In the United States, the most serious nuclear accident Connection to History
occurred in 1979 at the Three Mile Island nuclear power plant
in Pennsylvania. Human error, along with blocked valves and Three Mile Island The Three
broken pumps, caused the accident. Fortunately, only a small Mile Island accident was a wake-
amount of radioactive gas escaped. Since this accident, the U.S. up call for the nuclear industry.
Nuclear Regulatory Commission has required more than 300 Many reforms and safety meas-
safety improvements to nuclear power plants. ures were instituted throughout
the industry after the accident
The Future of Nuclear Power occurred. In 1989, 10 years after
the accident, the nuclear plant
One possible future energy source is nuclear fusion. Nuclear fusion received the best INPO rating in
occurs when lightweight atomic nuclei combine to form a heavier the world. The rating was based
nucleus and release tremendous amounts of energy. Figure 17 illus- on a measure of reliability, effi-
trates the process of nuclear fusion. Nuclear fusion powers all of ciency, and safety. In 1999, the
the stars, including our sun. Fusion is potentially a safer energy plant set a world record after run-
source than nuclear fission is because it creates less dangerous ning continuously for 688 days.
radioactive byproducts.
Unfortunately, although the potential of fusion is great, so is the
technical difficulty of achieving it. For fusion to occur, atomic nuclei
must be heated to extremely high temperatures (about
100,000,000°C, or 180,000,000°F). The nuclei must also be
maintained at very high concentrations and properly confined.
Achieving all three of these conditions simultaneously is extremely
difficult. The technical problems are so complex that building a
nuclear fusion plant may take decades or may never happen.
Figure 17 ̈ During nuclear fusion,
the nuclei of two forms of hydrogen
(deuterium and tritium in this case)
join to form helium, which releases
large amounts of energy.
S E C T I O N 2 Review
1. Compare a power plant that burns fossil fuels with a CRITICAL THINKING
nuclear power plant. 4. Applying Ideas Read about the advantages of
2. Describe two advantages and two disadvantages of nuclear energy. Explain why countries such as France
nuclear power plants. and Japan rely heavily on nuclear power.
3. Explain the difference between nuclear fission and READING SKILLS
nuclear fusion.
5. Making Decisions Which poses more of an envi-
ronmental threat: transporting spent nuclear fuel or
transporting toxic chemicals? Write your opinion in
the form of a short essay. WRITING SKILLS
Section 2 Nuclear Energy 479
17C H A P T E R Highlights
1 Energy Resources and Key Terms Main Ideas
Fossil Fuels
fossil fuel, 467 ̈ Most of the world’s energy needs are met by
electric generator, fossil fuels, which are nonrenewable resources.
468 ̈ Coal is abundant in North America and
petroleum, 472 Asia. In the United States, coal is used pri-
oil reserves, 474 marily to produce electricity.
̈ Petroleum can be refined into fuels to power
vehicles and machines. Petroleum can also be
used to manufacture many other products.
̈ Natural gas is often found above oil deposits.
In general, burning natural gas releases fewer
pollutants than burning coal or oil.
̈ The extraction, transportation, and use of
fossil fuels cause many environmental prob-
lems, including air and water pollution and
habitat destruction.
̈ Calculations of fossil-fuel reserves predict
that oil production will peak and then decline
in the early 21st century.
2 Nuclear Energy nuclear energy, 476 ̈ Nuclear energy is energy that exists within
nuclear fission, 476 the nucleus of an atom. When uranium nuclei
nuclear fusion, 479 are bombarded with neutrons, they undergo
fission and release large amounts of energy.
̈ In a nuclear power station, the heat gener-
ated by fission is used to heat water to form
steam. The steam drives turbines that generate
electricity.
̈ The main advantages of nuclear power are
that the fuel is compact and the power stations
generally do not pollute. The main disadvan-
tage is that nuclear power produces radioactive
waste, which will be dangerous for centuries.
480 Chapter 17 Highlights
17C H A P T E R Review
Using Key Terms 11. The main reason for the worldwide slow-
down in the construction of nuclear power
Use each of the following terms in a separate plants is that
sentence. a. we have run out of uranium fuel.
b. the electricity from nuclear power is gener-
1. fossil fuel ally more expensive to produce than elec-
2. petroleum tricity from other sources.
3. oil reserves c. nuclear reactors are inherently unsafe.
4. nuclear fission d. nuclear reactors release large quantities of
5. nuclear fusion greenhouse gases.
For each pair of terms, explain how the mean-
ings of the terms differ. 12. Which is an example of the direct use of fos-
6. petroleum and oil reserve sil fuels?
7. turbine and electric generator a. a nuclear reactor
8. nuclear fission and nuclear fusion b. an oil-fired furnace
c. a wind generator
STUDY TIP d. a wood-burning stove
Get Organized Being organized can help make 13. Which of the following statements describes
studying more efficient and less confusing. Start the process by which modern nuclear power
by reducing clutter and consolidating loose papers. plants use nuclear energy?
Arrange your items by subject, and be sure to a. Power plants use nuclear fusion to split
label your books, notebooks, and dividers. A plan- uranium atoms and release nuclear energy.
ner, or agenda book, can help you balance school- b. Power plants use nuclear fusion to combine
work with other activities. It also can serve as atomic nuclei and release nuclear energy.
reminder of upcoming deadlines and help you to c. Power plants use nuclear fission to split
prioritize multiple tasks. uranium atoms and release nuclear energy.
d. Power plants use nuclear fission to combine
Understanding Key Ideas atomic nuclei and release nuclear energy.
9. Which of the following statements provides a 14. If fossil fuels are still forming today, why are
reason for the widespread use of fossil fuels? they considered nonrenewable resources?
a. Fossil fuels are a renewable source of a. Fossil fuels are broken down by natural
energy. processes faster than they form.
b. Fossil fuels are readily available and b. We are depleting fossil fuels much faster
inexpensive. than they form.
c. Fossil fuels are not harmful to the c. The fossil fuels being formed today are
environment. deep under the ocean, where they cannot
d. all of the above be reached.
d. The only fossil fuels being produced
10. Which of the following pairs are design fea- are methane hydrates, which we cannot
tures that nuclear power plants and coal- use yet.
fired power plants share?
a. fuel rods and containment buildings 15. Which of the following is not a disadvantage
b. turbines and generators of nuclear energy?
c. combustion chamber and reactor cores a. the difficulty of safe storage of nuclear
d. none of the above waste
b. the high levels of air pollution produced
c. the use of natural gas to produce nuclear
energy
d. the possibility that a nuclear chain reaction
can get out of control
Chapter 17 Review 481
17C H A P T E R Review
Short Answer Concept Mapping ?
??
16. Why have fossil fuels become our primary
energy resource? 25. Use the following terms to create a concept
map: oil well, petroleum, refinery, gasoline,
17. How did the Three Mile Island accident natural gas, plastics, and oil reserve.
affect nuclear safety in the United States?
Critical Thinking
18. What factors make nuclear power expensive?
26. Demonstrating Reasoned Judgment The
19. What is the difference between oil reserves invention of artificial plastics had a damaging
and oil deposits? effect on the environment because most plas-
tics break down very slowly, so they remain
Interpreting Graphics in landfills and are dangerous to wildlife.
However, the invention of plastics also
The graph below shows the different contribu- affected the environment in many positive
tions of various fuels to the U.S. energy supply ways. List as many positive effects as you can.
since 1850. Use the graph to answer questions
20–24. 27. Analyzing Relationships Read the descrip-
tion of how fossil-fuel deposits form.
20. When did oil first become a more important Explain why fossil fuels are a form of
energy source than coal? stored solar energy. READING SKILLS
21. Why do you think the use of coal increased 28. Analyzing Relationships The United States
so rapidly between 1850 and 1920? currently imports about half of all the crude
oil it uses. Why might this be a problem?
22. The data for oil and natural gas are nearly Write a paragraph that describes the recom-
parallel—they rise and fall together. Why do mendations that you would make to U.S.
you think this pattern exists? lawmakers, manufacturers, and consumers
to reduce the country’s dependence on
23. Why do you think the use of coal is on the foreign oil. WRITING SKILLS
rise after having fallen in the 1950s?
Energy use (in quadrillion Btu) Cross-Disciplinary Connection
24. Why do you think that the use of wood as a
fuel has not significantly increased or 29. Economics What incentives could encourage
decreased since about 1850? automobile manufacturers in the United States
to produce more fuel-efficient cars? The U.S.
U.S. Energy Use Since 1850 government could increase the requirements
40 for fuel efficiency. However, at least two other
strong forces are likely to change the types of
Wood vehicles that manufacturers produce. What do
Coal you think these forces are?
30 Oil
Natural gas
Hydroelectric power
20 Nuclear power
10 Portfolio Project
0 1875 1900 1925 1950 1975 2000 30. Prepare a Display Find out how petroleum,
1850 Year natural gas, coal, or uranium are extracted.
For example, engineers have developed meth-
ods to drill sideways to reach oil deposits
thousands of feet underground. Research one
method and prepare a model or a posterboard
display that communicates your findings. Be
sure to include information about the environ-
mental effects of the method you studied.
482 Chapter 17 Review
MATH SKILLS READING SKILLS
The graph below compares the contribution of Read the passage below, and then answer
each world region to world oil production. Use the questions that follow.
the graph to answer question 31.
Paula Curtis became chief executive officer of
31. Analyzing Data If the total sales of oil in Zaft Motors in 2002. She has a strong interest
2002 were $500 billion, what is the value of in the environment. Because she is chief execu-
the oil produced by each region? tive of the country’s second-largest auto manu-
facturer, she has an influence on the automobile
North America Europe and former industry. For instance, Zaft left the Global
6% Soviet Union 8% Climate Coalition, a group of companies that
denied the scientific research proving global
South America Asia 4% warming. Within four months, two other auto
9% manufacturers also left. Zaft publishes a “cor-
Africa 7% porate citizenship” report each year. In 2001,
the report stated that Zaft’s vehicles and facto-
Middle East ries emit 350 million metric tons of carbon
66% dioxide annually and contribute to global
warming. The report also stated that Zaft was
WRITING SKILLS committed to reducing this number.
