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Science

Locking CO2 Away For Good 69

Posted by timothy from the and-stay-there dept.
HobbySpacer writes: "The BBC reports that waste CO2 from methane extraction in the North Sea has been succesfully pumped back into the pourous sandstone beneath the ocean for the past 6 years without any signs of leaking. Carbon sequestration techniques like this are looking increasingly practical. CO2 is being pumped back into depleted oil fields, where it also helps extract remaining oil deposits, and into coalseams. The ocean is the biggest natural bank of CO2 but tests of ocean sequestration in Hawaii and Norway have been blocked by environmentalists who hate this kind of quick fix approach to the CO2 problem. But with developing countries like India and China certain to rely on their large coal reserves, sequestration may be the only realistic approach to reducing their CO2 output. An Economist article discusses currently available steam reformation technology that could allow a coal plant to output power and neatly separated CO2 and hydrogen. The non-polluting hydrogen is then available for cars with fuel cells while the CO2 is stuffed away."
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Locking CO2 Away For Good More

Locking CO2 Away For Good

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  • CO2 is bad? (Score:1, Funny)

    by Anonymous Coward
    How long before environmentalists ban carbonated beverages? OMG I am breathing out CO2!! Must... stop... breathing.
  • What if something weird happens and the CO2 gets released in massive amounts? Like, a bomb, or a sinking ship, or an earthquake? Really though, the Earth's crust isn't a very stable place in its natural state and we don't have the resources and technology to put huge reinforced structures under the ocean to store the CO2 properly.
    The ocean floor in particular is a very unstable place. If you look at the pacific, all those tiny little islands were made by volcanos that appeared there all of a sudden, out of the blue, with no early warning. Apparently there are some "hotspots" in the magma layers below our surface, which puncture the Earth's crust forming temporary volcanos, that go extinct as the crust moves tectonically away from the hotspot below it. You never know what might hit an undersea CO2 deposit even if it was a solid, well engineered structure. The crust is very thin there! Cave-ins, earthquakes, volcanic activity in general, you wouldnt want to live at the bottom of the sea.
    It sounds like a quick hack that will solve the problem temporarily, but I can just see the CO2 getting released sooner or later.

    • Re:This is really cool and all but... (Score:4, Insightful)

      by 0x69 ( 580798 ) on Thursday September 12, 2002 @09:47AM (#4244612) Journal
      The CO2 would be in thousands or millions of old oil wells, coal seams, etc. and millions of square miles of deep ocean. Any one of those spots could have a problem & release some small fraction of 1% of the CO2.

      If anything big enough to release a large fraction of the CO2 comes along (giant asteroid, Iraq's "Planet Buster" nuclear doomsday device, etc.), then we'll have *far* greater worries than the CO2 release.

    • Re:This is really cool and all but... (Score:5, Insightful)

      by sofar ( 317980 ) on Thursday September 12, 2002 @10:10AM (#4244778) Homepage
      Near surface natural CO2 deposits (dry ice) have been discovered and found to be a huge danger to anything that comes around. These deposits generally lie very shallow under the seafloor and can be meters in thickness. The biggest danger is not their sudden release and toxic effects of that, but lies in a totally different factor.

      In several ocean slopes (offshore norway, east coast US) these deposits suddenly gave way in history, allowing the cover of these deposits to start sliding down the oceanic ramps. The gasses maybe killed some fish, but the Norway slide triggerd a tidal wave that reached elevations of over 100m in height when it crashed into the north of Scotland (that's 500-1000km further), destructing everything in it's path.

      Another danger is to ships and constructions. The massive amount of gasses makes the sea like a giant bubblebath. Anyone that every played with a rubber duck that barely floats in a bubblebath knows what happens when you turn on the bubbles hard enough: it sinks. A massive gas pipe blowout just below an oil righ in the North Sea caused a complete oil/gas rig to sink like a rock a few decades ago.

      That said CO2 looks like a dangerous thing to toy with, but that's not the case in the oil fields we are talking about here.

