MIT Team Makes a Case For Direct Carbon Capture From Seawater, Not Air - Slashdo...

Posted by BeauHD

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  By my calculation, that's $150-$300 USD per ton.

  • by timeOday ( 582209 ) on Friday February 17, 2023 @09:27PM (#63302747)

    Burning a gallon of gas creates 20 lbs of CO2.

    So 100 gallons of gas creates a ton of CO2.

    So $1.50 cleanup per gallon of gas at the low end.

    https://climatekids.nasa.gov/r... [nasa.gov]

    • Re:

      If these numbers are right, then that's acceptable.

      • Re:

        Amazing! the GP is now modded up to +4!!!

        Weight of a gallon of gas:
        https://www.jdpower.com/cars/s... [jdpower.com]

        So according to the +4 post we are now creating mass out of thin air, generating 20 pounds of output with only 8 pounds of input and managing to run our cars on apparently free energy on top of that along the way.

        Seriously?

        • Re:

          I'm not going to try to check the math directly (or I shall embarrass myself) but the point holds. For example, one propane molecule plus five oxygen molecules plus combustion equals three carbon dioxide molecules, plus four water molecules and some heat. On a cooktop the goal is to produce the heat, and the volume is wasted; in an ICE the goal is to produce the volume, and the heat is wasted.

          The EPA says CO2 Emissions from a gallon of gasoline: 8,887 grams CO2/ gallon [epa.gov]. 1G of gasoline masses 2840g [forestville.com] (its weig

        • Re:Cost, math, physics, chemistry

          Did you forget that the oxygen in the combustion-emitted CO2 molecule comes from the atmosphere, not from the gasoline?

        • Mass of thin air...

          ...is still mass.
          Ever held water, in container or otherwise, in your hand? Most of that weight was those O atoms, not the H ones. Despite there being twice as many of them in the mix.
          Now, take in account that CO2 has twice as many O atoms as H2O and that C is a lot heavier than H - and that all those O atoms come from the gas we call "air".
          As in thin.

    • Re:

      Maybe we should stop burning so many gallons of gas.

    • Re:

      Roughly 27 gallons of gasoline contains 1 MWh of energy.
      Gas engines produce electricity at roughly 30% efficiency.
      So this process allows 27/0.3=90 gallons of gas to capture the carbon released by 100 gallons of gas...

      Does anyone else see the problem?

      • Re:

        I can't decide whether 90% is surprisingly close, or it's surprising that it's not 100%. I mean the amount of energy you get from rolling a ball down a hill should be the same as it takes to roll back up...

        But, yeah, I think future generations are going to look back on the fossil fuel era and some will feel that we were only borrowing from the future and leaving it to them to repay.

        • Re:

          Poor analogy. This process doesn't turn CO2 back into gasoline. It just collects the CO2 so it can be sequestered. But it's still CO2.

      • Re: Cost

        Does anyone else see the problem?

        Yup. There's also a straightforward solution that has been known for 40 years. For a variety of reasons the solution has met fierce opposition from the vested lobbies and ButMahFreedom folks: drastically reduce fossils fuel consumption.

      • Re:

        Well, one clearly can't power this process with gas. But is there any reason that it needs to be? Gasoline should be restricted to uses where there isn't any decent alternative. (And by gasoline, I really mean all fossil fuels.) We're in the process of doing that now, but we really need to step up the pace a bit. Taxes on emission of CO2 and elimination of the "offsets" fake would be a good way to accomplish this. (But think carefully. It might be better to just tax fossil fuels more heavily. After

        • Re:

          Just who is going to vote for seeing the fuel they use everyday to travel being taxed even higher than it already has been? Since most nations with voting have a representative democracy there is the possibility of the representatives voting for these taxes when the represented didn't ask for it, but that only means some other representative that is opposed to these taxes gets voted in the next time.

          Taxes is a horrible way yo accomplish lower CO2 emissions.

          A far more effective way is to develop alternative

  • Re:

    Hey, wait a minute... isn't 0.77 MwH equal to 770 KwH? A KwH around here, retail, is 16 cents, so 770 of them should be $123.

