Transcript 9D – Water

Environmental Science
Unit 9 D-E-F
Resource Management Part 2
9D – Water
9E – Atmosphere
9F – Nonrenewable Energy
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Unit 9D-E-F Vocabulary Terms (42)
Air pollution
Air pressure
Air mass
Algal bloom
Aquifer
Atmosphere
Conduction
Convection
Cultural
eutrophication
Dam
Emissions
Energy
Fossil fuels
Fresh water
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Front
Greenhouse effect
Groundwater
Impermeable
Meltdown
Non point source
pollution
Nonrenewable energy
Nuclear energy
Nuclear fission
Nuclear waste
Oil sand
Oil shale
Ozone layer
Permeable
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Petroleum
Point source pollution
Primary pollution
Radiation
Recharge zone
Relative humidity
Renewable energy
Reservoir
Runoff
Secondary pollution
Surface water
Watershed
Water table
Xeriscaping
Unit 9D Chp. 14 – Water - Objectives
• Explain how & why fresh water can be both a renewable
yet limited resource.
• Compare/contrast surface water & groundwater
• Describe the structure of a watershed & suggest methods
to manage it
• Indicate the accessibility of ground water & surface
water, & discuss the consequences of overuse
• Outline solutions to freshwater depletion for agricultural,
industrial & individual use
• List & explain 2 terms used to describe sources of water
pollution
• List 3 types of water pollution & describe their effects
on the environment
• Describe how saltwater intrusion & ground water pollution
are serious threats to Florida’s aquifier
Chp. 14 Group Presentation Project
• Choose your own group (2-4 people).
• Choose an objective from the previous slide.
• Prepare a 1-2 minute presentation on that subject.
• You must have presentation visual that represents
the objective you are conveying. This may be a
poster, power point, model, song, or edible material
or anything else you might creatively come up with.
• Your group will present this information to the class
for a grade based on: accuracy of information,
presentation skills, and overall appearance of the
visual.
• Have fun with this. Due: Thursday March 26.
Chp. 14 Water Resources
• Central Case – Looking for Water….in the Desert Pg. 419
• Read this case study and propose/analyze a solution
1. What is the problem????
2. What is your proposed solution?
3. Now, analyze your solution: 3 Pros, 3 Cons, 3
Short-term consequences, 3 Long-term
consequences
4. Finally, form a conclusion about your proposed
solution: Was it a good or bad solution and why?
14.1 Earth: The Water Planet
• Where is all of our water????????
• Renewable resource – water cycle
• Limited resource – 97.5% salt water,
2.5% fresh water (mostly ice); 0.5% is
both fresh & liquid & available
• People & water – unequally distributed
• Seasonal availability – most parts of the
world experience rainy & dry seasons
Surface Water
• Surface water – water found on the surface,
1% of all fresh water; runoff – water that
flows over land but has not been absorbed
• River system – network of connected streams
and rivers that flow downhill (gravity) in
shallow grooves in the earth
• Watersheds – all the land area that supplies
water to a particular river system; St. Johns;
the Mississippi River Watershed is the 3rd
largest watershed in the world
Groundwater
• Water found below Earth’s surface
• Makes up 1/5 of Earth’s freshwater supply
• Aquifer – sponge-like formations of rock, sand,
or gravel that hold water in the permeable layer
• Permeable – layers of soil or rock that contain
spaces or pores through which water can pass
• Impermeable – layers with few or no pores,
traps water which cannot move any deeper
• Water table – boundary between the upper layer
or zone of aeration and the lower layer or zone
of saturation
Recharge Zone
• Any area where surface water soaks
into the ground and reaches an aquifer
below
• A water table’s depth is affected by
the shape of the land and by the
amount of water available. As rock
layers rise & dip, so does the water
table; heavy precipitation/snowmelt
causes it to rise, droughts to fall.
• Well – hole dug into an aquifer to reach
groundwater; usually dug into the zone
of saturation.
14.1 Review
1. Explain the conclusion that liquid fresh water on Earth
is a limited resource.
2. What is a watershed? Why is it more effective to
manage an entire watershed as compared to a single
water source?
3. Why might you have to dig a well deeper if it is
overused?
