Icosane, also commonly spelled eicosane, is an alkaline hydrocarbon with the chemical formula HC. It has 366,319 structural isomers. Its high flash point makes it a very inefficient fuel, so it is not much use in the petrochemical industry. However, an isomer of icosane, "n"-Icosane (the straight-chain structural isomer of icosane) is the shortest compound found in paraffin waxes (CH, where formula_1) used to form candles. Icosane's phase transition at a moderate temperature makes it a candidate for PCM, which is used to store thermal energy and control temperature.