6 ms·

Great thing about Jet A, it's actually pretty hard to get burning. Hydrogen: See Hindenburg. I would rather not fly in a bomb. I just don't see it being viabl

Great thing about Jet A, it's actually pretty hard to get burning. Hydrogen: See Hindenburg. I would rather not fly in a bomb. I just don't see it being viable for planes. We're starting to see short distance small planes electrify and then long haul will probably go synthetic fuels over the next 10 years.

huntertwo 5y ago
I read something that says Hindenburg was more about the mix of the gas and the material of the blimp. Properly mixed H2 doesn’t burn (it explodes quickly, which is what powers an ICE). I agree though, planes and H2 probably don’t mix. Jet fuel should not be a priority to replace with H2. Priority should be given to static applications before trying to apply it to moving vehicles.
- R0b0t1 5y ago
  You are right. The issue with the Hindenberg was not the hydrogen. It was the coating. The main concern for hydrogen as a fuel now is the high pressures. If the pressure vessel is damaged it explodes due to mechanical forces. This is not impossible to work around. Consider, for example, that gas tanks can already be punctured and lead to fires; it takes a fair accounting of the risks to really rule out hydrogen as a fuel.
  - jjoonathan 5y ago
    Right, but consider a punctured gas tank vs... well, have you played "spot the COPVs in the SpaceX explosion"? They spit fire and zoom around like party balloons. Good fun from a distance, but if I had to pick one to ride with every day, it's an easy choice in favor of the gas tank.
    - R0b0t1 5y ago
      Do you know what the fuel is? Rockets are unique in that they carry a significant amount of oxidizer with them. A hydrogen container is unlikely to zoom around spitting fire, there's too much fuel for how much oxygen there is and it rises very quickly. There are still dangers, but practically I'm not sure they are that much worse than a gasoline fire. There are also systems that reduce the pressures needed, like activated carbon beds. Research on them stalled mostly because there was no good way to generate H2.
      - mywittyname 5y ago
        I thought the fact that H2 burns invisibly combined with the fact that it goes boom once the burning mixture is stoichiometric is the big risk with H2 over typical hydro-carbon-based fuels, which burn a bright orange and are surprisingly hard to blow up.
        R0b0t1 5y ago
        The Mythbusters did a show on this exact thing with spraypaint, hairspray, and propane canisters. They didn't explode even when wrapped with flaming rags, but sometimes the released material would combust. In some cases the gas rushing out actually extinguished the flame. You rarely by accident get a stoichiometric mix. With a slow leak into an enclosed container is usually how it happens. Otherwise there is too much fuel to O2 in the atmosphere. People really need to stop trying to sound smart by thinking of imagined dangers. That is what stopped nuclear power, it's what's stopping hydrogen as a fuel, it's what's stopping gene therapy research, etc. Get over yourself.
        stevespang 5y ago
        and what about historically substantiated accidents ? Chernobyl, 3 mile island, Fukushima, etc. Not to mention that ~115 of the of all the 460 operational nuclear reactors in the world are close to the sea, just waiting for Tsunami's
        jjoonathan 5y ago
        > People really need to stop trying to sound smart > Get over yourself. Right back atcha. Good grief, "stoichiometric mixture" is not a reasonable person's danger threshold. The mechanical energy alone is terrifying, which was the point of bringing up COPVs. While we're at it, let's put giant flywheels in chemical cars to do regenerative breaking. They'll probably have less mechanical energy than the titanic so they're probably no big deal, right? Right.
        R0b0t1 5y ago
        Look, this stuff has been studied and you can find it with just a little bit of looking. How this conversation has been going is a bunch of chaff gets thrown up and then people are expected to answer. I'm doing as best I can. I happened to have a coworker who was involved in alternative fuels research, specifically the H2 cylinders that operated at lower pressures using a carbon substrate. But even if you don't use that you can still construct and secure the container so it splits instead of shatters and contains most or all of the debris. You can install a shield bulkhead into the car to deflect debris to the ground. You can do loads of things. You are not original, you are not the first person to raise these concerns, and very competent people have been working on them. https://xkcd.com/793/ https://xkcd.com/793/