      Most of these fields are at enormous depths, the typical North sea fields (in which these experiments have been done for quite a while) are at depths of over 500m. The rocks at that location are much more stable, and at 800m we're talking about serious tough rocks.

      Using CO2 to extract the oil better (by pressurizing depleted oil fields) and returning the CO2 they are hitting the jackpot twice: First they can revive old fields relatively cheap and extract more oil, and secondly they can do something back for the environment in a very safe way.

      The argument of cave-ins, earthquakes are however very serious ones. The typical example of a colorado experiment where fluids were injected into deep crustal fissures resulting in earthquakes occuring daily instead of yearly warn us against toying with the earth's structure.

      That said one must conclude that CO2 injection must be evaluated before it is even tried. As a geologist from the Netherlands I can honestly say this news is not new. CO2 injection has been discussed for over a decade now and thes tests were done in several other fields in small scale before this larger experiment by statoil.

      When you say "in general, you wouldnt want to live at the bottom of the sea" I can vough for that too, if you think the bottom of the sea is a safe place then you are wrong! But pumping some CO2 to fill up a hole you created again might be better than leaving the hole there. At least we should put a cover on the hole after we finished using it.
      • Near surface natural CO2 deposits (dry ice) have been discovered and found to be a huge danger to anything that comes around

        Are you sure that those were CO2 deposits, and not methane hydrates [orst.edu]?

        I've never heard of undersea dry ice, although there are a few lakes like Lake Nyos [marekinc.com] that contain very large amounts of dissolved CO2, and have occasionally released large clouds of the gas (killing hundreds of people in the valley below).
        • ahh yes, you are correct, I confused something there!

          As for the dissolved CO2, I once saw a video from one of my U. teachers trying to bounce a little submarine into a subsea pond of CO2 at 1100m depth, incredibly fascinating to see that the density was so dense that the sub (being neutrally buoyant to water) was too light and skidded right off, only to leave ripples on the surface!

          Many large lakes in Africa contain huge amounts of CO2 dissolved and sinking to the bottom. But there are quite some locations in oceans as well where smaller 'ponds' of CO2 exists. The mediteranean sea is a well known example.
      • The argument of cave-ins, earthquakes are however very serious ones. The typical example of a colorado experiment where fluids were injected into deep crustal fissures resulting in earthquakes occuring daily instead of yearly warn us against toying with the earth's structure.

        Doesn't that mean that the earthquakes are now far smaller in magnitude ? In fact, the problem with earthquakes is that they release a lot of energy in a short time.
      • Using CO2 to extract the oil better (by pressurizing depleted oil fields)
        If I understand correctly, the CO2 provides a lot more than just pressurization (otherwise, water would be just as good and a lot cheaper). Liquid CO2 is a solvent, and can dissolve and transport oil which would otherwise remain stuck in the pores of rocks. It offers a way to recover oil from "tapped out" fields (where water has infiltrated between the remaining spots of oil and keeps them from being pushed save by density differences), and of course - if the CO2 is there under the ground, it isn't in the atmosphere and might even form carbonate rocks to lock it into place permanently.
      • Is dry ice possible at the extreme pressure of the deep sea floor? I know, sofar acknowledged he/she really meant Methane hyrdrate ice, not dry ice. Still, I was curious. I found this page, which has an account of experimenting with liquid CO2 at depth. [noaa.gov] At that pressure CO2 is liquid, and denser than water.

        The clathrate [uni-mki.gwdg.de] the article mentions is a kind of slush of water ice with something else dissolved in it. So the methane hydrate we discussed is a clathrate too.

      • The biggest danger is not their sudden release and toxic effects of that, but lies in a totally different factor.

        When CO2 suddenly bubbles up from a lake near a population center (as it has in some cases), it can lead to a sudden and massive disaster. But I agree that that's probably not much of a danger if it's pumped into an off-shore oil-field.

