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We can accomplish the same by producing the jet fuel using electricity. Realistically this will likely involve methane (natural gas) extracted from the ground a

by eloff 7y ago

We can accomplish the same by producing the jet fuel using electricity. Realistically this will likely involve methane (natural gas) extracted from the ground and water, but it could one day be carbon neutral using captured carbon. The trick is to use clean energy like nuclear of renewables. There was an article on HN just recently about doing that with portable nuclear generators like those used on ships, this could be done right in the airport. We already have a fantastic dense energy battery called kerosene. All we need to do is make it carbon neutral and our existing aviation tech won't even need to change.

mrpopo 7y ago
> All we need to do is make it carbon neutral and our existing aviation tech won't even need to change. Except making it carbon neutral will require enormous amounts of energy, shift the price up, and make aviation available only to the richest among us. Aviation industry may keep existing, but will need to scale down.
- nine_k 7y ago
  If the fuel is synthetic anyway, uh can be made better than kerosene. Also, we have a huge amount of free nuclear energy, daily delivered from Sun, about 1 kW / m². It is nit stable enough for electric baseload, but, depending on the process, may be adequate for fuel synthesis. North of Sahara may become a primary source of jet fuel, given its vast amounts of insolation, cheapness of the land, and access to seawater. Not exactly tomorrow, though.
  - nradov 7y ago
    Better than kerosene how? You're not going to get higher energy density without increasing safety risks.
  - mrpopo 7y ago
    Not exactly tomorrow, but we're facing a problem today. What are we supposed to do to reduce CO2 emissions between today and the mythical day we will have unlimited amounts of synthetic fuel available shipped by tankers from Morocco?
- sansnomme 7y ago
  If you don't keep the scale, it would never get cheaper. Airlines struggle with profitability as-is, no point imposing additional undue burden.
- seanmcdirmid 7y ago
  Well, if we ever figure out fusion, we could get the enormous amount of energy part.
  - mrpopo 7y ago
    Ok; until then, we have to reduce CO2 emissions by 7% each year from now until we reach net zero in 2050. Even if we figured out fusion today (highly unlikely), it won't be deployed at scale by then (a modern fission reactor takes 10 years to build). So there are two choices really: progressively scale down the aviation industry, or ignore the climate crisis and let 100s of millions in poor countries die from climate-related causes.
    - seanmcdirmid 7y ago
      We could actually do that using fission alone, since we have we enough fuel for 70,000 years or so, and nuclear waste is free of green house gases. It would just be very expensive up front, as nuclear plants tend to be. Anyways, this is the way France is going.
jjoonathan 7y ago
Or biofuel. Plants are good at capturing atmospheric CO2 and the resulting biomass can be turned into fuel using well established technology. If it's nearly suitable for cars I suspect it's even more nearly suitable for aviation on account of the lower volumes and higher margins.
- munificent 7y ago
  Now I'm just imagining some sort of steampunk wood-burning airplane.
  - rdtsc 7y ago
    > Now I'm just imagining some sort of steampunk wood-burning airplane. Almost there https://en.wikipedia.org/wiki/Wood_gas https://en.wikipedia.org/wiki/Wood_gas "Flight attendants will resume service in just a moment, after they throw another tree trunk into the wood gas generator"
- konspence 7y ago
  Already underway[1]. It's completely viable, it just needs investment and commitment. [1]: https://www.alaskaair.com/content/about-us/sustainability-report/planet/aviation-biofuel https://www.alaskaair.com/content/about-us/sustainability-re...
- WalterBright 7y ago
  > Plants are good at capturing atmospheric CO2 and the resulting biomass can be turned into fuel using well established technology. I.e. burning coal.
  - philhippus 7y ago
    Yes, but it takes 100's of thousands of years for the planet to form fossil fuels such as coal. We can't wait that long.
    - WalterBright 7y ago
SEJeff 7y ago
Methane can be created via carbon capture entirely. It is in the SpaceX TODO list to create a factory to literally create metholox (methane + liquid oxygen is what they use as fuel for the new Starship / Superheavy rockets they want to use to go to mars) via carbon capture. Elon has already discussed this before. The end goal that the rocket launch is carbon neutral when you are using carbon already captured from the atmosphere. Here is a good overview of the plan: https://cleantechnica.com/2019/10/30/no-you-dont-have-to-worry-about-emissions-from-spacexs-mars-rocket/ https://cleantechnica.com/2019/10/30/no-you-dont-have-to-wor...
- WalterBright 7y ago
  The whole "carbon neutral" think is a crock. Coal is, after all, just dead trees, so coal plants run on "biofuel" and are "carbon neutral".
  - ben_w 7y ago
    Technically correct, but about as unhelpful as saying “solar isn’t renewable because the sun will eventually go out”. Our biology and our biosphere are not adapted to the atmospheric CO2 levels we would have if we burned all the fossil fuels.
    - WalterBright 7y ago
      My point is calling something "carbon neutral" if it is burning wood is equally unhelpful. Nothing is gained by burning a tree you just chopped down instead of burning a tree buried for a million years - the same amount of CO2 is released.
      - mkl 7y ago
        But the tree you just chopped down got its carbon from the atmosphere just a few years ago. That's what makes it carbon neutral. The coal (/gas/oil/etc.) got its carbon from the atmosphere in the far distant past, so from our point of view it's new additional carbon that wasn't in the system before. It can only be considered carbon neutral over a time span of millions of years, which is pretty meaningless.
hnick 7y ago
I don't really know where else to ask, so I'll ask here. Another topic of research is very rapid sub-orbital passenger flight. Are there any numbers on proposed fuel efficiency for that? I'd expect you gain a lot by removing hours and hours of wind resistance, but getting up to speed and out of the atmosphere probably (gut feel) uses more.
- umeshunni 7y ago
  No numbers, but you might have seen the SpaceX proposal / video here: https://www.youtube.com/watch?v=zqE-ultsWt0 https://www.youtube.com/watch?v=zqE-ultsWt0
- davedx 7y ago
  I also haven't seen numbers, but I imagine the energy usage even to reach sub-orbital altitude would be pretty huge compared to a jet plane takeoff -> cruising altitude. Sub-orbital means you also have to bring your own oxygen too (rocket vs jet engine), which can approximately double your fuel mass...
alex_duf 7y ago
Assuming we have infinite renewable energy supply to produce kerosene from electricity and therefore carbon neutral flights, it still doesn't quite solve the air quality issue. A step in the right direction, but I hope this doesn't get used as an excuse to fly more.