  - huntertwo 5y ago
    Those gas tanks are more risky when you have constraints on weight and material of the tank, like in moving vehicles. I agree though, people unfairly disqualify hydrogen on this risk only.
  - lizknope 5y ago
    https://en.wikipedia.org/wiki/Hindenburg_disaster#Incendiary_paint_hypothesis https://en.wikipedia.org/wiki/Hindenburg_disaster#Incendiary... They tested the incendiary paint hypothesis on the TV show Mythbusters. The MythBusters concluded that the paint may have contributed to the disaster, but that it was not the sole reason for such rapid combustion.
    - R0b0t1 5y ago
      Ah, you're right. I wasn't remembering the details exactly. But the burning material that falls is the skin and can be better fireproofed to let the hydrogen escape upwards.
  - raxxorrax 5y ago
    Diffusion is also a problem. A very efficient form to store hydrogen is a solid block of metal, which of course comes with similar restrictions as batteries, if not worse.
oblio 5y ago
> I would rather not fly in a bomb. I just don't see it being viable for planes. As opposed to the kerosene fueled bombs we're flying in right now? I'm not sure comparing things to close-to-wartime tech from 90 years ago is a valid approach.
- dragontamer 5y ago
  > I'm not sure comparing things to close-to-wartime tech from 90 years ago is a valid approach. You might be surprised how good WW2-era scientists were at chemistry and science. The earlier poster has a point. Gasoline, Diesel, and Kerosene have all been studied extensively (especially in the 1930s and 1940s BECAUSE of preparations for WW2). The safety of soldiers was paramount even to the Nazis. War machines: be they airplanes, tanks, or battleships, were all going to be exposed to enemy fire and explosions. These fuels (Kerosene and Diesel in particular) were chosen because they're extremely safe: high flash points and even higher auto-ignition points. That means that kerosene __literally__ can't catch on fire at room temperature. You need to warm up kerosene before its appropriate to burn (Of course, once its burning it will warm up the rest of the kerosene and keep burning. But this isn't some super-explosive volatile chemical we're talking about here) Gasoline is still safe, but not as safe as the other two (-40C Flash Point). Gasoline was safer than a lot of the other petroleum products that were investigated back then, and was still chosen as a fuel for war machines. --------- The same is not necessarily true for H2. H2 will explode at any temperature (even near absolute zero).
  - oblio 5y ago
    > You might be surprised how good WW2-era scientists were at chemistry and science. I'm well aware of chemical prowess in that period, especially on the German part. They had a bunch of Nobel prize winners. However, that's why I said "close-to-wartime". First of all, in case you weren't aware, the Hindenburg was supposed to use helium but due to a lack of helium in Germany (I think it was primarily due to American export restrictions), they had to use hydrogen. I don't know of other limitations for the Hindenburg, per se, but knowing the overall German shortages of the period, I wouldn't be surprised if they had other structural issues with the Hindenburg itself, especially since it wasn't designed to be used with hydrogen. On top of this, the Hindenburg design was from the late 20s, 1929, I believe. If materials science, modeling, etc haven't advanced since 1929, I'll eat a shoe. If we're somehow worse at managing hydrogen after almost 100 years, I'll eat the other shoe.
dragontamer 5y ago
Even if H2 isn't used directly, there are likely chemical processes that can convert it into some form that is more useful. EDIT: That's what its called. H2 is a component of Syngas (https://en.wikipedia.org/wiki/Syngas https://en.wikipedia.org/wiki/Syngas). Syngas can then be further processed into kerosene, gasoline, or other fuels we use.
lemmsjid 5y ago
This has some interesting comparisons between hydrogen and gasoline as fuel, in terms of historical experimentation as to the effects of rupturing or destroying tanks holding one or the other: https://hydrogen.wsu.edu/2017/03/17/so-just-how-dangerous-is-hydrogen-fuel/ https://hydrogen.wsu.edu/2017/03/17/so-just-how-dangerous-is.... Not my field so I'd be interested in if this more or less reflective of current knowledge on the subject.

huntertwo 5y ago

I read something that says Hindenburg was more about the mix of the gas and the material of the blimp. Properly mixed H2 doesn’t burn (it explodes quickly, which is what powers an ICE). I agree though, planes and H2 probably don’t mix. Jet fuel should not be a priority to replace with H2. Priority should be given to static applications before trying to apply it to moving vehicles.