    • If you look at the pacific, all those tiny little islands were made by volcanos that appeared there all of a sudden, out of the blue, with no early warning. Umm, last I checked, the emerging island off the coast of Hawaii won't poke it's little head above water for another few million years. Not quite what I'd call sudden or out of the blue. To my knowledge, this is normal, and islands don't just appear instantaneously. Then again, they didn't make us learn about hot-spots, volcanoes, and the creation of the Hawaiian island chain like every two years in school back in Hawaii...
    • What if something weird happens and the CO2 gets released in massive amounts?
      That's rather unlikely, due to the depths we're talking about here, but... what if it doesn't get released?

      The pH of the ocean is moderated by a carbonate/bicarbonate buffer. If you add acid to the ocean (including carbonic acid, H2CO3), some of the carbonate (CO3--) ions soak up hydrogen ions and become bicarbonate (HCO3-) ions. This is okay, but a lot of ocean organisms require carbonate ion to build their skeletons, including corals, molluscs, and a host of smaller things. Cut the fraction of carbonate in the ocean (and add acid, which tends to eat the carbonate they've already laid down) and they have a tough time surviving. The last thing we need at the moment is to put extra pressures on the surviving coral reefs, clam and oyster beds, and everything else out there.

      Dumping CO2 where it changs the ocean chemistry may be a bad idea.

    • Uh... This CO2 was being pumped back where it came from. Anything which releases it -- would have released it without we humans having removed the useful gases...along with releasing the other stuff.

  • CO2 future fuel... (Score:2, Interesting)

    by wiretrip ( 552807 )
    Cool, maybe in about 2000000 years CO2 will become the next major fuel and everyone will be fighting over land 'rich in ancient CO2 deposits'!
    • i was reading this and thinking, what if he pumped h2 down with the co2? Will the pressure cause oil to be made in the distant future?:)
      • what if he pumped h2 down with the co2? Will the pressure cause oil to be made in the distant future?

        I am not sure if you are joking.

        Pure hydrogen is, I believe, much more costly than crude oil. So this does not seem to be a win to me.

      • Well, if Dr. Gold is right... the bacteria which created the first batch of oil will get back to work and process the new stuff.

        It probably would be more efficient to pump H2O with the CO2, then let them trickle down to a depth where the heat provides enough energy for the bacteria to process them.

        And as the H2O and CO2 mix is acidic and dissolves some rock...good. That will make larger channels for faster upwelling of all the hydrocarbons...unless calcium deposits where the processing takes place ends up blocking those channels. But the bacterial action is probably eroding the rock in that area anyway.

      • Whoa.. .I forgot that sometimes water or steam is pumped into an oil field. And any rock below the water table may have water present.

        So by pumping the CO2 back down there...they are already providing carbon for whatever wants it. Assuming there are carbonate rocks which are unsatisfactory...and oil has been found in areas with no sedimentary rock, so carbonate rocks (and possible organic fossil material) are not required anyway.

  • for my beer keg, when the UK is throwing away perfectly good CO2?

    Oh yeah, it's the UK, they don't know that CO2 is supposed to be in beer.

  • Disposal? (Score:1, Flamebait)

    by dacarr ( 562277 )
    Why not plant more trees? Hell, any old plant will do. Not very efficient, but they would certainly make use of the carbon dioxide, and get the right landscaper and s/he'll make it look really nice. Or is this too simple for environmentalists to grasp?
    • Trees certainly do absorb a lot of CO2, and I think you'd be hard pressed to find environmentalists who would oppose planting trees to benefit the planet. Of course, it's important to grow the right type of trees -- evergreens grow really quickly, and it's tempting to always plant them first. But ultimately you want a good variation of trees, ideally native species.