4. Most civilizations began near a source of fresh water.
Over time, however, technology has enabled us to move
fresh water great distances. In what ways do you think
this kind of technology has contributed to the water
shortages many people face today?
• In addition to the above 4 questions, do 14.1 packet.
14.2 Use of Fresh Water
• Globally, 70% agriculture, 22% industry, 8%
personal.
• How can we change the way we use water?????
• Agriculture – used for crops & livestock; 1,500
liters/1 kg wheat, 15,000 liters/1 kg beef
• Industrial – used to make & transport products,
cool off machinery in energy production, & used
in refining process to make gasoline
• Personal use – av. person in the US drinks 2-5
liters of water, bathing, cooking, laundry,
flushing the toilet, watering yards, leaky pipes
Home Water Survey
• For homework, figure out your family’s daily
use of water (personal use).
• Poll your family on how long they take with
showers, brushing teeth, hand washing,… as
well as how many times/day they flush the
toilet, run the dishwasher, do laundry, etc.
• Finally determine how much water you use in
watering your lawn, washing your car, or any
other outdoor use.
• Complete the form, computing your family’s
daily use of water. Now list 3 ways you can
conserve your use of water.
Using Surface Water
• Because of overuse, surface water resources are
being depleted.
• Water diversion – process of moving water from its
source to places where humans use it (homes, fields)
• Dams – any obstruction placed in a river or stream to
block its flow; create artificial reservoirs
• Benefits of dams: clean power generation, crop
irrigation, flood control, shipping, recreation
• Costs of dams: habitat alteration, fisheries decline,
population displacement, sediment capture, loss of
fertile farmland, risk of failure, lost recreation
• Surface water depletion: drought and overuse have
significantly reduced surface water resources;
Colorado River, China’s Yellow River, Aral Sea
Using Groundwater
• Groundwater is being used, primarily for
irrigation, faster than it can be replenished
• Therefore, most groundwater use is
unsustainable
• 26% of fresh water used in US is from
groundwater, 68% of which is for irrigation
• Irrigated land has doubled since 1960, most of
which is inefficient (runoff, evaporation)
• Over-irrigation leads to waterlogging &
salinization (buildup of salts in the surface layers
of soil, eventually making the soil unusable)
• Groundwater mining – withdrawing groundwater
faster than it can be replaced
Real Data – Lake Powell
• Page 431 in your textbook
• Read the information, use
the graph, and complete
questions 1-4.
Solutions to Freshwater Depletion
• As groundwater is depleted, especially near the
coasts, salt water moves into the aquifer (FL)
• Desalination – removing salt from seawater
• 7500 desalination plants worldwide (Tampa has one)
• 2 methods: heat, filtration/reverse osmosis
• Reduce demand – conservation practices
implemented
• Agriculture – adopt efficient irrigation methods (drip)
& select climate-appropriate crops
• Industrial – water-saving steps, recycle wastewater
• Personal – water at night, xeriscaping, low-flow
toilets & shower heads, fix leaky pipes, etc.
14.2 Review
1. What are the 3 main categories of water use? Give an
example of each.
2. Explain how water diversions and dams affect surface
water depletion.
3. How does agriculture contribute to groundwater
depletion?
4. For each of the following actions, indicate if the
approach increases the supply of water or decreases
the demand for water: (a) xeriscaping, (b) desalination,
(c) fixing leaky pipes, (d) using drip irrigation.
• In addition, do 14.2 review packet.
14.3 Water Pollution
• How does water pollution affect humans and
ecosystems?
• Types of Water Pollution:
1. Point-source pollution – comes from distinct
locations (ex. Factory, sewer pipe,…)
2. Nonpoint-source pollution – comes from
many places spread over a large area (ex.
Runoff, storm sewers, oil-covered
streets,…)
• Point and nonpoint water pollution comes in
many forms and can have diverse effects.