R0b0t1 5y ago
You are right. The issue with the Hindenberg was not the hydrogen. It was the coating. The main concern for hydrogen as a fuel now is the high pressures. If the pressure vessel is damaged it explodes due to mechanical forces. This is not impossible to work around. Consider, for example, that gas tanks can already be punctured and lead to fires; it takes a fair accounting of the risks to really rule out hydrogen as a fuel.
- jjoonathan 5y ago
  Right, but consider a punctured gas tank vs... well, have you played "spot the COPVs in the SpaceX explosion"? They spit fire and zoom around like party balloons. Good fun from a distance, but if I had to pick one to ride with every day, it's an easy choice in favor of the gas tank.
  - R0b0t1 5y ago
    Do you know what the fuel is? Rockets are unique in that they carry a significant amount of oxidizer with them. A hydrogen container is unlikely to zoom around spitting fire, there's too much fuel for how much oxygen there is and it rises very quickly. There are still dangers, but practically I'm not sure they are that much worse than a gasoline fire. There are also systems that reduce the pressures needed, like activated carbon beds. Research on them stalled mostly because there was no good way to generate H2.
    - mywittyname 5y ago
      I thought the fact that H2 burns invisibly combined with the fact that it goes boom once the burning mixture is stoichiometric is the big risk with H2 over typical hydro-carbon-based fuels, which burn a bright orange and are surprisingly hard to blow up.
      - R0b0t1 5y ago
        The Mythbusters did a show on this exact thing with spraypaint, hairspray, and propane canisters. They didn't explode even when wrapped with flaming rags, but sometimes the released material would combust. In some cases the gas rushing out actually extinguished the flame. You rarely by accident get a stoichiometric mix. With a slow leak into an enclosed container is usually how it happens. Otherwise there is too much fuel to O2 in the atmosphere. People really need to stop trying to sound smart by thinking of imagined dangers. That is what stopped nuclear power, it's what's stopping hydrogen as a fuel, it's what's stopping gene therapy research, etc. Get over yourself.
        stevespang 5y ago
        and what about historically substantiated accidents ? Chernobyl, 3 mile island, Fukushima, etc. Not to mention that ~115 of the of all the 460 operational nuclear reactors in the world are close to the sea, just waiting for Tsunami's
        jjoonathan 5y ago
        > People really need to stop trying to sound smart > Get over yourself. Right back atcha. Good grief, "stoichiometric mixture" is not a reasonable person's danger threshold. The mechanical energy alone is terrifying, which was the point of bringing up COPVs. While we're at it, let's put giant flywheels in chemical cars to do regenerative breaking. They'll probably have less mechanical energy than the titanic so they're probably no big deal, right? Right.
        R0b0t1 5y ago
        Look, this stuff has been studied and you can find it with just a little bit of looking. How this conversation has been going is a bunch of chaff gets thrown up and then people are expected to answer. I'm doing as best I can. I happened to have a coworker who was involved in alternative fuels research, specifically the H2 cylinders that operated at lower pressures using a carbon substrate. But even if you don't use that you can still construct and secure the container so it splits instead of shatters and contains most or all of the debris. You can install a shield bulkhead into the car to deflect debris to the ground. You can do loads of things. You are not original, you are not the first person to raise these concerns, and very competent people have been working on them. https://xkcd.com/793/ https://xkcd.com/793/
- huntertwo 5y ago
  Those gas tanks are more risky when you have constraints on weight and material of the tank, like in moving vehicles. I agree though, people unfairly disqualify hydrogen on this risk only.
- lizknope 5y ago
  https://en.wikipedia.org/wiki/Hindenburg_disaster#Incendiary_paint_hypothesis https://en.wikipedia.org/wiki/Hindenburg_disaster#Incendiary... They tested the incendiary paint hypothesis on the TV show Mythbusters. The MythBusters concluded that the paint may have contributed to the disaster, but that it was not the sole reason for such rapid combustion.
  - R0b0t1 5y ago
    Ah, you're right. I wasn't remembering the details exactly. But the burning material that falls is the skin and can be better fireproofed to let the hydrogen escape upwards.
- raxxorrax 5y ago
  Diffusion is also a problem. A very efficient form to store hydrogen is a solid block of metal, which of course comes with similar restrictions as batteries, if not worse.

