Natural Gas

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Natural Gas
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[[Image:Natural gas, the cleanest of all fossil fuels.jpg|thumb|500 px|alt=Figure 1 Natural gas, the cleanest of all fossil fuels. |Figure 1 Natural gas, the cleanest of all fossil fuels.]]
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Th e same factors that promote the formation of petroleum also help in the
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[[Image:Total Natural Gas.jpg|thumb|500 px|alt=Table 1 Total Natural Gas Endowment. |Table 1 Total Natural Gas Endowment.]]
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The same factors that promote the formation of petroleum also help in the
formation of natural gas. It is therefore expected that natural gas is found
formation of natural gas. It is therefore expected that natural gas is found
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at locations near oil fi elds, oft en in association with petroleum (thus its
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at locations near oil fields, oft en in association with petroleum (thus its
name associated or dissolved gas). It is liberated when oil is brought to the
name associated or dissolved gas). It is liberated when oil is brought to the
surface in the same manner that carbon dioxide gas is liberated when
surface in the same manner that carbon dioxide gas is liberated when
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of sedimentary rocks and accumulates in a reservoir other than the oil
of sedimentary rocks and accumulates in a reservoir other than the oil
reservoir, the gas is called non-associated gas. Up to only a few decades ago,
reservoir, the gas is called non-associated gas. Up to only a few decades ago,
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most natural gas discovered was fl ared off or reinjected into the ground,
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most natural gas discovered was flared off or reinjected into the ground,
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as it was considered to be of litt le use. Its use increased during the latt er
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as it was considered to be of little use. Its use increased during the latter
half of the twentieth century, as it proved to be a convenient and relatively
half of the twentieth century, as it proved to be a convenient and relatively
clean fuel to be burned in gaseous burners for space heating and cooking
clean fuel to be burned in gaseous burners for space heating and cooking
(Figure 7-19).
(Figure 7-19).
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Natural gas is primarily methane (CH4), but a certain percentage of
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heavier hydrocarbons such as ethane (C2H6), propane (C3H8), butane
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Natural gas is primarily methane (CH<sub>4</sub>), but a certain percentage of
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(C4H10), and a small amount of pentane (C5H12) and hexane (C6H14) are
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heavier hydrocarbons such as ethane (C<sub>2</sub>H<sub>6</sub>), propane (C3H8), butane
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28 George, R L, “Mining for Oil,” Scientifi c American, March 1998.
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(C<sub>4</sub>H<sub>10</sub>), and a small amount of pentane (C<sub>5</sub>H<sub>12</sub>) and hexane (C<sub>6</sub>H<sub>14</sub>) are also present. At normal temperature and pressure, pentane and hexane
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29 Duncan, D. C., and Swanson, V. E., “Organic-rich shale of the United States and world land areas,” US Geological Survey Circular 523, 1965.
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30 “Annual Energy Outlook 2006,” Energy Information Energy, February 2006.
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Figure 7-19
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Natural gas, the cleanest of all fossil fuels.
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Figure 7-18
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The huge equipment used in strip-mining
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operations illustrates the dramatic impact that
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mining has on neighboring communities.
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165
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Chapter 7 - Fossil Fuels
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Table 7-8. Total Natural Gas
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Endowment
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(bbo equivalent)*
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World US
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Cumulative production
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Undiscovered reserves
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Reserve growth (inferred)
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Remaining (proven)reserves
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Total Endowment
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292
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866
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610
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799
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2567
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142
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88
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59
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29
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318
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* For defi nitions refer to Table 7-5.
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Source: USGS World Producti on Assessment