Nutrient Pollution
• Eutrophication – buildup of nutrients in a body
of water, aquatic plants & algae increase their
growth rate, decomposition then increases as
the autotrophs die, and dissolved O2
decreases
• Cultural eutrophication – nutrient pollution by
humans that speeds up the natural process,
usually phosphorus (fertilizers, detergents)
• Algal blooms – sudden explosions of algal
growth due to excess nutrients, can cover the
surface and block sunlight to other plants,
decomposition increases, oxygen levels drop
Lake Apopka
• Example of nonpoint-source pollution
resulting in cultural eutrophication
Revival of eelgrass
beds
Toxic Chemical Pollution
• Toxic chemicals can be organic or inorganic
• Petroleum products (plastics) contain Bisphenol-A
(organic) and heavy metals (inorganic)
• Toxic chemicals released during industrial and
manufacturing processes can make their way into
fresh water via point and nonpoint sources
• Results: poison aquatic animals & plants, human
health problems (cancer)
• Regulating industrial, manufacturing &
agricultural processes to control the amount of
toxic chemicals they use & release can help, but
is hard to control nonpoint-source pollution
Sediment Pollution
• Sediments transported by rivers & runoff
can harm aquatic ecosystems
• Aquatic environments change with increase in
sediments: photosynthesis decreases as
water clouds up, food webs collapse, water
quality degrades
• Sediment pollution is a result of erosion, so
decreasing erosion helps
• Mining, clear-cutting, clearing land for
houses, and careless farming practices all
expose soil to wind and water erosion
• Mississippi and China’s Yellow River (right)
Thermal Pollution
• The warmer the water, the less O2 it
can hold
• When human activities raise water
temperature, some aquatic organisms
may not survive due to increased water
temperature or decreased O2
• Water is used for cooling industrial
processes and power plants. It absorbs
a lot of heat, resulting in thermal
pollution
• Removal of trees & plants that shade
bodies of water can also cause thermal
pollution
Biological Pollution
• Pathogens (disease causing organisms) make
their way into our air, soil, & water.
• Exposure to animal or human waste
contaminates our drinking water.
• Biological pollution causes more human health
problems than any other type of water pollution
• Need to treat water & waste with chemicals or
other substances that ill the pathogens
• Over 3.4 million people die worldwide each year
because of diseases carried in water (2/3 in
South Asia and sub-Saharan Africa)
Groundwater Pollution
• It can take decades to clean up, so every
effort should be made to prevent it from
occurring.
• Sources: many pollutants enter from the
surface, human activities, multiple sources
• Cleaning up: chemicals break down more slowly
in aquifers than they do in surface water due
to less dissolved O2, microbes, minerals &
organic matter; groundwater moves slowly and
takes a long time to recharge
• Easier to prevent than clean up; EPA is working
on a nationwide program to locate leaky
gasoline tanks
Ocean Water Pollution
• Oceans are polluted with oil, toxic chemicals &
nutrients that run off from land.
• Oil pollution: major oil spills make headlines,
but most oil comes from many widely spread
small sources (nonpoint); largest single source
is naturally occurring deposits/oil seepage
• Mercury pollution: toxic heavy metal that
collects in tissues of animals; biomagnification
• Nutrient pollution: nitrogen (not phosphorus)
does most of the damage; algal bloom, red
tide, toxins, hurts the economy with closed
beaches and stopped fishing
Controlling Water Pollution
• Through Gov’t regulations & water treatment
• The Clean Water Act (1977) – made it illegal
to release pollution from a point source
without a permit, set standards for pollution
levels, & funded construction of sewage
treatment plants
• Great Lakes is a success story, decreasing
nutrient & toxic-chemical pollution, bird
populations are rebounding, & Lake Erie is
now home to the world’s largest walleye
fishery
Water Treatment
• Filtration, Coagulation, Settling, 2nd Filtration,
Chlorination, Aeration, Additional treatment.
• EPA sets the standards
• Wastewater: water from showers, sinks, dishwashers, washing machines, toilets
• Sewers carry wastewater from homes &
businesses to centralized treatment locations
• Effluent (treated water) is piped into rivers,
reservoirs, or the ocean
• Reclaimed water might not be treated to
drinking water standards, so is used for
irrigation or to cool power plants
• Septic systems used in rural areas
14.3 Review
1.What is the difference between point & nonpoint
sources of water pollution? Give an example of
each.
2.Why is groundwater pollution so hard to clean up?
