5 ms·

I would be very curious to see that math that you solved the problem with, given that all of the scientists in the world working on this missed your solution.

by Mizza 4y ago

kragen 4y ago
no they didn't, you did, because that's what happens when you don't read any of the existing research quoting my comment at https://news.ycombinator.com/item?id=32198793 https://news.ycombinator.com/item?id=32198793 about the theoretical thermodynamic minimum for direct air capture, as https://en.wikipedia.org/wiki/Direct_air_capture#Environment https://en.wikipedia.org/wiki/Direct_air_capture#Environment... explains, it is only 250 kWh/tonne CO₂, or 900 kJ/kg in SI units. To remove the ≈60 Gt/year of anthropogenic CO₂ currently being emitted and get us to carbon-neutral with direct air capture would consequently require a theoretical minimum of 1.7 terawatts, which is only about 10% of current world marketed energy consumption, and presumably about 5% of world marketed energy consumption 10 years from now. Kicking climate change into reverse would require a bit more than that, maybe double. Depending on the sorbent system, this energy can be solar thermal; it does not have to be electrical. Existing direct air capture systems like Climeworks's do not closely approach the theoretical minimum. ... Point source capture is of course much cheaper but it cannot get us to net negative CO₂ emissions. (note https://news.ycombinator.com/item?id=33504318 https://news.ycombinator.com/item?id=33504318 points out a way that point source capture could conceivably get us to net negative emissions) https://news.ycombinator.com/item?id=29327736 https://news.ycombinator.com/item?id=29327736 describes the lime approach. it uses a huge amount of energy, 1600 kWh/tonne CO2 (5700 kJ/kg CO2), much larger than the theoretical minimum above and much more than Climeworks, so the purpose of explaining it is only to demonstrate that there's no practical scalability limit to direct air capture. you don't have to ramp up your production of triethanolamine or aluminum formate or whatever the fuck. those are just a matter of optimizing the energy efficiency
- 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)
- pjc50 4y ago
  https://www.wolframalpha.com/input?i=1.7terawatt+years https://www.wolframalpha.com/input?i=1.7terawatt+years tells me " ≈ 4.7 × yearly electric energy production of all nuclear power plants ( ≈ 3.2×10^15 h W )" Or 14.9 trillion kilowatt hours, which at plausible retail prices of £0.10/kWh is approximately one and a half trillion pounds. Now, who's going to pay for that?
  - kragen 4y ago
    sounds about right, though presumably you wouldn't be paying retail if you're setting up shop to terraform the earth. numerous recent ppas provide much lower (wholesale) prices than that; see https://emp.lbl.gov/pv-ppa-prices https://emp.lbl.gov/pv-ppa-prices and https://www.greentechmedia.com/articles/read/merchant-income-is-key-in-latest-record-solar-bids https://www.greentechmedia.com/articles/read/merchant-income..., which have numerous prices below £0.02/kWh. and, as i said, you can probably use solar thermal for sorbent regeneration note, though, that the number you're using is the theoretical minimum energy used. existing practical technologies, as i said, consume several times more energy than that. it is unlikely that we will ever closely approach this theoretical efficiency there is indeed a real difficulty in the current human incentive structure where everybody hopes someone else will fix the problem so they don't have to bear the cost themselves. but that's not a question of engineering infeasibility due to resource limits; that's a question of politics
  - conductr 4y ago
    It’s not much on a global scale, given the nature of the problem it would be solving. And if it works we have a nice little renewable power infrastructure as a byproduct The real problem is people and our near inability to coordinate at that scale
    - kragen 4y ago
      agreed, or even, as demonstrated in parts of this thread, people's inability to come to an agreement on widely-known facts that conflict with their ego defense
      - 4y ago

I would be very curious to see that math that you solved the problem with, given that all of the scientists in the world working on this missed your solution.

by Mizza 4y ago

I would be very curious to see that math that you solved the problem with, given that all of the scientists in the world working on this missed your solution.

kragen 4y ago

no they didn't, you did, because that's what happens when you don't read any of the existing research quoting my comment at https://news.ycombinator.com/item?id=32198793 https://news.ycombinator.com/item?id=32198793 about the theoretical thermodynamic minimum for direct air capture, as https://en.wikipedia.org/wiki/Direct_air_capture#Environment https://en.wikipedia.org/wiki/Direct_air_capture#Environment... explains, it is only 250 kWh/tonne CO₂, or 900 kJ/kg in SI units. To remove the ≈60 Gt/year of anthropogenic CO₂ currently being emitted and get us to carbon-neutral with direct air capture would consequently require a theoretical minimum of 1.7 terawatts, which is only about 10% of current world marketed energy consumption, and presumably about 5% of world marketed energy consumption 10 years from now. Kicking climate change into reverse would require a bit more than that, maybe double. Depending on the sorbent system, this energy can be solar thermal; it does not have to be electrical. Existing direct air capture systems like Climeworks's do not closely approach the theoretical minimum. ... Point source capture is of course much cheaper but it cannot get us to net negative CO₂ emissions. (note https://news.ycombinator.com/item?id=33504318 https://news.ycombinator.com/item?id=33504318 points out a way that point source capture could conceivably get us to net negative emissions) https://news.ycombinator.com/item?id=29327736 https://news.ycombinator.com/item?id=29327736 describes the lime approach. it uses a huge amount of energy, 1600 kWh/tonne CO2 (5700 kJ/kg CO2), much larger than the theoretical minimum above and much more than Climeworks, so the purpose of explaining it is only to demonstrate that there's no practical scalability limit to direct air capture. you don't have to ramp up your production of triethanolamine or aluminum formate or whatever the fuck. those are just a matter of optimizing the energy efficiency

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)
pjc50 4y ago
https://www.wolframalpha.com/input?i=1.7terawatt+years https://www.wolframalpha.com/input?i=1.7terawatt+years tells me " ≈ 4.7 × yearly electric energy production of all nuclear power plants ( ≈ 3.2×10^15 h W )" Or 14.9 trillion kilowatt hours, which at plausible retail prices of £0.10/kWh is approximately one and a half trillion pounds. Now, who's going to pay for that?
- kragen 4y ago
  sounds about right, though presumably you wouldn't be paying retail if you're setting up shop to terraform the earth. numerous recent ppas provide much lower (wholesale) prices than that; see https://emp.lbl.gov/pv-ppa-prices https://emp.lbl.gov/pv-ppa-prices and https://www.greentechmedia.com/articles/read/merchant-income-is-key-in-latest-record-solar-bids https://www.greentechmedia.com/articles/read/merchant-income..., which have numerous prices below £0.02/kWh. and, as i said, you can probably use solar thermal for sorbent regeneration note, though, that the number you're using is the theoretical minimum energy used. existing practical technologies, as i said, consume several times more energy than that. it is unlikely that we will ever closely approach this theoretical efficiency there is indeed a real difficulty in the current human incentive structure where everybody hopes someone else will fix the problem so they don't have to bear the cost themselves. but that's not a question of engineering infeasibility due to resource limits; that's a question of politics
- conductr 4y ago
  It’s not much on a global scale, given the nature of the problem it would be solving. And if it works we have a nice little renewable power infrastructure as a byproduct The real problem is people and our near inability to coordinate at that scale
  - kragen 4y ago
    agreed, or even, as demonstrated in parts of this thread, people's inability to come to an agreement on widely-known facts that conflict with their ego defense
    - 4y ago