Propane basics
Where does propane come from?
Propane is a versatile fuel made from natural gas and crude oil. It’s an energy-rich gas, which means it provides a lot of power. Each molecule of propane has three carbon atoms and eight hydrogen atoms (C3H8). It belongs to a group called hydrocarbon gas liquids (HGLs).
Most propane in the United States is produced as a byproduct of natural gas processing and oil refining. The propane is separated from natural gas or crude oil during processing, but most U.S. propane production is from natural gas.
How is propane stored and used?
The propane that most consumers use is a mixture of propane and small amounts of other HGLs, such as butane. Propane occurs naturally as a gas. However, if you put it under high pressure or at low temperatures, it becomes a liquid. Liquid propane, or liquefied petroleum gas (LPG), takes up much less space than gaseous propane—about 270 times less—so propane is transported and stored as a liquid in pressurized containers.
When you open the valve on a propane container, it releases the pressure, and the propane turns back into a gas as it leaves. One example is the propane tank you use on a barbecue grill. Those tanks are filled with LPG. Once you connect an LPG tank to a gas grill and turn the valve on the tank, the liquid propane turns to gas and flows into your grill to fuel your fire.
How was propane discovered?
HGLs were discovered in 1912 when a U.S. scientist, Dr. Walter Snelling, found that these gases could be changed into liquids and stored under moderate pressure. Shortly before World War I, a problem in the natural gas distribution process revealed these gases to engineers.
A section of the pipeline in a natural gas field ran under a cold stream. The cold temperature caused a lot of liquids to build up in the pipeline, sometimes blocking the entire pipeline. Engineers quickly figured out a solution: they built facilities to cool and compress natural gas, separating these valuable HGLs from the methane in natural gas.
Uses of propane
Propane has a wide variety of uses.
In homes, propane is used for
- Heating the interior space
- Heating water
- Cooking
- Drying clothes
- Fueling gas fireplaces and barbecue grills
- Refrigerating food (in special types of refrigerators that use propane instead of electricity)
Households in rural areas use more propane than households in other areas of the country because many homes in rural areas do not have access to natural gas service, and propane is a more versatile fuel than heating oil. Many households all across the country use propane in barbecue grills.
On farms, propane is used to dry grains and to power farm equipment and irrigation pumps.
In businesses and industries, propane fuels forklifts, portable electricity generators, and other equipment.
As a transportation fuel, some government agencies and private companies have cars, trucks, and buses that use propane as a fuel. Propane is also used to heat the air for hot air balloons.
Learn more about how propane is used.
Getting propane to users
Propane travels long distances from where it is produced to its final destination. Large volumes of propane are moved from natural gas processing plants and oil refineries to bulk terminals across the country. Propane is transported through underground pipelines and in tanks on trains, barges, and large trucks. Special supertanker ships transport propane overseas to and from the United States.
Local propane dealers fill their propane delivery trucks at bulk terminals. These tank trucks, called bobtails, deliver propane to storage tanks located at homes and businesses that purchase the fuel. The average residential propane tank holds between 500 and 1,000 gallons of liquid propane, and a household may need to refill its tank several times a year. Propane for barbecue grills is sold in small tanks at convenience stores and hardware stores.
Did You Know?
The propane inside the tank of your barbeque grill is actually a liquid mixture of propane and other gases, and that's why the tank may be labelled as liquefied petroleum gas, or LPG.
Propane is naturally a gas but is stored and transported in its liquid state to save space. It becomes a gas again when released from its pressurized tank.
Propane and the environment
Propane is a clean-burning fossil fuel
Source: Stock photography (copyrighted)
Propane is often called a clean-burning fossil fuel because it produces much lower emissions compared with gasoline or diesel fuel. Because of its lower emissions, propane is a popular choice for engines operating indoors, such as a forklift in a warehouse, to reduce the emissions inside the building. However, like all fossil fuels, burning propane produces some carbon dioxide, a greenhouse gas.
Propane is a nonrenewable fossil fuel because it is produced from processing natural gas and crude oil. Propane is colorless, and because it is also naturally odorless, a foul-smelling substance called mercaptan is added to it to help people detect gas leaks in propane tanks and equipment.
