We know that the steam point = 100^{0} C = 100 + 273 = 373 K and the ice point is 0^{0}C = 0 + 273 = 273 K. Also, we know that the efficiency, η of the Carnot engine is defined as

Here T_{2} is the Kelvin temperature of hot reservoir and T_{1} is the Kelvin temperature of the sink. Hence, regarding the steam point as the hot reservoir and ice point as the sink between which the Carnot engine operates, we have

Percent efficiency =