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We burn oil to produce cheap energy and we get CO2 as a byproduct. If you want to reverse the process you need some energy, so what would be the point of burni

We burn oil to produce cheap energy and we get CO2 as a byproduct. If you want to reverse the process you need some energy, so what would be the point of burning the oil in the first place?

ams6110 10y ago
The energy could be from wind, solar -- in fact it might be an ideal use case for those sources if the process can be done intermittently, i.e. whenever the wind is blowing or the sun is shining. Or you could envision large carbon sequestration plants powered by on-site nuclear.
- bnegreve 10y ago
  > Or you could envision large carbon sequestration plants powered by on-site nuclear. I'm not sure I understand, you're suuggesting that we 1. Burn oil to produce energy (and CO2 as a byproduct) 2. Use the energy to do X 3. Use non-fossil energy to get rid of the CO2 we created during step 1. When we could just do: 1. Use non-fossil energy to do X Am I missing something?
  - bhickey 10y ago
    0. There's a lot of carbon in the air and we might want to get rid of it.
    - ams6110 10y ago
      Yes, I was unclear. We've presumably got 100+ years of industrial carbon emissions to clean up if we want to get back to "pre industrial" atmospheric carbon. Plus ongoing emissions from transportation even if all electrical power is converted to renewable or nuclear.
  - david-given 10y ago
    Transport. Fossil fuels are incredibly energy-dense and convenient to transport and work with, while renewables aren't. There's plenty of transport systems that are utterly reliant on fossil fuels and couldn't be converted to renewable energy. Carbon sequestering would allow continued use of these while staying carbon-neutral.
    - schiffern 10y ago
      That seems like a very circuitous and inefficient way to avoid electrifying transport. Batteries are hard, but they're not that hard (as Tesla's rapid progress is demonstrating).
      - philipkglass 10y ago
        Land transportation accounts for the majority of liquid fuel use, and much of that can be replaced by battery power assuming that battery costs continue to drop. I'd guess that battery powered airliners and long distance cargo ships will not become practical. Those and other transport applications particularly demanding of energy density account for a large enough residual of liquid fuel use that it's worth thinking about how to avoid fossil emissions from them. Synthetic liquid fuels made from non-fossil energy sources is one way to do it. (Biofuels are an option too, but plants are a lot less energetically efficient than solar farms, so you need a lot more production area for biofuel than synthetic fuel.)
        schiffern 10y ago
        >I'd guess that battery powered airliners and long distance cargo ships will not become practical. We shall see. For whatever it's worth, Tesla's CEO disagrees. https://www.youtube.com/watch?v=0871VJfvD1c&t=57s https://www.youtube.com/watch?v=0871VJfvD1c&t=57s >I think all transport, with the exception of rockets, will go fully electric. This is the most recent example, but he's been saying this since at least 2013. Surprisingly, he's also made it clear that he thinks this applies to ships and planes too. http://www.digitaltrends.com/cool-tech/elon-musk-electric-aircraft/ http://www.digitaltrends.com/cool-tech/elon-musk-electric-ai...
        bluGill 10y ago
        I do not think batteries will ever get a useful enough energy/weight ratio for airplanes. https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density Not only does jet fuel have a much better energy to weight ratio, but you don't have to carry the weight of your spent fuel. A battery powered airplane needs to get all its fuel to altitude while a fuel powered one has much less mass to get up (and stop when you get to the ground). Ships probably will see batteries as an asset: they can place them in ideal locations for weight distribution/stability.
PeterisP 10y ago
If we want to reverse the CO2 we released by burning all these fossil fuels, at some point we'll need to essentially "unburn" them - and yes, that would necessarily involve "paying back" all the energy humanity got from burning these fuels.
kmm 10y ago
We'd only need a large amount of energy if we want to turn it back into a high-energy compound like oil or coal. The method described in the article has CO2 turning into calcium carbonate, which does not need an energy input (in fact, it releases energy in the form of heat)

We burn oil to produce cheap energy and we get CO2 as a byproduct. If you want to reverse the process you need some energy, so what would be the point of burning the oil in the first place?

ams6110 10y ago

The energy could be from wind, solar -- in fact it might be an ideal use case for those sources if the process can be done intermittently, i.e. whenever the wind is blowing or the sun is shining. Or you could envision large carbon sequestration plants powered by on-site nuclear.

bnegreve 10y ago
> Or you could envision large carbon sequestration plants powered by on-site nuclear. I'm not sure I understand, you're suuggesting that we 1. Burn oil to produce energy (and CO2 as a byproduct) 2. Use the energy to do X 3. Use non-fossil energy to get rid of the CO2 we created during step 1. When we could just do: 1. Use non-fossil energy to do X Am I missing something?
- bhickey 10y ago
  0. There's a lot of carbon in the air and we might want to get rid of it.
  - ams6110 10y ago
    Yes, I was unclear. We've presumably got 100+ years of industrial carbon emissions to clean up if we want to get back to "pre industrial" atmospheric carbon. Plus ongoing emissions from transportation even if all electrical power is converted to renewable or nuclear.
- david-given 10y ago
  Transport. Fossil fuels are incredibly energy-dense and convenient to transport and work with, while renewables aren't. There's plenty of transport systems that are utterly reliant on fossil fuels and couldn't be converted to renewable energy. Carbon sequestering would allow continued use of these while staying carbon-neutral.
  - schiffern 10y ago
    That seems like a very circuitous and inefficient way to avoid electrifying transport. Batteries are hard, but they're not that hard (as Tesla's rapid progress is demonstrating).
    - philipkglass 10y ago
      Land transportation accounts for the majority of liquid fuel use, and much of that can be replaced by battery power assuming that battery costs continue to drop. I'd guess that battery powered airliners and long distance cargo ships will not become practical. Those and other transport applications particularly demanding of energy density account for a large enough residual of liquid fuel use that it's worth thinking about how to avoid fossil emissions from them. Synthetic liquid fuels made from non-fossil energy sources is one way to do it. (Biofuels are an option too, but plants are a lot less energetically efficient than solar farms, so you need a lot more production area for biofuel than synthetic fuel.)
      - schiffern 10y ago
        >I'd guess that battery powered airliners and long distance cargo ships will not become practical. We shall see. For whatever it's worth, Tesla's CEO disagrees. https://www.youtube.com/watch?v=0871VJfvD1c&t=57s https://www.youtube.com/watch?v=0871VJfvD1c&t=57s >I think all transport, with the exception of rockets, will go fully electric. This is the most recent example, but he's been saying this since at least 2013. Surprisingly, he's also made it clear that he thinks this applies to ships and planes too. http://www.digitaltrends.com/cool-tech/elon-musk-electric-aircraft/ http://www.digitaltrends.com/cool-tech/elon-musk-electric-ai...
        bluGill 10y ago
        I do not think batteries will ever get a useful enough energy/weight ratio for airplanes. https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density Not only does jet fuel have a much better energy to weight ratio, but you don't have to carry the weight of your spent fuel. A battery powered airplane needs to get all its fuel to altitude while a fuel powered one has much less mass to get up (and stop when you get to the ground). Ships probably will see batteries as an asset: they can place them in ideal locations for weight distribution/stability.

PeterisP 10y ago

If we want to reverse the CO2 we released by burning all these fossil fuels, at some point we'll need to essentially "unburn" them - and yes, that would necessarily involve "paying back" all the energy humanity got from burning these fuels.

kmm 10y ago

We'd only need a large amount of energy if we want to turn it back into a high-energy compound like oil or coal. The method described in the article has CO2 turning into calcium carbonate, which does not need an energy input (in fact, it releases energy in the form of heat)