LPG (Liquefied Petroleum Gas)
Although it is a fossil fuel, liquefied petroleum gascan help enhance the energysecurity of the United States and other significant emissions benefits. Commonly called propane, it is the most popular alternative fuel in the world.
LPG - is a mixture of hydrocarbon gases used as a fuel in heating appliances and vehicles, and increasingly replacing chlorofluorocarbons as an aerosol propellant and a refrigerant to reduce damage to the ozone layer.
What Are the Emissions Benefits of LPG?
Propane vehicles emit about one-third fewer reactive organic gases than gasoline fueled vehicles. Nitrogen oxide and carbon monoxide emissions are also 20% and 60% less. Unlike gasoline-fueled vehicles, there are no evaporative emissions while LPG vehicles are running or parked, because LPG fuel systems are tightly sealed. Small amounts of LPG may escape into the atmosphere during refueling, but these vapors are 50% less reactive than gasoline vapors, so they have less of a tendency to
generate smog-forming ozone. LPG’s extremely low sulfur content means that the fuel does not contribute significantly to acid rain.
Most people call liquefied petroleum gas (LPG) "propane." That is because LPG is mostly made up of propane. Varieties of LPG bought and sold include mixes that are primarily propane, mixes that are primarily butane, and the more common, mixes including both propane (60%) and butane (40%), depending on the season—in winter more propane, in summer more butane. Propylene and butylenes are usually also present in small concentration. A powerful odorant, ethanethiol, is added so that leaks can be detected easily. The international standard is EN 589.
LPG is manufactured during the refining of crude oil, or extracted from oil or gas streams as they emerge from the ground.
LPG is stored in special tanks that keep it under pressure, so it stays a liquid. The pressure of these tanks is usually about 200 pounds per square inch.
Most LPG produced in the U.S. comes from natural gas wellhead processing. That is because natural gas has LPG gases and water vapor in it, which have to be removed before the natural gas can be sent away in pipelines. Most of the LPG produced in California comes from petroleum refining.
The LPG used in vehicles is the same as that used in gas barbecues and camper appliances. LPG is also used in many homes in the country, where there are no natural gas pipelines. These homes use LPG for heating, cooking, hot water and other energy needs. The pressure at which LPG becomes liquid, called its vapor pressure, likewise varies depending on composition and temperature; for example, it is approximately 220 kilopascals (2.2 bar) for pure butane at 20 °C (68 °F), and approximately 2.2 megapascals (22 bar) for pure propane at 55 °C (131 °F). LPG is heavier than air, and thus will flow along floors and tend to settle in low spots, such as basements. This can cause ignition or suffocation hazards if not dealt with.
LPG fueled engines can pollute less than gasoline and diesel engines. LPG usually costs less than gasoline for the same amount of energy. In some countries LPG is used much more for vehicle fuel than in California. In the Netherlands over 10 percent of the motor fuel used is LPG.
