7 ms·

Hydrogen Cools Well, but Safety Is Crucial

27 points by tristanlukens 3y ago

pjc50 3y ago
Yup - hydrogen is a really good coolant, it's just explosive in air. Also popular in Stirling engines for this reason and its very low viscosity.
- ReptileMan 3y ago
  Has there been cases of them spontaneously turning into one stroke combustion engines?
someguydave 3y ago
This is why the idea of the public using hydrogen cars is kind of crazy.
- kylec 3y ago
  Just wait until you hear about this explosive fuel called "gasoline" that is quite popular for powering cars too
  - jjoonathan 3y ago
    Compressed gas at 200atm is a different kind of explosive.
  - bell-cot 3y ago
    Gasoline is an easily-contained liquid. Gasoline-vapor/air mixtures explode under relatively limited circumstances. Vs. hydrogen is a difficult-to-contain gas, the concentration range for hydrogen/air to be explosive is extremely wide, and triggering the explosion is extremely easy.
    - spookie 3y ago
      While I do not argue the explosive nature of it, safety can be improved by embracing how fast it disperses. Think Toyota went that path with interleaved fibers in their containers' outer enclosures, to augment that effect, so it isn't sufficient for an explosion to occur. https://www.youtube.com/watch?v=jVeagFmmwA0 https://www.youtube.com/watch?v=jVeagFmmwA0 (Edit: added Toyota's test where they shot an hydrogen tank, you can see the fibers and the gas dispersion)
      - bell-cot 3y ago
        True. But a hydrogen / air mixture is explosive from 4% hydrogen to 74% hydrogen, Americans love their attached garages, and most attached garages feature a perfectly-placed electric spark detonator...er, I mean electric garage door opener...which is triggered daily.
        spookie 3y ago
        Fair
  - abakker 3y ago
    ever watched someone extinguish a cigarette in gasoline? it's explosive, but in a narrow band of conditions.
    - glitchc 3y ago
      You've been watching too many movies. MythBusters tested this. A pool of gasoline will extinguish a cigarette dropped in it every time.
      - MPSimmons 3y ago
        I think you and the comment you replied to are agreeing.
      - abakker 3y ago
        I was not clear - I agree with you. I was saying that gasoline might be explosive, but it is not likely to happen. it is remarkably tolerant of heat/spark at STP conditions.
- Qwertious 3y ago
  Not really - hydrogen shoots straight up into the atmosphere, whereas petrol both pools in the area and also turns to gas and mixes with air quite easily (which is why it's used as a fuel in the first place) In practice, hydrogen cars are quite safe. They're just not worth the cost in infrastructure and lack of efficiency compared to BEVs.
  - bell-cot 3y ago
    > ...hydrogen shoots straight up into the atmosphere... Two words: Attached Garage
  - GravitasFailure 3y ago
    It also depends on storage method. Cryogenic and compressed hydrogen have extreme risks completely unrelated to the flammability of the gas itself, while various metal hydride options are mostly a danger if you drop the tank on your foot.
  - mattashii 3y ago
    > They're just not worth the cost in infrastructure and lack of efficiency compared to BEVs. Don't BEVs weigh more than hydrogen cars, given the same model and range? That would give at least some incentive to use hydrogen over BEV, as it decreases road wear, which reduces the costs associated with the operation of that car. Additionally, hydrogen cars could be considered safer once they've gotten into an accident, as risk of battery thermal runaway wouldn't usually be an issue for extended periods of time in hydrogen cars, whereas several car carrier ships have been lost due (in part or in full) to battery fires.
