In a fuel cell, methanol is used as a fuel and oxygen gas is used as an oxidizer. The reaction is ${\mathrm{CH}}_3\mathrm{OH}\left(\mathrm{l}\right)+\frac{3}{2}{\mathrm{O}}_2\left(\mathrm{g}\right)\to {\mathrm{CO}}_2\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$.

At $298 \mathrm{K}$, the standard Gibbs energies of the formation for ${\mathrm{CH}}_3\mathrm{OH}\left(\mathrm{l}\right), {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$ and ${\mathrm{CO}}_2\left(\mathrm{g}\right)$ are $-166.2,-237.2$ and $-394.4 \mathrm{kJ} {\mathrm{mol}}^{-1}$, respectively. If the standard enthalpy of combustion of methanol is $-726 \mathrm{kJ} {\mathrm{mol}}^{-1}$, the efficiency of the fuel cell will be: