Refinery fuel refers to all of the fuel used within a refinery to feed furnaces and provide heat to process units. Most of the process units in a refinery require the input of heat either from a furnace in the process unit, or from heat generated in furnaces elsewhere in the plant and sent the unit in the form of steam.

The fuel used in the furnaces typically includes all of the refinery gas generated in the refinery, supplemented with either purchased natural gas or low-value intermediates (propane or resid) generated in the refining process.