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It would be remarkable indeed if humans can invent a technology that sequesters carbon faster than self-replicating, adaptive, distributed independent biologica

• PaulHoule 2y ago
  Not necessary. The critical thing that limits CO2 capture by plants through photosynthesis is water, how they manage that gets you to the difference between C3 and C4 plants. A system based on PV might not need much water at all. Plants not only capture CO2 from the air (pump out entropy) but they also reverse the chemistry to bind C to something like a carbohydrate molecule, whereas in carbon capture they usually compress the CO2 to 1500 psi or so and inject it underground. If you do want to do something useful with the CO2 you might have an e-Fuel factory that turns CO2 into CO and, together with H2, builds up gasoline and diesel molecules via Fischer-Tropsch chemistry which directly competes with (say) making ethanol from biomass. You don’t need so much energy to separate CO2 from N2 and compress it.
  • Turing_Machine 2y ago
    > The critical thing that limits CO2 capture by plants through photosynthesis is water In the ocean, where most photosynthesis occurs, it's definitely not water. I believe it's iron. I think there have been a few small-scale experiments involving "fertilizing" the ocean by spraying iron compounds on the surface.
    • nwiswell 2y ago
      Yep. Geoengineering like seeding clouds or atmospheric aerosols (albedo modification) and fertilizing the ocean could absolutely have an impact on global temperature and CO2 levels respectively, but also would almost certainly cause environmental impacts at least on the scale of climate change, and possibly worse. So GP is mistaken: if we threw environmental caution to the wind, and given sufficient funding, we absolutely could produce tangible reductions in AGW using today's technology.
      • Turing_Machine 2y ago
        > but also would almost certainly cause environmental impacts at least on the scale of climate change, and possibly worse. Or, possibly better. The deep oceans don't have a lot of marine life because there's not much plankton, because all the nutrients have sunk to the bottom. Regions where there are natural upwellings that bring bottom nutrients to the surface tend to have massive plankton populations, leading to massive fish populations (Grand Banks, the west coast of South America, others). That's why it would be important to do experiments to see what happens when it begins to get scaled up. "We don't know what would happen" is not a reason to avoid experimentation (indeed, "we don't know what would happen" is pretty much the reason why you do experiments).
        • nwiswell 2y ago
          I definitely agree, but in the meantime we cannot depend on these strategies when making long-term plans to combat climate change because we don't know whether their side effects will prove to be tolerable.
          • Turing_Machine 2y ago
            How do you know that the "long-term plans to combat climate change" won't prove harmful in their own right? They would produce massive economic effects at a minimum. Then there are the unknown effects of (e.g.) removing a lot of energy from the desert and transporting it to other regions. I'd be very surprised if that didn't have some effect. Same thing with extracting energy from the winds on any large scale. Wind energy turned into electricity is energy that's not available to (e.g.) move rain clouds from one region to another. And so on.
            • nwiswell 2y ago
              In general the incoming power from the sun is so many orders of magnitude greater than the amount of power we usefully extract that it's hard to imagine it having any material impact on the biosphere. The physical presence of solar cells and wind turbines is a different matter, but it's largely a local effect.
    • _heimdall 2y ago
      Iron is an interesting one. We use a huge amount of iron to produce steel, but that production process releases a massive amount of carbon into the atmosphere. The scale is such that steel is much more a byproduct of releasing that carbon rather than the other way around.
    • PaulHoule 2y ago
      One concern is that if it’s not one thing it’s another: a particular spot in the ocean might be iron limited but if you supply iron you might burn up all the calcium (or something else.) so you are just bringing the carbon capture earlier in time. The water limit is important when you are considering agriculture and biomass projects that so far we are doing on land. Note there are biomass energy schemes where you capture CO2 from fermentation or combustion known as https://en.wikipedia.org/wiki/Bioenergy_with_carbon_capture_and_storage https://en.wikipedia.org/wiki/Bioenergy_with_carbon_capture_... and these do compete directly with direct air capture.
  • sidewndr46 2y ago
    if you make fuel from CO2 in the air, isn't that pointless? It'd wind up right back in the air once burnt
    • kiicia 2y ago
      then you don't need to get more from underground, just cycle what is already there
      • j-bos 2y ago
        Sounds like wood gas.
  • cyberax 2y ago
    > The critical thing that limits CO2 capture by plants through photosynthesis is water It's not really true. The critical limit is the inefficiency of photosynthesis, it's around 3-5%. The RuBisCo enzyme just sucks, compared to many other enzymes. So you can't improve the productivity of plants by adding more water. But if you do have a lot of fresh water, you can cultivate lands that are right now empty.
