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You don’t necessarily need fusion or nuclear power to remove carbon dioxide from the atmosphere. At least theoretically, you get more energy from burning hydroc

You don’t necessarily need fusion or nuclear power to remove carbon dioxide from the atmosphere. At least theoretically, you get more energy from burning hydrocarbons than is necessary to capture the released CO2 from the atmosphere. So you can (in theory) burn hydrocarbons while capturing the emissions and still producing energy.

peanutz454 6y ago
Aren't we running out of hydrocarbons?
- barry-cotter 6y ago
  No. At the most trivial level they grow on trees or anything else that grows using photosynthesis. On a more pragmatic level usable reserves is not a fixed description of the world, it depends on technology. Fracking gets oil out of the ground at economic prices from what would have been unusable trash twenty years ago. You see the same thing in many different kinds of mining. There are places where they’re making a profit extracting iron from old tailings now, i.e. the waste from mining iron a hundred years ago is now itself profitable to mine for iron.
  - sudhirj 6y ago
    As a thought experiment (don't try this at home) it's actually feasible to cut all the trees on earth down, burn them without releasing that CO2 into the air and use that energy to scrub the atmosphere. This is a horrible idea, of course, but the illustrates the point above. All organic life either creates (via photosynthesis) or consumes hydrocarbons, so we have a lot of it to burn – the trick is not to let the gases into the air, which is what we never should have done in the first place.
sudhirj 6y ago
Yeah, that sort of makes sense. Hydrocarbons are carbon + water + energy package, and burning them gives out the energy which you can use for scrubbing the atmosphere, provided you don't exhaust carbon byproduct into the atmosphere, which is really what got us into this mess in the first place.
posix_me_less 6y ago
> So you can (in theory) burn hydrocarbons while capturing the emissions and still producing energy. I like this theory, any example of trying it in practice?
- ZeroGravitas 6y ago
  Theres working examples, however they use the captured CO2 to get more oil out of nearly exhausted oil wells, so its a bit of a non-solution. We will probably need to capture carbon but it'll be cheaper to use renewables or nuclear to provide the energy than burn oil. Even if you use fossil fuels as an input (say because youre capturing methane that would otherwise escape i to the atmosphere), you can do stuff like break them down into grapgite and hydrogen so you getha clean burning fuel and useful material.
credit_guy 6y ago
I just did the math and you are right: burning enough natural gas to release 1kg of CO2 releases about 20 MJ of energy (but we can't capture all of it because second principle of thermodynamics). Capturing 1kg of CO2 from the atmosphere with this method requires 1.3 MJ, so it's feasible. But then, what do you do with the captured CO2? We put about 35 gigatons of CO2 in the air every year. Let's say we want to remove 15 of them, to get to the emissions level of 1980. 15 GT is staggering. For comparison, the world dumps about 2 GT of waste per year [1]. [1] https://www.theworldcounts.com/challenges/planet-earth/state-of-the-planet/world-waste-facts https://www.theworldcounts.com/challenges/planet-earth/state...

peanutz454 6y ago

Aren't we running out of hydrocarbons?

barry-cotter 6y ago
No. At the most trivial level they grow on trees or anything else that grows using photosynthesis. On a more pragmatic level usable reserves is not a fixed description of the world, it depends on technology. Fracking gets oil out of the ground at economic prices from what would have been unusable trash twenty years ago. You see the same thing in many different kinds of mining. There are places where they’re making a profit extracting iron from old tailings now, i.e. the waste from mining iron a hundred years ago is now itself profitable to mine for iron.
- sudhirj 6y ago
  As a thought experiment (don't try this at home) it's actually feasible to cut all the trees on earth down, burn them without releasing that CO2 into the air and use that energy to scrub the atmosphere. This is a horrible idea, of course, but the illustrates the point above. All organic life either creates (via photosynthesis) or consumes hydrocarbons, so we have a lot of it to burn – the trick is not to let the gases into the air, which is what we never should have done in the first place.

sudhirj 6y ago

Yeah, that sort of makes sense. Hydrocarbons are carbon + water + energy package, and burning them gives out the energy which you can use for scrubbing the atmosphere, provided you don't exhaust carbon byproduct into the atmosphere, which is really what got us into this mess in the first place.

posix_me_less 6y ago

> So you can (in theory) burn hydrocarbons while capturing the emissions and still producing energy. I like this theory, any example of trying it in practice?

ZeroGravitas 6y ago
Theres working examples, however they use the captured CO2 to get more oil out of nearly exhausted oil wells, so its a bit of a non-solution. We will probably need to capture carbon but it'll be cheaper to use renewables or nuclear to provide the energy than burn oil. Even if you use fossil fuels as an input (say because youre capturing methane that would otherwise escape i to the atmosphere), you can do stuff like break them down into grapgite and hydrogen so you getha clean burning fuel and useful material.

credit_guy 6y ago

I just did the math and you are right: burning enough natural gas to release 1kg of CO2 releases about 20 MJ of energy (but we can't capture all of it because second principle of thermodynamics). Capturing 1kg of CO2 from the atmosphere with this method requires 1.3 MJ, so it's feasible. But then, what do you do with the captured CO2? We put about 35 gigatons of CO2 in the air every year. Let's say we want to remove 15 of them, to get to the emissions level of 1980. 15 GT is staggering. For comparison, the world dumps about 2 GT of waste per year [1]. [1] https://www.theworldcounts.com/challenges/planet-earth/state-of-the-planet/world-waste-facts https://www.theworldcounts.com/challenges/planet-earth/state...