oblio 5y ago

> I would rather not fly in a bomb. I just don't see it being viable for planes. As opposed to the kerosene fueled bombs we're flying in right now? I'm not sure comparing things to close-to-wartime tech from 90 years ago is a valid approach.

dragontamer 5y ago
> I'm not sure comparing things to close-to-wartime tech from 90 years ago is a valid approach. You might be surprised how good WW2-era scientists were at chemistry and science. The earlier poster has a point. Gasoline, Diesel, and Kerosene have all been studied extensively (especially in the 1930s and 1940s BECAUSE of preparations for WW2). The safety of soldiers was paramount even to the Nazis. War machines: be they airplanes, tanks, or battleships, were all going to be exposed to enemy fire and explosions. These fuels (Kerosene and Diesel in particular) were chosen because they're extremely safe: high flash points and even higher auto-ignition points. That means that kerosene __literally__ can't catch on fire at room temperature. You need to warm up kerosene before its appropriate to burn (Of course, once its burning it will warm up the rest of the kerosene and keep burning. But this isn't some super-explosive volatile chemical we're talking about here) Gasoline is still safe, but not as safe as the other two (-40C Flash Point). Gasoline was safer than a lot of the other petroleum products that were investigated back then, and was still chosen as a fuel for war machines. --------- The same is not necessarily true for H2. H2 will explode at any temperature (even near absolute zero).
- oblio 5y ago
  > You might be surprised how good WW2-era scientists were at chemistry and science. I'm well aware of chemical prowess in that period, especially on the German part. They had a bunch of Nobel prize winners. However, that's why I said "close-to-wartime". First of all, in case you weren't aware, the Hindenburg was supposed to use helium but due to a lack of helium in Germany (I think it was primarily due to American export restrictions), they had to use hydrogen. I don't know of other limitations for the Hindenburg, per se, but knowing the overall German shortages of the period, I wouldn't be surprised if they had other structural issues with the Hindenburg itself, especially since it wasn't designed to be used with hydrogen. On top of this, the Hindenburg design was from the late 20s, 1929, I believe. If materials science, modeling, etc haven't advanced since 1929, I'll eat a shoe. If we're somehow worse at managing hydrogen after almost 100 years, I'll eat the other shoe.

dragontamer 5y ago

Even if H2 isn't used directly, there are likely chemical processes that can convert it into some form that is more useful. EDIT: That's what its called. H2 is a component of Syngas (https://en.wikipedia.org/wiki/Syngas https://en.wikipedia.org/wiki/Syngas). Syngas can then be further processed into kerosene, gasoline, or other fuels we use.

lemmsjid 5y ago

This has some interesting comparisons between hydrogen and gasoline as fuel, in terms of historical experimentation as to the effects of rupturing or destroying tanks holding one or the other: https://hydrogen.wsu.edu/2017/03/17/so-just-how-dangerous-is-hydrogen-fuel/ https://hydrogen.wsu.edu/2017/03/17/so-just-how-dangerous-is.... Not my field so I'd be interested in if this more or less reflective of current knowledge on the subject.