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A lot of people think carbon capture and storage has the potential to save us from climate change, but that idea ignores the scale of the situation. The world

A lot of people think carbon capture and storage has the potential to save us from climate change, but that idea ignores the scale of the situation. The world generates ~40 billion tons of CO2 a year, meanwhile the total mass of everything transported in the entire world is only around ~12b tons.

agumonkey 5y ago
And then there's the fossil fuel dependency. We still need more than will be produced, even ignoring CO2 levels.
DennisP 5y ago
Well we do move that 40 billion tons to the atmosphere. If we can do that, then in principle we can do the reverse. We just need an economic framework to pay for it. It's certainly going to be cheaper, in most cases, to avoid emissions in the first place. But there will also be cases, like long-haul jets, where it may be cheaper to remove the CO2 later. Plus the CO2 is already above a safe level, so we'll have to draw it down somehow anyway.
- halpert 5y ago
  We only move a small portion of the 40 billion tons. Most of the mass of CO2 is oxygen, which was already present in the atmosphere before we combined it with carbon.
  - lmm 5y ago
    Even assuming you can do some kind of reaction in-place, CO2 is over 25% carbon by mass. 10 billion tons is still a massive challenge.
    - czbond 5y ago
      But don't we only need to "first" remove just enough of that 10 billion tons to maintain where we are now, so that we can then remove more to "go back to levels earlier in modern time"?
      - dataflow 5y ago
        Yeah, we need to go extremely carbon-negative, not merely carbon-neutral. It's so easy to forget this.
        elzbardico 5y ago
        Why?
        dataflow 5y ago
        Why do we need to go carbon-negative? Because the atmosphere already has too much CO2, and reducing net emissions to 0 means that CO2 will stay there. We've emitted that CO2 in the course of (say) 300 years but need to pull it down in (say) < 50 years, hence we need to pull it down much faster than we emitted it. Not sure if that answered your question or if you meant something else.
        czbond 5y ago
        Thanks - that did help me.
        elzbardico 5y ago
        Yes, but what I wanted to know is if we kept the current concentrations would temeperature keep rising or would it stay basically the same as it is today.
        ummonk 5y ago
        It would stay the same. And nature would reduce current concentrations back to normal over the next few centuries.
_dain_ 5y ago
But only about 16% of that mass of CO2 was ever "transported" in the first place: the carbon atom. The O2 part appears for free because it comes out of the air the fuel is burned in. And that oxygen wouldn't be transported with carbon capture either, it would just be vented into the atmosphere again. I mean think about it, we can't be emitting more waste than we are transporting, because that waste comes from fuel, and the fuel itself is part of what we're transporting.
- deleted 5y ago
  [deleted]
colechristensen 5y ago
All of the carbon we put in the atmosphere was transported (oil, coal, etc) to the location where it was used so this rings false. Presumably the carbon will be pulled from the atmosphere on site and stored on site anyway. Maybe something like building solar arrays in semi-arid regions and mixing up the resulting solid carbon into the local soil for some ecological engineering or filling up old mining pits.
- 0xB31B1B 5y ago
  The carbon gains 2 oxygens when combusted, tripling the weight of the original fuel
  - hamandcheese 5y ago
    Presumably it also loses 2 oxygens when it is turned back into solid carbon.
dataflow 5y ago
Related, for comparison: apparently planting 20B trees/year requires only $80M/year (!) and would pull down a trillion tons of carbon over 50 years (!): https://www.youtube.com/watch?v=QyQvfaW54NU&t=14m53s https://www.youtube.com/watch?v=QyQvfaW54NU&t=14m53s
- cjameskeller 5y ago
  But they would decay, unless something is done to sequester enough of the wood, and release much of it back into atmosphere, right?
  - dataflow 5y ago
    > unless something is done to sequester enough of the wood I think that was the idea. He's viewing it as a mass transfer problem. You "harvest" CO2 with trees, then put it back in the ground. I think the hard part is not hurting ecosystems in the process, but at this point honestly this might still be the best solution we have available.
    - denton-scratch 5y ago
      Unfortunately, the people that plant trees have economic incentives to not put it back in the ground. Timber has considerable economic value, as fuel, or contruction materials or whatever. It's hard to imagine foresters cutting down valuable trees, and then discarding them in some lake.
      - dataflow 5y ago
        I imagine it would need to be government funded, not for private enterprise. If the order of magnitude of the costs they mention are to be taken at face value ($80M/year), for the entire world, it would be absolutely trivial for the government to fund, so I don't think expect any commercial enterprise would necessarily be forced to align this with its mission.
        5y ago

agumonkey 5y ago

And then there's the fossil fuel dependency. We still need more than will be produced, even ignoring CO2 levels.

