Download Understanding Our Environment

“Our civilization runs
by burning the remains
of humble creatures
who inhabited the
Earth hundreds of
millions of years before
the first humans…”
- Carl Sagan
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Catalytic converter
• Cerium
• Lanthanum
Battery
• Lanthanum
• Cerium
LCD screen
• Europium
• Yttrium
• Cerium
Electric motors
and generator
• Dysprosium
• Neodymium
• Praseodymium
• Terbium
Fig. 14-2, p. 350
 Dynamic processes within the earth and on its surface
produce the mineral resources on which we depend
 Mineral resources are nonrenewable
 Produced and renewed over millions of years mostly by the
earth’s rock cycle
 During the carboniferous period, lasting from about 350-
300 million years ago, much of the Earth was ideal for
plant growth.
 The overall climate
was warm. Glaciers
retreated.
 Much of the land
mass was near
the equator.
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 The dominant plants during
this time were fern-like
trees.
 The trees evolved a new
carbon-based chemical
compound called lignin.
This formed the basis of
their bark.
 No bacteria , fungus, or
insect had yet evolved the
ability to decompose lignin.
 The forests, with few
limiting factors, grew
massive and numerous.
Plants of the Carboniferous Age. Meyers
Konversationslexikon, 1885-1890.
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 The surplus of photosynthesis drove oxygen levels up,
reaching concentrations in the atmosphere near 35%.
 Arthropods, which breathe through their exoskeletons,
were no longer size-restricted by available oxygen.
Model of a Meganisoptera, a giant dragonfly.
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 A short, intense ice age eventually led to the demise of
these forests.
 Nearly 50 million years of accumulated plant matter
(lignin) became buried under swamps.
 As the plant material was exposed to greater amounts of
pressure and heat, it became coal.
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Increasing heat and carbon content
Increasing moisture content
Lignite
Peat
(brown coal)
(not a coal)
Anthracite
(hard coal)
Bituminous
(soft coal)
Heat
Heat
Heat
Pressure
Pressure
Pressure
Partially decayed plant
matter in swamps and
bogs; low heat content
Low heat content; low
sulfur content; limited
supplies in most areas
Extensively used as a fuel
because of its high heat
content and large supplies;
normally has a high sulfur
content
Highly desirable fuel
because of its high heat
content and low sulfur
content; supplies are
limited in most areas
Stepped Art
Fig. 15-11, p. 383
 Today, the countries
with the greatest coal
deposits line up with
the locations of
largest carboniferous
swamps – North
America, Northern
Europe, and Asia.
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TRADE-OFFS
Coal
Advantages
Ample supplies (225–
900 years)
High net energy yield
Low cost
Well-developed
technology
Air pollution can be
reduced with improved
technology
Disadvantages
Severe land
disturbance, air
pollution, and
water pollution
Severe threat to
human health when
burned
Environmental
costs not included
in market price
Large government
subsidies
High CO2 emissions
when produced and
burned
Radioactive particle
and toxic mercury
emissions
Fig. 15-15, p. 385
 Coal was first widely used in China.
 Europeans were astonished at its ability to produce
heat, as written by Marco Polo:
“Throughout the whole province of
Cathay are a kind of black stones cut
from the mountains in veins, which
burn like logs.
They maintain the fire better than
wood. If you put them on in the
evening they will preserve it the
whole night, and it will be found
burning in the morning.”
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 The demand for coal
increased tremendously
during the industrial
revolution of the late 19th
century as the steam engine
was developed.
 Today, it is almost exclusively
used for electricity
generation.
Midwest Generation Power Plant,
Waukegan, Illinois.
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 Today, the largest coal-fired power plant in the world
is the Taichung Power Plant, located in Taiwan.
 The plant uses a total of nearly 15 million tons of coal
per year.
 One open hopper
train car holds
100-125 tons of
coal.
 A coal train will
have 100-125 cars.
 Taichung uses over
1,100 train loads of
coal per year, just
over 3 per day.
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 Shallow deposits of coal can be removed by surface
mining.
