LPG Production
Liquid Petroleum Gas (LPG) is produced in a few different ways. It can be drawn from oil or natural gas seams in the ground, or it can be refined from crude oil or natural gas after these primary products have been extracted. The majority of LPG comes from the refining of natural gas, though a small but no less significant portion of LPG does come from crude oil refining (LPG is said to make up around 3% of the end product taken from crude oil manufacturing and refining).
Refining
The refining process involves separating propane (sometimes known as dimethylmethane or C3H8) and butane (sometimes known as C4H10) from the more prolific methane product (known as natural gas), and then creating the correct balance of propane and butane necessary for the climate and time of year, as well as the addition of propylene (C3H6), butylene (sometimes known as butene or C4H8) and ethanethiol (CH3CH2SH). The latter, which has a distinctive smell, is added to the LPG mix so that if a leak occurs during the use of the gas it will be easy to detect.
Variable Mix
Not all liquid petroleum gas is the same. While LPG will always contain both propane and butane, the mix is altered depending on requirements: if the gas is produced for use in the cold winter months, it will likely have more propane; if the gas is for use in the summer it will contain more butane. Another common combination is that which is close to a 50/50 mix between the two. Both butane and propane are hydrocarbons, meaning that they are high in energy and ideal for use as a fuel for powering engines.
Transportation
'Liquid petroleum gas' is a rather contradictory term which infers that the product is in both a liquid and gas state simultaneously. The name refers to the fact that both butane and propane tend to be in a gaseous form when at normal room temperature and pressure, but that with a little refrigeration and pressurization they can be converted into a liquid state that makes them easy to transport and use. Because LPG in liquid form takes up a significantly smaller amount of space than it does in gas form, it also makes sense to keep the product in its smallest form so that greater amounts can be stored and used (as in vehicles). Before the product can be used for combustion engines it must be vaporised (changed into its gaseous form), hence the need for a converter in any liquid petroleum gas combustion system.
Lower Pollutants
The very nature of LPG means that it is a much cleaner alternative to other hydrocarbon-based fuels (like oil, petrol or coal). Liquid petroleum gas is known for having a much lower particle count and thus releases far less particle-based pollution into the air. It is said to release 35% less carbon dioxide (CO2) than coal and around 12% less than oil, as well as releasing less nitrogen oxide and sulphur. All in all it proves to be a slightly more environmentally friendly option than its other fossil fuel relatives.