32. Communicating Main Ideas How would our However, Zaft has a long way to go to ful-
lives change if oil reserves became so fill this goal. Zaft has failed to improve the
depleted that gasoline was very expensive? fuel economy of its cars and trucks, so its new
vehicles get fewer miles per gallon, on average,
33. Recognizing Relationships Outline the major than the vehicles built in 1982. Modern tech-
forms of environmental change that have nology for engines, transmissions, and aerody-
resulted from fossil-fuel use. Include your namics could help Zaft achieve an average fuel
thoughts on subjects such as habitat loss, pol- economy of 40 mi/gal for its cars, pickups,
lution, and our use of land. Remember to and sport utility vehicles. As a result, the
include positive environmental changes. United States would save almost 1 million bar-
rels of oil per day—over half as much as the
country imports from Saudi Arabia.
1. Which of the following statements best
describes the thesis of the article?
a. Zaft Motors is jeopardizing its posi-
tion as the country’s second-largest
auto manufacturer by enacting envi-
ronmental controls.
b. Zaft left the Global Climate Coalition
because it acknowledged the scientific
evidence for global warming.
c. Although Zaft has taken some actions
to be an environmentally responsible
corporate citizen, the company still
needs to improve the fuel efficiency of
its vehicles.
d. none of the above
Chapter 17 Review 483
17C H A P T E R Standardized Test Prep
Understanding Concepts Reading Skills
Directions (1–3): For each question, write on a Directions (6–8): Read the passage below. Then
separate sheet of paper the letter of the correct answer the questions.
answer.
Today, fossil fuels supply about 90% of the
1 Where do coal, oil and natural gas come energy used in developed countries. Oil
production is increasing, but it is increasing
from? much more slowly than it has in the past.
A. the melting of polar ice packs Many different factors must be considered
B. the remains of organisms when predicting oil production. Oil reserves
C. the residue of volcanic eruptions are oil deposits that can be extracted
D. the understory of forests profitably at current prices using current
technology. Some projections suggest that by
2 When fossil fuels are burned and converted 2050 world demand for fossil fuels will have
doubled, mainly as a result of increased
to electricity, how does the total amount of population and industry in developing nations.
usable energy change? People in developed countries use much more
F. The amount of usable energy remains the energy than people in developing countries do.
As the demand for energy resources increases,
same. the cost of fossil fuels will likely increase
G. The amount of usable energy decreases enough to make other energy sources more
attractive.
during conversion.
H. The amount of usable energy doubles 6 How would you assess the effect of
during conversion. technology on oil prices?
I. The amount of usable energy depends on F. Technology raises production and lowers
how well the power plant is maintained. prices.
G. Technology lowers production and raises
3 Which of the following statements describes
prices.
energy consumption trends today? H. Technology raises production and raises
A. Developed nations are using less energy
prices.
per person. I. Technology lowers production and
B. Developing nations are using less
lowers prices.
energy per person.
C. Developed nations are using more energy 7 If oil prices continue to increase, what
than undeveloped nations. effect would this have on industries in
D. Developing nations are using more developing countries?
energy than developed nations. 8 Which of the following statements is false?
Directions (4–5): For each question, write a short A. Fossil fuels supply about 90% of the
response. energy used in developed countries.
4 The United States uses more than 25% of B. World demand for fossil fuels will
likely increase significantly by 2050.
its energy to transport goods and people.
This percentage of resources, used mostly C. People in developed countries use
by trucks and personal vehicles, is much more energy than people in developing
higher than energy used for transportation countries use.
in Japan or Switzerland. Why do these two
developed countries use less energy for D. The cost of fossil fuels will likely
transportation than the United States? decrease in the future.
5 Provide one reason why building and main-
taining nuclear power plants is expensive.
484 Chapter 17 Standardized Test Prep
Interpreting Graphics
Directions (9–12): For each question below, record the correct answer on a
separate sheet of paper.
The graph below shows past and predicted oil production. Use this graph
to answer questions 9 through 12.
Past and Predicted Oil Production
30
25
Oil production 20
(in billions of barrels)
15
10
5
0 1950 1970 1990 2010 2030 2050
1930 Year
9 If oil production after 2010 continues at the predicted rate, when will Test
the oil reserves run out? Sometimes, only a
F. 2040 portion of a graph or
G. 2050 table is needed to
H. 2060 answer a question.
I. 2070 Focus only on the nec-
essary information to
0What can be concluded about oil production from the graph? avoid confusion.
A. Oil production hit its peak in the mid 20th century.
B. Oil production saw a dramatic increase during the 1980s.
C. Oil production continued to increase throughout the 1900s.
D. Oil production more than doubled between 1965 and 1975.
q What can be inferred about the cost of oil after 2010?
F. It will increase.
G. It will decrease steadily.
H. It will remain unchanged.
I. It will increase until 2030, then decrease.
w What is the difference in billions of barrels produced in 1990
compared to 1970?
A. Production doubled.
B. Production fell by half.
C. Production hit a new low.
D. Production was up six billion barrels.
Chapter 17 Standardized Test Prep 485
17C H A P T E R Skills Practice Lab: CONSUMER
Objectives Your Household Energy Consumption
̈ USING SCIENTIFIC METHODS Identify We use electricity for many activities at home, such as drying
the ways in which electricity is clothes, cooking food, and heating and cooling. The total amount
consumed in your household. of energy that we use depends both on how much energy each
individual appliance consumes and on how long we use the appli-
̈ Compute the energy consumption ance each day. In this lab, you will survey your household to
of your household. determine how much electricity you consume and you will analyze
an electric bill to calculate how much you pay for your electricity.
̈ Interpret an electric utility bill and
an electric meter. Procedure
Materials 1. Create a table similar to the one shown below. To determine
daily energy consumption in kilowatt-hours, divide the
calculator wattage of an appliance by 1,000 and then multiply by the
electric bill number of hours the item is used per day.
notebook
pen or pencil
Energy Daily energy
̈ Keeping Track of Energy Use consumed in Hours used consumption
An electric meter (below) records the
amount of electricity that a house- Appliance 1 hour (watts) (per day) (Kwh)
hold uses. A utility bill ( below) calcu-
lates the cost of the electricity used. DO NOT WRITE IN THIS BOOK
2. Walk through your home, and identify all appliances and
devices that use electricity. List each item in your table.
3. Fill in each column in your table. Determine the wattage of
each item by referring to the table on the next page.
4. Find the electric meter. It may be on an outside wall of your
house or apartment building. Record the current reading on the
meter. The reading may change as you watch it. If so, electricity
is currently being consumed in your household. If the reading is
changing, write down an estimate of the current reading.
486 Chapter 17 Skills Practice Lab
Analysis Energy Consumption for
Common Household Appliances
1. Organizing Data Add up the energy consumption per day
for all items. This number is the total energy consumed by Appliance Energy
your household in one day. consumed
in 1 hour
2. Organizing Data On your electric bill, find the total number
of kilowatt-hours consumed during this time period. An elec- (watts)
tric bill usually lists a meter reading for the beginning of the
time period and for the end of the time period. The differ- Ceiling fan 120
ence is the energy consumption in kilowatt-hours.
Clock radio 10
3. Analyzing Data Divide the number of kilowatt-hours from
your electric bill by the number of days in the time period. Clothes washer 425
This number reflects the average daily energy consumption
for this time period. Clothes dryer 3,400
(electric)
4. Analyzing Results Compare the daily energy consumption
that you calculated from your home survey with the average Coffee maker 1,050
calculated from your electric bill. Is there a difference? If so,
what could explain the difference? Dishwasher 1,800
5. Analyzing Data Find the cost of electricity per kilowatt-hour Window fan 150
on your electric bill. How much does washing your clothes in
a washing machine cost? Hair dryer 1,500
Conclusions Heater (portable) 1,100
6. Drawing Conclusions What can you conclude about energy Iron 1,400
consumption in your home? What activities consume the
most energy? How could you reduce the energy consumption Light bulbs 60, 75, 100
in your home?
Microwave oven 900
7. Evaluating Methods How could the energy survey be refined
to estimate more accurately your daily energy consumption? Personal computer 270
Extension Refrigerator 725
(frost free, 16 ft3)
1. Communicating Ideas Even when an appliance is turned
off, it can still consume electricity. This type of electricity Stereo 400
consumption is called a phantom load. Find out about
phantom loads and prepare a booklet that shows how Television (color) 130
people can reduce this type of energy use.
Toaster 1,100
Toaster oven 1,225
Vacuum cleaner 1,200
VCR/DVD 19/22
Water heater 5,000
(40 gal)
Water pump 650
(deep well)
Window fan 150
Chapter 17 Skills Practice Lab 487
EARTH SCIENCE CONNECTION
NUCLEAR POWER PLANTS IN THE UNITED STATES
MAP SKILLS
1. Identifying Trends During what time period did 4. Identifying Relationships Why do you think
most of the nuclear plants in the United States begin that many nuclear reactors are built close together?
operation?
5. Calculating Problems The U.S. government is
2. Using the Key Use the symbols on the map to considering storing most of its nuclear waste pro-
describe the history of nuclear power in the duced in the United States in a facility in Yucca
Northeast, the Southeast, the Great Plains states, Mountain in Nevada. This location is marked on the
and the western states. map. What are the average distances from the
nuclear plants in California, Texas, Florida, and
3. Comparing Areas What region of the United New York to this site?
States has the most nuclear power plants? What
region has the fewest? Why?
488 Chapter 17 Maps in Action
EARTH SCIENCE CONNECTION
FROM CRUDE OIL TO PLASTICS
Can you imagine using shampoo ̈ A fractionation tower separates What Do You Think?
from a glass bottle? Your parents petroleum into its component
or grandparents might remember compounds. There are many possible sub-
a time when a dropped shampoo stitutes for petroleum fuels to
bottle meant shards of glass on All petroleum distillates are power vehicles and electric
the shower floor. Today, plastic is toxic. When their vapors are generators. However, finding
in everything from shampoo bot- breathed, they can cause chemical substitutes for petroleum used
tles, car fenders, artificial limbs, pneumonia, lung damage, or as solvents and in other prod-
refrigerators, and cameras, to death. Therefore, all household ucts is not easy. If petroleum
snowboards. While these products products that contain 10 percent supplies are limited, can you
are all vastly different, they or more petroleum distillates are think of any substitutes for
started out in the same way, as required to have hazard warnings. petroleum?
petroleum, or crude oil. Products containing petroleum dis-
tillates should be used carefully.