3.Explain how using nitrogen-rich fertilizers can
affect algal blooms in the oceans.
4.Describe (not list) the steps involved in a typical
public drinking water treatment process.
• In addition, do 14.3 review packet.
• In addition, do the chap. 14 assessment pgs.447-9
Unit 9E Atmosphere Chap. 15 Objectives
• List/describe the main properties of the atmosphere &
explain how each relates to the other systems & cycles
on the Earth.
• Describe the layers of the atmosphere & their
influences on the biosphere & weather.
• Explain the importance of the ozone layer as it relates
to Earth’s ability to sustain life.
• List 2 examples of air pollution formed by natural
processes & 2 examples caused by human activities.
• Identify the main components of the Clean Air Act &
explain how its provisions have set standards for air
quality.
Chp. 15 Central Case Study: Air in London
• How can we ensure everyone has clean air to breathe?
• Read the Central Case Study (pg. 451 in textbook)
• Work in pairs with the Decision Making Analysis format:
• Identify the problem
• Propose a solution
• Then analyze your proposed solution: 3 Pros, 3 Cons, 3
Short-term consequences, 3 Long-term consequences.
• Finally, draw a conclusion about your proposed solution,
explaining why or why not your solution was a good one.
15.1 Earth’s Atmosphere
• Atmosphere – thin layer of gases
that surround Earth
• We live at the bottom of the
atmosphere, which provides us with
oxygen, protects us from the most
harmful rays in sunlight, and
transports & recycles water.
• It also burns up incoming meteors
and helps control climate.
Composition of the Atmosphere
• Nitrogen (N2) – 78%
• Nitrogen-fixing bacteria
• Oxygen (O2) – 21%
• Living things need it,
combustion
• Water vapor (H2O)
• Other: Argon, CO2,
Neon, Helium, Methane,
Krypton, Hydrogen
Relative Humidity
• The ratio of water vapor the air contains
to the maximum amount it could have at
that temperature.
• When humidity is high, sweat does not
evaporate easily and the body cannot cool
itself
• Condensation – warm air holds more water
vapor than cool air, condensation as it
cools, dew & frost.
• Cloud formation – water vapor needs a
surface to condense on, clouds form on
tiny particles in the air (salt, dust, smoke)
Air Pressure
• The force exerted by air (particles) on the area
below it.
• Barometer – instrument that measures air
pressure
• Mercury barometers use a column of mercury
pushed upward in a tube by air, expressed as
inches
• Aneroid barometers use a metal chamber whose
walls bend inward (high) or outward (low) moving a
dial, expressed as millibars
• In general, the lower the altitude, the higher the
air pressure; the air at the bottom of the column
is bearing the weight of all the air above it
Layers of the Atmosphere
1. Troposphere – lowest layer; blankets the
Earth’s surface & contains the O2 we need,
contains most of the clouds & weather,
temperature decreases with height
2. Stratosphere – extends 11-50 km above sea
level; gases don’t mix much, so substances
stay there a long time; temperature rises
with height; ozone (O3) concentrates in a
portion of this layer filtering out UV light
3. Mesosphere – extends 50-80 km, temperatures decrease with height, low air pressure
4. Thermosphere – 80 km into space, air is
very thin, temperature is high
Troposphere and Weather
• Weather – atmospheric conditions over short
time periods in relatively small areas
• Ex. – weather on summer days can be hot, dry,
and sunny
• Climate – pattern of atmospheric conditions
in large geographic regions over long periods
• Ex. – London has a moist, temperate climate
• Energy from the sun heats the atmosphere,
driving air movement in the troposphere
• Heat transfers in the troposphere 3 ways:
radiation, conduction, convection
Heat Transfer in the Troposphere
1. Radiation – transfer of energy through
space; no direct contact between heat
source & object being heated, dark objects
absorb more, light objects reflect
2. Conduction – transfer of energy/heat
directly between 2 objects that are in
contact with one another; occurs when
molecules collide, only occurs between
Earth’s surface & molecules directly in
contact with it
3. Convection – transfer of heat by the
movement of currents within a fluid;
important method of heat transfer in the
troposphere
Convection Currents
• The process of convection is related to
density
• Density – mass of a substance in a given
volume
• As air near the surface of the Earth gets
heated, it becomes less dense; cool air sinks
and warm air rises above it.