    Then again, there's that floating spine-like thing that we've all seen over the last several weeks that touts "less than 1 cent per KwH" _if_ they get it working. And _if_ they got it working, they wouldn't need a big transmission line system since the generator is already IN THE SEA!!!! And if so, then $7.70 or less? Yeah, I think that's about right. Could actually be rea

    • Re:

      Wow, where do you live?

      • Re:

        According to the US Energy Information Agency [eia.gov], the average US price is $0.1564/kWh. However, some states are much cheaper. Considering states with ocean coastlines, Washington state has a cost of $0.1032/kWh. And those are residential prices. The industrial cost is $0.0603/kWh. It's even cheaper in Puerto Rico [lumapr.com], where the residential price is $0.05564/kWh, and likely even cheaper for industrial customers.

        And of all that is buying electricity at market prices. If this really works, then governments shou

        • Re:

          That's not too far off from what FPL charges residential customers in Florida once you go above 1,000 kWh in a month (which is a given since air conditioning is a year-round necessity). The elected critters in charge of such issues keep approving every rate request the utility makes, and the last time I did the math on it, a base Tesla model 3 would only end up cutting my "fuel" costs roughly in half. Since I already own a fairly efficient car (31 city / 39 highway MPG), I don't spend much on gas to begin

      • Re:

        Illinois here. My summer rates, including taxes and everything for heavy usage (servers, big house, AC, no electric vehicle) comes to 12.4c/kwh. Winter comes to about 12c per. So that's at least one good thing about Illinois.

      • Re:

        I honestly can't tell if you are surprised because 16 cents/kwh is so high or so low.

        in California, I pay 7 cents/kwh for off-peak power between 2 & 4 AM.

        • Re: Cost

          And tell them what you pay in daytime, esp after a small amount.

          • Re:

            In the daytime, I pay in tiers depending on consumption. The more I use, the higher the rate. The first tier is 15 cents/kwh. The second tier is 20 cents, and the third tier is 30.

            I have solar, so I've never gone beyond the first tier.

  • Re: Cost

    The actual paper doesn't appear to mention energy requirements in MWh equivalent values.

    However, they do give a direct cost estimate of $50-$100/tCO2.

• • Re:

    Maybe we could make something that is able to move on top of the water and travel around the world decarbonizing the oceans as it goes. Oh, we have this huge industry called shipping. If we could retrofit these vessels with a decarbonizer then as they travel around the the world they can make money by participating in carbon capture.

    • Re:

      The extra drag on the ship will increase fuel consumption far more than the CO2 extraction will help.

      Look, this is an interesting research project, but actually implementing it would be insane as long as fossil fuels are still being burned anywhere in the world. Installing wind and solar is ten times as cost-effective at reducing CO2 as this scheme.

      • Re:

        Let me not take away from your point that reducing the use of fossil fuels, especially for industry and short range transport is critical and should be done first. However there are ways to use this.

        An obvious place to do this on a massive scale is in the far North of Scotland and the correct use for the CO2 is converting it into various liquid fuels and gasses, especially hydrocarbons for uses such as long distance aviation where substitution is really difficult. If this could become cheap enough then it s

        • Re:

          It would make way more sense for Scotland to use surplus power for something like nitrates or ammonia, which have huge global markets (and currently shortages since Ukraine was a big producer).

          Even better would be to install some HVDC lines and export the surplus power to England or across the North Sea to the EU.

          • • Re:

              These lines are tiny for single digit GW transport. European power needs are in the 10s to low digit 100s of GWs. Scottish potential power generation is in the high hundreds of gigawatts up to terrawatts with more distant floating offshore wind. If Iceland was connected through Scotland also there's a potential for a huge transformation in how Europe is powered as a whole.

    • Re:

      So you're proposing that we burn more number 4 bunker oil (ship fuel) in order to extract CO2 from the oceans? You know it's one of the most environmentally damaging fuels around, right?
      
      Most of us are gonna die from climate disasters & food shortages at this rate.

      • Re:

        I propose the ships be nuclear powered. They can sail through the ocean to extract CO2, perhaps freeze it to dry ice, then offload it at a port for sale. Then head out to another port that wants bottled CO2 and/or dry ice and extract the CO2 from the water along the way. The CO2 they capture can be sequestered when it reaches port or used to replace CO2 that would have been produced by fossil fuels, either way this reversing CO2 emissions from fossil fuels.

