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Additionally, I don’t think jet engines have to pass clean air standards like cars do. I don’t know for certain that this makes a huge difference for global war

Additionally, I don’t think jet engines have to pass clean air standards like cars do. I don’t know for certain that this makes a huge difference for global warming, but there are many vectors for environmental damage besides CO2 emissions. Modern gasoline powered ICE vehicles produce fairly clean exhaust thanks to smog regulations.

usrusr 7y ago
Non-CO2 emissions are bad for us now, but their long-term impact on the future is insignificant. They are more bad now precisely because they don't just stick around forever, unlike CO2 they still contain bound energy and will happily participate in all kinds of undesirable reactions.
- imtringued 7y ago
  This implies that synthetic jet fuel isn't the answer either because it will still create local pollution. Does using hydrogen prevent these types of emissions?
  - usrusr 7y ago
    If you take a slightly closer look at the infamous diesel NOx emissions you'll notice that the nitrogen isn't coming from the diesel fuel, it's coming from the air intake. Our atmosphere is mostly nitrogen, with oxygen on second place, some argon on distant third and all the remaining bad stuff making up less than a tenth of a percentage point by volume. So all that nasty NOx is just clean air that has been thrown into molecular disarray by being present while some unrelated fuel has been violently oxidized. 2H2+O2 is a much more straight-forward reaction than cracking long-chained hydrocarbons, so maybe there are less of those side effects, but I doubt that it would be entirely free from that (I'm not a chemist at all, as you will have surely guessed by now). In terms of CO2 true synfuels would be clean in so far as the CO2 would have been captured earlier. The only feasible way to do this would be biomass and the synfuel would either be derived directly from a plant-based source or reuse CO2 captured from terrestrial biomass burning methanize H2 from an electrolysis plant (that would typically be run as an opportunistic sink for intermittent renewable electricity).

usrusr 7y ago

Non-CO2 emissions are bad for us now, but their long-term impact on the future is insignificant. They are more bad now precisely because they don't just stick around forever, unlike CO2 they still contain bound energy and will happily participate in all kinds of undesirable reactions.

imtringued 7y ago
This implies that synthetic jet fuel isn't the answer either because it will still create local pollution. Does using hydrogen prevent these types of emissions?
- usrusr 7y ago
  If you take a slightly closer look at the infamous diesel NOx emissions you'll notice that the nitrogen isn't coming from the diesel fuel, it's coming from the air intake. Our atmosphere is mostly nitrogen, with oxygen on second place, some argon on distant third and all the remaining bad stuff making up less than a tenth of a percentage point by volume. So all that nasty NOx is just clean air that has been thrown into molecular disarray by being present while some unrelated fuel has been violently oxidized. 2H2+O2 is a much more straight-forward reaction than cracking long-chained hydrocarbons, so maybe there are less of those side effects, but I doubt that it would be entirely free from that (I'm not a chemist at all, as you will have surely guessed by now). In terms of CO2 true synfuels would be clean in so far as the CO2 would have been captured earlier. The only feasible way to do this would be biomass and the synfuel would either be derived directly from a plant-based source or reuse CO2 captured from terrestrial biomass burning methanize H2 from an electrolysis plant (that would typically be run as an opportunistic sink for intermittent renewable electricity).