Petroleum is the most common
fuel used to power vehicles and Plastics
heat homes. But you may not real-
ize that this versatile fuel contains Plastic is one type of material that
many different organic com- is manufactured from petroleum
pounds, which are used to pro- distillates. Before plastics can be
duce many other products and made, however, the petroleum
chemicals of modern society. distillates must be processed.
However, before these compounds Ethane and propane, two petro-
can be used, they must be sepa- leum distillates, are “cracked,”
rated from petroleum. At a refin- or broken into smaller compounds
ery, petroleum is heated so that it called ethylene and propylene.
separates into petroleum distillates These compounds are combined
during a process called fractional with a catalyst and other additives
distillation. When petroleum is to create a powdered polymer.
heated, petroleum distillates This polymer is melted and
evaporate and condense at differ- formed into small pellets. Manu-
ent temperatures. These different facturers purchase the pellets,
compounds are then used to make melt them, add color, and create
many products we use every day. many products with which you
are familiar.
A Refined Resource
Plastics are also being used in
When the crude oil is heated, ways you may not have thought
volatile compounds that have very of before. Scientists at Ohio State
low boiling points, such as those University recently developed a
that make up gasoline and airplane plastic that can withstand temper-
fuel, evaporate first and are col- atures up to 800°F. Military air-
lected. Compounds that have very craft may soon take advantage of
high boiling points are left behind. this technology, and it may not be
These compounds are used to long before you find yourself in a
make products such as diesel oil, car that has an engine made of
heating oil, lubricants, asphalt, plastic.
paraffin wax, and tar. Petroleum
distillates are also used in pesti-
cides, cleaning fluids, metal pol-
ishes, spot removers, lubricants,
and many other products.
Chapter 17 Society and the Environment 489
Renewable Energy 18C H A P T E R
1 Renewable Energy Today
2 Alternative Energy and
Conservation
PRE-READING ACTIVITY
Double-
Door Fold
Before you
read this chap-
ter, create the FoldNote
entitled “Double-Door Fold”
described in the Reading and
Study Skills section of the
Appendix. Write “Advantages
of renewable energies” on
one flap of the double door
and “Disadvantages of
renewable energies” on the
other flap. As you read the
chapter, compare the two
topics, and write characteris-
tics of each type of renew-
able energy
on the
inside of
the appro-
priate flap.
The power of the wind is one of the
oldest energy resources used by
humans. These Spanish windmills
were built to grind grain hundreds of
years ago. Today, wind energy is a
rapidly growing industry.
490 Chapter 18 Renewable Energy
SECTION 1
Renewable Energy Today
EARTH SCIENCE CONNECTION
When someone mentions renewable energy, you may think of Objectives
high-tech solar-powered cars, but life on Earth has always been
powered by energy from the sun. Renewable energy is energy ̈ List six forms of renewable energy,
from sources that are constantly being formed. In addition to and compare their advantages and
solar energy, renewable energy sources include wind energy, the disadvantages.
power of moving water, and the Earth’s heat.
̈ Describe the differences between
Many governments plan to increase their use of renewable passive solar heating, active solar
sources. For example, the European Union plans to produce 12 heating, and photovoltaic energy.
percent of their energy from renewable sources by 2010. Such a
change will reduce the environmental problems caused by the use ̈ Describe the current state of wind
of nonrenewable energy. However, all sources of energy, including energy technology.
renewable sources, affect the environment.
̈ Explain the differences in biomass
Solar Energy—Power from the Sun fuel use between developed and
developing nations.
What does the space station shown in Figure 1 have in common
with a plant? Both are powered by energy from the sun. The sun is ̈ Describe how hydroelectric
a medium-sized star that radiates energy from nuclear fusion reac- energy, geothermal energy, and
tions in its core. Only a small fraction of the sun’s energy reaches geothermal heat pumps work.
the Earth. However, this energy is enough to power the wind, plant
growth, and the water cycle. So nearly all renewable energy comes Key Terms
directly or indirectly from the sun. You use direct solar energy
every day. When the sun shines on a window and heats a room, renewable energy
the room is being heated by solar power. Solar energy can also be passive solar heating
used indirectly to generate electricity in solar cells. active solar heating
biomass fuel
hydroelectric energy
geothermal energy
Figure 1 ̈ What does this plant
have in common with a space sta-
tion’s solar panels? Both use energy
from the sun.
Section 1 Renewable Energy Today 491
Figure 2 ̈ Seven hundred years Passive Solar Heating The cliff dwellings shown
ago, the Ancestral Puebloans, also in Figure 2 used passive solar heating, the sim-
called the Anasazi, lived in passive plest form of solar energy. Passive solar heating
solar cliff dwellings in Mesa Verde, uses the sun’s energy to heat something directly.
New Mexico. In the Northern Hemisphere, south facing win-
dows receive the most solar energy, so passive
solar buildings have large windows that face
south. Solar energy enters the windows and
warms the house. At night, the heat is released
slowly to help keep the house warm. Passive solar
buildings must be well insulated with thick walls
and floors in order to prevent heat loss.
Passive solar buildings are oriented according
to the yearly movement of the sun. In summer,
the sun’s path is high in the sky and the overhang
of the roof shades the building and keeps it cool.
In winter, the sun’s path is lower in the sky, so
sunlight shines into the home and warms it. If
there is reliable winter sunlight, an extremely effi-
cient passive solar heating system can heat a house even in very
cold weather without using any other source of energy. However,
an average household could reduce its energy bills by using any
of the passive solar features shown in Figure 3.
A Super-Efficient Home
Imagine a home located deep in cost more to build than a conven- Much of the building’s electric-
the Rocky Mountains, where winter tional structure, but that extra cost ity is provided by solar cells. If the
temperatures can plunge to –40°C was recovered through energy sav- building did not have equipment
(–40°F). The home has no furnace, ings in only three years. such as copiers and computers, it
yet it manages to stay comfortably might not require any outside
warm even in the coldest weather. Solar energy is the most impor- electricity at all. RMI staffer Owen
This home, built by energy experts tant energy source for RMI. An Bailey said, “When the copier is not
Hunter and Amory Lovins in abundance of south-facing windows running, we actually send power
Snowmass, Colorado, is a prime lets in plenty of sunshine. As a back to the utility company.”
example of a new generation of result, little daytime lighting is
super-efficient structures. required. Artificial lighting is pro- Solar energy, plus the heat
vided by compact fluorescent lamps from appliances and human bodies,
Efficiency without sacrifice was that draw only 18 W but provide as meets 90 percent of the heating
the goal in designing the Lovins’s much light as standard 75 W incan- needs. The other 10 percent is pro-
home, which also houses the Rocky descent bulbs. These lamps also last vided by two wood-burning stoves.
Mountain Institute (RMI), an energy- 10 to 13 times longer than ordinary The walls and roof of RMI are heavi-
research organization. The structure bulbs. Motion sensors turn the ly insulated, greatly reducing heat
uses one-tenth the electricity and lights off when a room is empty loss. Also, the walls and windows
one-half the water of a similar-sized and turn them back on when some- are airtight, eliminating another
conventional building. The building one enters the room. common source of heat loss.
492 Chapter 18 Renewable Energy
Figure 3 ̈ A passive solar
home is designed to reduce
heating and cooling expenses.
EARTH SCIENCE CONNECTION
̈ The Rocky Mountain Institute uses the energy of the sun so efficiently CRITICAL THINKING
that it can stay warm in the coldest Colorado winters.
1. Inferring Relationships
During extended cloudy winter The RMI structure shows that Specially designed homes in
weather (with no solar heat input) conservation does not require dis- Colorado are able to meet most of
the building loses only about 1°F comfort. The building is comfort- their heating needs using passive
per day. Nevertheless, the structure able and spacious. As Amory Lovins solar heating. But in parts of
is well ventilated. It has specially said, “The main thing that the Canada and Alaska where winter
designed air exchangers that vent Institute demonstrates is that con- weather can be similar to the
stale air and warm the incoming servation . . . doesn’t mean freezing weather in Colorado, solar-heating
fresh air. in the dark.” systems are often inadequate. Use
what you know about latitude and
solar radiation and write an expla-
nation for this. WRITING SKILLS
2. Applying Ideas Currently, only
about 1 percent of the homes built
in this country have energy-efficient
designs. What could be done to
increase this percentage?
Section 1 Renewable Energy Today 493
Figure 4 ̈ In a solar water heating
system, a liquid is pumped through
solar collectors. The heated liquid
flows through a heat exchanger that
transfers the energy to water, which
is used in a household.
Light- Electrons Active Solar Heating Energy from the sun can be gathered by col-
absorbing flow from lectors and used to heat water or to heat a building. This technol-
coating front contact ogy is known as active solar heating. More than 1 million homes
in the United States use active solar energy to heat water. Solar col-
Phosphorus- lectors, usually mounted on a roof, capture the sun’s energy, as
enriched shown in Figure 4. A liquid is heated by the sun as it flows through
silicon the solar collectors. The hot liquid is then pumped through a heat
exchanger, which heats water for the building. About 8 percent of
Boron- the energy used in the United States is used to heat water; therefore,
enriched active solar technology could save a lot of energy.
silicon
Photovoltaic Cells Solar cells, also called photovoltaic
Electrons are (FOHT oh vahl TAY ik) cells, convert the sun’s energy into
absorbed by electricity, as shown in Figure 5. Solar cells have no moving
back contact parts, and they run on nonpolluting power from the sun.
