Liquefied petroleum gas
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Liquefied petroleum gas (also called LPG, GPL, LP Gas, or autogas) is a mixture of hydrocarbon gases used as a fuel in heating appliances and vehicles, and increasingly replacing chlorofluorocarbons as an aerosol propellant and a refrigerant to reduce damage to the ozone layer, inferring that it is flammable.

Varieties of LPG bought and sold include mixes that are primarily propane, mixes that are primarily butane, and the more common, mixes including both propane (60%) and butane (40%), depending on the season—in winter more propane, in summer more butane. Propylene and butylenes are usually also present in small concentration. A powerful odorant, ethanethiol, is added so that leaks can be detected easily. The international standard is EN 589. In the United States, thiophene or amyl mercaptan are also approved odorants.

LPG is a low carbon emitting hydrocarbon fuel available in rural areas, emitting 19 percent less CO2 per kWh than oil, 30 percent less than coal and more than 50 percent less than coal-generated electricity distributed via the grid.[citation needed] Being a mix of propane and butane, LPG emits more carbon per joule than propane and LPG emits less carbon per joule than butane.