NATURAL GAS
28 Secondary Energy Infobook
What is Natural Gas?
Natural gas is generally considered a nonrenewable fossil fuel. (There are
some renewable sources of methane, the main ingredient in natural gas, also
most scientists believe that natural gas was formed from the remains of
tiny sea animals and plants that died 300 to 400 million years ago.
When these tiny sea animals and plants died, they sank to the bottom
of the oceans where they were buried by layers of sediment that turned
into rock. Over the years, the layers of sedimentary rock became
thousands of feet thick, subjecting the energy-rich plant and animal
remains to enormous pressure. Most scientists believe that the pressure,
combined with the heat of the Earth, changed this organic mixture into
petroleum and natural gas. Eventually, concentrations of natural gas
became trapped in the rock layers like a wet sponge traps water.
Raw natural gas is a mixture of different gases. The main ingredient is
methane, a natural compound that is formed whenever plant and animal
matter decays. By itself, methane is odorless, colorless, and tasteless. As
a safety measure, natural gas companies add a chemical odorant called
mercaptan (it smells like rotten eggs) so escaping gas can be detected.
Natural gas should not be confused with gasoline, which is made from
petroleum.
History of Natural Gas
The ancient peoples of Greece, Persia, and India discovered natural gas
many centuries ago. The people were mystified by the burning springs
created when natural gas seeping from cracks in the ground was ignited
by lightning. They sometimes built temples around these eternal flames
so they could worship the mysterious fire.
About 2,500 years ago, the Chinese recognized that natural gas could be
put to work. The Chinese piped the gas from shallow wells and burned it
under large pans to evaporate seawater for the salt.
Natural gas was first used in America in 1816 to illuminate the streets
of Baltimore with gas lamps. Lamplighters walked the streets at dusk to
light the lamps.
Soon after, in 1821, William Hart dug the first successful American
natural gas well in Fredonia, NY. His well was 27 feet deep, quite shallow
compared to today’s wells. The Fredonia Gas Light Company opened its
doors in 1858 as the nation’s first natural gas company.
By 1900, natural gas had been discovered in 17 states. In the past 40
years, the use of natural gas has grown. Today, natural gas accounts for
24.7 percent of the energy we use.
Natural Gas
© 2011 The NEED Project P.O. Box 10101, Manassas, VA 20108 1.800.875.5029 www.NEED.org 29
Classification: Major Uses:
— nonrenewable — heating, industry,
electricity
U.S. Energy Consumption: U.S. Energy Production:
— 23.36 Q — 24.04 Q
— 24.7% — 32.9%
Natural Gas at a Glance, 2009
Producing Natural Gas
Natural gas can be hard to find since it is usually trapped in porous rocks
deep underground. Geologists use many methods to find natural gas
deposits. They may look at surface rocks to find clues about underground
formations. They may set off small explosions or drop heavy weights on
the Earth’s surface and record the sound waves as they bounce back
from the sedimentary rock layers underground. They also may measure
the gravitational pull of rock masses deep within the Earth.
If test results are promising, the scientists may recommend drilling to
find the natural gas deposits. Natural gas wells average 6,100 feet deep
and can cost hundreds of dollars per foot to drill, so it’s important to
choose sites carefully.
In 2009, 43 percent of the exploratory wells produced gas. The others
came up dry. The odds are better for developmental wells—wells drilled
on known gas fields. That year, 54 percent of the developmental wells
yielded gas. Natural gas can be found in pockets by itself or in petroleum
deposits.
After natural gas comes out of the ground, it goes to a processing
plant where it is cleaned of impurities and separated into its various
components. Approximately 90 percent of natural gas is composed of
methane, but it also contains other gases such as propane and butane.
Natural gas may also come from several other sources. One source is
coalbed methane, natural gas found in seams of coal. Until recently,
coalbed methane was just considered a safety hazard to miners, but
now it is a valuable source of natural gas.
Another source of natural gas is the methane produced in landfills.
Landfill gas is considered a renewable source of methane since it comes
from decaying garbage. The gas from coalbeds and landfills accounts for
almost 10 percent of the total gas supply today, and experts predict this
figure will increase. The gas recovered from landfills is usually burned on
the landfill site to generate electricity for the facility itself.
Today, natural gas is produced in 32 states, but the top five states—
Texas, Wyoming, Oklahoma, Louisiana, and New Mexico—produce 65
percent of the total. Altogether, the U.S. produces about one-fifth of the
world’s natural gas each year.
Transporting and Storing Natural Gas
How does natural gas get to you? Usually by pipeline. Approximately
300,000 miles of underground pipelines link natural gas wells to
cleaning plants to major cities across the United States. Natural gas
is sometimes transported thousands of miles by pipeline to its final
destination.
A machine called a compressor increases the pressure of the gas,
forcing the gas to move along the pipelines. Compressor stations,
which are spaced about 50 to 100 miles apart, move the gas along the
pipelines at about 15 miles per hour.
