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Hydrogen has a higher energy density by volume compared to a li-ion battery. People really need to check their fact here.

by _hypx 3y ago

willmadden 3y ago
I meant compared to gasoline.
fragmede 3y ago
Hydrogen is a gas, which expands or compresses to fill all available space, so its density varies. People really need to check their understanding of physics here.
- Alupis 3y ago
  I would assume, but perhaps be wrong, that it would be liquid Hydrogen pumped into a vehicle's tank, and much like a tank of propane, the liquid expands back into a gas as pressure decreases (due to consumption). Hydrogen vehicles have the advantage of being refillable in minutes, much like petrol based vehicles - yet the only byproduct is water vapor, making them completely environmentally friendly. Hydrogen is also hugely abundant, and renewable in the sense that the water vapor could theoretically be split again via some other process. I would really like to know more about why Hydrogen vehicles did not take off as much as electric. They seem superior in many ways. My guess would be the chicken and egg problem - few Hydrogen refilling stations nation-wide vs. you can plug in at home and charge for 18 hours or whatever.
  - blacksmith_tb 3y ago
    Toyota does sell the Mirai[1] in California, it has pressurized tanks[2] I think keeping the hydrogen liquefied would take low temps as well, which would use a lot of energy for refrigeration (and or a lot of volume for insulation). 1: https://www.toyota.com/mirai/ https://www.toyota.com/mirai/ 2: https://en.wikipedia.org/wiki/Toyota_Mirai#High-pressure_hydrogen_tanks https://en.wikipedia.org/wiki/Toyota_Mirai#High-pressure_hyd...
    - Alupis 3y ago
      Thanks for the links. I had thought the Mirai was discontinued, but it looks like it's still in production. Regarding the tanks - they appear to be high pressure, but non-refrigerated and non-insulated. It would seem pressure alone keeps the Hydrogen in liquid state - if that's how it works.
      - lern_too_spel 3y ago
        The hydrogen is not in a liquid state.
  - deleted 3y ago
    [deleted]
  - starbase 3y ago
    Hydrogen's critical temperature is cryogenic. There's no keeping it liquid at any pressure if it's warmer than -240C
    - Alupis 3y ago
      Can you locate a source specifically for a vehicle like the Toyota Mirai or one of the newer big rig trucks using hydrogen? Everything I come across seems to imply they are using high pressure (10,000 PSI) but no talk about insulation or refrigerant. I could be missing it somewhere...
      - starbase 3y ago
        The hydrogen is stored as compressed gas. No doubt about it. The physics: https://www.engineeringtoolbox.com/docs/documents/1419/Hydrogen%20phase%20diagram.jpg https://www.engineeringtoolbox.com/docs/documents/1419/Hydro... Some photos: https://www.thedrive.com/news/37872/now-with-three-hydrogen-tanks-the-2021-toyota-mirai-gets-a-400-mile-range https://www.thedrive.com/news/37872/now-with-three-hydrogen-...
  - cogman10 3y ago
    > I would really like to know more about why Hydrogen vehicles did not take off as much as electric. Lots of reasons. So, here's some off the top of my head. * Infrastructure - There's no hydrogen distribution system in place. Further, hydrogen is trickier to distribute/store. It's not like gas where you can just have a big empty metal drum that you fill and discharge. Consider, for example, that as gases expand they cool down and as they compress they heat up (Boyle's law). Now consider the danger of refilling, go too fast (with any sort of oxygen present) and you run the real risk of explosion. Without oxygen, you still have to deal with the heat generated. On the flip side, pulling hydrogen out of a tanker will cause the tanker and the stored hydrogen to freeze, forcing you to wait for a defrost if you go too fast. * Hydrogen is not green. I know everyone THINKS that hydrogen production would primarily come from electrolysis, but that's not how commercial hydrogen is produced [1]. Instead, hydrogen primarily comes from fossil fuels (methane, natural gas). * Related to the first point, charging a hydrogen vehicle would require all the same headaches the current EV connectors have gone through. You can't just specify a diameter and go from there. You must create a seal to prevent hydrogen from leaking from the pump. It's doable, but also dangerous if you get it wrong. Hydrogen is far more flammable than gas which is really super risky if someone is smoking while recharging. * Electricity is already distributed. The fact that you are writing here on hacker news means you have a source of electricity that could potentially power your car. The EV charge station distribution is largely just a factor of setting up stations. Further, for relatively little money existing gas stations can easily be converted to support EVs. That's not so with Hydrogen. Another reason for the popularity of EVs is home charging is really fantastic. If you own a home and install a charger you'll almost never need any public fueling infrastructure. (also, with an EV charger refueling at home from 0 to 100 takes about 7 hours. Refueling for daily road trips generally takes more along the lines of 1 hour. Most cars are idle for more than an hour). [1] https://www.eia.gov/energyexplained/hydrogen/production-of-hydrogen.php https://www.eia.gov/energyexplained/hydrogen/production-of-h...