by eloff 7y ago

mrpopo 7y ago

> All we need to do is make it carbon neutral and our existing aviation tech won't even need to change. Except making it carbon neutral will require enormous amounts of energy, shift the price up, and make aviation available only to the richest among us. Aviation industry may keep existing, but will need to scale down.

nine_k 7y ago
If the fuel is synthetic anyway, uh can be made better than kerosene. Also, we have a huge amount of free nuclear energy, daily delivered from Sun, about 1 kW / m². It is nit stable enough for electric baseload, but, depending on the process, may be adequate for fuel synthesis. North of Sahara may become a primary source of jet fuel, given its vast amounts of insolation, cheapness of the land, and access to seawater. Not exactly tomorrow, though.
- nradov 7y ago
  Better than kerosene how? You're not going to get higher energy density without increasing safety risks.
- mrpopo 7y ago
  Not exactly tomorrow, but we're facing a problem today. What are we supposed to do to reduce CO2 emissions between today and the mythical day we will have unlimited amounts of synthetic fuel available shipped by tankers from Morocco?
sansnomme 7y ago
If you don't keep the scale, it would never get cheaper. Airlines struggle with profitability as-is, no point imposing additional undue burden.
seanmcdirmid 7y ago
Well, if we ever figure out fusion, we could get the enormous amount of energy part.
- mrpopo 7y ago
  Ok; until then, we have to reduce CO2 emissions by 7% each year from now until we reach net zero in 2050. Even if we figured out fusion today (highly unlikely), it won't be deployed at scale by then (a modern fission reactor takes 10 years to build). So there are two choices really: progressively scale down the aviation industry, or ignore the climate crisis and let 100s of millions in poor countries die from climate-related causes.
  - seanmcdirmid 7y ago
    We could actually do that using fission alone, since we have we enough fuel for 70,000 years or so, and nuclear waste is free of green house gases. It would just be very expensive up front, as nuclear plants tend to be. Anyways, this is the way France is going.