        Dying from climate disasters in our lifetime is

  • Re:

    The gulf stream flows a fair bit. Use a bunch of ships to cover the full width of it with HVDC cables to string them up to power?

    It's going to be a trillion dollar project to make a dent, but that's to be expected.

    • Re:

      I think his point was that, past removing CO2 from the immediate area around the operation and diluting the area, even if the dilution was going to be equialized by the flow of streams, the more you remove from the oceans, the less there'll be to remove (and thus harder). But I don't think we need to remove all the CO2 from the oceans. I don't know how much, but I bet it's at most 10-15%.

  • Re:

    I assume you'd do it where there's a current, and grab the water upstream and deposit it downstream. You want the highest carbon concentration anyhow, so you'd want to make sure you're not outputting in your input supply.

  • Re:

    Anchor the system adjacent to one of the major ocean currents. There are several ‘rivers’ within the sea that constantly move vast amounts of water (and trash) around the oceans. Put this system even *near* one and it will circulate plenty more co2 laden water to it.

• Wonder how areas of lower CO2 might impact growth of algae and other sealife. Sort of the opposite of an algal bloom from fertilizer runoff.

  I assume the top layer of ocean is the important part. Where the sunlight, gases, and other necessary parts all come together in the water for photosynthesis (one of the ways nature removes carbon from the atmosphere already). Wouldn't lower CO2 in the top layer mean less photosynthesis across the same area?

  I applaud the outside the box thinking, but I hesitate to su

  • Re:

    It literally won't make a dent. The sea has been fine without us pumping billions of tons of CO2 into the air and 40-60% of that getting absorbed in the ocean.
    
    It will be perfectly fine to fallback a little bit.

    • Re:

      The sea is mostly a nutrient desert. Toss a little iron in, and the plankton & algae go nuts fixing carbon, and the rest of the sea life chain is down steam from there. This is how all that carbon got sequestered as coal & oil in the first place. The 1991 Mt. Pinatubo eruption offers good clues here, but its somewhat obfuscated by the co-morbid atmospheric SO2 injection.

  • I would add, in fact, we've pumped too much CO2 into the oceans that it's becoming more acidic, killing off coral reefs.

    • Re:

      This is the first thing that came to mind for me - CO2 acidifies the ocean as well (surprised that isn't mentioned in the brief), so pulling CO2 out of the water hopefully will result in a more favourable PH.

      But that's a LOT of carbon to remove.

      • Re: CO2 is used in the ocean.

        But isn't the constant releasing of co2 into the ocean the problem? And the ocean naturally processes this co2? So the issue in not removing it after we dump it but not dumping it in the first place?

  • Re:

    It will make no difference. Carbon is not the bottleneck. For life in the ocean, iron and phosphorous are the bottlenecks.

  • Re: CO2 is used in the ocean.

    im not a biologist but I wonder how this process will effect the ocean life cycle myself. I can't imagine it helping at all.

  • Re:

    The ocean currently is overacidified (technically, insufficiently alkaline, since the point of comparison is neutral Ph) because there's too much CO2 in it.

• Not mWh clearly, that needs to be MWh. Still, if that is the dominant cost it's still quite cheap.

• > Best of all, the concentration of carbon dioxide in seawater is more than 100 times greater than in air.

  1. Co2 creates global warming
  2. global warming melts polar ice caps which means more sea water
  3. ??? --> more sea water absorbs more Co2
  4. less Co2 means global warming

  We finally solved the equation!

• I literally made the case for this in the other stories about capturing from air.
  
  Still won't really make up for pumping billions of tons of it into the atmosphere in the first place.

• Yes, this action is valuable in itself, but it'll go down smoother with something one can SELL.
  Is there something else we can extract at the same time, something like the 17 rare earth elements, precious metals, lithium, or uranium that can be found in sea water?

  Perhaps one or more of these will just naturally collect on the emitter/receiver plates?

  Or since we're doing the work of pumping it around and through a channel, does that make the mining operation cheaper to start with and thus make element

  • Is there something else we can extract at the same time

    You suggested lithium. With the increasing popularity of electric cars, and with products like Tesla Megapack for grid storage, there is now huge demand for battery-grade lithium.