      This is why preserving old growth forests and rainforests is important. The trees are already there, so they don't need to planted! We just have to somehow keep ourselves from chopping them down all the time.
      • The only problem is that the trees we chop down are usually used for something. Sure we can recycle paper (which uses energy and releases polutants) but would yo want a house built out of recycled wood? Steel and Aluminum are becoming more popular building materials, but those have to come from somewhere. How do you feel about mining?
        No, we will chop down trees and we will replant. We will mine and we will polute. We will eventually make the Earth uninhabitable for humanity, and then humans will be extinct. "Take only photographs and leave only footprints," may work at Yosemite, but it doesn't scale very well.
        • Sure we can recycle paper (which uses energy and releases polutants) but would yo want a house built out of recycled wood?
          We're pretty much there already. Have you looked at structural beams and floor joists lately? They are no longer solid wood. The beams are laid up of layers of veneer, and the joists are I-beams with small cap-strips of solid wood (finger-jointed) joined by a web of waferboard. You can practically crank out floor joists out of debarked scrub timber and the chips and shavings you get from milling the cap strips.

          We already make insulation out of used newsprint. If the price of wood goes much higher, it may become economical to make joists and beams out of recycled paper.

          Steel and Aluminum are becoming more popular building materials, but those have to come from somewhere. How do you feel about mining?
          Looks to me like a steel building could be recycled fairly easily, and a huge fraction of the earth's crust is aluminum (in the form of aluminum silicates). Then there are the low-tech standbys of adobe and rammed earth. How do you feel about digging up your building materials wherever you happen to be? Regardless of how primitive our methods are now, they won't remain so any more than aluminum remained more precious than gold.
        • "...would yo want a house built out of recycled wood?"

          Aren't you aware that taking a tree and sealing it inside a wall is carbon sequestration? You're taking that carbon and locking it away so it doesn't reenter the environment. So you do want the trees to be used for something.

    • What could be more efficient? It takes all the energy in a tic-tac to dig a little hole, drop in a seed and cover it up. The sun and rain take over from there.

      True, it will take a while to grow into a great big tree but the energy you put in is virtually nothing.

    • Re:Disposal? (Score:3, Funny)

      by sofar ( 317980 )
      We might be better off getting rid of all the case-modders using dry ice to cool their mobos! Liquid Nitrogen is sooooo much more environmental conscious!
    • Why not plant more trees? Hell, any old plant will do.

      Most land that isn't paved or built over has plants growing on it, to my eyes. Certainly trees would absorb more CO2 than grass, but grassy areas are generally mowed, and thus planting a tree will result in a mowed-down seedling in a few weeks. So Johnny Appleseed ain't gonna work; you need the owners of the grasslands to do the planting. But most landowners landscape based on their desires, not to have an individually trivial effect on CO2 levels. Are you going to legally require landowners to plant trees?

      You could have governments do more tree planting by roads and the like, but then a few years after a planting they'll be widening the road and chop everything down to grass level again.

      Now, people are clearing the Amazon rainforest for small short-term gains. One suggestion has been to pay the Brazilians to restrict Amazon clear-cutting, to keep that carbon in the trees. But for some reason, politicians aren't exactly jumping at the prospect.
      • One thing I don't understand about this argument. An old tree has a lot of carbon in it. At some point the growth of this tree is going to slow, and so will it's CO2 consumption. If I cut down that tree I've made room for a younger faster growing tree that will in turn lock up a bunch more carbon. Assuming I don't burn the tree I've cut down the carbon is still traped. Granted the seedling won't process as much CO2 to start with as the old Oak, but since it's still growing it will probably consume more in total over the next n years. So why exactly are environmentlists so fascinated by leaving old trees in the ground? Old growth forests are also more likely to have out of control fires which leads to more carbon release.

        • If I cut down that tree I've made room for a younger faster growing tree that will in turn lock up a bunch more carbon. Assuming I don't burn the tree I've cut down the carbon is still trapped.

          It may rot, which will also release carbon, but yes you are generally correct. A landfill is a carbon sink! The reason to recycle paper is not carbon-related; it's that tree farms are generally unsuitable for most wildlife.

          So why exactly are environmentalists so fascinated by leaving old trees in the ground?

          I can't by any means speak for all environmentalists (nor, for that matter, do they speak with one voice), but I would think that carbon is not the issue. Dead trees provide habitat for a number of creatures. Decomposing trees are natural mulch. And generally when timber companies come in, it's much more economical to clear-cut, which leads to erosion and makes the land unsuitable for the wildlife that was living there.