 This process requires the removal of all vegetation and
topsoil before the deposit can be accessed.
 Open-pit mining is where
large holes are dug into
the earth and the
minerals removed.
Ffos-y-fran Land Reclamation
Scheme, Wales, U.K.
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 Strip mining actually
carves away horizontal
beds of coal deposit close
to the surface.
 Mountaintop removal is
a method that uses
machines and explosives
to expose seams of coal
underneath entire
mountain tops.
19
 The cumulative effects of mountaintop removal can be
seen from satellite, as shown in this NASA Earth
Observatory slideshow of the Hobet Mine in West
Virginia.
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 Subsurface, or underground mining, removes coal
through deep tunnels and shafts.
 Most of the removal is done by machine and conveyor
belt.
 The mining machines
generate high
amounts of
explosive coal
dust.
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 Coal dust can build up in the lungs over long periods of
time, causing Black Lung disease.
Normal lung tissue.
Mild case of Black
Lung disease.
Severe case of Black
Lung disease.
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 Once the coal is extracted, its potential energy converted
to electricity in a power plant.
 The coal is pulverized into
a powder, then blown
into the boiler.
 The heat from the boiler
converts water into steam.
 Pressure from the steam
causes a giant set of turbine blades to spin.
 The shaft of the turbine is connected to a generator, where
magnets spin within wire coils to generate electricity.
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 Coal is about 90% carbon, 4% hydrogen, and 3% oxygen,
and about 1% sulfur.
 This is similar to the chemical
composition of plants.
 When coal is burned for fuel,
it combines with oxygen in air
to form several air pollutants,
including:
 Carbon dioxide, CO2
 Sulfur dioxide, SO2
 Nitrogen oxides, NOx
 Fine black particles of
carbon (soot)
Pleasant Prairie Power Plant, Wisconsin.
Source: www.kevinpalmer.com
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 Burning coal also produces a great deal of leftover ash.
 The ash contains toxins and heavy metals including
arsenic, cadmium, chromium, lead, mercury, and
radioactive radium.
 The ash is usually mixed
with water, to minimize
dust, then pumped into
a temporary storage
pond.
 Eventually, 70-80% of
this ash is disposed of
in landfills. The rest is
used in concrete,
asphalt, and
other applications.
Power plant and coal ash ponds,
Asheville, North Carolina.
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 Conversion of solid coal to
 Synthetic natural gas (SNG) by coal gasification
 Methanol or synthetic gasoline by coal liquefaction
 Are there benefits to using these synthetic fuels?
TRADE-OFFS
Synthetic fuels
Advantages
Disadvantages
Large potential
supply
Low to moderate net
energy yield
Higher cost than coal
Vehicle fuel
Requires mining 50%
more coal
Environmental costs not
included in market price
Moderate cost
High environmental
impact
Large government
subsidies
Lower air pollution
than coal when
burned
High water use
Higher CO2 emissions
than coal
Fig. 15-16, p. 386
 Like coal, most of the oil on Earth
was formed millions of years ago.
 Certain warm shallow seas, such as
the Gulf of Mexico and Tethys Sea,
were so ideal for life that organic
material was formed faster than it
could decompose.
 Large masses of organic material
became buried at the sea bottom,
were heated and pressurized,
forming oil.
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 The present day distribution of oil lines up with these
ancient shallow seas.
 Majority of oil reserves are in Middle Eastern countries.
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32
 In elemental
composition, oil is
similar to coal.
 Mostly carbon,
but also hydrogen,
nitrogen, oxygen
and sulfur.
 As a liquid, oil can
be distilled
(separated) into
other fuels such as
gasoline, kerosene,
and diesel fuel.
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 As a liquid, oil can be pumped
directly out of the ground.
This eliminates the need for
mining.
 A long drill is used to bore
deep into the Earth to reach
the deposit.
 The hole is lined with a steel
pipe and cement.
 The top is outfitted with
collection pipes and valves.
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 The ease of transporting oil has enabled drilling at very
remote locations.
 At its peak, Alaska accounted for about 25% of the U.S.
oil production.
