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(disclaimer: I work in a Climate&Energy research group) Ignoring the perverse incentive problem... ... enhanced weathering only works under certain conditions

(disclaimer: I work in a Climate&Energy research group) Ignoring the perverse incentive problem... ... enhanced weathering only works under certain conditions. Randomly spreading some olivine around at a specific GPS location does not effectively sequester CO2 on a useful timescale, for example. Olivine also needs water, and the reaction is very slow, so almost all olivine proposals end up dumping the material in the shallow ocean (or grinding it small enough, say <2um, so that it stays in the mix layer before it fully reacts with CO2). Grinding energy is not linear, so a bunch of 100um rock (easy to produce) requires a lot less energy than a bunch of 2um rock. Vespa gets around this (they claim) by sticking the rock in the wave/tidal zone to break it apart naturally, and keep it from sinking out of the mix layer. There are also issues with this from a biological standpoint (e.g. olivine contains some amount of nickel and cadmium), so doing this a gigaton scale would require a lot of research before incentivizing it. TLDR, there are things one could do on land that might work, but not what is proposed. === Long story short, I can't see a carbon coin being super successful if it is overly prescriptive on the method of CO2 capture, unless it gets very very lucky and happens to pick the right one. Since the proposal already requires an auditing methodology (which is basically all the proposal really is, if I am reading it right), it may as well drop the exact technology being audited. At that point, it mimics a normal carbon market, but with printed money, so not clear how it's going to get traction over a fiat currency.

endisneigh 5y ago
> TLDR, there are things one could do on land that might work, but not what is proposed. I'm curious what these might be.
asdfasgasdgasdg 5y ago
> so not clear how it's going to get traction over a fiat currency. Everything else in your post was great, but there's certainly a precedent for even obviously unworkable ideas attracting much investment in the crypto space. Having something that could be beneficial is already way better than many crypto launches.
- chris_va 5y ago
  It was not meant as critical, just that it's unclear to me. Unlike mining traditional crypto currencies, a carbon coin would require a large amount of capital equipment up front before mining. Bootstrapping without fiat capital would be an extra wrinkle.
RayVR 5y ago
I’m curious, what is currently the most promising carbon capture methodology that’s actually scalable? Already in use or ready to use, so we can exclude research projects with no path to mega-scale
- chris_va 5y ago
  There are only a few that are truly scalable and plausible. A lot of investment today is going into the low hanging fruit (afforestation, methane capture, etc). These are cheap (<$15/ton), but they cap out at a couple of Gt-CO2/yr equivalent. BECCS isn't really scalable past a certain point, either, which leaves direct air capture and enhanced weathering. Enhanced weathering is basically moving around alkalinity, which the CO2+water (carbonates) will neutralize. There are other ways of doing this besides dumping olivine rock into the sea (which gives you a very large surface area to absorb co2), though dumping rock is very inexpensive (probably less than $20/ton, modulo grind size and bio toxicity issues). If humans disappeared today, the CO2 would revert back to pre-industrial levels predominantly through the ocean. The ocean is a large sponge for CO2, and it will stay in equilibrium with the atmosphere. As it turns over (~5000 years), it brings the extra CO2 down to depth, where it reacts with sediment. Extra CO2 will initially raise the carbonate compensation depth, reacting slopes of marine snow with the extra CO2 (kind of like snow melting) fairly quickly (on a geologic timescale). If/when that is exhausted, the ocean floor (which in places is covered with basalt and other material that will neutralize CO2) will (very very) slowly eat the rest of the CO2. As the carbonates drop in the ocean, the ocean will start to absorb more CO2 from the atmosphere. The ppm will drop slowly, until it hits the biosphere equilibrium (marine cycle, etc) of ~280ppm. One scalable way (personal disclaimer, one of my research areas) to do carbon capture is to just speed up this process. There is no reason CO2 has to react with basalt, it can just as easily react with NaOH or some other source of alkalinity, which can be minutes instead of millennia. In fact, some direct air capture proposals (long ago) were just waterfalls of fine droplets with NaOH embedded as a sorbent. So, long story short, if you can create alkalinity, you can easily turn that into sequestered CO2. Literally throwing an antacid tablet into the ocean sequesters CO2. Depending on the method of creation (e.g. chloralkali process), you may also have to dispose of an equal amount of acid, but that can be injected underground (e.g. poured out onto a bunch of olivine). Doing it all on land is a little trickier, as the ocean has some nice surface area and mixing ... but a large pond with a vertical firehose of high PH solution may be effective, though it starts to bleed over into the definition of DAC at some point and eats more power.

endisneigh 5y ago

> TLDR, there are things one could do on land that might work, but not what is proposed. I'm curious what these might be.

asdfasgasdgasdg 5y ago

> so not clear how it's going to get traction over a fiat currency. Everything else in your post was great, but there's certainly a precedent for even obviously unworkable ideas attracting much investment in the crypto space. Having something that could be beneficial is already way better than many crypto launches.

chris_va 5y ago
It was not meant as critical, just that it's unclear to me. Unlike mining traditional crypto currencies, a carbon coin would require a large amount of capital equipment up front before mining. Bootstrapping without fiat capital would be an extra wrinkle.

RayVR 5y ago

I’m curious, what is currently the most promising carbon capture methodology that’s actually scalable? Already in use or ready to use, so we can exclude research projects with no path to mega-scale

chris_va 5y ago
There are only a few that are truly scalable and plausible. A lot of investment today is going into the low hanging fruit (afforestation, methane capture, etc). These are cheap (<$15/ton), but they cap out at a couple of Gt-CO2/yr equivalent. BECCS isn't really scalable past a certain point, either, which leaves direct air capture and enhanced weathering. Enhanced weathering is basically moving around alkalinity, which the CO2+water (carbonates) will neutralize. There are other ways of doing this besides dumping olivine rock into the sea (which gives you a very large surface area to absorb co2), though dumping rock is very inexpensive (probably less than $20/ton, modulo grind size and bio toxicity issues). If humans disappeared today, the CO2 would revert back to pre-industrial levels predominantly through the ocean. The ocean is a large sponge for CO2, and it will stay in equilibrium with the atmosphere. As it turns over (~5000 years), it brings the extra CO2 down to depth, where it reacts with sediment. Extra CO2 will initially raise the carbonate compensation depth, reacting slopes of marine snow with the extra CO2 (kind of like snow melting) fairly quickly (on a geologic timescale). If/when that is exhausted, the ocean floor (which in places is covered with basalt and other material that will neutralize CO2) will (very very) slowly eat the rest of the CO2. As the carbonates drop in the ocean, the ocean will start to absorb more CO2 from the atmosphere. The ppm will drop slowly, until it hits the biosphere equilibrium (marine cycle, etc) of ~280ppm. One scalable way (personal disclaimer, one of my research areas) to do carbon capture is to just speed up this process. There is no reason CO2 has to react with basalt, it can just as easily react with NaOH or some other source of alkalinity, which can be minutes instead of millennia. In fact, some direct air capture proposals (long ago) were just waterfalls of fine droplets with NaOH embedded as a sorbent. So, long story short, if you can create alkalinity, you can easily turn that into sequestered CO2. Literally throwing an antacid tablet into the ocean sequesters CO2. Depending on the method of creation (e.g. chloralkali process), you may also have to dispose of an equal amount of acid, but that can be injected underground (e.g. poured out onto a bunch of olivine). Doing it all on land is a little trickier, as the ocean has some nice surface area and mixing ... but a large pond with a vertical firehose of high PH solution may be effective, though it starts to bleed over into the definition of DAC at some point and eats more power.