ENERGY: What is Energy
Energy is simply put the ability to do work. It is not something we can create, instead we take it in one form and convert it to another form to enable its use. For example, Natural gas is an example of an energy source. In its gas state only, we cannot use the energy. When it is combusted inside a furnace, it generates very hot flue gas. The combustion is a process of mixing fuel with air which on ignition causes a chemical reaction between the carbon and hydrogen in the fuel and oxygen in air. The resulting product from the reaction is the hot flue gas. The chemical energy inside the fuel is converted to heat energy in the flue gas
This heat in the flue gas is the useful form of the energy. The hot gas can be used to heat water for instance. This is evident in a household boiler. The heat in the produced flue gas is tranferred into cold water using a heat exchanger inside the boiler to heat it. The principle is the same inside industrial boilers.
Energy can be measured in joules and calorific valve (CV) is used to determine the energy available in a fuel. For instance Natural gas has a calorific value of around 40 MJ/m3 meaning 40 mega joules is available for every 1 m3 (volume) of natural gas
