Low pressure hydrogen storage

[Capt_Maloche]

I want my nephew!

Even if there is 10% loss on an electric transmission, it's even better, and I bet on the improvement of the battery yields

[Remundo]

Rescwood ...

You are too smart not to understand what I wrote

OK for yields, but it's not the dominant criterion for transportation, it's autonomy ET ease of fuel storage

And there, the rub for hydrogen ...

[jonule]

I do not want to offend you, but in my opinion the storage of hydrogen will still do well more fearful than LPG, like those prohibited in city car parks.
it's a bit like nuclear: a poll "WHO wants to have a tank full of unstable hydrogen"? (see Ariane rocket) ...........

if not captive again, say that a few drops of oil = several liters of hydrogen, what type of H2 are you talking about? monoatomic? or parahydrogen?

[Capt_Maloche]

Mmm no,

if hydrogen is stored in solid form

if not captive again, say that a few drops of oil = several liters of hydrogen, what type of H2 are you talking about? monoatomic? or parahydrogen?

ah no, you're wrong, it's Remundo who must answer you

but do not mix the genres with hydrogen in the gas phase and a liquid fuel ...

That said, taking into account:
Density H2 0.08988 kg / m³
its calorific value in dioxygen is 141,79 MJ / Kg and per unit of mass (120 kJ / g) slightly different ... according to http://fr.wikipedia.org/wiki/Dihydrog%C ... Combustion

1L of hydrogen at Patm. only represents 0.09g !!
the combustion of a liter of H2 gives: 0.09 x 141 790/1000 = 12 KJ

What about the same relationship with gasoline in the gas phase?

[tigrou_838]

Hello everyone, I fully understand your points of view, but for me the security for the development of hydrogen fuel car would be production on demand.
no tank, no LPG or other style valve, only water so no danger.
the problem is that in the current state of things, the industrialists prefer to have a grip on the thing, therefore production of hydrogen at low petroleum and nuclear product, pump station distribution, equal fuel almost at the same price as petroleum, and in addition not really ecological considering the mode of production. nuclear and petroleum.

little rant on this subject.

well I stop it before I get out by christophe.
a big smile

[Remundo]

Well Tigger, I agree with you!

Production on demand in situ in the toto, with water and a highly electropositive metal capable of breaking water!

@+

[rescwood]

1L of hydrogen at Patm. only represents 0.09g !!
the combustion of a liter of H2 gives: 0.09 x 141 790/1000 = 12 KJ

What about the same relationship with gasoline in the gas phase?

1 liter of fuel oil: 43200 KJ / Kg
1 liter of gaseous fuel oil (average PM 240) at PAtm: 10 gr, i.e. 432 KJ but 0.09 gr of fuel oil: 3,888 KJ
1 liter of gasoline, half as much PM: about 5 gr, or about 215 KJ but 0.09 gr of gasoline: 3,888 KJ

I approximated the combustion energy of gasoline to that of fuel oil.

At a given pressure and temperature, for any gas, the number of molecules will always be the same. In terms of mass, the higher the molecular weight, the higher the mass of 1l of gas will be. The molar mass of H2 (2) is not to its advantage in this type of comparison. On the other hand in its liquid form ... Roughly: 1 Kg of H2 "equals" 3,5 Kg of energetically speaking hydrocarbons.

[Remundo]

Well yes, I took 120 MJ / kg of H2 and 40 MJ / kg of gasoline ... Compared to your calculation, I should have even taken 35 MJ (factor 3,5).

But the essence is liquid in normal condition ... Hence transport and easy transfer.

And also droplet injection, so the whole room can be filled with air.

H2, on the other hand, is almost always gaseous, except at 700 Bar or at -250 ° C ... Injected into a cylinder, it passes into the gaseous state to burn and takes up a very large space than the air has. more.

In addition, its energy volume density is too low and the excellent (60%) efficiency of a heat pump "does not catch up" compared to a good thermal engine of 30% efficiency because its fuel has a very high energy volume density.

Look again at my little bit of calculation, and have fun calculating the energy density of the 7 kg of H2 in 100kg of metal assumed to 3000 kg / m3 ... then compare to 1L of gasoline

[Remundo]

Come on, I do it:

100kg of metal at 3000kg / m3, this gives a volume of 33 L.

Which contain 7 kg of H2, i.e. a storage density of
7 x 120 MJ / 33 = 25,45 MJ / L

Gasoline now ... density 0,75 kg / L and 40 MJ / kg
Or 30 MJ / L. So it's better.

But these beautiful calculations present hydrogen in a rather utopian light because they are made from an "experimental" technology that may not even work.

it must be a hell of a mess to put 7kg of H2 in 100 kg of metal, and even more the bazaar to get them out ... I see from there the mismanagement in a gas station

In practice, the CEA forecasts a density of 2015 kWh / L for 2,7, i.e. 9,72 MJ / L Far too low, because 10 MJ / 40 MJ = 0,25. To compete with hydrocarbons, the efficiency of a heat pump should be 4 times that of a heat engine (30%): impossible (120% , except for fans of hydrogen overunits)

An interesting doc which also reports on metal hydrides and the adsorption of H2 by metals ...
http://www.cea.fr/var/plain/storage/ori ... 58a669.pdf

@+

[tigrou_838]

Hello everyone.
for remundo, I see that the Auvergne are out, in addition with the same ideas !!!
a pity that I don't go down too often to Clermont at home.
solar greetings