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The article makes a valid point that the amount of energy required for direct air capture (DAC) is extremely prohibitive and far beyond current capacity, but as

The article makes a valid point that the amount of energy required for direct air capture (DAC) is extremely prohibitive and far beyond current capacity, but assume for the sake of argument that this is a problem that could be solved. This still leaves the problem that the industrial plant and chemical feedstock required to physically do the DAC at the scale of billions of tons per year is several orders of magnitude beyond what is possible with current supply chains and natural resources. You would have to strip mine the planet just to have the raw materials to build the necessary DAC infrastructure, and we need those resources for other critical things as well. Some proposed DAC chemistries have upstream mineral dependencies that, if done at the scale required just to offset a year's emissions, would consume all known global reserves immediately. This is not solved by recycling because of compounding loss rates; recycling is not 100% efficient, and the amount of energy required to improve recycling efficiency is essentially exponential for rapidly diminishing returns, and we already have an energy problem with DAC. DAC at any scale that is not an exercise in futility will be an exercise in environmental and economic destruction at unprecedented scale. The solution would almost certainly be worse than the problem. There really isn't a path forward that doesn't involve dramatically reducing emissions and letting nature remove the excess carbon.

DennisP 2y ago
This could use some citations. In particular, I'm interested in these new methods, which are very energy efficient: https://engineering.princeton.edu/news/2024/03/14/engineers-use-moisture-pull-carbon-dioxide-out-air https://engineering.princeton.edu/news/2024/03/14/engineers-... https://news.mit.edu/2019/mit-engineers-develop-new-way-remove-carbon-dioxide-air-1025 https://news.mit.edu/2019/mit-engineers-develop-new-way-remo... The second article says "the team has proven the system can withstand at least 7,000 charging-discharging cycles, with a 30 percent loss in efficiency over that time. The researchers estimate that they can readily improve that to 20,000 to 50,000 cycles." That's without consumables, just a stack of electrodes coated with an organic compound and carbon nanotubes.
- jandrewrogers 2y ago
  Your examples are illustrative of the point. These are the equivalent of "in mice" articles in medicine. Showing DAC in a lab is the easy part. Just to offset current emissions, we need to pull 40 billion tons of CO2 out of the air each year. This must work within the constraints of supply chains, upstream chemical feedstock, and available planetary mineral reserves. People are not comprehending the scale: this would be the largest industrial chemistry process in history by orders of magnitude, larger than all other industrial chemistry combined. Scaling either of the above DAC processes to 40 billion tons per year is infeasible. You don't just have to scale the process, you also have to scale the upstream processes and resource extraction activities that enable the process to be built. At 40 billion tons, any chemical engineer can quickly pencil out that these processes have upstream dependencies that have no ability to be scaled sufficient to support the target production process, not even close. In computer terms, it is like trying to train the latest LLMs on a computer from the 1990s. I see a lot of DAC proposals that, at scale, imply a supply chain that instantly consumes the global reserves of critical agricultural minerals like potassium or phosphorus, or which would literally produce e.g. concentrated acid waste at the scale of billions of tons, with no plan for how to keep people from starving or disposing of the chemical waste. Consequently, these processes are not real solutions.
  - DennisP 2y ago
    Yes I understand the argument, but you're still not posting actual numbers for any specific materials required by these particular technologies. I could just as well mention the immense materials required for grid-scale batteries, but that doesn't mean they're necessarily infeasible; it all depends on which materials we use. Before you say "industrial chemistry is different" I'll note that the MIT tech is actually quite similar to a battery. Aside from the CO2 it doesn't have a flow of chemicals that turn into waste; I've seen proposals like that too and this is different. The Princeton method is new in the lab but the MIT project started a company that has been working on commercializing for five years now. So far they've won an XPrize, gotten investment from the Gates fund, and started collaborating with an aluminum company. https://news.mit.edu/2022/cracking-carbon-removal-challenge-verdox-0915 https://news.mit.edu/2022/cracking-carbon-removal-challenge-... https://verdox.com/ https://verdox.com/
gary_0 2y ago
> extremely prohibitive and far beyond current capacity, but assume for the sake of argument that this is a problem that could be solved. Even if we did have this magical way to add another Earth's worth of energy production, it would first need to be put to use replacing about 25,000 TWh of carbon-emitting energy (used in electricity production, transportation, heating, metal refining, concrete production, etc). We need to close the sucking chest wound of carbon emissions before we worry about anything else.
- DennisP 2y ago
  Yes, and it looks like the quickest, cheapest way to do that is by electrifying everything we can and generating electricity with wind, solar, and battery storage. In the US, the most economical way to get a reliable grid out of that is 2X energy overproduction and four days of battery (citation in another comment I posted here.) With 2X overproduction, we've got lots of spare energy, so by the time we're getting most of our energy this way, we'll also have lots of energy for DAC, which can soak up the excess power whenever it's available.
  - gary_0 2y ago
    I feel like that's the obvious solution at this point, but there's still so much waffling going on. And half the political parties on Earth still aren't even interested. If we could just get to work building like our lives depended on it (because they do), I would actually have some hope for the future. I do want to stress that we shouldn't be thinking about DAC until we've carpeted the world's deserts with solar, and it's going to be a long fight to make that a possibility. The economy still hasn't kicked its oil addiction, and it's starting to look really pale and disheveled...
    - DennisP 2y ago
      The politics is awful but the one thing we have going for us is the stunning and continuing price drop for wind, solar, and batteries. Now that's it's getting cheaper than other sources, the transition is unstoppable. Meanwhile, all the non-disastrous IPCC scenarios include large scale carbon absorption after 2050. We can't start on a dime. The price drop for solar happened because the more of something you make, cumulatively, the cheaper it gets. We need that process to start for DAC, so it's cheap when we need it. And we already have places with lots of renewables, that pay people to consume power when there's extra. With more renewables, that will be a bigger issue. DAC can already start being the flexible demand we need.

