Flue gas refers to the exhaust gas released through a flue, or a pipe that releases gases from fireplaces, ovens, furnaces etc. Flue gas is generally treated to remove pollutants before being released into the atmosphere. However, flue gas can be an important source of heat energy.
Flue gas constitutes a source of high grade heat. Heat from flue gas can be used as energy to run industrial processes. It can also be used to increase the amount of heat generated by lower grade sources of heat. Utilization of waste heat from flue gas has significant environmental benefits.