So why don’t solar cells meet all of our energy needs? A
Figure 5 ̈ Sunlight falls on a semi- solar cell produces a very small electrical current. So meeting
conductor, causing it to release elec- the electricity needs of a small city would require covering
trons. The electrons flow through a hundreds of acres with solar panels. Solar cells also require
circuit that is completed when extended periods of sunshine to produce electricity. This
another semiconductor in the solar energy is stored in batteries, which supply electricity when
cell absorbs electrons and passes the sun is not shining.
them on to the first semiconductor.
Despite these limitations, energy production from solar
494 Chapter 18 Renewable Energy cells has doubled every four years since 1985. Solar cells have
become increasingly efficient and less expensive. Solar cells
have great potential for use in developing countries, where
energy consumption is minimal and electricity distribution
networks are limited. Currently, solar cells provide energy for
more than 1 million households in the developing world.
■✓● Reading Check How is liquid used in active solar heating? (See
the Appendix for answers to Reading Checks.)
U.S. Wind Power Production and Cost: 1981–2003 Figure 6 ̈ The cost of wind power
has been steadily falling as wind tur-
7,000 60 bines have become more efficient.
55
Figure 7 ̈ California wind farms,
Megawatts installed6,000 50 such as this one in Altamont Pass,
Cost (cents/kwh)45 generate more than enough electricity
to light a city the size of San Francisco.
5,000 40
495
4,000 Megawatts installed 35
3,000 30
Cost 25
20
2,000 15
1,000 10
5
00
1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003
Year
Source: American Wind Energy Association.
Wind Power—Cheap and Abundant
Energy from the sun warms the Earth’s surface unevenly, which
causes air masses to flow in the atmosphere. We experience the
movement of these air masses as wind. Wind power, which con-
verts the movement of wind into electric energy, is the fastest-
growing energy source in the world. New wind turbines are cost
effective and can be erected in three months. As a
result, the cost of wind power has declined dra-
matically, as shown in Figure 6. The world pro-
duction of electricity from wind power
quadrupled between 1985 and 2000.
Wind Farms Large arrays of wind turbines, like
the one shown in Figure 7, are called wind farms.
In California, large wind farms supply electricity
to 280,000 homes. In windy rural areas, small
wind farms with 20 or fewer turbines are also
becoming common. Because wind turbines take up
little space, some farmers can add wind turbines
to their land and still use the land for other pur-
poses. Farmers can then sell the electricity they
generate to the local utility.
An Underdeveloped Resource Scientists estimate
that the windiest spots on Earth could generate
more than ten times the energy used worldwide.
Today, all of the large energy companies are devel-
oping plans to use more wind power. Wind experts
foresee a time when prospectors will travel the
world looking for potential wind-farm sites, just as
geologists prospect for oil reserves today. However,
one of the problems of wind energy is transporting
electricity from rural areas where it is generated to
urban centers where it is needed. In the future, the
electricity may be used on the wind farm to pro-
duce hydrogen from water. The hydrogen could
then be trucked or piped to cities for use as a fuel.
Figure 8 ̈ The consumption Biomass—Power from Living Things
of wood as an energy source has
increased by nearly 80 percent Plant material, manure, and any other organic matter that is used
since 1960. In developing countries as an energy source is called a biomass fuel. While fossil fuels are
such as Nepal, Burma, Guatemala, organic and can be thought of as biomass energy sources, fossil
Congo (DRC), and Kenya, the use fuels are nonrenewable. Renewable biomass fuels, such as wood
of fuelwood places an enormous and dung, are major sources of energy in developing countries, as
burden on local environments. shown in Figure 8. More than half of all wood cut in the world is
used as fuel for heating and cooking. Although wood is a renew-
FIELD ACTIVITY able resource, if trees are cut down faster than they grow, the
resulting habitat loss, deforestation, and soil erosion can be
Biomass Survey Walk around severe. In addition, harmful air pollution may result from burning
your neighborhood, and list as wood and dung.
many sources of biomass fuel as
you can find. Are any of these Methane When bacteria decompose organic wastes, one by-
(such as a pile of firewood) large product is methane gas. Methane can be burned to generate heat
enough to be used as fuel or electricity. In China, more than 6 million households use bio-
sources? What do you think the gas digesters to ferment manure and produce gas used for heating
advantages and disadvantages of and cooking. In the developed world, biomass that was once
using biomass as a fuel in your thought of as waste is being used for energy. In 2002, Britain’s
area would be? Record your first dung-fired power station started to produce electricity. This
observations in your EcoLog. power station uses the methane given off by cow manure as fuel.
Similarly, some landfills in the United States generate electricity
by using the methane from the decomposition of trash.
Alcohol Liquid fuels can also be derived from biomass. For
example, ethanol, an alcohol, can be made by fermenting fruit or
agricultural waste. In the United States, corn is a major source of
ethanol. Cars and trucks can run on ethanol or gasohol, a blend
of gasoline and ethanol. Gasohol produces less air pollution than
fossil fuels do. For this reason, some U.S. states require the use of
gasohol in vehicles as a way to reduce air pollution.
496 Chapter 18 Renewable Energy
Hydroelectricity—Power from Moving Water Figure 9 ̈ Hydroelectric dams con-
vert the potential energy, or stored
Energy from the sun causes water to evaporate, condense in the energy, of a reservoir into the kinetic
atmosphere, and fall back to the Earth’s surface as rain. As water energy, or moving energy, of a spin-
flows across the land, the energy in its movement can be used to ning turbine. The movement of the
generate electricity. Hydroelectric energy, which is energy produced turbine is then used to generate
from moving water, is a renewable resource that accounts for about electricity.
20 percent of the world’s electricity. The countries that lead the
world in hydroelectric energy are, in decreasing order, Canada, the Figure 10 ̈ The Itaipu Dam in
United States, Brazil, China, Russia, and Norway. Paraguay supplies about 75 percent
of the electricity used by Paraguay
Figure 9 shows how a hydroelectric power plant works. Large and 25 percent of the electricity
hydroelectric power plants have a dam that is built across a river used by Brazil.
to hold back a reservoir of water. The water in the reservoir is
released to turn a turbine, which generates electricity. The energy
of this water is evident in Figure 10, which shows the spillway of
the world’s largest hydroelectric dam.
The Benefits of Hydroelectric Energy Although hydroelectric
dams are expensive to build, they are relatively inexpensive to
operate. Unlike fossil fuel plants, hydroelectric dams do not
release air pollutants that cause
acid precipitation. In addition,
hydroelectric dams tend to last
much longer than fossil fuel-
powered plants. Dams also
provide other benefits such as
flood control and water for
drinking, agriculture, industry,
and recreation.
■✓● Reading Check Explain how
hydroelectric energy begins
with the sun.
Section 1 Renewable Energy Today 497
Figure 11 ̈ Geothermal power Disadvantages of Hydroelectric Energy A dam changes a river’s
plants generate electricity using flow, which can have far-reaching consequences. A reservoir
the following steps: steam rises floods large areas of habitat above the dam. The water flow
through a well; steam drives tur- below the dam is reduced, which disrupts ecosystems down-
bines, which generate electricity; stream. For example, many of the salmon fisheries of the north-
western United States have been destroyed by dams that prevent
leftover liquid water is pumped the salmon from swimming upriver to spawn. When the land
back into the hot rock. behind a dam is flooded, people are often displaced. An estimated
50 million people around the world have been displaced by dam
projects. Dam failure can be another problem—if a dam bursts,
people living in areas below the dam can be killed.
Dams can also affect the land below them. As a river slows
down, the river deposits some of the sediment it carries. This
fertile sediment builds up behind a dam instead of enriching the
land farther down the river. As a result, farmland below a dam
can become less productive. Recent research has also shown
that the decay of plant matter trapped in reservoirs can release
large amounts of greenhouse gases—sometimes more than a
fossil fuel-powered plant.
Modern Trends In the United States, the era of
large dam construction is probably over. But in
developing countries, such as Brazil, India, and
China, the construction of large dams continues.
A modern trend is micro-hydropower, which is
electricity produced in a small stream without hav-
ing to build a big dam. The turbine may even float
in the water, not blocking the river at all. Micro-
hydropower is much cheaper than large hydroelec-
tric dam projects, and it permits energy to be
generated from small streams in remote areas.
Geothermal Energy—Power from
the Earth
In some areas, deposits of water in the Earth’s
crust are heated by energy within the Earth. Such
places are sources of geothermal energy—the
energy from heat in the Earth’s crust. As Figure 11
shows, this heat can be used to generate electricity.
Geothermal power plants pump heated water or
steam from rock formations and use the water or
steam to power a turbine that generates electricity.
Usually the water is returned to the Earth’s crust
where it can be heated and used again.
The United States is the world’s largest produ-
cer of geothermal energy. The world’s largest
geothermal power plant is The Geysers, in Cali-
fornia, which produces electricity for about
498 Chapter 18 Renewable Energy
Figure 12 ̈ In the winter (left), the
ground is warmer than the air is. A
fluid is circulated underground to
warm a house. In the summer (right),
the ground is cooler than the air is,
and the fluid is used to cool a house.
1.7 million households. Other countries that produce geothermal www.scilinks.org
energy include the Philippines, Iceland, Japan, Mexico, Italy, and
New Zealand. Although geothermal energy is considered a renew- Topic: Renewable
able resource, the water in geothermal formations must be man- Sources of Energy
aged carefully so that it is not depleted.
Code: HE81292
Geothermal Heat Pumps: Energy for Homes More than 600,000
homes in the United States are heated and cooled using geother-
mal heat pumps such as the one shown in Figure 12. Because
the temperature of the ground is nearly constant year-round, a
geothermal heat pump uses stable underground temperatures to
warm and cool homes. A heat pump is simply a loop of piping
that circulates a fluid underground. In warm summer months,
the ground is cooler than the air, and the fluid is used to cool a
home. In the winter, the ground is warmer than the air, and the
fluid is used to warm the home.
S E C T I O N 1 Review
1. List six forms of renewable energy, and compare the CRITICAL THINKING
advantages and disadvantages of each. 5. Making Decisions Which renewable energy source
2. Describe the differences between passive solar heat- would be best suited to your region? Write a para-
ing, active solar heating, and photovoltaic energy. graph that explains your reasoning. WRITING SKILLS
3. Describe how hydroelectric energy, geothermal 6. Identifying Trends Identify a modern trend in
energy, and geothermal heat pumps work. hydroelectric power and in wind energy.
