4 ms·

Simple question: will it take less energy to do the conversion than you get out the other end? Will the process itself generate less carbon than the existing pr

Simple question: will it take less energy to do the conversion than you get out the other end? Will the process itself generate less carbon than the existing process? All these “net zero” claims never mention how the rest of the system is affected. Eg, zero emission electric cars: where I live, our electricity comes from coal power plants.

danielheath 6y ago
Obviously not (laws of thermodynamics), but if we ever get eg a profitable fusion reactor going, it'll be a huge deal to be able to do this - because existing petroleum-fuel stock will still need to run.
- jeffbee 6y ago
  We already enjoy the services of a massive optically-coupled fusion energy source. All we need to do it plug it in.
- nradov 6y ago
  If fusion power ever works it could be a useful base load source to replace coal and fission. But fusion is unlikely to ever be cost competitive with solar and wind, so I expect those sources to be used for synthesizing liquid fuel.
  - tempestn 6y ago
    Agreed; this kind of thing seems like a more attractive target for unused peak capacity of renewables. But it only makes sense if the capital costs are low enough that the economics still work even if it's only run part time. Which is a pretty high bar.
carbonguy 6y ago
Taking your questions in turn: 1) The conversion will always be energy-negative due to the laws of thermodynamics, as a sibling comment mentioned. This is true even of existing fossil fuels, though we tend not to think of it that way. 2) The process of converting CO2 to hydrocarbon fuels leads to a decrease in atmospheric carbon. Burning these fuels or fossil fuels (what I assume you mean by "the existing process") produces an increase in atmospheric carbon. This means it's possible to create a net-positive, net-neutral, or net-negative outcome with respect to atmospheric CO2 concentration depending on how you balance these two processes. As you point out, "zero emission" doesn't mean the same thing as "no net CO2 release"; rather, it more often means "zero emissions of CO2 at the point of energy usage," with CO2 emissions usually occurring elsewhere. That said, with a system of hydrocarbon fuel production from air-captured CO2 it is genuinely possible to have "zero emission" mean "zero net emission of CO2 over the entire energy transport process." EDIT: The key enabling technology is, of course, carbon-free renewable energy, of which solar is likely to represent the lions' share as time passes.

danielheath 6y ago

Obviously not (laws of thermodynamics), but if we ever get eg a profitable fusion reactor going, it'll be a huge deal to be able to do this - because existing petroleum-fuel stock will still need to run.

jeffbee 6y ago
We already enjoy the services of a massive optically-coupled fusion energy source. All we need to do it plug it in.
nradov 6y ago
If fusion power ever works it could be a useful base load source to replace coal and fission. But fusion is unlikely to ever be cost competitive with solar and wind, so I expect those sources to be used for synthesizing liquid fuel.
- tempestn 6y ago
  Agreed; this kind of thing seems like a more attractive target for unused peak capacity of renewables. But it only makes sense if the capital costs are low enough that the economics still work even if it's only run part time. Which is a pretty high bar.

carbonguy 6y ago

Taking your questions in turn: 1) The conversion will always be energy-negative due to the laws of thermodynamics, as a sibling comment mentioned. This is true even of existing fossil fuels, though we tend not to think of it that way. 2) The process of converting CO2 to hydrocarbon fuels leads to a decrease in atmospheric carbon. Burning these fuels or fossil fuels (what I assume you mean by "the existing process") produces an increase in atmospheric carbon. This means it's possible to create a net-positive, net-neutral, or net-negative outcome with respect to atmospheric CO2 concentration depending on how you balance these two processes. As you point out, "zero emission" doesn't mean the same thing as "no net CO2 release"; rather, it more often means "zero emissions of CO2 at the point of energy usage," with CO2 emissions usually occurring elsewhere. That said, with a system of hydrocarbon fuel production from air-captured CO2 it is genuinely possible to have "zero emission" mean "zero net emission of CO2 over the entire energy transport process." EDIT: The key enabling technology is, of course, carbon-free renewable energy, of which solar is likely to represent the lions' share as time passes.