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2000 ( htt p://energy.cr.usgs.gov)
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also present. At normal temperature and pressure, pentane and hexane
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are liquid, but in elevated temperatures and pressures underground, they
are liquid, but in elevated temperatures and pressures underground, they
become gas and fl ow out with other gases. Commercial natural gas is
become gas and fl ow out with other gases. Commercial natural gas is
primarily a mixture of methane and ethane. Th e propane and butane are
primarily a mixture of methane and ethane. Th e propane and butane are
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liquefi ed and sold separately as liquefi ed petroleum gas (LPG) or “bott led”
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liquefied and sold separately as liquefied petroleum gas (LPG) or “bottled”
gas. For a long time, many producer countries used to burn natural
gas. For a long time, many producer countries used to burn natural
gas at the well. Th is was very wasteful and caused huge environmental
gas at the well. Th is was very wasteful and caused huge environmental
problems. Because of its lower density, it costs about four times as much
problems. Because of its lower density, it costs about four times as much
to transport natural gas through pipelines as it does for crude oil; these
to transport natural gas through pipelines as it does for crude oil; these
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gases are liquefi ed and shipped to their destinations as liquefi ed natural
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gases are liquefied and shipped to their destinations as liquefied natural
gas (LNG) in huge cryogenic containers aboard large tankers and ocean
gas (LNG) in huge cryogenic containers aboard large tankers and ocean
liners.
liners.
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Reserves, and Resources
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Th e total amount of available natural gas is shown in Table 7-8. Roughly
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==Reserves, and Resources==
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[[Image:World Proven Natural Gas Reserves.jpg|thumb|500 px|alt=Table 2 Total World Proven Natural Gas Reserves. |Table 2 World Proven Natural Gas Reserves.]]
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[[Image:The outlook for worldwide natural gas consumption.jpg|thumb|500 px|alt=Figure 2 The outlook for worldwide natural gas consumption. |Figure 2 The outlook for worldwide natural gas consumption.]]
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The total amount of available natural gas is shown in Table 7-8. Roughly
two-third of all natural gas reserves lie in Russia and the Middle East
two-third of all natural gas reserves lie in Russia and the Middle East
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(Table 7-9). Th e United States with 193 trillion cubic feet has a litt le more
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(Table 7-9). Th e United States with 193 trillion cubic feet has a little more
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than 3% of the world’s natural gas reserves.31
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than 3% of the world’s natural gas reserves ([[#References|1]]).
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Because natural gas is relatively clean, its rate of consumption is increasing
Because natural gas is relatively clean, its rate of consumption is increasing
by an average of 2.8% annually, faster than other sources of fossil fuels
by an average of 2.8% annually, faster than other sources of fossil fuels
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reserves remain available for another 75 years. However, this number is
reserves remain available for another 75 years. However, this number is
believed to be optimistic, as natural gas substitutes coal and petroleum in
believed to be optimistic, as natural gas substitutes coal and petroleum in
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an eff ort to reduce the eff ect of greenhouse gases.32
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an effort to reduce the effect of greenhouse gases ([[#References|2]]).
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Besides wells, however, there are other sources of natural gas such as
Besides wells, however, there are other sources of natural gas such as
hydrates that if they could be extracted, would provide energy for many
hydrates that if they could be extracted, would provide energy for many
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of the deep oceans and Arctic permafrost that have been formed by the
of the deep oceans and Arctic permafrost that have been formed by the
disintegration of certain bacteria. It is estimated that gigantic hydrate
disintegration of certain bacteria. It is estimated that gigantic hydrate
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fi elds around the world contain twice the energy of all other forms of
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fields around the world contain twice the energy of all other forms of
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fossil fuels combined. Th ese reserves are virtually untapped, as there
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fossil fuels combined. These reserves are virtually untapped, as there
are major obstacles that have to be overcome before the reserves can
are major obstacles that have to be overcome before the reserves can
be accessed. Any major changes in temperature or pressure may be
be accessed. Any major changes in temperature or pressure may be
capable of breaking down the material, releasing huge amounts of
capable of breaking down the material, releasing huge amounts of
