Liquefied petroleum gas (LPG) is a different chemical compound to natural gas even though they are both hydrocarbons. LPG consists of propane and/or butane. Propane (C₃H₈) contains three carbon atoms and eight hydrogen atoms. Butane (C₄H₁₀) contains four carbon atoms and ten hydrogen atoms. By comparison methane is a much lighter gas than propane or butane.

Although gaseous under normal atmospheric conditions, LPG (propane) is stored under modest pressures in liquid form. In this way LPG can be transported and stored in a concentrated form to provide a source of high-energy fuel.

Other characteristics of LPG include:

• A high heating value ("calorific value")
• A virtual absence of sulphur, leading to cleaner burning
• A consistent quality ensuring reliability, particularly in applications such as gas engines. Examples of specialist applications include: forklifts and burners on boilers. LPG is also the perfect choice for cooking, heating and hot water in the home.

LPG is produced during the oil refining process or is extracted during the natural gas production process. Because of its high calorific value, LPG is ideally suited for use in industrial, commercial, agricultural, horticultural and residential applications for heating, lighting, powering vehicles, metal cutting and in cogeneration.

For homes and businesses that are not connected to the natural gas underground mains network, LPG is a cost effective alternative energy source because it is easy to transport and store.