes it to the ocean floor. It’s only a small fraction, and most of the carbon gets respired in subsurface waters, lowering the pH and releasing the CO2 when that water mass surfaces 14/17
The nail in the coffin here is how much of the biomass makes it to the ocean floor. It’s only a small fraction, and most of the carbon gets respired in subsurface waters, lowering the pH and releasing the CO2 when that water mass surfaces 14/17
6. Blue carbon
This category is the broadest, and it refers to restoring wetland/coastland ecosystems. Locally, this has a LOT of benefits, like air quality, water quality, ecosystem health, native species with more biodiversity and biomass… 15/17
This category is the broadest, and it refers to restoring wetland/coastland ecosystems. Locally, this has a LOT of benefits, like air quality, water quality, ecosystem health, native species with more biodiversity and biomass… 15/17
Blue carbon pt 2
… mitigation against sea level rise and wave damage, also cultural and native heritage. This is REALLY beneficial, particularly since so many coastal wetlands have been destroyed for development. I highly recommend. 16/17
… mitigation against sea level rise and wave damage, also cultural and native heritage. This is REALLY beneficial, particularly since so many coastal wetlands have been destroyed for development. I highly recommend. 16/17
Blue carbon pt 3
On a global scale, however, I don’t think that it will sequester enough CO2 to dent the amount that we’ve released. It could be one of our best defenses, though. This is another extensive topic, and I will end the thread there 17/17
On a global scale, however, I don’t think that it will sequester enough CO2 to dent the amount that we’ve released. It could be one of our best defenses, though. This is another extensive topic, and I will end the thread there 17/17
