LPG is a naturally occurring co-product of natural gas extraction (60%) and crude oil refining (40%). It is therefore either used or it is wasted. It is a combination of propane and butane molecules, along with trace amounts of other compounds.
LPG is colourless and odourless and a strong “stenching” agent is added so that even a very small leak can be easily detected. At a normal temperature, LPG is a gas. When subjected to modest pressure or cooling, it transforms into a liquid. As a liquid, it is easy to transport and store. Once it has been cooled or pressurized, LPG is usually stored in containers made of either steel or aluminum.