Liquefied Petroleum Gas is the generic name for mixtures of hydrocarbons (mainly propane and butane). When these mixtures are lightly compressed (approx. 800 kPa or 120 psi), they change from a gaseous state to a liquid and become denser (by approx. 270 times). Eg. 1 liter of LPG liquid is equal to 270 liters of LPG vapor. LPG is colorless, odorless, and heavier than air, so a sulfur-based chemical (ethyl mercaptan) is added to give it a smell like rotten cabbage so that even a very small leak can be easily detected. LPG burns readily in the air and has an energy content similar to petrol, which makes it an excellent fuel for heating, cooking, and for automotive use.

Liquefied Petroleum Gas can be obtained from several sources. Most commonly in Australia it is extracted directly from 'wet' natural gas and is referred to by the industry as 'naturally occurring LPG.' The main supply sources for naturally occurring LPG include Bass Strait (VIC), Cooper Basin (SA), Kwinana and North West Shelf (WA) plus Surat Basin (QLD). Approximately 77% of Australia's LPG production is obtained from these supply points. The remainder of Australian LPG production is sourced from oil refining processes at the following refineries - Shell Clyde and Caltex Kurnell (NSW), BP Bulwer Island and Caltex Lytton (QLD), Mobil Altona and Shell Geelong (VIC), and BP Kwinana (WA)