4 ms·

Converting CO2 on its own seems like a useful thing, don’t you think?

by 9dev 1y ago

myrmidon 1y ago
Not necessarily. The problem is the somewhat low atmospheric CO2 concentration; this is why all the "lets just pollute now and remove the CO2 from the atmosphere with some futuristic tech!" approaches are also kinda doomed, because even if you had some workable process that did not cause excessive costs by itself (like this one possibly), you still need to process millions of cubic meters of air, every year, just to compensate for a single (!!) car.
- leereeves 1y ago
  That sounds like a lot, but a million cubic meters is only a cube 100 meters on each side. So it's on the order of the air in a football stadium. A 1200 CFM home air conditioning system moves roughly 20 million cubic meters per year.
  - myrmidon 1y ago
    Sure. But thats still very much a lower bound, and it makes a bunch of idealizing assumptions that are hopelessly overoptimistic (assuming your intake gets the full 400ppm of CO2, and you manage to extract all of it in one go). Even from those numbers, you already get up to a football stadium of processed air per hour for every small town. For a big city, you need to process that football stadium worth of air every second. Building infrastructure of that magnitude is a major commitment, and if most nations can not be arsed to replace a small number of fossil power plants per country, I honestly don't see us building large air processing plants in every single town in a timely manner (that are extremely likely to be less profitable than replacing the power plants).
    - themaninthedark 1y ago
      What is the size of these process units? Can it be coupled with current air processes? Every house, office building and factory has air handling units. Factories and other industrial sites also use compressors.
      - teamonkey 1y ago
        Right now they’re a fantasy so they can be as large or small as your imagination permits.
      - gus_massa 1y ago
        It converts CO2 and H2O into ethane and ethylene, oversimplifying the output is natural gas. What do you do with the natural gas? You can put it in pipes and send it to a central location, but you need pumps and the pipes are a nightmare. You can store it in a local tank but you need a pump again, and burn it but it release the CO2 again. Using a solar panel and a battery is easier and more efficient. (Do they need also some water pipes?) For a distributed production, solar panels are much better. Pipes and pumps may work in a centralized setup, but I'm still not convinced it's better that biodiesel or ethanol. Photosynthesis is very inefficient, so there is a lot of room for improvement. But plants are like self building robots and they store the output in grains that are easy to transport.
  - alnwlsn 1y ago
    Earth's atmosphere is 5.15×10^18 kg and at atmospheric pressure density is 1.293 kg m−3. The whole thing would be more like 4 billion billion cubic meters. So a billion AC units could have the whole thing cleaned up in just 200 years. Which would suggest that maybe as much as 0.1% to 1% of earth's atmosphere has ever passed through an air conditioner.
    - nancyminusone 1y ago
      This just has me picturing a scene where global warming is solved not by cleaning it up, but by leaving tons of window air conditioners everywhere, troll physics style, "to cool down the outside"
      - the_sleaze_ 1y ago
        Psh, that's not reasonable. Outer space is like really really cold. What we need is a huge heat pump in outer space that pumps the planets heat out into deep space. All we need is a space-elevator style tube and we're good to go!
        lukan 1y ago
        You would need GIANT radiators. Space is cold but there is also allmost no cold material to transfer heat. So even with a space elevator .. not so easy.
        the_sleaze_ 1y ago
        You forget the least realistic miracle required - the space elevator itself.
      - filoeleven 1y ago
        > The Stanford team’s passive cooling system chills water by a few degrees with the help of radiative panels that absorb heat and beam it directly into outerspace. This requires minimal electricity and no water evaporation, saving both energy and water. The researchers want to use these fluid-cooling panels to cool off AC condensers. https://spectrum.ieee.org/efficient-airconditioning-by-beaming-heat-into-space https://spectrum.ieee.org/efficient-airconditioning-by-beami...
  - reverendsteveii 1y ago
    okay but what's several million cubic meters of air times all the cars operating on earth right now?

