4 ms·

> You can manufacture synthetic hydrocarbons anywhere so long as you have water, carbon dioxide You need coal or some biomass to manufacture synthetic hydrocar

by mayama 6y ago

> You can manufacture synthetic hydrocarbons anywhere so long as you have water, carbon dioxide You need coal or some biomass to manufacture synthetic hydrocarbons. And tail emission is still a concern.

kolinko 6y ago
You can extract carbon from atmosphere.
- gus_massa 6y ago
  Organic reactions to produce complex molecules have an horrible efficiency. (For example, photosynthesis in plants has a 1% or 2% of efficiency.) Perhaps the efficiency to produce methane is not so bad, but a chain with 6 or 7 carbons like gasoline is very complicated. It is not equivalent if they are aligned or they form a ramified structure like a tree, and it is very difficult to choose which one they will form unless you have a very complex process. There are some graphics in https://en.wikipedia.org/wiki/Octane_rating#Isooctane_as_a_reference_standard https://en.wikipedia.org/wiki/Octane_rating#Isooctane_as_a_r...
  - jabl 6y ago
    > Perhaps the efficiency to produce methane is not so bad, but a chain with 6 or 7 carbons like gasoline is very complicated. The Fischer-Tropsch process is almost a hundred years old, and has been used on an industrial scale. E.g. Nazi Germany used it to produce a non-trivial fraction of their liquid fuels during WWII. Similarly South Africa used it during Apartheid. Now FT itself is better suited for producing mostly straight hydrocarbon chains like diesel or jet fuel rather than the branched ones seen in high octane gasoline. The efficiency of traditional FT is around 40%, but by adding extra hydrogen to the process it can be increased by around a factor of 3 (the efficiency meaning the energy content of the carbon carrying feedstock vs the output, so over 100% is possible as hydrogen provides some of the energy in the final product). The problem is to get the CO needed for FT in a carbon-neutral manner. Biomass is limited, capturing and reducing CO2 is expensive and requires a lot of energy.
    - Qwertious 6y ago
      "The Fischer-Tropsch process is almost a hundred years old, and has been used on an industrial scale. E.g. Nazi Germany used it to produce a non-trivial fraction of their liquid fuels during WWII." I know it's not an argument against, but the Nazis lost WW2 because they ran out of oil. They invaded Russia at the last moment they could before they wouldn't have the oil to invade, and when they invaded they made a beeline for Russia's oil fields. They were desperate for fuel from anywhere, because their tanks are useless and they either have to fight to the death wherever their tanks run out of fuel, or abandon their tanks. ...also, the main non-fossil fuel the nazis used was probably hay. For their horses. It's just a super weird example.
      - jabl 6y ago
        > I know it's not an argument against, but the Nazis lost WW2 because they ran out of oil. Well, they would most likely have lost anyway, but failing to capture the Caucasian oil fields as well as the Allies attacking their fuel infrastructure certainly hastened their demise. One can make a good argument that the strategic bombing on the western front in WWII was largely ineffective, but there were parts that were wildly successful, like attacking the fuel infrastructure. As for why they didn't just use synthetic fuel all the way instead of just a fraction of the total use, I don't know. I guess they just couldn't scale it up fast enough. And certainly getting oil from the ground is much cheaper than creating synthetic fuel from coal in huge industrial parks. > ...also, the main non-fossil fuel the nazis used was probably hay. For their horses. It's just a super weird example. Sure. Blitzkrieg captured the public imagination, but in reality only a small fraction of the German army were these mechanized shock troops. Most were infantry that moved by train or marched with horses carrying equipment.

by mayama 6y ago

kolinko 6y ago

You can extract carbon from atmosphere.

gus_massa 6y ago
Organic reactions to produce complex molecules have an horrible efficiency. (For example, photosynthesis in plants has a 1% or 2% of efficiency.) Perhaps the efficiency to produce methane is not so bad, but a chain with 6 or 7 carbons like gasoline is very complicated. It is not equivalent if they are aligned or they form a ramified structure like a tree, and it is very difficult to choose which one they will form unless you have a very complex process. There are some graphics in https://en.wikipedia.org/wiki/Octane_rating#Isooctane_as_a_reference_standard https://en.wikipedia.org/wiki/Octane_rating#Isooctane_as_a_r...
- jabl 6y ago
  > Perhaps the efficiency to produce methane is not so bad, but a chain with 6 or 7 carbons like gasoline is very complicated. The Fischer-Tropsch process is almost a hundred years old, and has been used on an industrial scale. E.g. Nazi Germany used it to produce a non-trivial fraction of their liquid fuels during WWII. Similarly South Africa used it during Apartheid. Now FT itself is better suited for producing mostly straight hydrocarbon chains like diesel or jet fuel rather than the branched ones seen in high octane gasoline. The efficiency of traditional FT is around 40%, but by adding extra hydrogen to the process it can be increased by around a factor of 3 (the efficiency meaning the energy content of the carbon carrying feedstock vs the output, so over 100% is possible as hydrogen provides some of the energy in the final product). The problem is to get the CO needed for FT in a carbon-neutral manner. Biomass is limited, capturing and reducing CO2 is expensive and requires a lot of energy.
  - Qwertious 6y ago
    "The Fischer-Tropsch process is almost a hundred years old, and has been used on an industrial scale. E.g. Nazi Germany used it to produce a non-trivial fraction of their liquid fuels during WWII." I know it's not an argument against, but the Nazis lost WW2 because they ran out of oil. They invaded Russia at the last moment they could before they wouldn't have the oil to invade, and when they invaded they made a beeline for Russia's oil fields. They were desperate for fuel from anywhere, because their tanks are useless and they either have to fight to the death wherever their tanks run out of fuel, or abandon their tanks. ...also, the main non-fossil fuel the nazis used was probably hay. For their horses. It's just a super weird example.
    - jabl 6y ago
      > I know it's not an argument against, but the Nazis lost WW2 because they ran out of oil. Well, they would most likely have lost anyway, but failing to capture the Caucasian oil fields as well as the Allies attacking their fuel infrastructure certainly hastened their demise. One can make a good argument that the strategic bombing on the western front in WWII was largely ineffective, but there were parts that were wildly successful, like attacking the fuel infrastructure. As for why they didn't just use synthetic fuel all the way instead of just a fraction of the total use, I don't know. I guess they just couldn't scale it up fast enough. And certainly getting oil from the ground is much cheaper than creating synthetic fuel from coal in huge industrial parks. > ...also, the main non-fossil fuel the nazis used was probably hay. For their horses. It's just a super weird example. Sure. Blitzkrieg captured the public imagination, but in reality only a small fraction of the German army were these mechanized shock troops. Most were infantry that moved by train or marched with horses carrying equipment.