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Hydrocarbons are fantastic fuels when high energy density is required. In fact, airliners would be completely impossible without them. Even the most fantastic e

by fsh 5y ago

Hydrocarbons are fantastic fuels when high energy density is required. In fact, airliners would be completely impossible without them. Even the most fantastic experimental batteries have nowhere near enough energy density for efficient powered flight. There are some plausible concepts for hydrogen powered planes, but those waste a lot more space on fuel tanks compared to hydrocarbon powered ones. Synthetic hydrocarbons will probably remain the only option for carbon-neutral long-distance travel in the foreseeable future.

ZeroGravitas 5y ago
Simply offsetting the carbon, by replacing fossil fuel uses in other sectors, makes more financial/economic/practical sense than creating synthetic hydrocarbons to greenwash your own specific usage. People really are stuck in a fossil-fuel mindset when the real solution is to stop using them as fast as possible. A simple carbon fee does this without much fuss. People peddling synthetic hydrocarbons are, again like carbon capture and storage attached to fossil fuel generators, simply bullshitting. They might as well claim to be transitioning to perpetual motion powered flight that they have working today at lab scale. Because, basically that is what they are saying.
- PaulHoule 5y ago
  The concern about aviation is not so much today (being responsible for of 3.5% climate change) https://research.noaa.gov/article/ArtMID/587/ArticleID/2667/Aviation-is-responsible-for-35-percent-of-climate-change-study-finds https://research.noaa.gov/article/ArtMID/587/ArticleID/2667/... but tomorrow, in that we expect a lot of growth in aviation. That might not be the case, why take a lover for a weekend to Paris when you can go to Montréal? A nuclear powered aircraft carrier could synthesize jet fuel from the ocean and atmosphere and even if it is $15 a gallon it is a bargain -- so the US Military sponsors this kind of research. The best case for carbon capture now is this technology https://en.wikipedia.org/wiki/Bioenergy_with_carbon_capture_and_storage https://en.wikipedia.org/wiki/Bioenergy_with_carbon_capture_... applied to sugar cane alcohol factories in Brazil. You can catch CO2 from fermentation and not have to separate it from N2, compress to 1500 psi and inject into a saline aquifer. Those bioenergy plants are much better than bioenergy plants in the US by any economic or environmental metric. They'd have to get paid something per ton of CO2 captured to make it worth it. This industry is located close to populated areas such as São Paulo and does no harm to rainforests that Brazil must also protect. Another case is the petrochemical industry in the southern US where CO2 streams are abundant and could be aggregated for scalable saline injection. Any sort of space manufacturing will require a "circular economy" for carbon (it's precious) and whatever passes for a "petrochemical factory" will produce CO2 and that needs to have energy put into it into some form that can be put back into the "head end", methane would be great. The unique opportunity there is very high temperature chemistry with 24-7 sunlight concentrated with metallized plastic membranes made from the produce of the "petrochemical factory".
  - ZeroGravitas 5y ago
    I'm optimistic about turquoise hydrogen, which is effectively the same thing as your bioenergy link, except you don't burn the biofuel then capture the CO2 you just remove solid carbon from it, and use the hydrogen as a chemical feedstock (or, if really, really necessary and there's literally no other option, as a fuel). And the key reason that would be better, is because burning biofuel is kind of crappy, just like burning fossil fuel is, and you're better off just directly using the cheap renewable electrical energy that you're going to waste seperating and storing the CO2 you create. I'm also fairly sure electrical flight will be a thing long before we get to the last 3.5% of fossil fuel use anywhere on earth. Gasoline isn't magic, it's just something that we had a lot of lying around and didn't punish people for polluting and killing people with it, because the people with access to it became politically influential. That's it's only unique advantage, which thankfully seems to finally be fading. How long ago were EVs totally impossible because of the amazing energy density of gasoline? Like 5 years maybe, and now that's laughable. EVs are clearly better. Did gasoline get suddently less energy dense in that period or was that always just BS supported by nothing more than status quo bias?
    - fsh 5y ago
      No, EVs were not "totally impossible" 5 years ago. The first GM EV1s with NiMH batteries were produced 23 years ago, and the first Tesla roadsters with Li-ion batteries 14 years ago. The battery capacity and weight of the roadster are not dramatically different from that of modern EVs. In vehicles, energy density is not terribly important. The issue has always been the price of the cells. Only very recently they started becoming cost competitive compared to ICE powered vehicles. The situation is very different in airplanes. At takeoff, something like 40% of the total mass of an airliner is just fuel. The best Li-ion cells have something like 50 times lower energy density than kerosine. It is simply not possible to fly any useful distance with such a low energy density.
      - ZeroGravitas 5y ago
        Famous and highly cited energy theorist Vaclav Smil was still calling them an overhyped dead end 5 years ago, a decade ago he said "The myth that the future belongs to electric cars is one of the original misconceptions of the modern energy era". And he literally wrote a book published in 2015 on the topic of energy density. So I'm glad it's obvious now with 20/20 hindsight, but it seems a lot of people can be wrong about this stuff and have their opinions promoted.

