What is propane?
Propane is a gas, a derivative of natural gas and
petroleum. It is found mixed with natural gas and
petroleum deposits in rocks underground. Propane is
called a fossil fuel because it was formed millions of
years ago from the remains of tiny sea animals and
plants. When the plants and animals died, they sank to
the bottom of the oceans where they were buried by layers
of silt and sand. Over the years, the layers became
thousands of feet thick. The layers were subjected to
enormous heat and pressure, changing the energy-rich
remains into petroleum and natural gas deposits.
Eventually, pockets of these fossil fuels became trapped
in rocks much as a wet sponge holds water. Propane is one
of the many fossil fuels that are included in the
liquefied petroleum (LP) gas family.
Because propane is the type of LP-gas most commonly used
in the United States, propane and LP-gas are often used
synonymously. Butane is another LP-gas often used I
lighters. The chemical formula for propane is
C3H8. Just as water can change its physical state and
become a liquid or a gas (steam vapor), so can propane.
Under normal atmospheric pressure and temperature,
propane is a gas. Under moderate pressure and/or lower
temperatures, however, propane changes into a liquid.
Propane is easily stored as a liquid in pressurized
tanks. Think of the small tanks you see attached to a gas
barbecue grill, for example. Propane takes up much less
space in its liquid form. It is 270 times more compact in
its liquid state than it is as a gas. A thousand gallon
tank holding gaseous propane would provide a family
enough cooking fuel for only one week. A thousand gallon
tank holding liquid propane would provide enough cooking
fuel for more than five years!
When propane vapor (gas) is drawn from a tank, some of
the liquid in the tank instantly vaporizes to replace the
vapor that was removed. Propane is nicknamed the portable
gas because it is easier to store and transport than
natural gas. Like natural gas, propane is colorless and
odorless. An odorant called mercaptan is added to propane
(as it is to natural gas) to serve as a warning agent for
escaping gas. And, like all fossil fuels, propane is a
nonrenewable energy source. We cannot make more propane
in a short period of time.
History of Propane
Propane does not have a long history. It was discovered
in 1912 when people were trying to find a way to store
gasoline. The problem with gasoline was that it
evaporated when stored under normal conditions. Dr.
Walter Snelling, directing a series of experiments for
the U.S. Bureau of Mines, discovered that several
evaporating gases could be changed into liquids and
stored at moderate pressure. The most plentiful of those
gases was propane. Dr. Snelling developed a way to bottle
the liquid gas. One year later, the propane industry
began heating American homes. By 1915, propane was being
used in torches to but through metal.
Producing Propane
Propane comes from natural gas and petroleum wells.
Forty-six percent of the propane used n the United States
is extracted from raw natural gas. Taw natural gas
contains about 90 percent methane, five percent propane,
and five percent other gases. The propane is separated
from the raw natural gas and the other gases at a natural
gas processing plant. Forty-five percent of the propane
is extracted from crude petroleum. Petroleum is separated
into its various products at a processing plant called a
refinery. The other nine percent of the propane we use in
the U.S. is imported from other countries, mostly from
Canada and Mexico.
Transporting Propane
How does propane get from natural gas processing plants
or oil refineries to the consumer? Generally, propane
first moves through underground pipelines to distribution
terminals across the nation. There are about 70,000 miles
of pipeline in the United States, moving propane to
12,500 bulk storage and distribution terminals.
Distribution terminals, which are operated by propane
companies, function like warehouses that store
merchandise before shipping it to stores and shops.
Sometimes, especially in the summer when less energy is
needed for heating, propane is stored in large
underground storage caverns. After storage at
distribution terminals, railroad tank cars, transport
trucks, barges, and tanker ships to bulk plants transport
propane. A bulk plant is where local propane dealers fill
their small tank trucks, called bobtails. People who use
very little propane-backyard barbecuers, for example-must
bring their propane cylinders to a dealer to be filled.
There are about 165,000 propane dealers, such as hardware
stores and gas stations, in the U.S. today.
How Propane Is Used
Propane is a clean-burning, very sterile fuel. It is used
by nearly everyone in the United States-in homes, on
farms, by business, and industry-mostly for producing
heat and operating equipment.
Homes-
Homes and businesses use about one-third of the propane
consumed in the U.S. Propane is used mostly in homes in
rural areas that do not have natural gas service, as well
as in manufactured (mobile) homes. More than 12 million
households use propane to meet some of their energy
needs. Nearly a million household use propane as their
main heating source. About one-fourth of mobile homes use
propane for heating in general. Propane is also used in
homes for air conditioning, heating water, cooking
refrigeration, drying clothes, lighting, and fuel
fireplaces. Homes that use propane as a main energy
source usually have a large propane tank outside of the
house that stores propane under pressure as a liquid.
Propane dealer deliver propane to the residences in
trucks, filling the tanks several times a year as needed.
The average residential propane tank holds between
500-1,000 gallons of liquid fuel. Millions of backyard
cooks use propane-powered gas grills for cooking. And
recreation vehicles (RV's) usually have propane-fueled
appliances, giving them a portable source of energy for
cooking, hot water, and refrigeration.
Farms-
Half of America's farms-nearly 700,000-use propane to
help meet their energy needs. Farmers use propane to dry
crops such as corn, soybeans, grains, tobacco, apples,
peanuts, and onions. Propane is also used to ripen fruit,
heat water, and refrigerate foods. Propane flamethrowers
are used to control weeds. It is also used to heat barns,
chicken houses, stock tanks, nurseries, greenhouses,
orchards, and incubators. Propane is one fuel farmers use
to operate a variety of farm equipment, including
tractors, weeders, irrigation pumps, stand-by generators,
and seedling planters.
Business-
More than one million business and commercial
establishments-such as hotels, schools, hospitals,
restaurants, and Laundromats-use propane for heating and
cooling air, cooking, heating water, refrigeration, and
lighting.
Industry-
Certain industries find propane well suited to their
special needs. Metal workers use small propane tanks to
fuel their cutting torches and other equipment.
Industries also use propane for soldering, vulcanizing,
and other processes that need a ready heat source. More
than 350,000 industrial sites use propane as a fuel
source. Portable propane heaters provide a source of heat
for construction and road workers in cold weather.
Propane also heats asphalt for highway construction and
repairs. Propane heaters at construction sites are used
to dry concrete, plaster, and fuel pitch. And because
propane is a very low-emission fuel, forklift trucks
powered by propane can operate safely inside of factories
and warehouses. Propane is also a valuable feedstock for
the chemical industry. About one-third of the propane
used today is as a raw material for making plastic bags
and other products.
Propane Today
The United States uses more propane gas than any other
country in the world. Propane supplies 1.7 percent of our
total energy needs and ranks as the seventh most
important energy source. Nearly 90 percent of the propane
used in this country is produced in the United States.
The rest is imported from Canada, Mexico, Venezuela, and
the Middle East. Since we import half of the petroleum we
use, 15 to 20 percent of the propane we produce here is
made from imported fuel
Propane and the Environment
Propane is a very clean burning fossil fuel, which
explains its use in indoor settings. It has been approved
as an alternative fuel under the Clean Air Act, as well
as the Nation Energy Policy Act of 1992.
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