    My understanding is that it's possible but not cost-effective to extract lithium from seawater... but if you set up a desalinization plant, the more-concentrated brine you get when you remove some of the water as fresh water might be cost-effective for lithium recovery.

    I'm wondering how many things you can do at once and whether some of them help the others. Is it easier, or harder, to get carbon dioxide from desalinization brine than pure seawater?

    Also, Tony Seba and his think tank are predicting that we could transition to relying on "renewable" power only if we overbuild production by 3 to 5 times the minimum. That way, when it's a winter day (less sunlight) and the wind dies down, you aren't getting 100% production but you at least have more production of what you can get (and the plan also calls for enough backup battery power for 2 to 4 days). Well, the corollary of that is that most of the time, when sun and wind are normal, your overbuilt production makes excess energy that you can afford to sell cheaply.

    So I've started reading stories like this and wondered if they would be good candidates for the excess power from wind/solar on normal days. Collect lithium and carbon dioxide while the energy is cheap, and plan for some down time in December.

    For a real win, turn the carbon dioxide all the way into pure jet fuel, because long-haul jet airplanes aren't converting to battery power anytime soon. If you have carbon, and you can get hydrogen from the water (just need more electricity), you can make hydrocarbons. I don't know whether it would be economically feasible, but large amounts of cheap power might help with that.

    • Re:

      Well, the jet fuel returns the CO2 to the atmosphere, but I guess it prevents more fossil fuel being burned. The real win, though, is to turn it into something durable. Perhaps we could enter "the diamond age" with it. Graphite (and it's developed forms) are an easier alternative, though. (But that assumes enough energy to remove the oxygen. Plastics would be a lot easier.) Perhaps the easiest/best alternative is to use it for a synthetic photosynthesis process to produce various organic chemicals. W

  • Re:

    That's been the problem with every carbon capture proposal, they're fundamentally incompatible with free market economics. The product they produce (carbon) isn't worth the value of the energy it takes to extract it, so anyone with a lick of business sense can see where this is going.

    The general idea is that, should any of this geoengineering tech get past all the hurdles of implementing it on a scale which actually makes an impact, the next step would be to convince good ol' Uncle Sam to foot the bill. T

    • Re:

      Sure sucks to be responsible adults. Why can't we just also kick that can down the road to our kids...
      Oh, we're supposed to be adults. And care about our kids futures.

• Sea water is a complex soup. What kind of impact will this process have on microscopic sea life, and/or any micronutrients that may be present in the water, as it passes through this process?

  • Re:

    The life gets turned into micronutrients.

• It seems to me that the recapturing of protons won't work perfectly, and some will wash out to sea. Simularly, anyone with a boat knows sea water has a lot of gunk in it, and some of it will be attracted to the electrodes, or just naturally stick to them, further degrading performance.

  The New Atas article talks about this briefly, but doesn't say anything about the material the electrodes are made of, and what it costs to replace them:

  > And mineral precipitates are fouling the electrodes on the alkaliniz

  • Re:

    Reading some more, they do acknowledge this:

    "The bismuth electrode is inexpensive and can robustly modulate the pH of chloridecontaining salt water regardless of the type and concentration of cations. On the other hand, although silver has the advantage of large capacity and low energy penalty, electrode dissolutionwill need to be overcome by modifying the silver particles or replacing silver with another material; this is to be the subject of future studies."

    Seems like a pretty relevant caveat for New Atla

• • Re:

    I used to think this too.

    It's not a bad idea. It can definitely work to some extent. But trees are relatively expensive (if you're doing seedlings, not seeds) and fragile. They can only grow in places that really work for them, and open grasslands are 1. open grasslands for a reason -- it's not good forest area and 2. a highly evolved tree-killer (grass is much newer than trees, and evolved to steal the land trees have, albeit slowly).

    Ultimately forests do best in forests. The places were there are fores

    • Re:

      They also take a lot of water to grow.

    • Re:

      Often, the reason is that all the trees were cut and/or burned down. Even Native Americans burned down forests to increase range land for bison.

    • Re:

      What we need to do is plant more trees, cut them down, pulverize them or otherwise convert them into compressed bricks, bury the result deep in the ground, and repeat ad nauseum. The industrial part of this needs to be run on solar/wind, of course.