• As cooler air sinks to the ground level, it
picks up heat & begins to rise.
• Sinking cool air & rising warm air form
convection currents, which cause winds and
move heat through the troposphere.
Air Masses and Fronts
• Air mass – a large body of air with similar
temperature, pressure & humidity
• Front – boundary between air masses that differ
in temperature and moisture
• Warm front – boundary along which a mass of
warmer, moister air pushes against a mass of
colder, drier air; warm, moist air rises then
cools, water vapor condenses, forms clouds, rain
• Cold front – boundary along which a colder,
drier air mass pushes against a warmer, moister
air mass; cold air tends to wedge beneath
warmer air which then rises & forms clouds and
sudden weather changes like thunderstorms
15.1 Review
1. Think of a swimming pool with a shallow end & a deep
end. The pressure of water on the floor at the shallow
end is less than the pressure of water on the floor at
the deep end. How is this similar to the way air
pressure differs at different altitudes?
2. Why is the temperature in the upper stratosphere
higher than the temperature in the lower stratosphere?
3. How is a warm front different from a cold front?
4. Winds occur because of convection currents in the
troposphere. How do you think winds affect air
pollution?
• In addition, complete the 15.1 review packet.
Quick Lab Demo, page 459
• Obtain 2 100 ml. beakers; fill one halfway with cold
water, fill the other halfway with hot water; squirt
food coloring into the hot water until the water is a
dark color; use a dropper to remove colored hot
water, wipe dropper off with a paper towel; insert
dropper into the cold water halfway and squeeze to
release hot water
• Observe and answer the 3 questions on pg. 459:
1. How did the hot water move in the beaker?
2. Why did the hot water move the way it did?
3. How is the movement of the hot water similar to
the movement of air in the troposphere?
15.2 Pollution of the Atmosphere
• Emissions – substances released into the
atmosphere; particulate matter, gases
• What are the sources of air pollution?
• Natural processes – wind erosion blows dust,
volcanic eruptions release ash & gases, fires
produce smoke, soot & gases
• Human sources – point & nonpoint sources;
farming & grazing practices cause erosion;
power plants & factories release emissions;
combustion of fossil fuels from millions of cars
& trucks
Primary & Secondary Air Pollutants
• Primary – pollutants released directly
into the troposphere; include soot,
carbon monoxide, VOCs, dust, pollen,
lead; may cause damage themselves
or they may react with other
products
• Secondary – harmful products
produced when primary air pollutants
react chemically with other
substances; include ozone, sulfuric
acid
How Air Pollutants Affect Your Health
• Can damage the respiratory system, interfere
with the body’s uptake of O2, & cause cancer.
• Respiratory System Problems: irritate people’s
air passages & lungs; asthma, bronchitis,
emphysema.
• Carbon Monoxide: hemoglobin is a molecule in
red blood cells that combines chemically with
O2; carbon monoxide will bind to hemoglobin,
replacing the O2; headaches, tiredness,
nausea, heart damage, fatal.
• Cancer: soot if inhaled frequently, benzene
from car exhaust.
Smog & Temperature Inversions
• Smog – unhealthy mixture of air pollutants
that may form over cities & nearby areas
• Industrial smog is produced when soot
combines with sulfur compounds & water
droplets in air
• Photochemical smog is a thick, brownish haze
that forms when sunlight acts on certain air
pollutants (nitrogen oxides, hydrocarbons,
tropospheric ozone)
• Temperature inversions may trap smog close
to the surface of Earth, preventing the
pollutants from dispersing.
Temperature Inversions
• Air temperature decreases as altitude
increases.
• Since warm air rises, pollutants in the air are
carried away from the surface and higher into
the troposphere, with some vertical mixing
with the cool air
• Thermal inversion occurs when a layer of
cooler air is located above a layer of warmer
air. This prevents the warm air with pollutants
from rising, trapping them and any smog near
the surface.
Acid Deposition
• Results when products of combustion combine
with water, oxygen, & other substances in
the atmosphere, forming acids.
