What is principle of cogeneration?

Cogeneration is also known as combined heat and power and it is the most efficient way of utilizing fuel. It uses one single source of energy to produce two different forms of energy (one is heat/ thermal energy and the other one is electrical or mechanical energy). Fuel can be anything like natural gas, diesel, wood, coal, bagasse, propane, etc. Cogeneration uses the fuel to produce electricity which in turn generates heat and this heat is used to boil water to produce steam. Cogeneration is extremely utilized in cooling buildings and space heating.