      The coal industry has conveniently left a fair number of holes that would work well for that permanent storage. And the construction industry has conveniently developed extremely fast-growing trees.

      Win-win.

      It won't be the solution, but it will help work toward it

  • Re:

    There isn't enough suitable land on the surface of the earth to plant enough trees. And most "offset" projects the planted trees, the new trees were dead within a couple of years. (But the "offset" was collected, so that was considered a win.)

• Apparently seaweed has been removing carbon dioxide from the atmosphere for at least 500 million years, and you hipsters are using up all the world's seaweed with your trendy lunch-time sushi consumption. Think of the planet for once.
  • 1 hidden comment

  • Re:

    HAHA! This is actually a good point. It might be much cheaper to seed an area with nitrogen and phosphorus and iron, and periodically rip half the seaweed out and... well, bury it, probably.

    There's a comment above about planting trees. I'll bet seaweed works better for carbon capture.

    • Re:

      Yeah, but the ocean is not lacking for seaweed, or rather, algae. The problem is even they can't keep up by how fast we're pumping CO2 into the atmosphere, to get absorbed 40-60% into the ocean. Un-tethered CO2 in the ocean is raising acidity.

• If the co2 is already in solution, and the end goal is to sequester it, like in minerals, then wouldn't pulling it out as a gas be, at best a lateral move, given that minerals are generally more easily formed by aqueous chemistry?

  • Re:

    This sounds quite plausible. I'm not *sure* it's true, but it's certainly plausible. Certainly iron rusts more easily in sea water than in dry air. I guess it may depend on how you intend to sequester it. (Many of the suggestions I've heard seem very temporary.)

• 0.77 * 32 / 122 = 0.2 KWh/ton
  0.2 * 1000 KWh/MWh $0.10 = $20/ton
  1.6T * $0.02 = $32T at theoretical maximum efficiency

  humans have pumped about 1.6 trillion tons of carbon dioxide into the atmosphere

  Given their theoretical cheapest figure of 32 kJ/mol-CO2

  World/Gross domestic product
  96.51 trillion USD (2021)

  the team says its technique requires an energy input of 122 kJ/mol, equating by our math to 0.77 mWh per ton. And the team is confident it can do even better: "Though our base energy consumption of 122 kJ/mo

• Why not add Coca Cola syrup to sea water and make it a soda instead? When we could use fossil fuels and have unlimited coke.

• If they really wanted to sink carbon there are no shortages of smokestacks with way higher concentrations of CO2 to pick from.

  • Re:

    I thought about that too, but then I realized they'd probably be scrubbing it out with water mist anyway, so this process is the same thing but using the atmosphere as a filter. What could possibly go wrong, etc etc, but I see why they want to do it this way.

• I posted about this before. Diablo power plant uses seawater for cooling. The initial exposure is well over 200C, which part of this is then flash distilled for fresh water. However, at the time of heating the water, the CO2 and other gases, are released. Capture it at that point.
  
  Note that the utility gets to have fresh water, pull out purified CO2, and pull out other elements from the concentrated brine. Oddly, 2 of the easiest to pull out is uranium and thorium. Turns out they will stick to treated paper.
• This process collects CO2 as gas. How is it sequestered? Separating CO2 from air is going to be expensive. Collecting it from sea water seems more efficient. Still we have to sequester it.

  Wondering if it is possible to just add some sort of chemical to sea water, precipitate the dissolved CO2 into some nonsoluble inert carbonate particles that will simply sink to the sea bottom.

  • Re:

    What the fuck is wrong with you? Half of life on this planet lives in the deep and feeds on detritus on the sea floor. You put a coating of CO2 precipitate on the sea floor and who knows what havoc you'll wreak.

    Seriously, hear me out for a better solution. If only there were a way to take CO2, cleave the O2 from it, and use the C for something else, that would be pretty damn awesome. But, it looks like nobody has been able to figure that one out./s

• Some form of carbon scrubbing will be the main answer. Not hectoring, blaming, forming new eco-religions, etc.

• 71 percent of the world is ocean which is already performing carbon capture naturally. What makes anyone think that this idea is going to make any significant difference?

• Seawater also contains vast quantities of microscopic living organisms. if not done carefully this method may decimate these organisms which are an essential part of the marine ecosystem food chain.