    - tuatoru 3y ago
      The risk of explosion cannot be overemphasized. Methane will ignite when in concentrations of 4% - 17% in air, but with hydrogen the range is 4% to 75%. Hydrogen also has a higher flame speed than methane. (Boom!, not Whoosh!) Given hydrogen's propensity to escape from containers these properties make it unsuitable for domestic uses.
  - _hypx 3y ago
    Hydrogen in a car would be gas the whole time. It is just compressed high enough that the tanks can fit in a car.
  - surfaceofthesun 3y ago
    For a direct answer, this[1] is a good starting point discussing the difficulties with hydrogen (as a medium generally). Hydrogen fuel cell vs combustion isn’t a settled issue. Combustion is more familiar but Carnot Efficiency is going to reduce range (even further). Fuel cells are more efficient but more expensive. Anything with hydrogen needs to worry about embrittlement. It’s also very difficult to contain so the GWP of 11.6 shouldn’t be overlooked; methane is much easier to manage and still our natural gas infrastructure leaks all over the place. The electrification of industrial processes have allowed for increasingly-cheaper electric motors to operate efficiently at any size, from toy RC cars to massive (diesel) electric trains. Even barring any energy density breakthroughs, electrification with batteries for light duty applications seems inevitable. Having a gigantic battery (compared to residential electrical use) as backup is quite useful. Virtual power plants [2] and stationary deployment of secondhand battery cells should lessen the substantial cost of vehicle batteries — we’re at least a decade away from EV trade-ins being common outside of Norway (and maybe China). For heavy duty applications, we have an existing solution that works fairly well. We’re just going to end up reinventing catenaries for this era [2]. The operational challenges of maintaining catenary wire systems (especially with shared electric right of ways) is just easier than overcoming the chemistry. That is of course, unless we get in our own way [4]. —- [1] https://www.thechemicalengineer.com/features/the-unbearable-lightness-of-hydrogen/#:~:text=As%20a%20liquid%2C%20hydrogen%20is,MPa%2C%20respectively%20%5B1%5D https://www.thechemicalengineer.com/features/the-unbearable-.... [2] https://liftoff.energy.gov/vpp/ https://liftoff.energy.gov/vpp/ [3] https://www.carscoops.com/2021/10/germany-is-already-testing-overhead-charging-cables-for-long-haul-electric-trucks-on-highway/amp/ https://www.carscoops.com/2021/10/germany-is-already-testing... [4] https://www.gao.gov/products/gao-08-347r https://www.gao.gov/products/gao-08-347r
    - _hypx 3y ago
      This is outdated crap from 20 years ago. Virtually all of the problems of dealing with hydrogen have been solved. Even GWP has been known for decades (note: It is all about indirect methane emissions, so it is not particularly real). The main point is that hydrogen is vastly cheaper and less resource demanding than batteries. You can expect hydrogen cars to be as cheap as ICE cars. Something BEVs can never hope to achieve outside of short-ranged vehicles. A very plausible scenario is that efficiency of fuel cells and electrolyzers improve to the point where BEVs become obsolete. It's arguable we've already reached that point, and this conversation is just the "solar/wind power is impossible" phase of the conversation.
  - acdha 3y ago
    There are a few posters here who’ve reported first hand experience. It definitely sounds like a chicken-and-egg problem compounded by the impracticality of storing and pressurizing hydrogen - every part of the process costs a lot more than gasoline: https://news.ycombinator.com/item?id=28818305 https://news.ycombinator.com/item?id=28818305 https://news.ycombinator.com/item?id=34485260 https://news.ycombinator.com/item?id=34485260 https://news.ycombinator.com/item?id=35680544 https://news.ycombinator.com/item?id=35680544
- willmadden 3y ago
  lol
- canadianfella 3y ago
  [dead]
- _hypx 3y ago
  If you're assuming it is compressed, to say 700 bar, then it would have a higher volumetric density.