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methane – a very potent greenhouse gas (See box “Th e Deadly Lake”).33
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methane – a very potent greenhouse gas (See box “Th e Deadly Lake”) ([[#Additional Comments|a]]).
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Th e cost of extraction is prohibitively high and the natural gas, even if
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The cost of extraction is prohibitively high and the natural gas, even if
it is extracted, has to be transported thousands of miles from Arctic
it is extracted, has to be transported thousands of miles from Arctic
regions before it can be used. One solution is to convert it to liquid
regions before it can be used. One solution is to convert it to liquid
synthetic fuel, such as methanol, before it is sent through pipelines.
synthetic fuel, such as methanol, before it is sent through pipelines.
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31 Energy Information Agency Fact Sheet, htt p://www.eia.doe.gov.
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32 Meadows, D., Limits to Growth: 30-Year Update, Chelsea Green Publishing Company, 2002, p. 94.
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Converting natural gas to liquid first requires breaking its chemical bonds using steam, heat and a nickel-based catalyst to produce a mixture of carbon monoxide and hydrogen known as syngas. Th is process is called steam reforming. Syngas is then blown over various catalysts to transform it into gasoline, diesel, and other liquid hydrocarbons.
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33 A few petroleum geologists have gone so far as to blame the loss of ships and airplanes in the Bermuda Triangle on sudden pulses of methane gas released from a hydrate layer below the
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Atlantic Ocean. As the ocean boils with a sudden squirt of methane bubbles, ships can be swallowed before having time to make distress calls, and plane engines might be choked by the
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rising plume of methane gas.
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Table 7-9. World Proven Natural Gas
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Reserves as of Jan. 1, 2006
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Country Total
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Recoverable
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Reserves
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(trillion cubic
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feet)
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Percentage
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of
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the Total
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Russia 1680 30.5
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Iran 971 15.9
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Qatar 911 14.9
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Saudi
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Arabia
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241 3.9
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UAE 214 3.5
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Other
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Mid.East
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223 4.1
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US 193 3.1
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Rest of
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the World
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1,679 24.1
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Total 6112 100
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Source: Energy Informati on Agency, 2006.
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Figure 7-20
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The outlook for worldwide natural gas
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consumption
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Source: Energy Informati on Agency, 2005.
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􀀨􀁉􀁓􀁔􀁏􀁒􀁙 􀀰􀁒􀁏􀁊􀁅􀁃􀁔􀁉􀁏􀁎􀁓
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􀀗􀀓
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􀀘􀀗 􀀙􀀐
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􀀑􀀙􀀗􀀐 􀀑􀀙􀀘􀀐 􀀑􀀙􀀙􀀐 􀀒􀀐􀀐􀀐 􀀒􀀐􀀐􀀑 􀀒􀀐􀀐􀀕 􀀒􀀐􀀑􀀐 􀀒􀀐􀀑􀀕 􀀒􀀐􀀒􀀐 􀀒􀀐􀀒􀀕
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166
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Converting natural gas to liquid fi rst requires breaking its chemical bonds
+
-
using steam, heat and a nickel-based catalyst to produce a mixture of
+
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carbon monoxide and hydrogen known as syngas. Th is process is called
+
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steam reforming. Syngas is then blown over various catalysts to transform
+
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it into gasoline, diesel, and other liquid hydrocarbons.
+
==References==
==References==
 +
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(1) Energy Information Agency Fact Sheet, http://www.eia.doe.gov.
 +
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(2) Meadows, D., Limits to Growth: 30-Year Update, Chelsea Green Publishing Company, 2002, p. 94.
 +
 +
(3) Toossi Reza, "Energy and the Environment:Sources, technologies, and impacts", Verve Publishers, 2005
 +
 +
==Additional Comments==
 +
 +
(a) A few petroleum geologists have gone so far as to blame the loss of ships and airplanes in the Bermuda Triangle on sudden pulses of methane gas released from a hydrate layer below the
 +
Atlantic Ocean. As the ocean boils with a sudden squirt of methane bubbles, ships can be swallowed before having time to make distress calls, and plane engines might be choked by the
 +
rising plume of methane gas.
==Further Reading==
==Further Reading==
==External Links==
==External Links==

