There is a significant difference between a Captive Power Plant (CPP) and a Cogeneration plant. In a CPP setup, the equipment for generating power and equipment for generating process heat are seperate.

In a Cogeneration setup, only the excess heat in the steam generated is used and remaining heat is used for the process requirement. Therefore, steam is not specifically generated for power production. The same steam being generated for the process requirement is used to produce power. This makes the cost of fuel ZERO. This is especially true for industries that use their process waste as boiler fuel. Sugar factories use baggase and rice mills use rice husk as boiler fuel which makes the cost of fuel truly zero.