• These acids settle to the surface of Earth as
particles, or dissolve in fog or precipitation.
• pH scale measures acidic & alkaline solutions;
0-14, 7 is neutral, the lower the pH the
higher the acidity.
• Sources of acid deposition: sulfur dioxide,
nitrogen oxide, burning of fossil fuels,
electric power plants
• Effects: harm ecosystems & structures, kill
trees, plants, fishes
15.2 Review
1. Sulfuric acid & sulfur dioxide are both air pollutants.
Use Figure 12, pg. 463 to determine which is a primary
pollutant & which is a secondary pollutant. What is the
relationship between these 2 types of pollutants?
2. When people work with volatile organic compounds, why
should they wear special masks that cover their noses &
mouths?
3. Why does a temperature inversion trap smog & prevent
it from dispersing?
4. The rain that falls in an area has a pH of 5.8. Is this
acid precipitation? Explain your answer.
• In addition, do 15.2 review packet.
15.3 Controlling Air Pollution
• The Clean Air Act (1963, 1970, 1990)
• Goal is to protect &improve the quality of air in
order to safeguard human health & the
environment.
• The Act limits emissions of pollutants by motor
vehicles & industries
• It sets standards for air quality, limiting the
concentration of some specific pollutants (carbon
monoxide, particulates)
• It lets people sue industries that break the rules
• It sets aside funds for research into pollution
control.
Real Data Effects of the Clean Air Act
• Page 471 in textbook
• Read the paragraph and answer the 6 questions:
1. What do the green bars represent?
2. What do the purple bars represent?
3. What trend does the graph show?
4. Of the pollutants shown on the graph, which has
changed by the greatest percentage?
5. Why is the bar for lead shown separately from the
bars for the other pollutants? (hint: look at the axis
labels)
6. Do you think that the general trend shown in this
graph is also true for the air in London between 1952
& now? Explain your answer.
Reduction in Air Pollutants
• Since the Clean Air Act, the release of the worst
air pollutants has gone down by 57% even though
there are more people & we use more energy.
• Cars & trucks now cause less pollution due to
catalytic converters (changes harmful emissions into
less harmful substances)
• Gasoline once contained lead, which was part of the
emissions. Today, gasoline contains almost no lead.
• Industries & power plants are required to reduce
pollutants; scrubbers remove or chemically change
pollutants before they are emitted.
Ozone: Success Story
• Ozone is a pollutant in smog in the troposphere
• Ozone is highly beneficial in the lower
stratosphere, absorbing UV radiation
• By 1985, ozone over Antarctica was 40-60%
lower than 10 years before. In 1974, 2
scientists predicted ozone depletion, identifying
the cause as chlorofluorocarbons (CFCs).
• CFCs are found in refrigerators, a/c, aerosol
spray cans. CFCs were rising into the
stratosphere and releasing chlorine atoms that
react with ozone.
• 1987 Montreal Protocol called for major cuts in
CFC manufacture, & the ozone is recovering!!!
15.3 Review
1. Overall, what has been the effect of the Clean Air
Act? Give one reason why this has happened.
2. As time passes, what will happen to the amount of
ozone in the ozone layer in the stratosphere? Give a
reason for your prediction.
• Also, complete the 15.3 review packet.
Unit 9F – Chp. 17 Objectives
• Describe our need for a constant supply of energy for
industry, commerce, transportation & personal use.
• Explain the formation of fossil fuels and identify the 3
forms we use as fuel.
• Evaluate the consequences of using fossil fuels and
suggest conservation methods.
• Describe how a nuclear power is harnessed to generate
electricity and the pros & cons of its use.
Chp. 17 Central Case: Oil or Wilderness
on Alaska’s North Slope?
• Read page 515 Central Case.
• Identify the problem.
• Propose a solution to the problem.
• Now, analyze your proposed solution: 3 Pros, 3 Cons,
3 Short-term consequences, 3 Long-term
consequences.
• After completing your analysis, form a conclusion
about your solution (was it a good solution or not,
and why?)
17.1 Energy: An Overview
What is energy & how is it used?