4. Explain whether all renewable energy sources have 7. Analyzing Relationships Write an explanation of
their origin in energy from the sun. the differences in biomass fuel use between devel-
oped and developing countries. WRITING SKILLS
Section 1 Renewable Energy Today 499
SECTION 2 CONNECTION
Alternative Energy and Conservation
EARTH SCIENCE
Objectives To achieve a future where energy use is sustainable, we must make
the most of the energy sources we already have and develop new
̈ Describe three alternative energy sources of energy. Alternative energy describes energy sources that
technologies. are still in development. Some renewable energy sources that we
use now, such as geothermal power, were once considered alterna-
̈ Identify two ways that hydrogen tive energy. For an alternative energy source to become a viable
could be used as a fuel source in option for the future, the source must be proven to be cost effec-
the future. tive. Also, the environmental effects of using the energy source
must be acceptable. Government investment is often the only way
̈ Explain the difference between to research some of these future energy possibilities.
energy efficiency and energy con-
servation. Tidal Power
̈ Describe two forms of energy- Tides are the movement of water in the oceans and seas caused
efficient transportation. by gravitational attraction between the sun, Earth, and moon.
The tides, which happen twice each day, are marked by the rising
̈ Identify three ways that you can and falling of the sea level. The energy of the tides was used
conserve energy in your daily life. nearly a thousand years ago to power mills in France and Britain.
Today, tidal power is used to generate electricity in countries such
Key Terms as France, Russia, and Canada.
alternative energy As Figure 13 shows, a tidal power plant works much like a
ocean thermal energy hydroelectric dam. As the tide rises, water flows behind a dam;
when the sea level falls, the water is trapped behind the dam.
conversion (OTEC) When the water in the reservoir is released, it turns a turbine that
fuel cell generates electricity. Although tidal energy is renewable and non-
energy efficiency polluting, it will not become a major energy source in the future.
energy conservation The cost of building and maintaining a tidal power plant is high,
and there are few locations that are suitable.
Figure 13 ̈ As the tide rises, water As the tide rises, water is trapped
enters a bay behind a dam. The gate behind the dam.
then closes at high tide. At low tide,
the gate opens and the water in the Gate closes
bay rushes through, spinning a tur-
bine that generates electricity.
High tide
At low tide, water rushes through the dam and
spins a turbine, which generates electricity.
Gate opens
Low tide
500 Chapter 18 Renewable Energy
Ocean Thermal Energy Conversion Figure 14 ̈ In an open cycle OTEC
plant, warm surface water is brought
In the tropics, the temperature difference between the to boil in a vacuum chamber. The
surface of the ocean, which is warmed by solar energy, boiling water produces steam to
and deep ocean waters can be as much as 24°C (43°F). drive a turbine that generates elec-
An experimental power station off the shores of Hawaii tricity. Cold deep-ocean water is
uses this temperature difference to generate electricity. pumped in to condense the steam.
This technology, which is shown in Figure 14, is called Fresh water is a byproduct of this
ocean thermal energy conversion (OTEC). In this sys- type of OTEC plant.
tem, warm surface water is used to boil sea water.
This is possible because water boils at low tempera- www.scilinks.org
tures when it is at low pressure in a vacuum chamber.
The boiling water turns into steam, which spins a tur- Topic: Fuel Cells
bine. The turbine runs an electric generator. Cold Code: HE80625
water from the deep ocean cools the steam, turning
the steam into water that can be used again.
Japan has also experimented with OTEC power,
but so far, no project has been able to generate elec-
tricity cost-effectively. One problem with OTEC is
that the power needed to pump cold water up from
the deep ocean uses about one-third of the electricity
the plant produces. The environmental effects of pumping large
amounts of cold water to the surface are also unknown.
Hydrogen—A Future Fuel Source?
Hydrogen, the most abundant element in the universe, can be
burned as a fuel. Hydrogen is found in every molecule of living
things, and it is found in water. Hydrogen does not release pollu-
tants associated with burning fossil fuels and biomass. When
hydrogen is burned, it combines with oxygen to produce water
vapor, a harmless byproduct. Hydrogen gas (H2) can be produced
by using electricity to split molecules of water (H2O). In the
future, we may also be able to grow plants to produce hydrogen
cost-effectively, as shown in Figure 15.
■✓● Reading Check What are two advantages of using hydrogen as a
fuel source?
Figure 15 ̈ Hydrogen fuel can be
made from any material that con-
tains a lot of hydrogen, including the
experimental plot of switchgrass
shown here.
Section 2 501
Figure 16 ̈ This diagram shows The flow of electrons (e-) produces electricity.
how a fuel cell produces electrical –+
energy.
Hydrogen e- e- Oxygen,
fuel, H2 e- e- O2 , from air
H2O
Electrolyte Electrodes
solution
QuickLAB The Challenge of Hydrogen Fuel Why is hydrogen the fuel of the
future and not of today? There are two main problems. First, the
Hydrolysis current methods that are used to produce hydrogen are not very
efficient. They require a lot of energy, are expensive, and cause
Procedure pollution. In the future, this problem may be solved by producing
hydrogen from water using solar power. Second, a lot of hydrogen
1. Coat a 9 V cell with petroleum is needed to produce the same amount of energy as a tank of
jelly. Be careful not to get any gasoline. Therefore, the hydrogen must be compressed to fit into
on the terminals. a vehicle. Tanks that hold hydrogen safely at high pressure are
still being developed.
2. Mix 1 Tbsp of salt in a 600 mL
beaker of water. Fuel Cells Fuel cells, like the one in Figure 16, may be the
engines of the future. Like a battery, a fuel cell produces electric-
3. Fill two test tubes with the ity chemically, by combining hydrogen fuel with oxygen from the
saltwater solution, and invert air. When hydrogen and oxygen are combined, electrical energy is
them in the beaker, making produced and water is the only byproduct. Fuel cells can be
sure to cover the ends of the fueled by anything that contains plenty of hydrogen, including
test tubes. No air should be natural gas, alcohol, or even gasoline. The space shuttles have
trapped in the test tubes. used fuel cells for years. In the change from cars powered by
internal combustion engines to those powered by fuel cells, vehi-
4. Place the 9 V cell upright in cles may get hydrogen from gasoline so that they can be refueled
the beaker. Position a battery at existing gas stations.
terminal under the open
mouth of each test tube. You Energy Efficiency
will observe hydrogen gas col-
lecting in the test tube located Energy efficiency is the percentage of energy put into a system that
over the negative terminal and does useful work. Energy efficiency can be determined using this
oxygen gas collecting over the simple equation: energy efficiency (in %) = useful energy out/energy
positive terminal. in ҂ 100. Thus, the efficiency of a light bulb is the proportion of
electrical energy that reaches the bulb and is converted into light
Analysis energy rather than into heat. The relationship between the transfer
of energy to the work done and the heat transferred is known as
1. Did you collect the same vol- the first law of thermodynamics. This law explains that the energy
ume of hydrogen as oxygen? going in must equal the energy coming out of a system. Therefore
Explain why or why not. any heat transfer reduces the energy available for work, thus affect-
ing efficiency. This relationship holds true for biological systems
as well as physical systems. Most of our devices are fairly ineffi-
502 Chapter 18 Renewable Energy
cient. More than 40 percent of all commercial energy used in the Table 1 ̄
United States is wasted. Most of it is lost from inefficient fuel-
wasting vehicles, furnaces, and appliances and from leaky, poorly Energy Efficiency of Common
insulated buildings. We could save enormous amounts of energy Conversion Devices
by using fuel cells instead of internal combustion engines in cars,
and by changing from incandescent to fluorescent light bulbs, as Device Efficiency
shown in Table 1. However, many increases in efficiency involve
sacrifices or investments in new technology. Incandescent 5%
light bulb
Efficient Transportation Nothing would increase the energy effi- 22%
ciency of American life more than developing efficient engines to Fluorescent
power vehicles and increasing the use of public transportation light bulb 10%–15%
systems. The internal combustion engines that power most vehi- 20%–25%
cles use fuel inefficiently and produce air pollution. The design of Internal combustion
these engines has hardly changed since 1900, but they may engine (gasoline) 45%
change radically in the next 50 years. However, in the United 60%
States, gasoline prices have been so low that there has been little Human body
demand for fuel-efficient vehicles, which are more common in
other countries. Steam turbine
Hybrid Cars Hybrid cars, such as the one shown in Figure 17, Fuel cell
are examples of energy-efficient vehicles. Hybrid cars use a small,
efficient gasoline engine most of the time, but they also use an www.scilinks.org
electric motor when extra power is needed. Hybrid cars feature
other efficient technologies. They convert some of the energy of Topic: Mass Transit
braking into electricity and they store this energy in the battery. Code: HE80919
To save fuel, hybrid cars sometimes shut off the gasoline engine, Topic: Energy
such as when the car is idling. Hybrid cars are also designed to be
aerodynamic, and they are made of lightweight materials so they Conservation
need less energy to accelerate. Hybrid cars cost less to refuel than Code: HE80510
conventional vehicles, and they produce less harmful emissions.
These benefits are leading auto makers to design many hybrid car
models, including hybrid trucks and SUVs.
■✓● Reading Check Identify three ways that hybrid cars are energy
efficient.
Figure 17 ̈ A hybrid car has a
gasoline engine and an electric motor.
