3 ms·

None of this explains how using 10% of total human energy production (at a bare minimum, using technology that doesn't exist) isn't a "BFD", or how in the world

by Mizza 4y ago

None of this explains how using 10% of total human energy production (at a bare minimum, using technology that doesn't exist) isn't a "BFD", or how in the world lime burning - a process that emits CO2 - is in any way a solution. I have absolutely "read the research", spent months in training and worked in the industry, which is why I found your claim that you've solved it and that it's not a big deal to be so ridiculous.

kragen 4y ago
direct air capture normally requires cycling a sorbent, as you would know if you had worked in the industry as anything other than a janitor. you heat it up, it emits CO2 (hopefully into your underground caverns or wherever the fuck you're sequestering the stuff), you cool it back down, and it starts absorbing CO2 (for example, from the atmosphere). that's the same way scrubber systems like diethanolamine, triethanolamine, and zeolites work. calcium carbonate/calcium oxide/calcium hydroxide is one such cycle, just a particularly energy-hungry and slow one. conceivably there might be other approaches that don't rely on thermal cycling (pressure cycling, some kind of electrochemical thing) but afaik nobody has demonstrated one. they won't repeal the fundamental entropic limit anyway so they'll only be marginally better than existing thermal-cycling systems, we can't expect an order of magnitude improvement using 70 percent as much, or even several times more, energy than the humans currently produce is not a bfd because the amount of solar energy reaching earth is five orders of magnitude greater than current world marketed energy consumption. historically that was irrelevant because burning coal was cheaper than solar panels. now solar panels are cheaper and it's just a matter of scaling up production, which will happen unless people somehow run out of economically profitable ways to use energy. see my notes from 2008 at https://dercuano.github.io/notes/solar-economics.html https://dercuano.github.io/notes/solar-economics.html for details i note a total absence of any quantitative arguments in your comments thus far; instead they rely on handwaving and gee-whiz pop science claims of incredibleness and authority
- Mizza 4y ago
  You edited your comment after I posted, but it doesn't matter, you haven't talked about the topic at hand: atmospheric CO2, a pollutant that makes up 0.04% of the air. All of your calculations assume an infinite stream of pure CO2 - which is why sorbent based DAC work great for flue gas. Making that work with atmospheric CO2 requires tremendous pretreatment, which is hard and expensive and not something that can be handwaved away. It is the fundamental problem.
  - kragen 4y ago
    no, that is not correct; all of the calculations i have made and cited assume 400 ppm atmospheric air, not pure co2. it wouldn't even be coherent to talk about a theoretical thermodynamic minimum energy requirement to capture co2 from pure co2, which is the '10% of total human energy production' you're talking about upthread rather than handwaving it away i linked to the calculation of what that theoretical minimum is, provided my own calculation of a trivially feasible and scalable approach that takes less than seven times as much energy as that, and mentioned climeworks, which is one of several companies doing direct air capture today for less energy than that (but obviously more than the theoretical minimum)
    - Mizza 4y ago
      I don't see where you're solving this problem. How do you move the air? How do you remove the water? How do you concentrate the CO2?
      - kragen 4y ago
        if you don't know anything about how atmospheric CO2 scrubbers work i suggest reading https://en.wikipedia.org/wiki/Direct_air_capture https://en.wikipedia.org/wiki/Direct_air_capture and some of its 45 references the top of the article has a flow diagram of a lye-catalyzed version of the lime process i was describing, a chemistry that has been used in submarines, anesthesia, and scuba diving for about a century https://en.wikipedia.org/wiki/Carbon_dioxide_scrubber https://en.wikipedia.org/wiki/Carbon_dioxide_scrubber has a nice overview of the different process chemistries commonly used

by Mizza 4y ago

kragen 4y ago

direct air capture normally requires cycling a sorbent, as you would know if you had worked in the industry as anything other than a janitor. you heat it up, it emits CO2 (hopefully into your underground caverns or wherever the fuck you're sequestering the stuff), you cool it back down, and it starts absorbing CO2 (for example, from the atmosphere). that's the same way scrubber systems like diethanolamine, triethanolamine, and zeolites work. calcium carbonate/calcium oxide/calcium hydroxide is one such cycle, just a particularly energy-hungry and slow one. conceivably there might be other approaches that don't rely on thermal cycling (pressure cycling, some kind of electrochemical thing) but afaik nobody has demonstrated one. they won't repeal the fundamental entropic limit anyway so they'll only be marginally better than existing thermal-cycling systems, we can't expect an order of magnitude improvement using 70 percent as much, or even several times more, energy than the humans currently produce is not a bfd because the amount of solar energy reaching earth is five orders of magnitude greater than current world marketed energy consumption. historically that was irrelevant because burning coal was cheaper than solar panels. now solar panels are cheaper and it's just a matter of scaling up production, which will happen unless people somehow run out of economically profitable ways to use energy. see my notes from 2008 at https://dercuano.github.io/notes/solar-economics.html https://dercuano.github.io/notes/solar-economics.html for details i note a total absence of any quantitative arguments in your comments thus far; instead they rely on handwaving and gee-whiz pop science claims of incredibleness and authority

Mizza 4y ago
You edited your comment after I posted, but it doesn't matter, you haven't talked about the topic at hand: atmospheric CO2, a pollutant that makes up 0.04% of the air. All of your calculations assume an infinite stream of pure CO2 - which is why sorbent based DAC work great for flue gas. Making that work with atmospheric CO2 requires tremendous pretreatment, which is hard and expensive and not something that can be handwaved away. It is the fundamental problem.
- kragen 4y ago
  no, that is not correct; all of the calculations i have made and cited assume 400 ppm atmospheric air, not pure co2. it wouldn't even be coherent to talk about a theoretical thermodynamic minimum energy requirement to capture co2 from pure co2, which is the '10% of total human energy production' you're talking about upthread rather than handwaving it away i linked to the calculation of what that theoretical minimum is, provided my own calculation of a trivially feasible and scalable approach that takes less than seven times as much energy as that, and mentioned climeworks, which is one of several companies doing direct air capture today for less energy than that (but obviously more than the theoretical minimum)
  - Mizza 4y ago
    I don't see where you're solving this problem. How do you move the air? How do you remove the water? How do you concentrate the CO2?
    - kragen 4y ago
      if you don't know anything about how atmospheric CO2 scrubbers work i suggest reading https://en.wikipedia.org/wiki/Direct_air_capture https://en.wikipedia.org/wiki/Direct_air_capture and some of its 45 references the top of the article has a flow diagram of a lye-catalyzed version of the lime process i was describing, a chemistry that has been used in submarines, anesthesia, and scuba diving for about a century https://en.wikipedia.org/wiki/Carbon_dioxide_scrubber https://en.wikipedia.org/wiki/Carbon_dioxide_scrubber has a nice overview of the different process chemistries commonly used