Hydrogen has a higher energy density by volume compared to a li-ion battery. People really need to check their fact here.

by _hypx 3y ago

Hydrogen has a higher energy density by volume compared to a li-ion battery. People really need to check their fact here.

willmadden 3y ago

I meant compared to gasoline.

fragmede 3y ago

Hydrogen is a gas, which expands or compresses to fill all available space, so its density varies. People really need to check their understanding of physics here.

Alupis 3y ago
I would assume, but perhaps be wrong, that it would be liquid Hydrogen pumped into a vehicle's tank, and much like a tank of propane, the liquid expands back into a gas as pressure decreases (due to consumption). Hydrogen vehicles have the advantage of being refillable in minutes, much like petrol based vehicles - yet the only byproduct is water vapor, making them completely environmentally friendly. Hydrogen is also hugely abundant, and renewable in the sense that the water vapor could theoretically be split again via some other process. I would really like to know more about why Hydrogen vehicles did not take off as much as electric. They seem superior in many ways. My guess would be the chicken and egg problem - few Hydrogen refilling stations nation-wide vs. you can plug in at home and charge for 18 hours or whatever.
- blacksmith_tb 3y ago
  Toyota does sell the Mirai[1] in California, it has pressurized tanks[2] I think keeping the hydrogen liquefied would take low temps as well, which would use a lot of energy for refrigeration (and or a lot of volume for insulation). 1: https://www.toyota.com/mirai/ https://www.toyota.com/mirai/ 2: https://en.wikipedia.org/wiki/Toyota_Mirai#High-pressure_hydrogen_tanks https://en.wikipedia.org/wiki/Toyota_Mirai#High-pressure_hyd...
  - Alupis 3y ago
    Thanks for the links. I had thought the Mirai was discontinued, but it looks like it's still in production. Regarding the tanks - they appear to be high pressure, but non-refrigerated and non-insulated. It would seem pressure alone keeps the Hydrogen in liquid state - if that's how it works.
    - lern_too_spel 3y ago
      The hydrogen is not in a liquid state.
- deleted 3y ago
  [deleted]
- starbase 3y ago
  Hydrogen's critical temperature is cryogenic. There's no keeping it liquid at any pressure if it's warmer than -240C
  - Alupis 3y ago
    Can you locate a source specifically for a vehicle like the Toyota Mirai or one of the newer big rig trucks using hydrogen? Everything I come across seems to imply they are using high pressure (10,000 PSI) but no talk about insulation or refrigerant. I could be missing it somewhere...
    - starbase 3y ago
      The hydrogen is stored as compressed gas. No doubt about it. The physics: https://www.engineeringtoolbox.com/docs/documents/1419/Hydrogen%20phase%20diagram.jpg https://www.engineeringtoolbox.com/docs/documents/1419/Hydro... Some photos: https://www.thedrive.com/news/37872/now-with-three-hydrogen-tanks-the-2021-toyota-mirai-gets-a-400-mile-range https://www.thedrive.com/news/37872/now-with-three-hydrogen-...
- cogman10 3y ago
  > I would really like to know more about why Hydrogen vehicles did not take off as much as electric. Lots of reasons. So, here's some off the top of my head. * Infrastructure - There's no hydrogen distribution system in place. Further, hydrogen is trickier to distribute/store. It's not like gas where you can just have a big empty metal drum that you fill and discharge. Consider, for example, that as gases expand they cool down and as they compress they heat up (Boyle's law). Now consider the danger of refilling, go too fast (with any sort of oxygen present) and you run the real risk of explosion. Without oxygen, you still have to deal with the heat generated. On the flip side, pulling hydrogen out of a tanker will cause the tanker and the stored hydrogen to freeze, forcing you to wait for a defrost if you go too fast. * Hydrogen is not green. I know everyone THINKS that hydrogen production would primarily come from electrolysis, but that's not how commercial hydrogen is produced [1]. Instead, hydrogen primarily comes from fossil fuels (methane, natural gas). * Related to the first point, charging a hydrogen vehicle would require all the same headaches the current EV connectors have gone through. You can't just specify a diameter and go from there. You must create a seal to prevent hydrogen from leaking from the pump. It's doable, but also dangerous if you get it wrong. Hydrogen is far more flammable than gas which is really super risky if someone is smoking while recharging. * Electricity is already distributed. The fact that you are writing here on hacker news means you have a source of electricity that could potentially power your car. The EV charge station distribution is largely just a factor of setting up stations. Further, for relatively little money existing gas stations can easily be converted to support EVs. That's not so with Hydrogen. Another reason for the popularity of EVs is home charging is really fantastic. If you own a home and install a charger you'll almost never need any public fueling infrastructure. (also, with an EV charger refueling at home from 0 to 100 takes about 7 hours. Refueling for daily road trips generally takes more along the lines of 1 hour. Most cars are idle for more than an hour). [1] https://www.eia.gov/energyexplained/hydrogen/production-of-hydrogen.php https://www.eia.gov/energyexplained/hydrogen/production-of-h...