Section 2 Alternative Energy and Conservation 503
Spider Map Cogeneration
Create the
Graphic Organizer entitled One way to use fuel more efficiently is cogeneration, the produc-
“Spider Map” described in the tion of two useful forms of energy from the same fuel source. For
Appendix. Label the circle “Ways example, the waste heat from an industrial furnace can power a
to Conserve Energy At Home.” steam turbine that produces electricity. The industry may use the
Create a leg for each way to con- electricity or sell it to a utility company. Small cogeneration sys-
serve energy at home. Then, fill in tems have been used for years to supply heat and electricity to mul-
the map with details tiple buildings at specific sites. Small units suitable for single
about each way to buildings are now available in the United States.
conserve energy at
home. Energy Conservation
MATHPRACTICE Energy conservation means saving energy. It can occur in many
ways, including using energy-efficient devices and wasting less
Energy Efficiency In the energy. The people in Figure 18 are conserving energy by bicy-
United States, each person cling instead of driving. Between 1975 and 1985, conservation
uses an average of 459 gallons made more energy available in the United States than all alterna-
of gasoline per year. In Germany, tive energy sources combined did.
each person uses an average of 140
gallons a year. Auto manufacturers Cities and Towns Saving Energy The town of Osage, Iowa, num-
estimate that vehicles would use 2 bers 3,600 people. You might not think that a town this small
percent less gasoline if everyone could make much of a difference in energy conservation. Yet the
kept their tires inflated to the correct town adopted an energy conservation plan that saves more than
pressure. How much gasoline would $1 million each year. The residents plugged the leaks around win-
a person in the United States save dows and doors where much of the heat escapes from a house. In
and a person in Germany save each addition, they replaced inefficient furnaces and insulated their hot
year if their tires were kept inflated water heaters. Businesses in Osage also found ways to conserve
to the correct pressure? energy. In addition to saving energy, the town has greatly improved
its economy through energy conservation. Businesses have relo-
cated to the area in order to take advantage of low energy costs.
Unemployment rates have also declined. This small town in Iowa is
just one example of the dramatic benefits of energy conservation.
Conservation Around the Home The average household in the
United States spends more than $1,500 on energy bills each year.
Unfortunately, much of that energy is wasted. Most of the energy
lost from homes is lost through poorly insulated windows, doors,
Figure 18 ̈ In Copenhagen,
Denmark, companies provide free
bicycles in exchange for publicity.
Anyone wishing to use a bike is free
to borrow one after paying a refund-
able deposit. The program helps cut
down on pollution and auto traffic.
504 Chapter 18 Renewable Energy
walls, and the roof. So a good way to increase energy efficiency is Table 2 ̄
to add to the insulation of a home. Replacing old windows with
new high efficiency windows can reduce your energy bill by Energy Conservation Tips
15 percent. Two of the best places to look for ways to conserve • Walk or ride a bicycle for
energy are doors and windows. Much of the energy lost from a
house escapes as hot air in winter or cold air in summer passes short trips.
through gaps around doors and windows. Hold a ribbon up to • Carpool or use public
the edges of doors and windows. If it flutters, you’ve found a
leak. Sealing these leaks with caulk or weather stripping will help transportation whenever
conserve energy. There are dozens of other ways to reduce energy possible.
use around the home. Some of these are shown in Figure 19. • Drive a fuel-efficient
automobile.
Conservation in Daily Life There are many simple lifestyle • Choose ENERGY STAR® products.
changes that can help save energy. First, remember that using less • Recycle and choose recycled
of any resource usually translates into saving energy. For exam- products whenever possible.
ple, washing your clothes in cold water uses only 25 percent of • Set computers to “sleep” mode
the energy needed to wash your clothes in warm water. Table 2 when they are not in use.
lists a few ways that you can conserve energy every day. Can you
think of other ways? Figure 19 ̈ Ways to Save Energy
Around the House
S E C T I O N 2 Review
1. Describe three alternative energy technologies, and CRITICAL THINKING
identify two ways that hydrogen could be used as a
fuel source in the future. 4. Making Inferences What factors influence a per-
son’s choice to conserve energy?
2. List as many ways as you can for individuals and
communities to conserve energy. 5. Making Comparisons Read the description of
hydrogen fuel cells and explain why hydrolysis (split-
3. Describe the difference between energy conserva- ting water molecules with electricity to produce
tion and energy efficiency. hydrogen and oxygen) is the opposite of the reaction
that occurs in a hydrogen fuel cell. READING SKILLS
Section 2 Alternative Energy and Conservation 505
18C H A P T E R Highlights
1 Renewable Energy Today Key Terms Main Ideas
renewable energy, ̈ Renewable energy is energy from sources
491 that are constantly being formed.
passive solar heating, ̈ Solar energy can be used to heat a house
492 directly or to heat another material, such as
water, which can then be used to heat a
active solar heating, house. Solar cells can also be used to gener-
494 ate electricity.
biomass fuel, 496 ̈ Wind power is the fastest growing source of
energy in the world.
hydroelectric energy,
497 ̈ Many people in developing countries get
most of their energy from biomass such as
geothermal energy, fuelwood. Biomass is increasingly used in
498 developed countries to generate electricity.
̈ Hydroelectric energy is electricity generated
by the energy of moving water.
̈ Geothermal energy, the heat within the
Earth, can be used to generate electricity.
2 Alternative Energy alternative energy, ̈ Alternative energy sources are energy sources
and Conservation 500 that are still in development.
ocean thermal ̈ Ocean thermal energy conversion (OTEC)
energy conversion uses the temperature difference between layers
(OTEC), 501 of ocean water to generate electricity.
fuel cell, 502 ̈ Hydrogen may be one of the fuels of the
future. It can be made from any organic ma-
energy efficiency, terial and produces only water as a waste
502 product when burned.
energy conservation, ̈ Hydrogen fuel cells may be the engines of
504 the future. Many experiments with them are
now underway.
̈ Energy efficiency is the percentage of energy
put into a system that does useful work. Energy
conservation means saving energy.
506 Chapter 18 Highlights
18C H A P T E R Review
Using Key Terms 10. A house that uses passive solar heating in the
Northern Hemisphere will
Use the correct key term to complete each of the a. be built of a material such as concrete or
following sentences. adobe that stores heat well.
b. have little insulation.
1. Much of the energy needs of the developing c. have large north-facing windows.
world are met by _________, such as fuel- d. have an overhang to shade the house from
wood. direct winter sun.
2. A __________ converts the potential energy 11. A passive solar house in the Southern
of a reservoir into the kinetic energy of a Hemisphere will face
spinning turbine. a. north.
b. south.
3. Turning off the lights when you leave a room c. east.
is an example of __________. d. west.
Use each of the following terms in a separate 12. Photovoltaic cells convert the sun’s energy into
sentence. a. heat.
b. fuel.
4. renewable energy c. electricity.
d. light.
5. geothermal energy
13. In a developing country, you are most likely
6. alternative energy to find biomass used
a. to generate electricity.
7. energy conservation b. for manufacturing.
c. for heating and cooking.
STUDY TIP d. as a source of hydropower.
Get Some Exercise Ride a bike, go for a walk, or 14. Which of the following is not true of
play Frisbee or basketball. Try to get at least a half fuel cells?
hour of exercise before you begin studying. Then a. They produce electricity.
when you study you will be more relaxed and you b. They will work with many different fuels.
will be able to focus on the subject you want to c. They are more energy efficient than most
learn. As you study, take a moment to notice if the engines used today.
exercise helped. Scientists have proven that regu- d. They cannot be fueled by hydrogen.
lar physical exercise helps fight memory loss.
15. Which renewable energy source is the fastest
Understanding Key Ideas growing energy source in the world?
a. oil
8. Which of the following forms of renewable b. wind
energy uses the sun’s energy most directly? c. biomass
a. biomass fuel d. photovoltaic cells
b. passive solar heating
c. geothermal energy 16. Which statement describes why geothermal
d. a hydrogen fuel cell heat pumps work?
a. They are located in areas with abundant
9. Which of the following energy sources is use- geothermal energy.
ful in most parts of the world? b. The ground is warmer than the air in sum-
a. tidal power mer and colder than the air in winter.
b. OTEC c. The ground is colder than the air in sum-
c. geothermal energy mer and warmer than the air in winter.
d. active solar energy d. They run on hydrogen fuel cells.
Chapter 18 Review 507
18C H A P T E R Review
Short Answer Concept Mapping ?
??
17. Rivers are recharged by the water cycle, so
what is the original source of hydroelectric 23. Use the following terms to create a concept
energy? map: sun, hydroelectric energy, solar energy,
passive solar heating, active solar heating,
18. Salt water corrodes metals rapidly. What water cycle, biomass fuel, wind energy,
effect is this likely to have on the cost of photovoltaic cell, and electric current.
electricity produced from tidal power?
Critical Thinking
19. Why is it likely that hydroelectric energy
will be generated increasingly by micro- 24. Making Comparisons Read the description
hydropower plants rather than by large of energy efficiency and energy conservation
hydroelectric dams? in this chapter. How are the two concepts
related? Give several examples. READING SKILLS
Interpreting Graphics
25. Analyzing Ideas Does the energy used by fuel
Use the information in the figure below to cells come from the sun? Explain your answer.
answer questions 20–22.
26. Analyzing Ideas Explain whether you think
20. Describe the path of the water in the loop the most important advances of the 21st cen-
during winter. Where is the water warmed? tury will be new sources of energy or more
Where is the water cooled? efficient use of sources that already exist.
21. Describe the path of the water in the loop 27. Drawing Inferences Don Huberts of Shell
during summer. Where is the water warmed? Hydrogen said, “The Stone Age didn’t end
Where is the water cooled? because the world ran out of stones.” He
was talking about the future of fossil fuels.
22. What is the difference in the temperature Write a short essay that explains what he
between the house, the closed loop, and the meant. WRITING SKILLS
air in the summer? What is the temperature
difference in the winter? Cross-Disciplinary Connection
28. Geography Create a world map that shows
at least 10 renewable energy or alternative
energy projects currently in operation.
Annotate your map with details and photo-
graphs of each project.
Portfolio Project
29. Energy Timeline The first energy source used
by human societies was human muscle. It was
used to build houses, make clothing, and
shape tools that could be used to dig up
plants and kill animals for food. What was
the next source of energy? Make a timeline of
the energy sources that humans began to use
at various times in history. Add interesting
facts and images that relate to each energy
source on your timeline. Continue your time-
line into the future. What energy sources do
you think we will use in the future?
508 Chapter 18 Review
MATH SKILLS READING SKILLS
The pie graph below shows electric generating capa- Read the passage below, and then answer
city from renewable sources in the United States in the questions that follow.