by fsh 5y ago

ZeroGravitas 5y ago

Simply offsetting the carbon, by replacing fossil fuel uses in other sectors, makes more financial/economic/practical sense than creating synthetic hydrocarbons to greenwash your own specific usage. People really are stuck in a fossil-fuel mindset when the real solution is to stop using them as fast as possible. A simple carbon fee does this without much fuss. People peddling synthetic hydrocarbons are, again like carbon capture and storage attached to fossil fuel generators, simply bullshitting. They might as well claim to be transitioning to perpetual motion powered flight that they have working today at lab scale. Because, basically that is what they are saying.

PaulHoule 5y ago
The concern about aviation is not so much today (being responsible for of 3.5% climate change) https://research.noaa.gov/article/ArtMID/587/ArticleID/2667/Aviation-is-responsible-for-35-percent-of-climate-change-study-finds https://research.noaa.gov/article/ArtMID/587/ArticleID/2667/... but tomorrow, in that we expect a lot of growth in aviation. That might not be the case, why take a lover for a weekend to Paris when you can go to Montréal? A nuclear powered aircraft carrier could synthesize jet fuel from the ocean and atmosphere and even if it is $15 a gallon it is a bargain -- so the US Military sponsors this kind of research. The best case for carbon capture now is this technology https://en.wikipedia.org/wiki/Bioenergy_with_carbon_capture_and_storage https://en.wikipedia.org/wiki/Bioenergy_with_carbon_capture_... applied to sugar cane alcohol factories in Brazil. You can catch CO2 from fermentation and not have to separate it from N2, compress to 1500 psi and inject into a saline aquifer. Those bioenergy plants are much better than bioenergy plants in the US by any economic or environmental metric. They'd have to get paid something per ton of CO2 captured to make it worth it. This industry is located close to populated areas such as São Paulo and does no harm to rainforests that Brazil must also protect. Another case is the petrochemical industry in the southern US where CO2 streams are abundant and could be aggregated for scalable saline injection. Any sort of space manufacturing will require a "circular economy" for carbon (it's precious) and whatever passes for a "petrochemical factory" will produce CO2 and that needs to have energy put into it into some form that can be put back into the "head end", methane would be great. The unique opportunity there is very high temperature chemistry with 24-7 sunlight concentrated with metallized plastic membranes made from the produce of the "petrochemical factory".
- ZeroGravitas 5y ago
  I'm optimistic about turquoise hydrogen, which is effectively the same thing as your bioenergy link, except you don't burn the biofuel then capture the CO2 you just remove solid carbon from it, and use the hydrogen as a chemical feedstock (or, if really, really necessary and there's literally no other option, as a fuel). And the key reason that would be better, is because burning biofuel is kind of crappy, just like burning fossil fuel is, and you're better off just directly using the cheap renewable electrical energy that you're going to waste seperating and storing the CO2 you create. I'm also fairly sure electrical flight will be a thing long before we get to the last 3.5% of fossil fuel use anywhere on earth. Gasoline isn't magic, it's just something that we had a lot of lying around and didn't punish people for polluting and killing people with it, because the people with access to it became politically influential. That's it's only unique advantage, which thankfully seems to finally be fading. How long ago were EVs totally impossible because of the amazing energy density of gasoline? Like 5 years maybe, and now that's laughable. EVs are clearly better. Did gasoline get suddently less energy dense in that period or was that always just BS supported by nothing more than status quo bias?
  - fsh 5y ago
    No, EVs were not "totally impossible" 5 years ago. The first GM EV1s with NiMH batteries were produced 23 years ago, and the first Tesla roadsters with Li-ion batteries 14 years ago. The battery capacity and weight of the roadster are not dramatically different from that of modern EVs. In vehicles, energy density is not terribly important. The issue has always been the price of the cells. Only very recently they started becoming cost competitive compared to ICE powered vehicles. The situation is very different in airplanes. At takeoff, something like 40% of the total mass of an airliner is just fuel. The best Li-ion cells have something like 50 times lower energy density than kerosine. It is simply not possible to fly any useful distance with such a low energy density.
    - ZeroGravitas 5y ago
      Famous and highly cited energy theorist Vaclav Smil was still calling them an overhyped dead end 5 years ago, a decade ago he said "The myth that the future belongs to electric cars is one of the original misconceptions of the modern energy era". And he literally wrote a book published in 2015 on the topic of energy density. So I'm glad it's obvious now with 20/20 hindsight, but it seems a lot of people can be wrong about this stuff and have their opinions promoted.