For the hydrogen -oxygen reaction: dH = - 68,317 cal/g mole of H _{2},
and dG = - 56,690 cal/g mole of H_{2} .
The efficiency of the Ideal Fuel Cell is therefore:Efficiency = (56,690/68,317) = 83%Another
measure of the fuel cell efficiency is known as the "Voltage Efficiency" and
is the ratio of the actual voltage under operating conditions to the theoretical
cell voltage.Voltage Efficiency = (Actual Voltage)/(Theoretical
Voltage) = (V _{A} / 1.23) |