1998. Use the data to answer questions 30–31.
Aluminum is refined from the ore bauxite,
Biomass Geothermal which is deposited in a thin layer at the
11.0% 3.0% Wind Earth’s surface. Worldwide, bauxite strip
1.5% mines cover more of the Earth’s surface than
any other type of metal ore mine. Aluminum
Solar production uses so much electrical energy that
0.5% the metal has been referred to as “congealed
electricity.” Producing six aluminum cans
Hydroelectric takes the energy equivalent of 1 L of gasoline.
84.0% For this reason, aluminum smelters are located
close to cheap and reliable energy sources,
30. Making Calculations How much generating such as hydroelectric dams in the Pacific
capacity came from biomass, geothermal, Northwest, Quebec, and the Amazon. When
wind, and solar combined? the environmental effects of producing new
aluminum are considered, the importance of
31. Making Calculations In 1998, the United recycling becomes clear. Recycling one alu-
States had a total of 94,822 MW of electric minum can saves enough energy to run a tele-
generating capacity from renewable energy. vision set for 4 hours! Currently, the United
How much of that capacity came from bio- States obtains about 20 percent of its alu-
mass? How much came from wind power? minum from recycling.
WRITING SKILLS 1. Why is aluminum referred to as “con-
gealed electricity”?
32. Communicating Main Ideas Explain why a. Smelting aluminum requires a different
scientists are working to reduce the use of form of electrical energy.
the two main sources of energy people use b. Aluminum has an electric charge.
today—fossil fuels and biomass. c. Like electrical energy, aluminum can
also be recycled.
33. Writing Persuasively Write a guide that d. So much electrical energy is required to
encourages people to conserve energy and produce aluminum that it is almost as
offers practical tips to show them how. if aluminum were solidified electricity.
2. Which of the following statements
describes the author’s main point?
a. Hydroelectricity is a cheap, reliable
source of energy.
b. Recycling aluminum can make a
significant contribution to energy
conservation.
c. Aluminum is available in many places,
so there is no need to conserve it.
d. The environmental effects of hydroelec-
tric dams are not related to the con-
sumption of aluminum.
Chapter 18 Review 509
18C H A P T E R Standardized Test Prep
Understanding Concepts Reading Skills
Directions (1–4): For each question, write on a Directions (7–8): Read the passage below. Then
separate sheet of paper the letter of the correct answer the questions.
answer.
Ancient cliff dwellings contain elements of
1 What is the ultimate source of all the simplest form of solar energy called passive
solar heating. Passive solar heating uses the
renewable energy? sun’s energy to heat something directly. In the
A. the biosphere Northern Hemisphere, windows facing south
B. the moon receive the most solar energy, so passive solar
C. the ocean buildings have large windows that face south.
D. the sun Solar energy enters the windows and warms
the house. At night, the heat is released slowly
2 Which of the following is a renewable to keep the house warm. Passive solar
buildings must be insulated with thick walls
energy source? and floors.
F. coal mine
G. gas pipeline Passive solar buildings are oriented accord-
H. power plant ing to the yearly movement of the sun. In
I. wind farm summer, the sun’s path is high in the sky and
the overhang of the roof shades the building
3 What is the most important factor in the and keeps it cool. If there is reliable winter
light, an extremely efficient passive solar
development and implementation of heating system can heat a house in very cold
alternative energy sources? weather without using any other source of
A. The most important factor is the energy.
abundance of the source. 7 In the Northern Hemisphere, in what direc-
B. The most important factor is its cost
tion should the largest windows face in
effectiveness. order for the house to be as cool as possible?
C. The most important factor is whether A. north
B. south
government approval can be obtained. C. east
D. The most important factor is if the D. west
source can gain social acceptance. 8 Why do passive solar houses require thick
4 Why is hydrogen called the fuel of the walls and insulation to be efficient at
heating the house in winter?
future?
F. It is very inexpensive to produce. Directions (9): Read the passage below. Then
G. It requires very little energy to produce. answer the question.
H. It is the most abundant element in the
Energy conservation means saving energy. It
universe. can occur in many ways, including using
I. It contains carbon which disperses in the energy-efficient devices and wasting less
energy. Between 1975 and 1985, conservation
atmosphere when burned. made more energy available in the United
States than all alternative energy sources
Directions (5–6): For each question, write a short combined did.
response.
9 Describe two ways that a family could
5 Energy efficiency is the percentage of
reduce the amount of energy wasted in
energy put into a system that does useful their home by increasing energy efficiency.
work. Why is energy efficiency always less
than 100%?
6 Estimate the potential of wind power as an
energy source.
510 Chapter 18 Standardized Test Prep
Interpreting Graphics
Directions (10–12): For each question below, record the correct answer on
a separate sheet of paper.
The map below shows hydroelectric power generation in the United States.
Use this map to answer questions 10 and 11.
Hydroelectric Power
0 What can be inferred about the use of hydroelectric power in the
United States?
F. There are more dams in Oregon than in Kansas.
G. There is more hydroelectric power used in New Mexico than in
Alabama.
H. The upper Midwest uses more water for hydroelectric power than
New England.
I. The biggest users of water for hydroelectricity are located along the
Mississippi River.
q How many states use 10,000 million gallons of water or less per day?
A. 5 C. 15
B. 10 D. 20
Use the diagram below to answer question 12.
The flow of electrons (e-) produces electricity.
–+ Test
Hydrogen e- e- Oxygen, Carefully read the
fuel, H2 e- e- O2, from air instructions, the ques-
tion, and the answer
H2O options before choos-
ing an answer.
Electrolyte Electrodes
solution
w What type of electrical generation is depicted in the diagram?
F. fuel cell
G. geothermal plant
H. ocean thermal energy
I. tidal plant
Chapter 18 Standardized Test Prep 511
18C H A P T E R Inquiry Lab: MODELING
Objectives Blowing in the Wind
̈ USING SCIENTIFIC METHODS Prepare a MEMO
detailed sketch of your solution to
the design problem. To: Division of Research and Developers
̈ Design and build a functional Quixote Alternative Energy Systems is accepting
windmill that lifts a specific weight design proposals to develop a windmill that can be
as quickly as possible. used to lift window washers to the tops of buildings.
As part of the design engineering team, your division
Materials has been asked to develop a working model of such
a windmill. Your task is to design and build a proto-
blow-dryer, 1,500 W type of a windmill that can capture energy from a
dowel or smooth rod 1,500 W blow-dryer. Your model must lift 30 large
foam board paper clips a vertical distance of 50 cm (approxi-
glue, white mately 2 ft) as quickly as possible.
paper clips, large (30)
paper cup, small (1) Procedure
spools of thread, empty (2)
string, 50 cm 1. Build the base for your windmill (shown below). Begin by
attaching the two spools to the foam board using the glue.
optional materials for windmill Make sure the spools are parallel before you glue them.
blades: foam board, paper
plates, paper cups, or any 2. Pass a dowel or a smooth rod through the center of the
other lightweight materials spools. The dowel should rotate freely. Attach one end of the
string securely to the dowel between the two spools.
3. Poke a hole through the middle of the foam board to allow
the string to pass through.
4. Attach the cup to the end of the string. You will use the cup
to lift the paper clips.
5. Place your windmill base between two lab tables or in any
other area that will allow the string to hang freely.
̈ Windmill Base Your windmill
base should allow the dowel to spin as
freely as possible. The pinwheel shown
at the end of the dowel is a suggested
design for your windmill blades.
512 Chapter 18 Inquiry Lab
6. Prepare a sketch of your prototype windmill blades based on ̈ Sample Windmill Blade Designs
the objectives for this lab. Include a list of the materials that
you will use and safety precautions (if necessary).
7. Have your teacher approve your design before you begin
construction.
8. Construct a working prototype of your windmill blades. Test
your model several times to collect data on the speed at
which it lifts the paper clips. Record your data for each trial.
9. Vary the type of material used for construction of your wind-
mill blades. Test the various blades to determine whether
they improve the original plan.
10. Vary the number and size of the blades on your windmill.
Test each design to determine whether the change improves
the original plan.
Analysis
1. Summarize Results Create a data table that lists the speed
for each lift for several trials. Include an average speed.
2. Graphing Data Prepare a bar graph that shows your results
for each blade design.
Conclusions
3. Evaluating Methods After you observe all of the designs,
decide which ones you think best solve the problem and
explain why.
4. Evaluating Models Which change improved your windmill
the most—varying the materials for the blades, varying the
number of blades, or varying the size of the blades? Would
you change your design further? If so, how?
Extension
1. Research Windmills have been used for more than 2,000
years. Research the three basic types of vertical-axis
machines and the applications in which they are used.
Prepare a report of your findings.
2. Making Models Adapt your design to make a water wheel.
You’ll find that water wheels can pull much more weight
than a windmill can. Find designs on the Internet for
micro-hydropower water wheels such as the Pelton wheel,
and use the designs as inspiration for your models. You
can even design your own dam and reservoir.
Chapter 18 Inquiry Lab 513
EARTH SCIENCE CONNECTION
WIND POWER IN THE UNITED STATES
MAP SKILLS 4. Using the Key The Great Plains states have been
called the “Saudi Arabia of wind energy.” Use the key
1. Analyzing Data Why are most of the wind farms to explain what this statement means.
located in the western and central United States and
not in the eastern United States? 5. Finding Locations The first offshore wind farm in
the United States is proposed off the East Coast. Find
2. Understanding Topography Examine Idaho, where the proposed wind farm will be located, and
Wyoming, Montana, and Colorado. What landscape describe the wind conditions in that area.
feature might account for the strong winds in those
states? 6. Using the Key Use the map to determine which
state has the greatest unused potential for wind
3. Using the Key Use the wind power key to locate energy. Explain your reasoning.
where you would plan five wind power projects that
are larger than 50 MW.