    - zdragnar 3y ago
      Even if car registration was taxed completely commensurate with their road wear (i.e. weight) the difference wouldn't be enough to move people over from BEV given the lack of refilling options. Gas still has the infrastructure, but batteries are closer to having what they need than hydrogen for critical adoption. Unless you're in the upper Midwest and your car is one of those stuck at a charger unable to fast charge because it's too cold and you didn't have an hours worth of time and energy to preheat it.
- flextheruler 3y ago
  Right since we haven’t already used an equal or even more so flammable substance for the past century As far as I’m aware gasoline ignites at much lower mixtures of oxygen than hydrogen. The Hindenburg can’t hurt you and if it was filled with gasoline vapors instead of hydrogen, well it would never get of the ground, but it would have been more dangerous.
  - phkahler 3y ago
    Nope. Hydrogen is not just flammable, the article tells you it is EXPLOSIVE at concentration of 4 percent to 74 percent in air. If the Hindenburg was a hydrogen-air mixture, it would have leveled a large portion of the area rather than just burning where it fell. I've worked in areas where they were developing hydrogen fuel cell vehicles at major auto makers. The facilities are equipped with collectors, detectors, and alarms, and everyone knows to GTFO if the alarm goes off. Hydrogen leaks indoors are extremely dangerous.
    - foobarbecue 3y ago
      Hydrocarbon-air mixtures are also "EXPLOSIVE". See, e.g thermobaric weapons. Possibly what you're trying to say is that it's easier to get the air in? Or that it's stored under pressure?
      - thsksbd 3y ago
        The point is that, as scary as gasoline is, the explosive mixture is quite narrow compared to H2. Add in a minuscule spark energy and H2 is no joke
        foobarbecue 3y ago
        Ah, I see, that's true.
        bell-cot 3y ago
        And gasoline is very easily contained. And leaks are visually obvious. And the vapors form & accumulate very slowly. Hydrogen has zero of those safety virtues.
Karellen 3y ago
> Kilmartin said one of the questions he asked when he first got into the business was “who came up with this idea? He had to be a madman.” Kilmartin should spend more time around rocket scientists. After hearing a few tales of some of the stuff they've come up with in the name of performance - like a Hydrogen/Lithium/Fluorine(!) tripropellant engine (but you get an Isp of 542s!!!) - using Hydrogen for cooling will sound positively tame, and easily controlled.
- Tuna-Fish 3y ago
  Rocket science as a field moved out of exotic energetic fuels by the end of the 90's, because the juice wasn't worth the squeeze, and there is currently an ongoing industry-wide exodus from hydrogen to methane for the same reason. Getting the peak of performance sounds cool when you ignore costs, but in the real world with limited budgets, building a rocket twice as large is easily worth it if it means you never have to touch liquid hydrogen.
  - njarboe 3y ago
    Even more so in the era of re-usable rockets. Cheap fuel and reliability are now the focus.
  - le-mark 3y ago
    > there is currently an ongoing industry-wide exodus from hydrogen to methane for the same reason. Exodus seems a bit of an overstatement. Other than spacex who else has or is planning to develop a methane engine? And other than SSME and Vulcain which other widely used engines used H2?
