Liquefied petroleum gases (LPG) are a constituent of crude oil or the condensate of natural gas fields. They are the C3 and C4 hydrocarbons, propane and butane respectively, which have the property of being gases at normal ambient temperature but can be liquefied and kept in the liquid state by quite moderate pressure. The most successful exploitation of LPG has been its use as a fuel gas. Originally used in refineries for process heating, its value as a fuel was first realized before the Second World War when it was sold in small portable containers. From primarily domestic use this spread after the war to commercial and industrial utilization with bulk storage on-site. A standard life cycle assessment (LCA) methodology was used to compare the environmental impacts of different cooking fuels (charcoal, biogas and LPG) before a national policy is set up.