with a great appreciation
so if you don't mind to add :
1joul =1 watt *1 sec
12753.96kj =12753.96 kw *1sec
this means that
we may produce this value of energy
by using such gas within one second
or
3.54 kw per one hour
for demotic voltage (220 v) this power provide 16 amp.
as i think
am I right
or
left
1m^3 of H2 with O2 gas produce 3.54 kw as heat not electrical energy
The Gibbs free energy of 237.1 kJ/mol of H2
the enthalpy ΔH = -285.83 kJ
237.1/285.8 x100% = 83%
the fuel energy is converted to electrical energy at an efficiency 83% not more than that .
thats mean 1m^3 of hydrogen will produce less energy than we used to produce it
ΔG = ΔH - TΔS
-285.83 kJ + 48.7 kJ = -237.1 kJ
the lost will be TΔS = 48.7kj
actually we need 3.65 kw to produce 1m^3 H2 -this value change with temperature and pressure -(the value 2.69 mistake in the calculation) and 1m^3 H2 will produce 3.02kw at 83% in the full cell .
usually the full cells efficiency between 60%to 70%