  - tuatoru 3y ago
    The risk of explosion cannot be overemphasized. Methane will ignite when in concentrations of 4% - 17% in air, but with hydrogen the range is 4% to 75%. Hydrogen also has a higher flame speed than methane. (Boom!, not Whoosh!) Given hydrogen's propensity to escape from containers these properties make it unsuitable for domestic uses.
- _hypx 3y ago
  Hydrogen in a car would be gas the whole time. It is just compressed high enough that the tanks can fit in a car.
- surfaceofthesun 3y ago
  For a direct answer, this[1] is a good starting point discussing the difficulties with hydrogen (as a medium generally). Hydrogen fuel cell vs combustion isn’t a settled issue. Combustion is more familiar but Carnot Efficiency is going to reduce range (even further). Fuel cells are more efficient but more expensive. Anything with hydrogen needs to worry about embrittlement. It’s also very difficult to contain so the GWP of 11.6 shouldn’t be overlooked; methane is much easier to manage and still our natural gas infrastructure leaks all over the place. The electrification of industrial processes have allowed for increasingly-cheaper electric motors to operate efficiently at any size, from toy RC cars to massive (diesel) electric trains. Even barring any energy density breakthroughs, electrification with batteries for light duty applications seems inevitable. Having a gigantic battery (compared to residential electrical use) as backup is quite useful. Virtual power plants [2] and stationary deployment of secondhand battery cells should lessen the substantial cost of vehicle batteries — we’re at least a decade away from EV trade-ins being common outside of Norway (and maybe China). For heavy duty applications, we have an existing solution that works fairly well. We’re just going to end up reinventing catenaries for this era [2]. The operational challenges of maintaining catenary wire systems (especially with shared electric right of ways) is just easier than overcoming the chemistry. That is of course, unless we get in our own way [4]. —- [1] https://www.thechemicalengineer.com/features/the-unbearable-lightness-of-hydrogen/#:~:text=As%20a%20liquid%2C%20hydrogen%20is,MPa%2C%20respectively%20%5B1%5D https://www.thechemicalengineer.com/features/the-unbearable-.... [2] https://liftoff.energy.gov/vpp/ https://liftoff.energy.gov/vpp/ [3] https://www.carscoops.com/2021/10/germany-is-already-testing-overhead-charging-cables-for-long-haul-electric-trucks-on-highway/amp/ https://www.carscoops.com/2021/10/germany-is-already-testing... [4] https://www.gao.gov/products/gao-08-347r https://www.gao.gov/products/gao-08-347r
  - _hypx 3y ago
    This is outdated crap from 20 years ago. Virtually all of the problems of dealing with hydrogen have been solved. Even GWP has been known for decades (note: It is all about indirect methane emissions, so it is not particularly real). The main point is that hydrogen is vastly cheaper and less resource demanding than batteries. You can expect hydrogen cars to be as cheap as ICE cars. Something BEVs can never hope to achieve outside of short-ranged vehicles. A very plausible scenario is that efficiency of fuel cells and electrolyzers improve to the point where BEVs become obsolete. It's arguable we've already reached that point, and this conversation is just the "solar/wind power is impossible" phase of the conversation.
- acdha 3y ago
  There are a few posters here who’ve reported first hand experience. It definitely sounds like a chicken-and-egg problem compounded by the impracticality of storing and pressurizing hydrogen - every part of the process costs a lot more than gasoline: https://news.ycombinator.com/item?id=28818305 https://news.ycombinator.com/item?id=28818305 https://news.ycombinator.com/item?id=34485260 https://news.ycombinator.com/item?id=34485260 https://news.ycombinator.com/item?id=35680544 https://news.ycombinator.com/item?id=35680544
willmadden 3y ago
lol
canadianfella 3y ago
[dead]
_hypx 3y ago
If you're assuming it is compressed, to say 700 bar, then it would have a higher volumetric density.