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I think the misconception stems from thinking that we could be net-positive energywise. We cannot. We can (and currently sort of have to) extract energy from f

I think the misconception stems from thinking that we could be net-positive energywise. We cannot. We can (and currently sort of have to) extract energy from fossil sources because our economy runs on hydrocarbons but we will need to expend more energy later to put the extra carbon back where it belongs. The energy we will expend for this in the future has to be renewable. We are basically borrowing from our future selves and will have to pay back the debt one day.

m4rtink 6y ago
This is a good summary - and it might just work out. There is a trend in our energy sources being more powerful and more efficient over time. More efficient solar panels, biger and more flexible wind turbines, bigger and safer nuclear reactors. So paying the "energy dept" in the future might be much easier than going without the fosil energy sources right now.
- renw0rp 6y ago
  The "borrowing" is not without some side effects which might be hard or impossible to revert in the future. It's like driving accelerating train without the breaks and hoping that someone builds tracks fast enough that we won't derail
  - TeMPOraL 6y ago
    Loss of biodiversity is one big thing. The species that went extinct due to us industrializing the planet, and the species that will go extinct due to climate change (even if brief and ultimately mitigated) will not come back. Sure, evolution keeps running its RNG and eventually new and interesting species will start showing up. But that doesn't replace the causal link that is lost. Today, the variety of organisms on our planet gives biologists a chance to understand how crucial mechanisms of life evolved. As we erase that history, we make biological sciences that much harder, and by extension, slow the progress of everything from medicine through biotech to chemistry and material sciences.
iguy 6y ago
> but we will need to expend more energy later to put the extra carbon back where it belongs Is this actually a given? I mean trying to make gasoline from the atmosphere would certainly require more energy than you get by burning it, a lot more. But I thought sensible capture proposals ran on different chemistry, possibly relying on a wet/dry cycle under which the affinity for carbon is different in the two halves. And letting evaporation (i.e. solar energy) move you from wet to dry. It's not obvious that these must use more energy than you got by burning the coal in the first place.
- _Microft 6y ago
  This was not meant to mean synthetic fuels but that we will eventually have to undo the damages that we currently bring about.
  - iguy 6y ago
    Sure, I agree. The part I question is "more energy later". Or at least, this is not obvious from a first-principles no-perpetual-motion argument. It's a technology question.
jofer 6y ago
From a purely thermodynamic standpoint, you actually _can_ be net-energy-positive. You're gaining a lot of energy going from CH4/etc + O2 to H2O + CO2. You're then directly sequestering CO2 (usually in solution in a deep brine), rather than C. You need to expend energy to concentrate the CO2, but it's less than you gain from combustion. In practice, it's more difficult to come out energy positive overall if we're capturing CO2 at atmospheric concentrations rather than from flue gases/etc at the time of combustion. Regardless, though, "driving roads in reverse" is not a good analogy. We don't need to expend anywhere remotely as much energy as was generated from the original combustion.
- _Microft 6y ago
  Good to know, I'll keep that in mind!

m4rtink 6y ago

This is a good summary - and it might just work out. There is a trend in our energy sources being more powerful and more efficient over time. More efficient solar panels, biger and more flexible wind turbines, bigger and safer nuclear reactors. So paying the "energy dept" in the future might be much easier than going without the fosil energy sources right now.

renw0rp 6y ago
The "borrowing" is not without some side effects which might be hard or impossible to revert in the future. It's like driving accelerating train without the breaks and hoping that someone builds tracks fast enough that we won't derail
- TeMPOraL 6y ago
  Loss of biodiversity is one big thing. The species that went extinct due to us industrializing the planet, and the species that will go extinct due to climate change (even if brief and ultimately mitigated) will not come back. Sure, evolution keeps running its RNG and eventually new and interesting species will start showing up. But that doesn't replace the causal link that is lost. Today, the variety of organisms on our planet gives biologists a chance to understand how crucial mechanisms of life evolved. As we erase that history, we make biological sciences that much harder, and by extension, slow the progress of everything from medicine through biotech to chemistry and material sciences.

iguy 6y ago

> but we will need to expend more energy later to put the extra carbon back where it belongs Is this actually a given? I mean trying to make gasoline from the atmosphere would certainly require more energy than you get by burning it, a lot more. But I thought sensible capture proposals ran on different chemistry, possibly relying on a wet/dry cycle under which the affinity for carbon is different in the two halves. And letting evaporation (i.e. solar energy) move you from wet to dry. It's not obvious that these must use more energy than you got by burning the coal in the first place.

_Microft 6y ago
This was not meant to mean synthetic fuels but that we will eventually have to undo the damages that we currently bring about.
- iguy 6y ago
  Sure, I agree. The part I question is "more energy later". Or at least, this is not obvious from a first-principles no-perpetual-motion argument. It's a technology question.

jofer 6y ago

From a purely thermodynamic standpoint, you actually _can_ be net-energy-positive. You're gaining a lot of energy going from CH4/etc + O2 to H2O + CO2. You're then directly sequestering CO2 (usually in solution in a deep brine), rather than C. You need to expend energy to concentrate the CO2, but it's less than you gain from combustion. In practice, it's more difficult to come out energy positive overall if we're capturing CO2 at atmospheric concentrations rather than from flue gases/etc at the time of combustion. Regardless, though, "driving roads in reverse" is not a good analogy. We don't need to expend anywhere remotely as much energy as was generated from the original combustion.

_Microft 6y ago
Good to know, I'll keep that in mind!