• Energy is the ability to do work or cause
a change; classified as either kinetic or
potential
• Kinetic: energy that an object has due to
it motion; whizzing baseball, crashing
waves
• Potential: energy that an object has
because of its position or shape, energy
that is stored; stretched rubberband,
skier at top of hill
Forms of Energy
• Mechanical – energy associated with the motion
& position of an object
• Electrical – energy associated with electric
charges
• Thermal – kinetic energy of all the atoms &
molecules in an object; faster they move, the
warmer they become
• Electromagnetic – energy traveling through space
in the form of waves; visible light, radio, UV
• Chemical – potential energy stored in bonds that
hold atoms together in molecules; bonds break &
release energy
• Nuclear – energy involving forces within atoms;
nucleus holds a lot of potential energy
Energy Conversion
• Energy can be converted or changed from one
form to another
• Combustion – the process in which a fuel burns
because it combines rapidly with oxygen;
chemical energy stored in the fuel is converted
to thermal and electromagnetic energy
• Chemical equation for the combustion of fossil
fuels (natural gas is composed mostly of
methane/CH4) is shown below:
CH4 + 2O2
CO2 + 2H2O
*principal products of combustion of methane
are carbon dioxide and water vapor, both
greenhouse gases
Sources of Energy
• Renewable energy – nearly always
available somewhere on Earth’s
surface, or they are replaced in a
relatively short time; sun, wind,
moving water, wood, heat from the
mantle
• Nonrenewable energy – cannot be
replaced, once they are used up
they are gone forever; fossil fuels,
nuclear energy
17.2 Fossil Fuels
• Fossil fuels form from the remains of
organisms that lived millions of years ago.
• Fossil fuels are composed mostly of
hydrocarbons, and formed in an environment
with little or no oxygen (deep lakes, swamps,
shallow seas)
• Temperature, pressure, and chemical
composition of the starting material
determine which fossil fuels are produced;
oil comes from microscopic organisms, coal
from plant remains compressed under very
high pressure
Coal
• Used to generate electricity, obtained by mining
• Is the world’s most abundant fossil fuel, and its
use goes back to ancient times
• ¼ of the world’s coal is located in the U.S.
• Today, China & the U.S. are the main producers
• Coal-fired steam engines drove the Industrial
Revolution, powering factories, trains, & ships
• Today, coal generates ½ the electricity used by
Americans
• Strip mining, mountaintop removal and subsurface
mining are the methods used to remove coal from
the ground
• Advantages: abundant, less expensive, minimal
processing, easily transported (no pipelines)
Oil
• Obtained by drilling, major source of energy
• Found in the Middle East, Russia, N.A. & S.A.
• Petroleum is the source of fuel for most forms
of transportation
• Petrochemicals are derived from oil & used to
make many products, especially plastics
• Oil deposits are deep underground, usually
within sandstone & limestone
• Extracted using pressure to force oil to surface
• Crude oil must be refined to be usable,
separating the crude oil into diff. fuels
Natural Gas
• Yields a large amount of energy and is less
polluting than other fossil fuels
• Consists of the gas methane mixed in with
small amounts of other gases.
• Colorless and odorless; less polluting than gas
or coal, & emits less carbon dioxide/unit of
energy
• Pockets of natural gas are often located above
oil deposits, both on land and offshore
• In U.S., pipelines carry natural gas from its
source to where it is used
• Also goes into products like paints, plastics,
dyes, and fertilizers
Supply of Fossil Fuels
• No one knows for sure how long our supplies
of fossil fuels will last, but they are finite
• The most accessible reserves have already
been used up; remaining deposits are often
difficult & expensive to extract
• Oil is in the least supply (40 years), coal
supplies will last the longest (130 years in
U.S.)
• New sources, but many drawbacks:
• Oil Sands – moist sand & clay containing bitumen
• Oil Shale – rock filled with hydrocarbons
• Methane Hydrate – icelike methane solid on ocean
floor
17.2 Review
1. Where did the energy in fossil fuels originally come from
? What type of energy is stored in fossil fuels?
2. What are 2 major methods of obtaining coal from the
ground? Compare these 2 methods.
3. How are rocks that contain oil similar to a sponge?
4. What is one advantage that natural gas has over coal
and oil?
