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The laws of thermodynamics mean we'll have to expend at least as much energy removing CO2 as we did emissing it initially. Right now, from what google searchin

by ianai 5y ago

The laws of thermodynamics mean we'll have to expend at least as much energy removing CO2 as we did emissing it initially. Right now, from what google searching I've done, the best option would be planting the fastest growing bamboo species and sequestering them once cut down. The sequestering is 'tough', but I suspect more surmountable via a range of means than other carbon removal strategies. Anything else is a poor approximation of a tree.

homo_nullius 5y ago
Regular forests work just fine, and we have been doing logging for a while so sequestration is not a problem. We just need to do it more, and selectively, not cutting down everything at once.
frankbreetz 5y ago
The laws of thermodynamics doesn't take into account the assumption that future energy production is cheaper then today's. If there is a change in energy production like a breakthrough in fusion or an over production of renewables, it is at least theoretically possible that would be cheaper to remove then to not emit
- ianai 5y ago
  Right. The costs of future production have to be less than they were in the past or it’s even worse. Regardless though it represents a huge transfer of wealth from the future to the past.
- nradov 5y ago
  Even if we get working fusion power the laws of thermodynamics tell us that it's not going to be much cheaper than current fission power. The heat will be generated in a different way but the process for using that heat to boil water and spin a turbine will be basically the same. That means huge capital investments and then constant maintenance to keep everything running.
  - twobitshifter 5y ago
    Much of the high cost of fission power is due to the radioactive waste. The cost of fuel per kWh of nuclear is very low. >The cost of raw uranium contributes about $0.0015/kWh to the cost of nuclear electricity, while in breeder reactors the uranium cost falls to $0.000015/kWh https://en.m.wikipedia.org/wiki/Economics_of_nuclear_power_plants https://en.m.wikipedia.org/wiki/Economics_of_nuclear_power_p... When you’re talking about thermal power generation - the process is the same in any power plant, so you could use your same argument with gas, coal, or geothermal - all steam and turbines. It’s not fair to use this to just make the comparison to nuclear power alone.
jofer 5y ago
For what it's worth, that's just not true. You're gaining energy in combustion by going from CH4/etc + O2 and producing CO2 + H2O. The added energy comes from breaking those carbon-hydrogen bonds. You're then sequestering CO2. Not C2. You're not doing anything other than concentration. Yes it takes energy to re-concentrate it for sequestration. No, that's not necessary as much energy as you gain from combustion. It's energy positive overal from a thermodynamic perspective. Yes, practicalities make that more energy intensive and more difficult (e.g. capture after emission into the air instead of from a high concentration source), but it's not quite what folks keep articulating when claiming "thermodynamics demands that this takes at least as much energy". The original article is about those practalities and whether or not they amount to more energy than what's released during combustion. It's far from obvious whether or not they do overall, though.
- 8note 5y ago
  Nit: The released energy from the bonds is not the energy you have available to sequester the carbon at the end.
marcosdumay 5y ago
No, they don't. Unless what you call emitting energy to be what you gain by dispersing it into the air (that we never capture, by the way), the energy cost of removing CO2 can be orders of magnitude lower than what we get by burning it. And if you are talking about the dispersion only, then it's exactly the same.
twobitshifter 5y ago
If you look at the chemical reaction of a hydrocarbon and then what CO2 sequestration is you’ll see that it’s still within the laws of thermodynamics. You’d potentially have a thermodynamics problem if you were trying to remake synthetic fuel from the air and hydrogen. And even if you’re doing that - there’s still an argument that it’s better to recycle the carbon than to continue to dig it out of the ground. You then talk about trees (which aren’t free from the laws of thermodynamics). The process of a tree for fixing carbon is not efficient, typically less than 1%. See https://en.m.wikipedia.org/wiki/Photosynthetic_efficiency https://en.m.wikipedia.org/wiki/Photosynthetic_efficiency And that’s before you get to the step of sequestering the carbon locked up in the plants.

by ianai 5y ago

homo_nullius 5y ago

Regular forests work just fine, and we have been doing logging for a while so sequestration is not a problem. We just need to do it more, and selectively, not cutting down everything at once.

frankbreetz 5y ago

The laws of thermodynamics doesn't take into account the assumption that future energy production is cheaper then today's. If there is a change in energy production like a breakthrough in fusion or an over production of renewables, it is at least theoretically possible that would be cheaper to remove then to not emit

ianai 5y ago
Right. The costs of future production have to be less than they were in the past or it’s even worse. Regardless though it represents a huge transfer of wealth from the future to the past.
nradov 5y ago
Even if we get working fusion power the laws of thermodynamics tell us that it's not going to be much cheaper than current fission power. The heat will be generated in a different way but the process for using that heat to boil water and spin a turbine will be basically the same. That means huge capital investments and then constant maintenance to keep everything running.
- twobitshifter 5y ago
  Much of the high cost of fission power is due to the radioactive waste. The cost of fuel per kWh of nuclear is very low. >The cost of raw uranium contributes about $0.0015/kWh to the cost of nuclear electricity, while in breeder reactors the uranium cost falls to $0.000015/kWh https://en.m.wikipedia.org/wiki/Economics_of_nuclear_power_plants https://en.m.wikipedia.org/wiki/Economics_of_nuclear_power_p... When you’re talking about thermal power generation - the process is the same in any power plant, so you could use your same argument with gas, coal, or geothermal - all steam and turbines. It’s not fair to use this to just make the comparison to nuclear power alone.

jofer 5y ago

For what it's worth, that's just not true. You're gaining energy in combustion by going from CH4/etc + O2 and producing CO2 + H2O. The added energy comes from breaking those carbon-hydrogen bonds. You're then sequestering CO2. Not C2. You're not doing anything other than concentration. Yes it takes energy to re-concentrate it for sequestration. No, that's not necessary as much energy as you gain from combustion. It's energy positive overal from a thermodynamic perspective. Yes, practicalities make that more energy intensive and more difficult (e.g. capture after emission into the air instead of from a high concentration source), but it's not quite what folks keep articulating when claiming "thermodynamics demands that this takes at least as much energy". The original article is about those practalities and whether or not they amount to more energy than what's released during combustion. It's far from obvious whether or not they do overall, though.

8note 5y ago
Nit: The released energy from the bonds is not the energy you have available to sequester the carbon at the end.

marcosdumay 5y ago

No, they don't. Unless what you call emitting energy to be what you gain by dispersing it into the air (that we never capture, by the way), the energy cost of removing CO2 can be orders of magnitude lower than what we get by burning it. And if you are talking about the dispersion only, then it's exactly the same.

twobitshifter 5y ago

If you look at the chemical reaction of a hydrocarbon and then what CO2 sequestration is you’ll see that it’s still within the laws of thermodynamics. You’d potentially have a thermodynamics problem if you were trying to remake synthetic fuel from the air and hydrogen. And even if you’re doing that - there’s still an argument that it’s better to recycle the carbon than to continue to dig it out of the ground. You then talk about trees (which aren’t free from the laws of thermodynamics). The process of a tree for fixing carbon is not efficient, typically less than 1%. See https://en.m.wikipedia.org/wiki/Photosynthetic_efficiency https://en.m.wikipedia.org/wiki/Photosynthetic_efficiency And that’s before you get to the step of sequestering the carbon locked up in the plants.