DennisP 2y ago

This could use some citations. In particular, I'm interested in these new methods, which are very energy efficient: https://engineering.princeton.edu/news/2024/03/14/engineers-use-moisture-pull-carbon-dioxide-out-air https://engineering.princeton.edu/news/2024/03/14/engineers-... https://news.mit.edu/2019/mit-engineers-develop-new-way-remove-carbon-dioxide-air-1025 https://news.mit.edu/2019/mit-engineers-develop-new-way-remo... The second article says "the team has proven the system can withstand at least 7,000 charging-discharging cycles, with a 30 percent loss in efficiency over that time. The researchers estimate that they can readily improve that to 20,000 to 50,000 cycles." That's without consumables, just a stack of electrodes coated with an organic compound and carbon nanotubes.

jandrewrogers 2y ago
Your examples are illustrative of the point. These are the equivalent of "in mice" articles in medicine. Showing DAC in a lab is the easy part. Just to offset current emissions, we need to pull 40 billion tons of CO2 out of the air each year. This must work within the constraints of supply chains, upstream chemical feedstock, and available planetary mineral reserves. People are not comprehending the scale: this would be the largest industrial chemistry process in history by orders of magnitude, larger than all other industrial chemistry combined. Scaling either of the above DAC processes to 40 billion tons per year is infeasible. You don't just have to scale the process, you also have to scale the upstream processes and resource extraction activities that enable the process to be built. At 40 billion tons, any chemical engineer can quickly pencil out that these processes have upstream dependencies that have no ability to be scaled sufficient to support the target production process, not even close. In computer terms, it is like trying to train the latest LLMs on a computer from the 1990s. I see a lot of DAC proposals that, at scale, imply a supply chain that instantly consumes the global reserves of critical agricultural minerals like potassium or phosphorus, or which would literally produce e.g. concentrated acid waste at the scale of billions of tons, with no plan for how to keep people from starving or disposing of the chemical waste. Consequently, these processes are not real solutions.
- DennisP 2y ago
  Yes I understand the argument, but you're still not posting actual numbers for any specific materials required by these particular technologies. I could just as well mention the immense materials required for grid-scale batteries, but that doesn't mean they're necessarily infeasible; it all depends on which materials we use. Before you say "industrial chemistry is different" I'll note that the MIT tech is actually quite similar to a battery. Aside from the CO2 it doesn't have a flow of chemicals that turn into waste; I've seen proposals like that too and this is different. The Princeton method is new in the lab but the MIT project started a company that has been working on commercializing for five years now. So far they've won an XPrize, gotten investment from the Gates fund, and started collaborating with an aluminum company. https://news.mit.edu/2022/cracking-carbon-removal-challenge-verdox-0915 https://news.mit.edu/2022/cracking-carbon-removal-challenge-... https://verdox.com/ https://verdox.com/

gary_0 2y ago

> extremely prohibitive and far beyond current capacity, but assume for the sake of argument that this is a problem that could be solved. Even if we did have this magical way to add another Earth's worth of energy production, it would first need to be put to use replacing about 25,000 TWh of carbon-emitting energy (used in electricity production, transportation, heating, metal refining, concrete production, etc). We need to close the sucking chest wound of carbon emissions before we worry about anything else.

DennisP 2y ago
Yes, and it looks like the quickest, cheapest way to do that is by electrifying everything we can and generating electricity with wind, solar, and battery storage. In the US, the most economical way to get a reliable grid out of that is 2X energy overproduction and four days of battery (citation in another comment I posted here.) With 2X overproduction, we've got lots of spare energy, so by the time we're getting most of our energy this way, we'll also have lots of energy for DAC, which can soak up the excess power whenever it's available.
- gary_0 2y ago
  I feel like that's the obvious solution at this point, but there's still so much waffling going on. And half the political parties on Earth still aren't even interested. If we could just get to work building like our lives depended on it (because they do), I would actually have some hope for the future. I do want to stress that we shouldn't be thinking about DAC until we've carpeted the world's deserts with solar, and it's going to be a long fight to make that a possibility. The economy still hasn't kicked its oil addiction, and it's starting to look really pale and disheveled...
  - DennisP 2y ago
    The politics is awful but the one thing we have going for us is the stunning and continuing price drop for wind, solar, and batteries. Now that's it's getting cheaper than other sources, the transition is unstoppable. Meanwhile, all the non-disastrous IPCC scenarios include large scale carbon absorption after 2050. We can't start on a dime. The price drop for solar happened because the more of something you make, cumulatively, the cheaper it gets. We need that process to start for DAC, so it's cheap when we need it. And we already have places with lots of renewables, that pay people to consume power when there's extra. With more renewables, that will be a bigger issue. DAC can already start being the flexible demand we need.