• jeffbee 2y ago
  Aren't plants actually incredibad at photosynthesis? I thought that a really exceptional plant was 3-4% efficient, most of them are << 1%
• eliaspro 2y ago
  It's a shame we suck at acknowledging the obvious inefficiencies in our systems and adapting our behavior accordingly and instead waste huge amounts of money, brainpower and energy for magical and unlikely to ever work techno fixes. In this case: if we all agreed to drastically reduce our consumption of animal-based products, we'd free up huge amounts of land which we could use now to plant rapid growing, carbon-capturing plants. Then harvest them and either process them as biochar, where roughly 50% of the carbon remains captured and use the generated heat for energy/heat generation - or maybe even bury the harvested biomass in a way which ensures no methane or carbon will be emitted. The plants would do all the hard work, we "just" need to reap its result.
  • DarmokJalad1701 2y ago
    > It's a shame we suck at acknowledging the obvious inefficiencies in our systems Plants a significantly extremely inefficient at capturing carbon compared to industrial technology like carbon capture using Calcium Hydroxide. > we'd free up huge amounts of land which we could use now to plant rapid growing, carbon-capturing plants You severely underestimate the problem and overestimate the ability of trees to fix it. Planting trees doesn't scale to the levels required to make any difference even if we used all land on Earth. It would take around ~2 trillion trees planted per year just to offset the 40-50 gigatons of CO2 being pumped out per year. That is around ~2 billion acres of land - is more than the entire land area of the contiguous US - every year, just to break even. Ref: https://news.ycombinator.com/item?id=38187573 https://news.ycombinator.com/item?id=38187573
  • _heimdall 2y ago
    What do we fertilize those plants with once we dramatically reduced animal product consumption? And how do we handle the health issues of removing almost all animal products from our diets?
  • jaredhallen 2y ago
    The overlap between land that's good for growing crops and land that's used for raising livestock is pretty small.
• function_seven 2y ago
  Evolution gave us legs. We invented wheels. Nature gave us eyes. We invented telescopes and microscopes. Natural selection “only” does the bare minimum that beats the competition. It didn’t design plants to be maximally efficient at removing CO2. Plants do so while also having to deal with respiration, water conservation, heat management, reproduction, nutrient intake, disease prevention, etc. I’m sure we can do better when we don’t concern ourselves with all that other stuff.
  • soperj 2y ago
    Wheels are pretty useless without roads. Boats were much more useful.
    • thih9 2y ago
      Building boats and navigating them would require colonies of large brain specimens; this approach would carry a big energy cost. Not to mention boat propulsion, especially if you wanted to sail without depending on weather. Instead of boats it seems more efficient to replace hands/legs with fins/tails. Tongue in cheek, but only half - natural selection works on a different scale and with different goals, and in that it seems pretty good.
• jaggederest 2y ago
  Nah industrial direct capture is a proven technology. Energy isn't the problem, plenty of sun in the southwest. The chemistry isn't a problem, we have sorbents that work great, it's just cost. We don't want to spend 1/3rd of global GDP on carbon sequestration for the next decade.
• xboxnolifes 2y ago
  Not really. Living things absorb CO2 with the intent to live. The CO2 isn't the important part, the living (replicating) is. It's entirely plausible that one could improve efficiency by removing the requirement of living.
• _heimdall 2y ago
  It'd be a lot more simple, and faster, for us to just stop releasing so much carbon into the atmosphere if we really cared. The idea that we can invent our way into a scenario where we can have our cake and eat it too is just a lie that kicks the can down the road. How likely does it really seem that we will find a solution in which we can continue to use more and more natural resources but magically make all the negative externalities suddenly disappear? And is that likelihood more realistic or reasonable than just stopping creating the damage as much as possible?
  • enragedcacti 2y ago
    We could of course use more willingness to sacrifice luxuries but "just stop releasing so much carbon" isn't the solution because emissions is just one part of the optimization problem. The entire global economy is the engine that will produce alternatives to fossil fuels despite it running on fossil fuels. There are obvious cases where carbon is worth emitting e.g. Concrete for a nuclear power plant, Diesel trucks to deliver solar panels, smelting steel for train tracks. Barring turning everything off tomorrow at astronomical human cost, there is some optimal amount of emissions and if used effectively Carbon Capture/Storage (primarily point source) could shift the Pareto front in the right direction.
• dullcrisp 2y ago
  Others have said the same but it seems you can use this argument against just about any machine.