          Now, if forests were thinned in less destructive ways, with a good fraction of the large trees left and fewer roads needed, it wouldn't do such lasting damage to the land.

          Old growth forests are also more likely to have out of control fires which leads to more carbon release.

          I'm not sure that you're right about that, but after a fire the land is primed for new growth, so the carbon gets recaptured over time.
          • I agree with all of your points, and the answer certainly lies in some moderate middle ground. However, I have never seen an environmentalist (by that I mean professionals who dedicate a large portion of their time to being interviewied, lobbying, forming other's opinions, etc. wrt environmental issues) who was in favor of moderation in anything.
          • "And generally when timber companies come in, it's much more economical to clear-cut, which leads to erosion and makes the land unsuitable for the wildlife that was living there."

            In what way is bare clear-cut land different from the result of a natural forest fire? The difference would be the greater layer of natural ash. Ash isn't particularly suitable to wildlife in the short term.

            • In what way is bare clear-cut land different from the result of a natural forest fire?

              Most forest fires don't burn every plant down to the roots. Take a google search for "forest fire plant growth", and you'll see a number of articles that are more informative than anything I can write here.

              Clear-cutting tends to be followed up with herbicides and single-species planting, also not conducive to animal life.
        • At some point the growth of this tree is going to slow, and so will it's CO2 consumption.
          Your whole argument rests on this. Do you have any evidence for it?
    • While I don't think any rational person is going to be against planting trees, they don't do as much good as wetlands. Unfortunately most of our wetlands are disappearing, and trees can't take up the slack.

  • Mineral carbonation is more permanent (Score:4, Informative)

    by pfdietz ( 33112 ) on Thursday September 12, 2002 @10:57AM (#4245059)
    This approach is useful, but it always leaves the possibility of leaks, and has limited capacity.

    The process of mineral carbonation [doe.gov] exothermically reacts CO2 with certain silicate minerals (or materials derived from these minerals) to yield carbonates that are stable on a geological time scale. There are more than enough of the desirable silicates (serpentine, olivine) to react with all the CO2 that will ever be produced by fossil fuel combustion.
  • An interesting article at:

    http://www.spacedaily.com/news/energy-tech-02o.h tm l

    Seems like another interesting way to sequester CO2. More ideas, more ways of approaching the problem...especially since peanuts are a pretty good soil-poor crop and have all those other uses.

    I mean, you're going to have peanut shells anyways...

    --foolish
  • Last month, Lawrence Livermore National Laboratory scientists released a study modeling the effectiveness of direct injection of carbon dioxide into different oceans at different depths. They've proposed injection into the ocean as a way to slow the accumulation of CO2 in the atmosphere.

    Injections were simulated at 800 meters, 1500 meters and 3000 meters for 100 hypothetical years near the Bay of Biscay, New York City, Rio de Janeiro, San Francisco, Tokyo, Jakarta and Bombay.

    The models showed that injection at 3000 meters is quite effective at sequestering carbon from the atmosphere for several centuries while injections at shallower depths are less effective. (Not too surprising.) In general, injections into the Pacific Ocean (San Francisco and Tokyo) were more effective than injection at the same depth in the Atlantic Ocean (New York City, Rio de Janeiro and the Bay of Biscay).

    The full press release is available here [llnl.gov].

  • In the 1970s dissolved CO2 that was deposited in lake Malawi by volcanic activity was released by a landslide that occurred during a heavy rainstorm. The effect was like shaking up a soda can. A huge amount of CO2 was released, lake levels dropped several *feet* and the released CO2 displaced the O2 around the lake (because it is heavier than O2 and the lake is in a depression). The effect was that hundreds of people who lived around the lake died because of lack of O2.

    Got to be aware of the unintended consequences of such actions. If the CO2 gets released it may not have global effect, but it can have an extremely serious local effect.

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