Liquefied petroleum gas. Is fired with a number of carbon atoms than methane. Basically, it is a gas, propane (C3 H8) and butane (C4 H10) commingle. The mixture is compressed into steel cylinders under high pressure, change the status of a fluid. Most liquefied petroleum gas will be used as a fuel in the household is also called LPG. Typically, propane gas and butane are colorless and odorless. But to safety need add chemical down in order to have a smell. Will know when the gas leaked. In addition to household LPG gas. Also used as fuel in the car as well.