DennisP 5y ago

Well we do move that 40 billion tons to the atmosphere. If we can do that, then in principle we can do the reverse. We just need an economic framework to pay for it. It's certainly going to be cheaper, in most cases, to avoid emissions in the first place. But there will also be cases, like long-haul jets, where it may be cheaper to remove the CO2 later. Plus the CO2 is already above a safe level, so we'll have to draw it down somehow anyway.

halpert 5y ago
We only move a small portion of the 40 billion tons. Most of the mass of CO2 is oxygen, which was already present in the atmosphere before we combined it with carbon.
- lmm 5y ago
  Even assuming you can do some kind of reaction in-place, CO2 is over 25% carbon by mass. 10 billion tons is still a massive challenge.
  - czbond 5y ago
    But don't we only need to "first" remove just enough of that 10 billion tons to maintain where we are now, so that we can then remove more to "go back to levels earlier in modern time"?
    - dataflow 5y ago
      Yeah, we need to go extremely carbon-negative, not merely carbon-neutral. It's so easy to forget this.
      - elzbardico 5y ago
        Why?
        dataflow 5y ago
        Why do we need to go carbon-negative? Because the atmosphere already has too much CO2, and reducing net emissions to 0 means that CO2 will stay there. We've emitted that CO2 in the course of (say) 300 years but need to pull it down in (say) < 50 years, hence we need to pull it down much faster than we emitted it. Not sure if that answered your question or if you meant something else.
        czbond 5y ago
        Thanks - that did help me.
        elzbardico 5y ago
        Yes, but what I wanted to know is if we kept the current concentrations would temeperature keep rising or would it stay basically the same as it is today.
        ummonk 5y ago
        It would stay the same. And nature would reduce current concentrations back to normal over the next few centuries.

_dain_ 5y ago

But only about 16% of that mass of CO2 was ever "transported" in the first place: the carbon atom. The O2 part appears for free because it comes out of the air the fuel is burned in. And that oxygen wouldn't be transported with carbon capture either, it would just be vented into the atmosphere again. I mean think about it, we can't be emitting more waste than we are transporting, because that waste comes from fuel, and the fuel itself is part of what we're transporting.

deleted 5y ago
[deleted]

colechristensen 5y ago

All of the carbon we put in the atmosphere was transported (oil, coal, etc) to the location where it was used so this rings false. Presumably the carbon will be pulled from the atmosphere on site and stored on site anyway. Maybe something like building solar arrays in semi-arid regions and mixing up the resulting solid carbon into the local soil for some ecological engineering or filling up old mining pits.

0xB31B1B 5y ago
The carbon gains 2 oxygens when combusted, tripling the weight of the original fuel
- hamandcheese 5y ago
  Presumably it also loses 2 oxygens when it is turned back into solid carbon.

dataflow 5y ago

Related, for comparison: apparently planting 20B trees/year requires only $80M/year (!) and would pull down a trillion tons of carbon over 50 years (!): https://www.youtube.com/watch?v=QyQvfaW54NU&t=14m53s https://www.youtube.com/watch?v=QyQvfaW54NU&t=14m53s

cjameskeller 5y ago
But they would decay, unless something is done to sequester enough of the wood, and release much of it back into atmosphere, right?
- dataflow 5y ago
  > unless something is done to sequester enough of the wood I think that was the idea. He's viewing it as a mass transfer problem. You "harvest" CO2 with trees, then put it back in the ground. I think the hard part is not hurting ecosystems in the process, but at this point honestly this might still be the best solution we have available.
  - denton-scratch 5y ago
    Unfortunately, the people that plant trees have economic incentives to not put it back in the ground. Timber has considerable economic value, as fuel, or contruction materials or whatever. It's hard to imagine foresters cutting down valuable trees, and then discarding them in some lake.
    - dataflow 5y ago
      I imagine it would need to be government funded, not for private enterprise. If the order of magnitude of the costs they mention are to be taken at face value ($80M/year), for the entire world, it would be absolutely trivial for the government to fund, so I don't think expect any commercial enterprise would necessarily be forced to align this with its mission.
      - 5y ago