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Fossil Fuels
Chapter 11
Coal
FOSSIL FUELS
85% of the world’s
FOSSIL FUELS
Of theof
world’s
com85%
85%
thecommercial
world’s
energy
commercial energy
mercial energy
COAL
COAL
NANANNATURAL
OIL
OIL
Per capita commercial energy
consumption in selected countries
Energy consumption in developed and
developing countries
• Farmers in developing nations rely on their own
physical energy or the energy of animals to plow
and tend fields.
• Agriculture in highly developed countries involves
many energy consuming machines, such as
tractors, loaders. Additional energy is required to
produce fertilizers and pesticides widely used in
agriculture.
• Read Environews in page number 235 regarding
energy for China.
Energy density and Energy efficiency
• Energy density: The amount of energy contained within
a given volume or mass of an energy source. Gasoline has an
higher energy density than does dry wood, which in turn has a
higher density than wet wood
• Gasoline -> dry wood-> wetwood.
• Energy efficiency: a measure of the fraction of energy
used relative to the total energy available in a given source.
Energy efficiency ranges from 0 to 100%: use of natural gas for
heating has an efficiency of close to 100% while the efficiency
of burning natural gas to generate electricity has maximum
efficiency of about 60%
Energy consumption in the United
States
overall in U.S industries consume 42% buildings 33%
Transportation 25%
Definition of Fossil Fuel
• Combustible deposits in earth’s crust, composed
of the remnants (fossils) of prehistoric organisms
that existed millions of years ago. Coal, oil
(petroleum), and natural gas are the three types
of fossil fuel.
• Coal is a black, combustible solid composed
mainly of carbon, water, and trace elements
found in earth’s crust; formed from the remains
of ancient plants that lived millions of years ago.
Oil and Natural gas
• Oil is a thick, yellow to black, flammable liquid
hydrocarbon mixture found in Earth’s crust;
formed from the remains of ancient
microscopic aquatic organisms
• Natural gas: A mixture of energy-rich gaseous
hydrocarbons (primarily methane) that occurs,
often with oil deposits, in Earth’s crust.
How Fossil Fuels Formed?
• http://video.google.com/videoplay?docid=39623093780
12938462
• Reconstruction of a Carboniferous swamp
• The plants of the Carboniferous period, 360 millions to
286 millions years ago, included giant ferns, horsetails
and clubmosses that formed our present day coal
deposits.
• Read page No.
236-237 to know
How coal, oil, and
Natural gas is formed.
Percent of proved recoverable coal
reserves
Largest coal deposits are in the Northern Hemisphere. United States, Russia, China,
Australia, India, Germany and South Africa. The United States has 25% of the world’s
Coal supply.
Types of coal
• Lignite: soft coal, brown, woody texture, moist and produces little heat. It
is used to fuel electric power plant.
• Largest producer is in the United States is North Dakota
• Subbituminous coal: relaitvely low heat value and sulfur content. Cola
fired power plants in U.S use this coal because of low sulfur value. It is
found in Alaska and few Western States Montana and Wyoming.
• Bituminous coal: Also called soft coal, harder than lignite and
subbituminous coal. It contains sulfur and causes severe environmental
problems. Electric power plants use this coal as it produces a lot of heat. It
is found in the Applachian region, in the Mississippi alley, and in central
Texas.
• Anthracite or hard coal, dark, burns most cleanly, it produces the fewest
pollutants per unit of heat released – as it does not contain large amounts
of sulfur. Anthracite has the highest heat-producing capacity of any grade
of coal.
• It is found in Pennsylvania
Heat value of coal types
Coal Mining
• Surface Mining: the extraction of mineral and energy
resources near Earth’s surface by first removing the soil,
subsoil, and overlying rock strata. ( if the coal bed is within 30
m (100ft) or so of the surface.
Subsurface mining
Surface mining
Contd.,
• Subsurface Mining: when the coal is deeper in
the ground this method is used.
• Advantages of surface mining:
• Surface mining is less expensive and safer for
miners, and it generally allows a more complete
removal of coal from the ground.
• Disadvantage: Disrupts the land much more
extensively than subsurface mining.
• Cause several serious environmental problems.
Safety Problems Associated With Coal
Effects on Health
• Underground mining is a hazardous occupation.
• Miners have an increased risk of cancer and black lung
disease, a condition in which the lung are coated with
inhaled coal dust, and the exchange of oxygen between the
lungs and blood is severely restricted.
• 2000 miners in the United States die each year because of
the above said problems.
Black Lung disease
Respiratory illness
Environmental Impacts of the Mining
Process
• Before the passage of the 1977 Surface Mining Control and
Reclamation Act (SMCRA) , abandoned surface coal mines
were usually left as large open pits or trenches.
• Acid and toxic mineral drainage from such mines, along with
the removal of topsoil, prevented most plants from naturally
recolonizing the land.
• Streams were polluted with sediments and acid mine
drainage, produced when rainwater seeps through iron sulfide
mineral exposed in mine wastes.
• Landlsides occurred on hills as they were unstable from the
lack of vegetation
Effects of Mining On Land
• Mountain top removal. This has leveled 15
and 25% of the mountaintops in Southern
West Virginia, Kentucky, Pennsylvania,and
Tennessee.
Coal Sludge
Mountain top removal
Environmental Impacts of Burning Coal
Emission of Greenhouse Gases
•Oxides of Sulfur
•Oxides of Nitrogen
•Carbon Dioxide
•Toxics – Mercury
•Acid Deposition
Effects of Acid Rain
• pH of 6.0 kills insects and crabs.
• pH <5 kills fish, trees (decline of forest)
Making coal a cleaner fuel
use of coal scrubber
Scrubbers remove 98% of the sulfur and 99%
Of the particulate matter in smokestack.
Coal Scrubber
Contd.
• Resource recovery: The process of removing any material-sulfur or metal,
for example-from polluted emission or solid waste and selling it as
marketable product is known as resource recovery.
• The Clean Air Act Amendment of 1990 also directed the coal-burning
power plants to cut sulfur-dioxide emissions
• Clean coal technologies.
• Fluidized-bed combustion: A clean- coal technology in which crushed
coal is mixed with limestone to neutralize acid sulfur compounds
produced during combustion.
Surface Mining Control and
Reclamation Act (SMCRA) 1977
• Requires coal companies to resotre areas that
have been surface mined, beginning 1977.
• Protects the environment by requiring permits
and inspections of active coal mining operations
and reclamation sites.
• Prohibits coal mining in sensitive areas such as
National Parks, wildlife refuges, wild and scenic
rivers, and sites listed on the National Register of
Historic Places.
• It stipulates that surface-mined land abandoned
prior to 1977 should be gradually restored.