Some gas moved along this subterranean highway is temporarily
stored in huge underground reservoirs. The underground reservoirs
are typically filled in the summer so there will be enough natural gas
during the winter heating season.
Eventually, the gas reaches the city gate of a local gas utility. The
pressure is reduced and an odorant is added so leaking gas can be
detected. Local gas companies use smaller pipes to carry gas the last
few miles to homes and businesses. A gas meter measures the volume
of gas a consumer uses.
Compressor
Station
Compressor
Station
50-100
Miles
15 MPH
Over 300,000 Miles of Pipeline
Natural Gas Distribution System
2
WYOMING
5
NEW MEXICO
Data: Energy Information Administration
Top Natural Gas Producing States, 2009
3
ration
4
LOUISIANA
Coalbed Methane
GGaass--rriicchh SShhaallee
Sandstone Oil
Tight Sand Gas
Seal
Conventional
Associated Gas
Conventional
Non-associated Gas
Locations of Natural Gas
30 Secondary Energy Infobook
Natural Gas Use
Just about everyone in the United States uses natural gas. Natural gas ranks
second in energy consumption, after petroleum. About 24.7 percent of the
energy we use in the United States comes from natural gas.
Industry is the biggest consumer of natural gas, using it mainly as a
heat source to manufacture goods. Industry also uses natural gas as
an ingredient in fertilizer, photographic film, ink, glue, paint, plastics,
laundry detergent, and insect repellents. Synthetic rubber and manmade
fibers like nylon also could not be made without the chemicals
derived from natural gas.
Homes and businesses—the residential/commercial sector—are the
second biggest users of natural gas, consuming a third of the gas in the
country. About half of homes use natural gas for heating. Many homes
also use gas water heaters, stoves, and clothes dryers. Natural gas is used
so often in homes because it is clean burning. Commercial use of natural
gas is mostly for indoor space heating of stores, office buildings, schools,
churches, and hospitals.
Natural gas is also used to make electricity. It is the second largest
producer of electricity after coal. Natural gas power plants are cleaner
than coal plants and can be brought on-line very quickly. Natural gas
plants produce electricity more efficiently than new coal plants and
produce it with fewer emissions. Today, natural gas generates 22 percent
of the electricity in the U.S.
Natural gas is sometimes used as a transportation fuel. Natural gas can
be used in any vehicle that has been modified with a special carburetor
and fuel tank. Natural gas is cleaner burning than gasoline, costs less,
and has a higher octane (power boosting) rating. Today, more than
114,000 vehicles run on natural gas in the United States.
Natural Gas Reserves
People in the energy industry use two special terms when they talk
about how much natural gas there is—resources and reserves. Natural
gas resources include all the deposits of gas that are still in the ground
waiting to be tapped. Natural gas reserves are only those gas deposits
that geologists know, or strongly believe, can be recovered given today’s
prices and drilling technology.
The United States has large reserves of natural gas. Most reserves are in
the Gulf of Mexico and in the following states: Texas, Wyoming, Oklahoma,
Colorado, Louisiana, New Mexico, and Arkansas. If we continue to use
natural gas at the same rate as we use it today, the United States has
about a 110 year supply of natural gas.
The U.S. natural gas proved reserves increased by 11 percent in 2009
to 284 trillion cubic feet (Tcf ), the highest level since 1971. Major
improvements in shale gas exploration and production technologies
drove the increase in natural gas reserves.
Natural Gas Prices
Since 1985, natural gas prices have been set by the market. The federal
government sets the price of transportation for gas that crosses state
lines. State public utility commissions will continue to regulate natural
gas utility companies—just as they regulate electric utilities. These
commissions regulate how much utilities may charge and monitor the
utilities’ policies.
How much does it cost to heat your home with natural gas? Compared
to other energy sources, natural gas is an economical choice, though the
price is increasing with demand. It is about three times cheaper than
electricity when you use resistance heat and also less expensive than
electric heat pumps.
Natural Gas and the Environment
All the fossil fuels—coal, petroleum, and natural gas—release pollutants
into the atmosphere when burned. The good news is that natural gas is
the most environmentally friendly fossil fuel.
Burning natural gas produces less sulfur, carbon, and nitrogen than
burning other fossil fuels. Natural gas also emits little ash particulate into
the air when it is burned.
Like all fossil fuels, burning natural gas produces carbon dioxide, a
greenhouse gas. Many scientists believe that increasing levels of carbon
dioxide in the atmosphere, caused in large part by fossil fuel use, could
have long-term effects on global climate.
Natural Gas
Gasoline is sold in gallons, coal in pounds, and wood in cords.
Natural gas is sold in cubic feet. We can measure the heat
contained in all these energy sources by one common unit of
measure. The heat stored in a gallon of gasoline, a pound of coal,
or a cubic foot of natural gas can all be measured in British thermal
units or Btu.