Converting CO2 on its own seems like a useful thing, don’t you think?

by 9dev 1y ago

Converting CO2 on its own seems like a useful thing, don’t you think?

Not necessarily. The problem is the somewhat low atmospheric CO2 concentration; this is why all the "lets just pollute now and remove the CO2 from the atmosphere with some futuristic tech!" approaches are also kinda doomed, because even if you had some workable process that did not cause excessive costs by itself (like this one possibly), you still need to process millions of cubic meters of air, every year, just to compensate for a single (!!) car.

leereeves 1y ago
That sounds like a lot, but a million cubic meters is only a cube 100 meters on each side. So it's on the order of the air in a football stadium. A 1200 CFM home air conditioning system moves roughly 20 million cubic meters per year.
- myrmidon 1y ago
  Sure. But thats still very much a lower bound, and it makes a bunch of idealizing assumptions that are hopelessly overoptimistic (assuming your intake gets the full 400ppm of CO2, and you manage to extract all of it in one go). Even from those numbers, you already get up to a football stadium of processed air per hour for every small town. For a big city, you need to process that football stadium worth of air every second. Building infrastructure of that magnitude is a major commitment, and if most nations can not be arsed to replace a small number of fossil power plants per country, I honestly don't see us building large air processing plants in every single town in a timely manner (that are extremely likely to be less profitable than replacing the power plants).
  - themaninthedark 1y ago
    What is the size of these process units? Can it be coupled with current air processes? Every house, office building and factory has air handling units. Factories and other industrial sites also use compressors.
    - teamonkey 1y ago
      Right now they’re a fantasy so they can be as large or small as your imagination permits.
    - gus_massa 1y ago
      It converts CO2 and H2O into ethane and ethylene, oversimplifying the output is natural gas. What do you do with the natural gas? You can put it in pipes and send it to a central location, but you need pumps and the pipes are a nightmare. You can store it in a local tank but you need a pump again, and burn it but it release the CO2 again. Using a solar panel and a battery is easier and more efficient. (Do they need also some water pipes?) For a distributed production, solar panels are much better. Pipes and pumps may work in a centralized setup, but I'm still not convinced it's better that biodiesel or ethanol. Photosynthesis is very inefficient, so there is a lot of room for improvement. But plants are like self building robots and they store the output in grains that are easy to transport.
- alnwlsn 1y ago
  Earth's atmosphere is 5.15×10^18 kg and at atmospheric pressure density is 1.293 kg m−3. The whole thing would be more like 4 billion billion cubic meters. So a billion AC units could have the whole thing cleaned up in just 200 years. Which would suggest that maybe as much as 0.1% to 1% of earth's atmosphere has ever passed through an air conditioner.
  - nancyminusone 1y ago
    This just has me picturing a scene where global warming is solved not by cleaning it up, but by leaving tons of window air conditioners everywhere, troll physics style, "to cool down the outside"
    - the_sleaze_ 1y ago
      Psh, that's not reasonable. Outer space is like really really cold. What we need is a huge heat pump in outer space that pumps the planets heat out into deep space. All we need is a space-elevator style tube and we're good to go!
      - lukan 1y ago
        You would need GIANT radiators. Space is cold but there is also allmost no cold material to transfer heat. So even with a space elevator .. not so easy.
        the_sleaze_ 1y ago
        You forget the least realistic miracle required - the space elevator itself.
    - filoeleven 1y ago
      > The Stanford team’s passive cooling system chills water by a few degrees with the help of radiative panels that absorb heat and beam it directly into outerspace. This requires minimal electricity and no water evaporation, saving both energy and water. The researchers want to use these fluid-cooling panels to cool off AC condensers. https://spectrum.ieee.org/efficient-airconditioning-by-beaming-heat-into-space https://spectrum.ieee.org/efficient-airconditioning-by-beami...
- reverendsteveii 1y ago
  okay but what's several million cubic meters of air times all the cars operating on earth right now?