In article ,
Skywise wrote:

Larry Dighera wrote in
:

She also said the hydrogen would be compressed to ten bar,
which would raise its energy density comparable to that of
gasoline.

I'm not so sure about that.

An article I found many many years ago, published in 2002,
discusses such things. If the information in the article is
correct, it is extremely difficult to beat gasoline for
energy density.

It lists gasoline as having an energy density of 9000Wh/l
(watt-hours per liter).

150 bar H2 is only 405 Wh/l.

Liquid H2 is 2600 Wh/l.

Lithium batteries are listed as 250 Wh/l, but mind you
this was published 12 years ago. Battery technology has
made large leaps since then. Even if they've only
doubled in energy density since then, that would still
beat 150 bar H2.

http://www.tinaja.com/glib/energfun.pdf

Brian

Battery technology hasn't (and probably never will) reached a
competitive level with hydrocarbons for energy density.

Just think, for back-of-the-envelope calculation, that the energy stored
in a battery represents the entire mass of all the fuel (and air) that a
combustion engine uses for power. The fuel represents only 1/15 the
total mass, which means that, for every gallon of gasoline (6 lb) 90 lb
of air must pass through the motor. So, for a 50-gallon fuel tank (300
lb), one must also carry 4500 lb of air.