One Btu is the amount of heat needed to raise the temperature
of one pound of water one degree Fahrenheit. One candy bar (an
energy source for the human body) has about 1,000 Btu. One cubic
foot of natural gas has about 1,031 Btu. Natural gas is usually sold
to pipeline companies in standard measurements of thousands of
cubic feet (Mcf). One thousand cubic feet of natural gas would fit
into a box that is 10 feet deep, 10 feet long, and 10 feet wide. Most
residential customers are billed by the number of therms of natural
gas they use each month. A therm is a measure of the thermal
energy in the gas and is equal to about 97 cubic feet.
Measuring Natural Gas
Data: Energy Information Administration
Natural Gas Consumption by Sector, 2009
TRANSPORTATION
2.9%
COMMERCIAL
13.6%
RESIDENTIAL
20.9%
ELECTRICITY
30.2%
INDUSTRIAL
32.4%
© 2011 The NEED Project P.O. Box 10101, Manassas, VA 20108 1.800.875.5029 www.NEED.org 31
Future of Natural Gas
ƒƒ Shale Gas
Shale gas is natural gas that is trapped in shale formations. Shale is
essentially a common form of sedimentary rock. It is formed by the
compaction of silt and clay-size mineral particles. Shale formations are
found all over the world. The Annual Energy Outlook projects that by
2035, production of shale gas will make up 45 percent of the U.S. natural
gas supply.
SHALE GAS PRODUCTION
Horizontal Drilling: A vertical well is drilled to the formation that has
been identified as a natural gas reservoir. Then the drill bit can be turned
up to a 90 degree angle so that the well parallels the natural gas reservoir.
This allows the maximum amount of natural gas to be recovered.
Hydraulic Fracturing: Hydraulic fracturing, or “fracking,” uses water, silica
(sand), and chemical compounds piped several thousand feet below the
Earth’s surface, creating cracks or fissures in shale formations. This allows
natural gas to be released and flow into the well. Hydraulic fracturing can
be used along with horizontal drilling. Once the shale area is reached, the
water, chemicals, and sand are pumped in to unlock the hydrocarbons in
the shale.
BENEFITS AND CHALLENGES
There are benefits to natural gas development. When burned, it is
cleaner than coal or oil, and releases fewer emissions. Advancements in
drilling and fracturing techniques have made the extraction of shale gas
possible to meet increasing demand for natural gas.
Development of natural gas from shale plays using hydraulic fracturing
presents some challenges, including the need for access to water for
use in the process and the need to protect local drinking water and
other natural resources. In some areas, development of shale gas brings
drilling operations closer to local residential communities too, making
land and homeowner cooperation and collaboration a high priority for
companies engaged in development of these resources.
Continued technological innovations promise to make shale gas an
important part of the United States’ energy future.
ƒƒMethane Hydrates
Buried in the sediments of the ocean floor is a reserve of methane so
vast it could possibly fuel the entire world. In sediments on the ocean
floor, tiny bacteria continuously break down the remains of sea animals
and plants, producing methane gas. Under the enormous pressures and
cold temperatures at the bottom of the sea, this methane gas dissolves
and becomes locked in water molecules to form crystals. These
crystals cement together the ocean sediments into solid layers—called
methane hydrates—that can extend down into the sea floor.
Scientists also suspect that huge deposits of free methane gas are
trapped beneath the hydrate layer. Researchers estimate there is more
carbon trapped in hydrates than in all the fossil fuels; however, they
aren’t sure how to capture this methane. When a hydrate breaks down,
it loses its solidity and turns to mush, causing major landslides and
other disturbances to the ocean floor, as well as an increase in methane
escaping into the atmosphere.
ƒƒ Biomass
Scientists are also researching new ways to obtain natural (methane)
gas from biomass—a fuel source derived from plant and animal wastes.
Methane gas is naturally produced whenever organic matter decays.
Today, we can drill shallow wells into landfills to recover the methane
gas. Landfills are already required to collect methane gas as a safety
measure. Typically, landfills collect the gas and burn it to get rid of it; but
the gas can be put to work. In 2009, landfill gas generated 15.8 billion
kilowatt-hours of electricity.
There are other ways to convert biomass into natural gas. One method
converts aquatic plants, such as sea kelp, into methane gas. In the future,
huge kelp farms could also produce renewable gas energy.
ƒƒ Liquefied Natural Gas
Another successful development has been the conversion of natural gas
into a liquid. As a liquid, natural gas is called LNG, or liquefied natural
gas. LNG is made by cooling natural gas to a temperature of -259°F. At
that temperature, natural gas becomes a liquid and its volume is reduced
600 times. Liquefied natural gas is easier to store than the gaseous form
since it takes up much less space. LNG is also easier to transport. People
can put LNG in special tanks and transport it on trucks or ships. Today,
more than 113 LNG storage facilities are operating in the United States.
Likely Methane Hydrate Deposits
MARCELLUS
FAYETTEVILLE
WOODFORD
BARNETT
BAKKEN
HAYNESVILLE-BOSSIER
Shale Gas Plays Major Shale Gas Plays
Location of Shale Gas Plays
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