4 ms·

I am just being mean but kilogram would not be my first choice for measuring hydrogen.

by somat 3y ago

BenjiWiebe 3y ago
Kilogram is a measure of mass. The fact that hydrogen is buoyant in our atmosphere doesn't make 1 kg of hydrogen any less.
credit_guy 3y ago
Hydrogen is generally stored compressed at 700 bar. At that pressure the density is 42 kg/m3, or one kilogram per 24 liters. Roughly one kilogram per one jerry can.
- p1mrx 3y ago
  The thought of a jerry can at 700 bar is mildly terrifying.
  - craig_s_bell 3y ago
    No need to worry; Hydrogen's exceptional permeability means the gas will diffuse through the jerry can, into the atmosphere; thus lowering its internal pressure. We can make vessels which will contain increasingly high pressures; however their permeability is higher, vs. older materials. This is a central problem of hydrogen as a primary fuel... Better to burn it (or convert it into methane) where and when it is produced.
    - credit_guy 3y ago
      I keep hearing this, and sometimes people claiming it's not true anymore, so I decided to look into it. Compressed hydrogen storage tanks are of 4 types [1]. Types 1,2 metal tanks, but they can be used only up to 300 bar. Their permeability rate is negligible. Type 4 is composite (e.g. carbon fiber) with a polymer interior lining. It operates at 700 bar (and various manufacturers state their product can work up to 850 bar). They have some permeability. Type 3 is similar, but with metal interior lining. Negligible permeability, but more expensive. I don't know how much more expensive, with these things all providers tell you to "call for quote". In any case, the only problem is Type 4. They are the affordable alternative to Type 3, and they are also in much wider use. There are some regulations and standards that govern them. Specifically EU 406/2010 and ISO 19881:2018 which prescribe a maximum steady state permeation rate of 6.0 Ncm3 of hydrogen per hour and per liter internal volume of the container [2]. To be honest, I'm not sure how to read this rate. Toyota Mirai uses such tanks (2 of them), so it can't be that bad. Each has a volume of about 60 liters, and holds about 5kg of hydrogen [3]. The more important thing is that permeability is a function of the surface area. A tank 1000 times larger has a surface area only 100 times higher, so the permeability per volume goes down by a factor of 10. Such tanks do exist and are commercially available. I'm aware of the Hexagon Titan XL that can hold 220 kg of hydrogen. The latest quarterly revenues of the manufacturer [4] show 57% year-on-year growth, so it looks like customers are quite happy with their offering. [1] https://en.wikipedia.org/wiki/Hydrogen_tank https://en.wikipedia.org/wiki/Hydrogen_tank [2] https://www.sciencedirect.com/science/article/pii/S0360319923005281?ref=cra_js_challenge&fr=RR-1 https://www.sciencedirect.com/science/article/pii/S036031992... [3] https://www.toyota.com/mirai/2023 https://www.toyota.com/mirai/2023 [4] https://hexagonpurus.com/news/hexagon-purus-asa-results-for-the-second-quarter-2023 https://hexagonpurus.com/news/hexagon-purus-asa-results-for-...
bagels 3y ago
It would be for me. What kind of measure would you use?
- jakear 3y ago
  kilomoles?
  - avmich 3y ago
    TI are going to use the hydrogen internally, so they can measure that in whatever they want. If they'd sell it or transported - good luck talking with the truckin' industry in kilomoles.
- somat 3y ago
  liters or cubic meters at pressure, whatever unit you use to measure it in.
  - bagels 3y ago
    Don't you also need the temperature to know how much there is? Seems needlessly complex.
jakear 3y ago
> In fact, if you asked me to produce a kilogram of hydrogen I don't know what I would do. Is it buoyancy? do you want -1 kilo of the stuff? Nerd sniped. Atmosphere is 1.2 kg/m^3, hydrogen is 0.090 kg/m^3. So 1 kg of hydrogen at STP would be 11 m^3. The buoyancy force would then be 13kg-1kg. Accordingly, 1kg of H weighs -12kg.
Prcmaker 3y ago
What would be better though? 1kg is 1kg, regardless of temperature, pressure and volume. A litre, gallon, cc, all need clarification with respect to something else. You could use moles, but for a given compound, mass is just a more accessible, yet equally accurate, scaled value.
fbdab103 3y ago
1 kg hydrogen = 1.02 gallons of gasoline (3.9 liters) https://epact.energy.gov/fuel-conversion-factors https://epact.energy.gov/fuel-conversion-factors

I am just being mean but kilogram would not be my first choice for measuring hydrogen.

by somat 3y ago

I am just being mean but kilogram would not be my first choice for measuring hydrogen.

