Propane -- A Fossil Fuel

Propane from Natural Gas and Oil How Propane is Used Getting Propane to Users More on Liquefied Petroleum Gases Environmental Issues links page

Did you know- the propane inside the tank of your barbeque grill is actually a liquid?

PROPANE FROM NATURAL GAS OR OIL

Propane is an energy-rich gas, C₃H₈. It is one of the liquefied petroleum gases(LP-Gas or LPGs) that are found mixed with natural gas and oil. Propane and other liquefied gases, including ethane and butane, are separated from natural gas at natural gas processing plants, or from crude oil at refineries. The amount of propane produced from natural gas and from oil is roughly equal.

Propane naturally occurs as a gas. However, at higher pressure or lower temperatures, it becomes a liquid.  Because propane is 270 times more compact as a liquid than as a gas, it is transported and stored in its liquid state. Propane becomes a gas again when a valve is opened to release it from its pressurized container. When returned to normal pressure, propane becomes a gas so that we can use it.

HOW PROPANE IS USED

Although propane accounts for less than 2 percent of all energy used in the United States, it has some very important uses. Propane is the most common source of energy in rural areas that do not have natural gas service. It is used for heating homes, heating water, cooking and refrigerating food, drying clothes, and fueling gas fireplaces and barbecue grills.

On farms, it is used to dry corn and power farm equipment and irrigation pumps. Businesses and industry use propane to run their fork lifts and other equipment. About 45 percent of propane is used by the chemical industry as a raw material for making plastics, nylon, and other materials. While only a small fraction of propane is used for transportation, it is the largest alternative transportation fuel in use today. Instead of gasoline, propane is often used to fuel fleets of vehicles used by school districts, government agencies, and taxicab companies. In recreational pursuits, hot air balloons use propane to heat the air that makes them rise.

GETTING PROPANE TO USERS

How does propane get to the people who use it? Propane usually goes by underground pipeline to terminals across the country. Railroads, barges, trucks, and supertankers also ship the propane to bulk distributors.

Local propane dealers come to the distributor's bulk plant to fill up their small tank trucks. These tank trucks, called "bobtails", deliver propane to large storage tanks that are outside homes. The average residential propane tank holds between 500 - 1,000 gallons of liquid fuel, and is refilled several times a year. People who use just a little propane - for a backyard barbecue, for example -  bring their tanks to convenience and hardware stores to be filled or to be exchanged for full ones.

MORE ABOUT LIQUEFIED PETROLEUM GASES

Liquefied petroleum gases (LP-gases or LPGs) are mixtures of propane, ethane, butane and other gases that are produced at natural gas processing plants and refineries. Other plants, called fractionation plants, separate the liquids from each other.

LP-gases were discovered in 1912 when an American scientist, Dr. Walter Snelling, discovered that these gases could be changed into liquids and stored under moderate pressure. The LP-gas industry got its start shortly before World War I when a problem in the natural gas distribution process popped up. A section of the pipeline in one natural gas field ran under a cold stream, and the coldness led to a lot of liquids building 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 the gases that could be turned into liquids (including propane and butane).

ENVIRONMENTAL ISSUES

Propane is a non-renewable fossil fuel, like the natural gas and oil it is produced from. Like natural gas (methane), propane is colorless and odorless. Although propane is nontoxic and odorless, foul-smelling mercaptan is added to it to make gas leaks easy to detect. Propane is a clean burning fossil fuel, which is why it is often chosen to fuel indoor equipment such as fork lifts. Its clean burning properties and its portability also make it popular as an alternative transportation fuel. Propane-fueled engines produce much fewer emissions of carbon monoxide and hydrocarbons compared to gasoline engines. Like all fossil fuels, propane emits water vapor and carbon dioxide, a greenhouse gas.

Last Revised: July 2008
Sources: Energy Information Administration, Propane Prices: What Consumers Should Know, January 2008,
Energy Information Administration, Estimated Consumption of Alternative Transportation Fuels in the United States, February 2004.