    - Karellen 3y ago
      > who else has or is planning to develop a methane engine? BO's New Glenn first stage, RocketLab's Neutron, and Relativity Space's Terran 1/Terran R, are all/will all be methane. > which other widely used engines used H2? Ariane 5 and 6, and the upper stages of previous Ariane rockets https://en.wikipedia.org/wiki/Rocket_propellant#Current_cryogenic_types https://en.wikipedia.org/wiki/Rocket_propellant#Current_cryo... Edit: Long March 9 will be mostly methane, with hydrogen upper stage.
MPSimmons 3y ago
Hydrogen sucks to work with, from everything I've heard. In addition to the combustion risk when oxygen is introduced, there's the fact that hydrogen molecules are tiny and like to slip through otherwise solid materials, which is annoying if you're trying to fuel a rocket, but it's eventually catastrophic for containment vessels, due to hydrogen embrittlement[1]. As tempting as it is for its benefits, I don't see it being worth the long-term risks and engineering trades. https://en.wikipedia.org/wiki/Hydrogen_embrittlement https://en.wikipedia.org/wiki/Hydrogen_embrittlement
- standeven 3y ago
  I've worked with hydrogen (H2) quite a bit recently. Embrittlement and leakage are easy to work around, but here are the pain points I've seen: 1. H2 is still expensive. Most fuel cells require very pure H2 (five nines; 99.999%), or else it can damage the internal membrane. This pure H2 is not very affordable outside of a limited number of fuelling stations. 2. The rules around H2 use and transportation are still fuzzy. Despite being around for so long, regulations are still lacking or unclear. 3. H2 is light weight but takes up a lot of volume, limiting the usefulness of small-scale applications. Compressing it to liquid takes a lot of energy. 4. Fire/explosion risks, as you mentioned. 5. Fuel cells are expensive. If you look at financial statements for most fuel cell companies, they are selling them at a loss, meaning most fuel cells sold today are subsidized by government grants and investors. 6. The oil/gas industry is still pushing "grey" and "blue" hydrogen, which uses natural gas and emits carbon to produce H2. I think H2 will play an important role, especially in decarbonizing steel making and large transportation applications, but people need to be aware of the limitations and longer timelines required for widespread adoption of green H2.
  - ViewTrick1002 3y ago
    I love the hydrogen ladder to visualize this concept. To decarbonize fertilizer hydrogen is unavoidable, for personal transports it has been uncompetitive the past decade. https://www.linkedin.com/pulse/clean-hydrogen-ladder-v40-michael-liebreich/ https://www.linkedin.com/pulse/clean-hydrogen-ladder-v40-mic...
  - 3y ago
pfdietz 3y ago
Another reason hydrogen is good for cooling is its low viscosity. The low viscosity is the reason the energy needed to transport hydrogen by pipeline is only slightly higher than natural gas, even though the combustion energy per molecule is considerably lower.
christkv 3y ago
The no longer existing hydrogen fuel station outside of Oslo agrees. The detonation was heard for miles
willis936 3y ago
If you want to get really nuts: consider that high temperature superconductors are a good match for hydrogen cryogen coolant. Hight temperature superconductors work with liquid nitrogen, but work best with liquid helium and there just isn't that much helium in the world compared to how much superconducting magnets we could use.