jjoonathan 7y ago

Or biofuel. Plants are good at capturing atmospheric CO2 and the resulting biomass can be turned into fuel using well established technology. If it's nearly suitable for cars I suspect it's even more nearly suitable for aviation on account of the lower volumes and higher margins.

munificent 7y ago
Now I'm just imagining some sort of steampunk wood-burning airplane.
- rdtsc 7y ago
  > Now I'm just imagining some sort of steampunk wood-burning airplane. Almost there https://en.wikipedia.org/wiki/Wood_gas https://en.wikipedia.org/wiki/Wood_gas "Flight attendants will resume service in just a moment, after they throw another tree trunk into the wood gas generator"
konspence 7y ago
Already underway[1]. It's completely viable, it just needs investment and commitment. [1]: https://www.alaskaair.com/content/about-us/sustainability-report/planet/aviation-biofuel https://www.alaskaair.com/content/about-us/sustainability-re...
WalterBright 7y ago
> Plants are good at capturing atmospheric CO2 and the resulting biomass can be turned into fuel using well established technology. I.e. burning coal.
- philhippus 7y ago
  Yes, but it takes 100's of thousands of years for the planet to form fossil fuels such as coal. We can't wait that long.
  - WalterBright 7y ago

SEJeff 7y ago

Methane can be created via carbon capture entirely. It is in the SpaceX TODO list to create a factory to literally create metholox (methane + liquid oxygen is what they use as fuel for the new Starship / Superheavy rockets they want to use to go to mars) via carbon capture. Elon has already discussed this before. The end goal that the rocket launch is carbon neutral when you are using carbon already captured from the atmosphere. Here is a good overview of the plan: https://cleantechnica.com/2019/10/30/no-you-dont-have-to-worry-about-emissions-from-spacexs-mars-rocket/ https://cleantechnica.com/2019/10/30/no-you-dont-have-to-wor...

WalterBright 7y ago
The whole "carbon neutral" think is a crock. Coal is, after all, just dead trees, so coal plants run on "biofuel" and are "carbon neutral".
- ben_w 7y ago
  Technically correct, but about as unhelpful as saying “solar isn’t renewable because the sun will eventually go out”. Our biology and our biosphere are not adapted to the atmospheric CO2 levels we would have if we burned all the fossil fuels.
  - WalterBright 7y ago
    My point is calling something "carbon neutral" if it is burning wood is equally unhelpful. Nothing is gained by burning a tree you just chopped down instead of burning a tree buried for a million years - the same amount of CO2 is released.
    - mkl 7y ago
      But the tree you just chopped down got its carbon from the atmosphere just a few years ago. That's what makes it carbon neutral. The coal (/gas/oil/etc.) got its carbon from the atmosphere in the far distant past, so from our point of view it's new additional carbon that wasn't in the system before. It can only be considered carbon neutral over a time span of millions of years, which is pretty meaningless.

hnick 7y ago

I don't really know where else to ask, so I'll ask here. Another topic of research is very rapid sub-orbital passenger flight. Are there any numbers on proposed fuel efficiency for that? I'd expect you gain a lot by removing hours and hours of wind resistance, but getting up to speed and out of the atmosphere probably (gut feel) uses more.

umeshunni 7y ago
No numbers, but you might have seen the SpaceX proposal / video here: https://www.youtube.com/watch?v=zqE-ultsWt0 https://www.youtube.com/watch?v=zqE-ultsWt0
davedx 7y ago
I also haven't seen numbers, but I imagine the energy usage even to reach sub-orbital altitude would be pretty huge compared to a jet plane takeoff -> cruising altitude. Sub-orbital means you also have to bring your own oxygen too (rocket vs jet engine), which can approximately double your fuel mass...

alex_duf 7y ago

Assuming we have infinite renewable energy supply to produce kerosene from electricity and therefore carbon neutral flights, it still doesn't quite solve the air quality issue. A step in the right direction, but I hope this doesn't get used as an excuse to fly more.