Propane basics

Propane is produced from natural gas and crude oil

Propane is an energy-rich gas with a chemical formula of C3H8; each molecule of propane has three carbon atoms and eight hydrogen atoms. Propane is one of the hydrocarbon gas liquids (HGL) that are separated from natural gas at natural gas processing plants or produced at oil refineries. Most U.S. propane production is from natural gas processing.

Propane occurs naturally as a gas. However, at high pressure or low temperatures, it becomes a liquid. As a liquid, propane is 270 times more compact than as a gas, and it is transported and stored in its liquid state in pressurized containers. Propane becomes a gas again when a valve is opened to release it from its pressurized container, and it is then burned as a gas.

The propane that most consumers use is actually sold as a mixture of mostly propane and small amounts of other HGL, such as butane, and it is often called or labelled as liquefied petroleum gas or LPG.

HGL 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. The HGL/LPG industry started shortly before World War I when a problem in the natural gas distribution process occurred. A section of the pipeline in a natural gas field ran under a cold stream, and the coldness caused a lot of liquids to build up in the pipeline, sometimes to the point of blocking the entire pipeline. Soon, engineers figured out a solution: facilities were built to cool and compress natural gas and to separate HGL from the methane in natural gas.

Learn more about hydrocarbon gas liquids.

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

Large volumes of propane are moved from natural gas processing plants and oil refineries to bulk terminals across the country in underground pipelines and on trains, barges, and large trucks. Propane is transported overseas to and from the United States in special supertankers.

Local propane dealers fill their propane delivery trucks at bulk terminals. These tank trucks, called bobtails, deliver propane to storage tanks located outside of homes and businesses. The average residential propane tank holds between 500 and 1,000 gallons of liquid propane, and it might be refilled several times a year. Propane for barbecuing is sold in small tanks at convenience and hardware stores.

Environmental issues

Propane is a clean-burning fossil fuel

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 detect gas leaks in propane tanks and equipment.

Propane is a clean-burning fuel, which is why it is often used to fuel forklifts in warehouses. Propane-fueled engines produce much lower emissions of carbon monoxide and hydrocarbons compared with gasoline engines and diesel engines. Similar to all fossil fuels, burning propane produces carbon dioxide, a greenhouse gas.