Kilogram is a measure of mass. The fact that hydrogen is buoyant in our atmosphere doesn't make 1 kg of hydrogen any less.

credit_guy 3y ago

Hydrogen is generally stored compressed at 700 bar. At that pressure the density is 42 kg/m3, or one kilogram per 24 liters. Roughly one kilogram per one jerry can.

p1mrx 3y ago
The thought of a jerry can at 700 bar is mildly terrifying.
- craig_s_bell 3y ago
  No need to worry; Hydrogen's exceptional permeability means the gas will diffuse through the jerry can, into the atmosphere; thus lowering its internal pressure. We can make vessels which will contain increasingly high pressures; however their permeability is higher, vs. older materials. This is a central problem of hydrogen as a primary fuel... Better to burn it (or convert it into methane) where and when it is produced.
  - credit_guy 3y ago
    I keep hearing this, and sometimes people claiming it's not true anymore, so I decided to look into it. Compressed hydrogen storage tanks are of 4 types [1]. Types 1,2 metal tanks, but they can be used only up to 300 bar. Their permeability rate is negligible. Type 4 is composite (e.g. carbon fiber) with a polymer interior lining. It operates at 700 bar (and various manufacturers state their product can work up to 850 bar). They have some permeability. Type 3 is similar, but with metal interior lining. Negligible permeability, but more expensive. I don't know how much more expensive, with these things all providers tell you to "call for quote". In any case, the only problem is Type 4. They are the affordable alternative to Type 3, and they are also in much wider use. There are some regulations and standards that govern them. Specifically EU 406/2010 and ISO 19881:2018 which prescribe a maximum steady state permeation rate of 6.0 Ncm3 of hydrogen per hour and per liter internal volume of the container [2]. To be honest, I'm not sure how to read this rate. Toyota Mirai uses such tanks (2 of them), so it can't be that bad. Each has a volume of about 60 liters, and holds about 5kg of hydrogen [3]. The more important thing is that permeability is a function of the surface area. A tank 1000 times larger has a surface area only 100 times higher, so the permeability per volume goes down by a factor of 10. Such tanks do exist and are commercially available. I'm aware of the Hexagon Titan XL that can hold 220 kg of hydrogen. The latest quarterly revenues of the manufacturer [4] show 57% year-on-year growth, so it looks like customers are quite happy with their offering. [1] https://en.wikipedia.org/wiki/Hydrogen_tank https://en.wikipedia.org/wiki/Hydrogen_tank [2] https://www.sciencedirect.com/science/article/pii/S0360319923005281?ref=cra_js_challenge&fr=RR-1 https://www.sciencedirect.com/science/article/pii/S036031992... [3] https://www.toyota.com/mirai/2023 https://www.toyota.com/mirai/2023 [4] https://hexagonpurus.com/news/hexagon-purus-asa-results-for-the-second-quarter-2023 https://hexagonpurus.com/news/hexagon-purus-asa-results-for-...

bagels 3y ago

It would be for me. What kind of measure would you use?

jakear 3y ago
kilomoles?
- avmich 3y ago
  TI are going to use the hydrogen internally, so they can measure that in whatever they want. If they'd sell it or transported - good luck talking with the truckin' industry in kilomoles.
somat 3y ago
liters or cubic meters at pressure, whatever unit you use to measure it in.
- bagels 3y ago
  Don't you also need the temperature to know how much there is? Seems needlessly complex.

jakear 3y ago

> In fact, if you asked me to produce a kilogram of hydrogen I don't know what I would do. Is it buoyancy? do you want -1 kilo of the stuff? Nerd sniped. Atmosphere is 1.2 kg/m^3, hydrogen is 0.090 kg/m^3. So 1 kg of hydrogen at STP would be 11 m^3. The buoyancy force would then be 13kg-1kg. Accordingly, 1kg of H weighs -12kg.

Prcmaker 3y ago

What would be better though? 1kg is 1kg, regardless of temperature, pressure and volume. A litre, gallon, cc, all need clarification with respect to something else. You could use moles, but for a given compound, mass is just a more accessible, yet equally accurate, scaled value.

fbdab103 3y ago

1 kg hydrogen = 1.02 gallons of gasoline (3.9 liters) https://epact.energy.gov/fuel-conversion-factors https://epact.energy.gov/fuel-conversion-factors