27 points by tristanlukens 3y ago

Yup - hydrogen is a really good coolant, it's just explosive in air. Also popular in Stirling engines for this reason and its very low viscosity.

ReptileMan 3y ago
Has there been cases of them spontaneously turning into one stroke combustion engines?

someguydave 3y ago

This is why the idea of the public using hydrogen cars is kind of crazy.

kylec 3y ago
Just wait until you hear about this explosive fuel called "gasoline" that is quite popular for powering cars too
- jjoonathan 3y ago
  Compressed gas at 200atm is a different kind of explosive.
- bell-cot 3y ago
  Gasoline is an easily-contained liquid. Gasoline-vapor/air mixtures explode under relatively limited circumstances. Vs. hydrogen is a difficult-to-contain gas, the concentration range for hydrogen/air to be explosive is extremely wide, and triggering the explosion is extremely easy.
  - spookie 3y ago
    While I do not argue the explosive nature of it, safety can be improved by embracing how fast it disperses. Think Toyota went that path with interleaved fibers in their containers' outer enclosures, to augment that effect, so it isn't sufficient for an explosion to occur. https://www.youtube.com/watch?v=jVeagFmmwA0 https://www.youtube.com/watch?v=jVeagFmmwA0 (Edit: added Toyota's test where they shot an hydrogen tank, you can see the fibers and the gas dispersion)
    - bell-cot 3y ago
      True. But a hydrogen / air mixture is explosive from 4% hydrogen to 74% hydrogen, Americans love their attached garages, and most attached garages feature a perfectly-placed electric spark detonator...er, I mean electric garage door opener...which is triggered daily.
      - spookie 3y ago
        Fair
- abakker 3y ago
  ever watched someone extinguish a cigarette in gasoline? it's explosive, but in a narrow band of conditions.
  - glitchc 3y ago
    You've been watching too many movies. MythBusters tested this. A pool of gasoline will extinguish a cigarette dropped in it every time.
    - MPSimmons 3y ago
      I think you and the comment you replied to are agreeing.
    - abakker 3y ago
      I was not clear - I agree with you. I was saying that gasoline might be explosive, but it is not likely to happen. it is remarkably tolerant of heat/spark at STP conditions.
Qwertious 3y ago
Not really - hydrogen shoots straight up into the atmosphere, whereas petrol both pools in the area and also turns to gas and mixes with air quite easily (which is why it's used as a fuel in the first place) In practice, hydrogen cars are quite safe. They're just not worth the cost in infrastructure and lack of efficiency compared to BEVs.
- bell-cot 3y ago
  > ...hydrogen shoots straight up into the atmosphere... Two words: Attached Garage
- GravitasFailure 3y ago
  It also depends on storage method. Cryogenic and compressed hydrogen have extreme risks completely unrelated to the flammability of the gas itself, while various metal hydride options are mostly a danger if you drop the tank on your foot.
- mattashii 3y ago
  > They're just not worth the cost in infrastructure and lack of efficiency compared to BEVs. Don't BEVs weigh more than hydrogen cars, given the same model and range? That would give at least some incentive to use hydrogen over BEV, as it decreases road wear, which reduces the costs associated with the operation of that car. Additionally, hydrogen cars could be considered safer once they've gotten into an accident, as risk of battery thermal runaway wouldn't usually be an issue for extended periods of time in hydrogen cars, whereas several car carrier ships have been lost due (in part or in full) to battery fires.
  - zdragnar 3y ago
    Even if car registration was taxed completely commensurate with their road wear (i.e. weight) the difference wouldn't be enough to move people over from BEV given the lack of refilling options. Gas still has the infrastructure, but batteries are closer to having what they need than hydrogen for critical adoption. Unless you're in the upper Midwest and your car is one of those stuck at a charger unable to fast charge because it's too cold and you didn't have an hours worth of time and energy to preheat it.
flextheruler 3y ago
Right since we haven’t already used an equal or even more so flammable substance for the past century As far as I’m aware gasoline ignites at much lower mixtures of oxygen than hydrogen. The Hindenburg can’t hurt you and if it was filled with gasoline vapors instead of hydrogen, well it would never get of the ground, but it would have been more dangerous.
- phkahler 3y ago
  Nope. Hydrogen is not just flammable, the article tells you it is EXPLOSIVE at concentration of 4 percent to 74 percent in air. If the Hindenburg was a hydrogen-air mixture, it would have leveled a large portion of the area rather than just burning where it fell. I've worked in areas where they were developing hydrogen fuel cell vehicles at major auto makers. The facilities are equipped with collectors, detectors, and alarms, and everyone knows to GTFO if the alarm goes off. Hydrogen leaks indoors are extremely dangerous.
  - foobarbecue 3y ago
    Hydrocarbon-air mixtures are also "EXPLOSIVE". See, e.g thermobaric weapons. Possibly what you're trying to say is that it's easier to get the air in? Or that it's stored under pressure?
    - thsksbd 3y ago
      The point is that, as scary as gasoline is, the explosive mixture is quite narrow compared to H2. Add in a minuscule spark energy and H2 is no joke
      - foobarbecue 3y ago
        Ah, I see, that's true.
      - bell-cot 3y ago
        And gasoline is very easily contained. And leaks are visually obvious. And the vapors form & accumulate very slowly. Hydrogen has zero of those safety virtues.

Karellen 3y ago

> Kilmartin said one of the questions he asked when he first got into the business was “who came up with this idea? He had to be a madman.” Kilmartin should spend more time around rocket scientists. After hearing a few tales of some of the stuff they've come up with in the name of performance - like a Hydrogen/Lithium/Fluorine(!) tripropellant engine (but you get an Isp of 542s!!!) - using Hydrogen for cooling will sound positively tame, and easily controlled.

