"...Liquified nitrogen gas can store a lot of energy, pressure-wise..."

Not so. The reason people store N2 in the liquid phase is that the density
is high so you store a lot of mass for little volume. Also if you keep it
liquified you can store it in a lightweight thin wall tank. To keep it
liquified you have to allow it to boil slightly and vent off the gaseous
component, to remove the heat coming in through the insulation. So the tank
and the liquid is at a LOW pressure, and a LOW temperature of course. If
you don't vent it, it will just continue to boil & pressurize as the heat
keeps coming in. Eventually you will have a tank of pressurized gaseous N2
if you're lucky, or an empty tank because it's all gone out of the safety
valve, or a ruptured tank if you're unlucky.

If you try to use pressurized N2 [vs liquid] to power your a/c you will need
a heavy tank to withstand the pressure. The energy you will get out of
expanding the gas through a turbine or recip engine probably won't drag it
into the air, and it will be all gone before you know it.

Now with a tank of LH2 and a tank of LOX, you could.... but that's another
story

nuke
"sanman" wrote in message
om...
Hi,

snip