 It is transported to the southern ports of the state through
the Alaska Oil Pipeline.
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 As a liquid, oil can also escape more easily, forming an oil
spill.
 Oil spills are devastating to marine life.
 Penetrates through the fur and feathers of animals,
reducing their ability to fly, float, and insulate themselves.
 Benthic organisms, living at the bottom of the sea, can be
suffocated.
 Entire populations of krill and plankton can be wiped out.
Exxon Valdez oil
spill, 1987.
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 Of the fossil fuels, oil has been
the most quickly depleted.
 Peak oil is defined as the point
at which known all known oil
reserves have been tapped and
production will begin
declining in the following
years.
 The United States reached its
peak production in the 1970s.
 The estimated date of
worldwide peak oil is
unknown.
 Natural gas is actually a mixtures of gases.
 50-90% methane.
 Smaller amounts of propane and butane.
 As a gas, it is the most difficult fossil fuel to transport.
 A supply of natural gas exists above most oil wells,
however, if no pipelines are nearby, it will often simply
be burned off.
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TRADE-OFFS
Conventional Natural Gas
Advantages
Disadvantages
Ample supplies
High net energy yield
Low cost
Less air pollution
than other fossil
fuels
Lower CO2 emissions
than other fossil fuels
Easily transported by
pipeline
Low land use
Good fuel for fuel
cells, gas turbines,
and motor vehicles
Nonrenewable
resource
Releases CO2 when
burned
Gas turbine Government subsidies
Environmental costs
not included in market
price
Methane (a greenhouse
gas) can leak from
pipelines
Difficult to transfer
from one country to
another
Can be shipped across
ocean only as highly
explosive LNG
Fig. 15-10, p. 382
 One of the biggest advantages in natural gas is the
relatively small amount of pollution produced by
burning it.
 The only two waste products are carbon dioxide and water
vapor.
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 Hydraulic fracturing, or “fracking”, is a controversial
technique used to extract natural gas from rock
formations (such as shale) that are not very
permeable.
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 Fracturing has become
an increasingly popular
tool for extracting
natural gas, especially
with the discovery of
the methane-rich
Marcellus Shale.
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 First, a mixture of water and other chemicals is pumped
into a narrow hole drilled into the rock formation.
 The pressure created from this fluid causes the rock
formation to crack.
 Sand is injected
afterwards to fill the
cracks, because it is
more permeable and
allows the methane
to seep out.
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 There are two big issues
that make hydraulic
fracturing controversial.
 Millions of gallons of
water are needed to
“frack” the well.
 The water that returns
back to the surface,
called flowback water, is
contaminated with
minerals, fracturing fluid
chemicals, and natural
gas itself.
Water trucking containers, Dimock,
Pennsylvania.
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 The disposal of flowback water has been a major
source of contamination.
 Due to an exemption given to gas drillers in a 2006
law, they do not have to disclose the full list of
chemicals injected into a well.
 These chemicals include carcinogens and endocrine
disruptors.
Water collected from
a well in rural
Bradford County,
Pennsylvania.
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 Fossil Fuels currently
provide about 85% of all
commercial energy in
the world.
 Other renewable
sources (wind, solar,
hydroelectric) make
up 7% of commercial
power.
 Nuclear power makes
up 8% of commercial
power.
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 The richest 20 countries
consume nearly 80% of natural
gas, 65% of oil, and 50% of coal
production annually.
 On average, each person in the
U.S. and Canada uses more than
300 GJ of energy annually.
 In the poorest countries of the
world, each person generally
consumes less than one GJ
annually.
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 The environmental and human costs of extracting fossil
fuels ultimately lies with those who use them the most.
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Sludge
Pharmaceutical plant
Local farmers
Sludge
Greenhouses
Waste
heat
Waste
heat
Waste
heat
Fish farming
Waste heat
Oil refinery
Surplus natural Electric power
plant
gas
Surplus
sulfur
Surplus
natural gas
Waste
calcium
sulfate
Fly ash
Waste Cement manufacturer
heat
Sulfuric acid producer
Wallboard factory
Area homes
Fig. 14-25, p. 367