5. Why is the supply of fossil fuels dwindling?
6. The cost of researching technology to extract
alternative fossil fuels, such as oil sands & oil shale, is
high. Do you think this is a wise investment? Explain your
answer.
• In addition, do 17.2 review.
17.3 Consequences of Fossil Fuel Use
• Workers risk their lives to obtain the fuels.
• Pollution from burning of Fossil Fuels,
contributing to climate change & cause pollution
• Greenhouse Gases – all fossil fuels contain carbon, &
release CO2 when burned, warming the atmosphere
• Air pollution – burning coal & oil releases sulfur
dioxide & nitrogen oxides, contributing to smog and
acid deposition
• Water pollution – oil from nonpoint sources runs off
& contaminates water in & on the ground, huge oil
spills cause environmental damage, offshore drilling
rig spills
• Health effects – mercury released in the air from
burning coal, motor vehicles release irritants
Damage Caused by Extracting Fuels
• Mining is one of our most dangerous
occupations, risking injury, death, respiratory
disease
• Strip mining destroys large tracts of habitat
and acid drainage
• Mountaintop removal has an even greater
impact, destroying habitat and clogging
waterways
• Oil & Gas extraction involves drilling, roads,
housing, pipelines, etc., all of which can harm
plants, animals and ecosystems.
Dependence on Foreign Sources
• Since fossil fuels are unevenly distributed in the
world, many nations need to depend on foreign
sources
• U.S. has extensive coal deposits, Middle East
have far more crude oil reserves
• Almost all of our modern technology & services
depend in some way on fossil fuels
• The U.S. imports 2/3rds of its crude oil, so
seller nations control the price and supply
• We have diversified our sources of petroleum,
importing from Canada, Mexico, Venezuela &
Nigeria, but we need to develop renewable
energy sources such as solar & wind power!!!!
Energy Conservation
• To save fossil fuels & limit the damage they
cause, we need to conserve energy.
• This means reducing our use of them!!!!!!!!!!!!!!!!
• Transportation accounts for 2/3rds of oil use in
the U.S., so we need to design & sell motor
vehicles that use less gasoline
• Increasing the tax on gasoline would cause people
to conserve it
• Individual people need to make choices that save
energy: driving less, turn lights off when not in
the room, turn down thermostats
17.4 Nuclear Power
• Nonpolluting, yet radioactive waste disposal
and nuclear power accidents cause concern
• Nuclear energy – energy that holds protons
& neutrons together in the nucleus
• Nuclear fission – splitting of an atoms
nucleus into 2 smaller nuclei
• To produce nuclear fission, nuclei of large,
unstable atoms (uranium, plutonium) are
bombarded with neutrons, breaking up the
nucleus & releasing heat & radiation, causing
a chain reaction that is controlled and used
to generate electricity
Nuclear Reactor
Benefits & Costs of Nuclear Power
• Benefits: generates electricity without polluting,
small amounts of uranium can produce far more
energy than the same amount of coal, under
normal conditions nuclear power plants are safer
for workers than coal-fired power plants
• Costs: plants are very expensive to build and
maintain, fear of nuclear accidents is real
(Chernobyl 1985), disposal of the radioactive
waste materials left over
• Currently, used fuel rods are held at nuclear
power plants temporarily. U.S. chose Yucca Mtn.
in Nevada desert (far away from people, little
rain or risk of earthquakes, deep water table)
Nuclear Fusion: The Future?
• Nuclear fusion – small nuclei of
lightweight elements are forced
together to form a heavier nucleus,
releasing a neutron & huge amounts
of energy
• Nuclear fusion has advantages over
fission, but the technology does not
yet exist to use fusion to generate
power
• Nuclear fusion reactions generate
the energy released by the sun
17.4 Review
1. What is a nuclear chain reaction?
2. List the steps involved in using nuclear fission to
generate electricity. Begin with the role of the fuel
rods.
3. Why is the disposal of nuclear waste a greater problem
than the disposal of the trash that you and your family
need to get rid of?
4. Compare and contrast nuclear fusion and nuclear
fission. How are they similar? How are they different?
• In addition, do 17.4 review packet.