II. Calorific Value of producer gas is calculated on the basis of 1 kg carbon

The calorific value of gaseous fuel when air is used for gasification

Therefore % CV of 1 Kg of C available in producer gas is   69.5%
That means 30.5 % of calorific value of C represents sensible heat and heat losses.

Calorific value of producer gas when produced by gasifying carbon with a mixture of air+steam is
Calorific value of producer gas considering gaseous state is the standard state                                                                                

Calorific value of producer gas as expressed in % of calorific value of

We observe that the gasification of C with a mixture of air and steam increases the calorific value of producer gas which is mainly due to addition of hydrogen.

Calorific value of producer gas when produced by gasifying carbon with a mixture of oxygen+steam
The calorific value is almost similar to that of air + steam. But the volume of producer gas is only 62% that of air + steam and 48% that of air only. Benefit of using steam is self evident.