Tuna-Fish 3y ago
Rocket science as a field moved out of exotic energetic fuels by the end of the 90's, because the juice wasn't worth the squeeze, and there is currently an ongoing industry-wide exodus from hydrogen to methane for the same reason. Getting the peak of performance sounds cool when you ignore costs, but in the real world with limited budgets, building a rocket twice as large is easily worth it if it means you never have to touch liquid hydrogen.
- njarboe 3y ago
  Even more so in the era of re-usable rockets. Cheap fuel and reliability are now the focus.
- le-mark 3y ago
  > there is currently an ongoing industry-wide exodus from hydrogen to methane for the same reason. Exodus seems a bit of an overstatement. Other than spacex who else has or is planning to develop a methane engine? And other than SSME and Vulcain which other widely used engines used H2?
  - Karellen 3y ago
    > who else has or is planning to develop a methane engine? BO's New Glenn first stage, RocketLab's Neutron, and Relativity Space's Terran 1/Terran R, are all/will all be methane. > which other widely used engines used H2? Ariane 5 and 6, and the upper stages of previous Ariane rockets https://en.wikipedia.org/wiki/Rocket_propellant#Current_cryogenic_types https://en.wikipedia.org/wiki/Rocket_propellant#Current_cryo... Edit: Long March 9 will be mostly methane, with hydrogen upper stage.

MPSimmons 3y ago

Hydrogen sucks to work with, from everything I've heard. In addition to the combustion risk when oxygen is introduced, there's the fact that hydrogen molecules are tiny and like to slip through otherwise solid materials, which is annoying if you're trying to fuel a rocket, but it's eventually catastrophic for containment vessels, due to hydrogen embrittlement[1]. As tempting as it is for its benefits, I don't see it being worth the long-term risks and engineering trades. https://en.wikipedia.org/wiki/Hydrogen_embrittlement https://en.wikipedia.org/wiki/Hydrogen_embrittlement

standeven 3y ago
I've worked with hydrogen (H2) quite a bit recently. Embrittlement and leakage are easy to work around, but here are the pain points I've seen: 1. H2 is still expensive. Most fuel cells require very pure H2 (five nines; 99.999%), or else it can damage the internal membrane. This pure H2 is not very affordable outside of a limited number of fuelling stations. 2. The rules around H2 use and transportation are still fuzzy. Despite being around for so long, regulations are still lacking or unclear. 3. H2 is light weight but takes up a lot of volume, limiting the usefulness of small-scale applications. Compressing it to liquid takes a lot of energy. 4. Fire/explosion risks, as you mentioned. 5. Fuel cells are expensive. If you look at financial statements for most fuel cell companies, they are selling them at a loss, meaning most fuel cells sold today are subsidized by government grants and investors. 6. The oil/gas industry is still pushing "grey" and "blue" hydrogen, which uses natural gas and emits carbon to produce H2. I think H2 will play an important role, especially in decarbonizing steel making and large transportation applications, but people need to be aware of the limitations and longer timelines required for widespread adoption of green H2.
- ViewTrick1002 3y ago
  I love the hydrogen ladder to visualize this concept. To decarbonize fertilizer hydrogen is unavoidable, for personal transports it has been uncompetitive the past decade. https://www.linkedin.com/pulse/clean-hydrogen-ladder-v40-michael-liebreich/ https://www.linkedin.com/pulse/clean-hydrogen-ladder-v40-mic...
- 3y ago

pfdietz 3y ago

Another reason hydrogen is good for cooling is its low viscosity. The low viscosity is the reason the energy needed to transport hydrogen by pipeline is only slightly higher than natural gas, even though the combustion energy per molecule is considerably lower.

christkv 3y ago

The no longer existing hydrogen fuel station outside of Oslo agrees. The detonation was heard for miles

willis936 3y ago

If you want to get really nuts: consider that high temperature superconductors are a good match for hydrogen cryogen coolant. Hight temperature superconductors work with liquid nitrogen, but work best with liquid helium and there just isn't that much helium in the world compared to how much superconducting magnets we could use.