The calorific value (CV) of gas is a measure of the heating power of gas. The CV refers to the amount of energy released when gas is combusted under specified conditions. CV is dependent upon the composition of the gas.
The calorific value of natural gas is measured, in accordance with statutory regulations, using chromatographs and combustion calorimeters located on the pipeline system. Gas chromatographs separate natural gas into its constituent compounds (methane, ethane, carbon dioxide etc) and measure the amount of each in the gas. The physical characteristics of each component are programmed into the chromatograph and an overall CV is derived from the measured composition.
The CV of gas is usually given in megajoules per cubic meter (MJ/m3).
Knowledge of the CV of natural gas is an essential part of day-to-day activities, as this information is used in determining the amount of energy transported on behalf of the gas shippers. CV information is provided to gas shippers and suppliers on a daily basis for use in billing gas consumers.