Liquefied petroleum gas (LPG) is often confused with liquefied natural gas (LNG), but there are obvious differences between them. The main components of liquefied petroleum gas are propane and butane, and a small amount of olefins. Liquefied petroleum gas (LPG) is stored in liquid state in storage tanks under appropriate pressure, and is often used as cooking fuel, that is, liquefied petroleum gas (LPG) that we often use. In foreign countries, liquefied petroleum gas has been used as fuel for light vehicles for many years. There are already LPG taxis in Hong Kong.