Revision as of 16:38, 21 July 2010

Figure 1 Natural gas, the cleanest of all fossil fuels.
Figure 1 Natural gas, the cleanest of all fossil fuels.
Table 1 Total Natural Gas Endowment.
Table 1 Total Natural Gas Endowment.

The same factors that promote the formation of petroleum also help in the formation of natural gas. It is therefore expected that natural gas is found at locations near oil fields, oft en in association with petroleum (thus its name associated or dissolved gas). It is liberated when oil is brought to the surface in the same manner that carbon dioxide gas is liberated when someone opens a carbonated drink. If the gas diff uses through the pores of sedimentary rocks and accumulates in a reservoir other than the oil reservoir, the gas is called non-associated gas. Up to only a few decades ago, most natural gas discovered was flared off or reinjected into the ground, as it was considered to be of little use. Its use increased during the latter half of the twentieth century, as it proved to be a convenient and relatively clean fuel to be burned in gaseous burners for space heating and cooking (Figure 7-19).

Natural gas is primarily methane (CH4), but a certain percentage of heavier hydrocarbons such as ethane (C2H6), propane (C3H8), butane (C4H10), and a small amount of pentane (C5H12) and hexane (C6H14) are also present. At normal temperature and pressure, pentane and hexane are liquid, but in elevated temperatures and pressures underground, they become gas and fl ow out with other gases. Commercial natural gas is primarily a mixture of methane and ethane. Th e propane and butane are liquefied and sold separately as liquefied petroleum gas (LPG) or “bottled” gas. For a long time, many producer countries used to burn natural gas at the well. Th is was very wasteful and caused huge environmental problems. Because of its lower density, it costs about four times as much to transport natural gas through pipelines as it does for crude oil; these gases are liquefied and shipped to their destinations as liquefied natural gas (LNG) in huge cryogenic containers aboard large tankers and ocean liners.

Contents

Reserves, and Resources

Table 2 Total World Proven Natural Gas Reserves.
Table 2 World Proven Natural Gas Reserves.
File:The outlook for worldwide natural gas consumption.jpg
Figure 2 The outlook for worldwide natural gas consumption.

The total amount of available natural gas is shown in Table 7-8. Roughly two-third of all natural gas reserves lie in Russia and the Middle East (Table 7-9). Th e United States with 193 trillion cubic feet has a little more than 3% of the world’s natural gas reserves (1).

Because natural gas is relatively clean, its rate of consumption is increasing by an average of 2.8% annually, faster than other sources of fossil fuels (Figure 7-20). If consumption continues to grow at this rate, natural gas reserves remain available for another 75 years. However, this number is believed to be optimistic, as natural gas substitutes coal and petroleum in an effort to reduce the effect of greenhouse gases (2).

Besides wells, however, there are other sources of natural gas such as hydrates that if they could be extracted, would provide energy for many hundreds of years. Hydrates are icy deposits of crystallized natural gas and water, buried under the extreme pressures and cold temperatures of the deep oceans and Arctic permafrost that have been formed by the disintegration of certain bacteria. It is estimated that gigantic hydrate fields around the world contain twice the energy of all other forms of fossil fuels combined. These reserves are virtually untapped, as there are major obstacles that have to be overcome before the reserves can be accessed. Any major changes in temperature or pressure may be capable of breaking down the material, releasing huge amounts of methane – a very potent greenhouse gas (See box “Th e Deadly Lake”) (a). The cost of extraction is prohibitively high and the natural gas, even if it is extracted, has to be transported thousands of miles from Arctic regions before it can be used. One solution is to convert it to liquid synthetic fuel, such as methanol, before it is sent through pipelines.

Converting natural gas to liquid first requires breaking its chemical bonds using steam, heat and a nickel-based catalyst to produce a mixture of carbon monoxide and hydrogen known as syngas. Th is process is called steam reforming. Syngas is then blown over various catalysts to transform it into gasoline, diesel, and other liquid hydrocarbons.

References

(1) Energy Information Agency Fact Sheet, http://www.eia.doe.gov.

(2) Meadows, D., Limits to Growth: 30-Year Update, Chelsea Green Publishing Company, 2002, p. 94.

(3) Toossi Reza, "Energy and the Environment:Sources, technologies, and impacts", Verve Publishers, 2005

Additional Comments

(a) A few petroleum geologists have gone so far as to blame the loss of ships and airplanes in the Bermuda Triangle on sudden pulses of methane gas released from a hydrate layer below the Atlantic Ocean. As the ocean boils with a sudden squirt of methane bubbles, ships can be swallowed before having time to make distress calls, and plane engines might be choked by the rising plume of methane gas.

Further Reading

External Links