514 Chapter 18 Maps in Action
EARTH SCIENCE CONNECTION
BACK TO MUSCLE POWER
In 2001, U.S. forces dropped radios advantage is that there is no haz- dozens of experiments going on all
into remote parts of Afghanistan so ardous waste to dispose of in the over the world. A new line of
that people could hear news broad- form of used batteries. Also, batter- windup generators will power
casts. The radios did not contain ies are heavy. Replacing batteries everything from computers and
batteries, and there are few electrical with longer-lasting, lighter sources mobile phones to land-mine detec-
outlets in rural Afghanistan. So how of electricity has long been a goal tors and water purification systems.
were people supposed to power the of inventors.
radios? The answer is surprisingly Watchmakers have developed
simple. The radios use our oldest The Secret Is in the Design watches whose batteries never need
form of energy—human muscle. to be changed. These watches are
Thirty seconds of cranking a handle The first Freeplay radios worked powered by movement of the wrist.
on one of these radios stores enough like clockwork toys. The user would Typing your term paper or playing
energy for an hour of listening. turn the handle, winding up a long volleyball powers your watch.
spring, which then slowly unwound, Another watch is powered by the
All Wound Up releasing energy. In a newer model, heat of your body.
cranking drives an alternator that
The windup radios were invented by charges a tiny battery. A shoe company is investigating
Trevor Bayliss in a London garden ways to charge small batteries by
shed. They were first marketed in How are these devices different walking. One design contains a
1995 by Freeplay Energy. Now there from older clockwork devices, such material that generates electricity
are also flashlights and electric gen- as the first record players? They are every time your heel hits the ground.
erators powered by cranks. Some much lighter and much easier to
people use them for boating and crank. The secret, says Freeplay, is Defense agencies are studying
camping trips and for times when enormously strong, lightweight com- ways to convert mechanical energy
the power goes out. In developing ponents that survive for a long time. and heat energy into electricity.
countries, these devices are used in The goal is to make lighter versions
areas where there is no power supply. An Inspiring Invention of equipment that has to be car-
ried. Soldiers would no longer have
These windup devices have sev- This new technology has captured to carry heavy batteries in their
eral advantages over battery- the imagination of many groups packs. The possible applications
powered devices. One main with different goals. There are for these new energy technologies
are almost endless.
̈ The Freeplay Radio (below) was invented in a London garden shed,
and now the idea is being used all over the world. The flashlight (right)
is powered by shaking.
What Do You Think?
Can you think of any other
lightweight gadgets that could
be powered by human muscle
or body heat instead of by bat-
teries? In what ways are the
devices described here more
environmentally friendly than
the devices they replace?
Chapter 18 Society and the Environment 515
Waste 19C H A P T E R
516 Chapter 19 Waste 1 Solid Waste
2 Reducing Solid Waste
3 Hazardous Waste
PRE-READING ACTIVITY
Three-Panel
Flip Chart
Before you
read this chap-
ter, create the FoldNote enti-
tled “Three-Panel Flip Chart”
described in the Reading and
Study Skills section of the
Appendix. Label the flaps of
the chart with “Solid Waste,”
“Reducing Solid Waste,” and
“Hazardous Waste.” As you
read the chapter, write infor-
mation you learn about each
category
under the
appropri-
ate panel.
This landfill in New Jersey stores
municipal solid waste that people
throw away on a day-to-day basis.
Every year, the United States gener-
ates more than 210 million metric
tons of municipal solid waste.
SECTION 1
Solid Waste
It is lunchtime. You stop at a fast-food restaurant and buy a burger, Objectives
fries, and a soda. Within minutes, the food is gone, and you toss
your trash into the nearest wastebasket. Figure 1 shows what might ̈ Name one characteristic that
be in your trash: a paper bag, a polystyrene burger container, the makes a material biodegradable.
cardboard carton that held the fries, a paper cup with a plastic lid,
a plastic straw, a handful of paper napkins, and several ketchup and ̈ Identify two types of solid waste.
mustard packets. Once you throw away your trash, you probably ̈ Describe how a modern landfill
do not give it a second thought. But where does the trash go?
works.
The trash from the wastebasket probably will be picked up ̈ Name two environmental prob-
by a collection service and taken to a landfill, where the trash
will be dumped with thousands of tons of other trash and lems caused by landfills.
covered with a layer of soil. A landfill provides a place to store
trash, but the trash does not simply disappear. Where will your Key Terms
trash go when the landfill fills up? What would happen if rain-
water ran down into the landfill, and leached a harmful chemi- solid waste
cal, such as paint thinner, and it seeped into the groundwater? biodegradable
Suddenly, the trash that was not bothering anyone is causing an municipal solid waste
environmental problem. landfill
leachate
The Generation of Waste
www.scilinks.org
Imagine multiplying the waste disposal problems that come with
your lunch by the number of things that you and everyone else Topic: Solid Waste
throw away each day. Every year, the United States generates Code: HE81419
more than 10 billion metric tons of solid waste. Solid waste is
any discarded solid material. Solid waste includes everything
from junk mail to coffee grounds to cars. Many products that we
buy today are used once and then thrown away. As a result, the
amount of solid waste each American produces every year has
more than doubled since the 1960s.
Figure 1 ̈ Where does your trash
go when you throw it away?
Section 1 Solid Waste 517
Figure 2 ̈ The barge Mobro (right)
from Islip, New York, sailed up and
down the East Coast and to the Gulf
of Mexico for five months looking for
a place to dump its load of garbage.
The map below shows its route.
Space and Waste Today, many towns are running out of space
to dispose of the amounts of waste that people create. For exam-
ple, in 1987, the barge shown in Figure 2 was loaded with 3,200
tons of garbage and left the town of Islip, New York, in search of
a place to unload its waste. The barge sailed along the Atlantic
coast to the Gulf of Mexico for more than five months in search
of a state that would be willing to dispose of the waste. When no
one would accept the garbage, it was finally burned in New
York, and the 430 tons of ash was sent to Islip to be buried.
Population and Waste While the Earth’s human population and
the amount of waste we produce grows larger, the amount of land
available per person becomes smaller. Thousands of years ago, in
the time of hunter-gatherer societies, the human population was
smaller and the waste created consisted mostly of animal and veg-
etable matter. This type of waste combined with a large amount of
available land made disposing the waste much easier. However,
today, the average person living in the United States produces
4.4 pounds of solid waste per day, as shown in Figure 3. Because
the human population and the amount of waste we create is
increasing and the amount of available land is decreasing, it is
getting harder to dispose of the waste we create.
Municipal Solid Waste Generation (U.S.)
250 10
Figure 3 ̈ The total amount of Total waste generation200 Total waste 8
municipal solid waste generated in (in millions of tons)generation 6
the United States has more than Waste generation
doubled in the past 40 years. (pounds/person/day)150
518 Chapter 19 Waste 100 4
50 Waste per person 2
0 1970 1980 1990 2000 0
1960 2005
Year
Source: U.S. Environmental Protection Agency.
Not All Wastes Are Equal www.scilinks.org
Problems are caused not only by the amount of solid waste but Topic: Biodegradable
also by the type of solid waste. There are two main types of and Nonbiodegradable
solid waste: biodegradable and nonbiodegradable. A material is Materials
biodegradable if it can be broken down by biological processes. Code: HE80150
Plant and animal matter are examples of biodegradable materials.
Products made from natural materials are usually biodegradable. Ecofact
Examples of biodegradable products include newspapers, paper
bags, cotton fibers, and leather. Breaking Down Biodegradable
Material Decomposers, such as
Many products made from synthetic materials are not fungi and bacteria, are examples of
biodegradable. A nonbiodegradable material cannot be broken organisms that break down bio-
down by biological processes. Synthetic materials are made by degradable material. Once these
combining chemicals to form compounds that do not form natu- materials are broken down, they
rally. Polyester and plastic are examples of synthetic materials. can be reused by other organisms.
Scavengers, such as vultures, and
Plastic Problems Plastics illustrate how nonbiodegradable insects, such as dung beetles, also
materials can cause problems. Plastics are made from petroleum help recycle organic waste.
or natural gas. Petroleum and natural gas consist mostly of carbon
and hydrogen, which are the same elements that make up most
molecules found in living things. But in plastics, these elements are
put together in molecular chains that are not found in nature.
Over millions of years, microorganisms have evolved the ability to
break down nearly all biological molecules. However, microorgan-
isms have not yet evolved ways to break down the molecular
structures of most plastics. Therefore, some plastics that we throw
away may accumulate and last for hundreds of years.
Types of Solid Waste
Most of what we throw out on a day-to-day basis is called munici-
pal solid waste. Manufacturing waste, such as the computers
shown in Figure 4, and mining waste make up about 70 percent
of the other types of solid waste produced in the United States.
■✓● Reading Check Is a product made of polyester biodegradable or
nonbiodegradable?
Figure 4 ̈ These discarded com-
puters have been exported from the
United States and disposed of in
China. Unwanted computers, televi-
sions, audio equipment, and printers
are types of electronic waste.
Section 1 Solid Waste 519
United States Municipal Solid Waste Municipal Solid Waste About 2 percent of the total solid waste in
(Percentage by Weight) the United States is made up of municipal solid waste, which is the
waste produced by households and businesses. Figure 5 shows the
Wood Other composition of municipal solid waste in the United States.
5.3% 3.2% Although municipal solid waste makes up only 2 percent of the
Glass total solid waste in the United States, this amounts to more
5.5% than 236 million tons each year. That is enough waste to fill
a convoy of garbage trucks that would stretch around the
Rubber, Paper Earth about six times. Furthermore, the amount of
leather, 38.1% municipal solid waste is growing much faster than the
and textiles amount of mining or agricultural waste.
6.6%
Metals Solid Waste from Manufacturing, Mining, and
7.8% Agriculture Solid waste from manufacturing, mining,
and agriculture make up most of the rest of the total
Plastics solid waste produced in the United States. Solid waste
10.5% from manufacturing includes items such as scrap metal,
plastics, paper, sludge, and ash. Although consumers do not
Yard waste directly produce waste from manufacturing, they indirectly
Food waste 12.1% create it by purchasing products that have been manufactured.
10.9% Waste from mining consists of the rock and minerals that are
left over from excavation and processing. This waste is left exposed
Source: U.S. Environmental Protection Agency. in large heaps, is dumped in oceans or rivers, or is disposed of by
refilling and landscaping abandoned mines. Agricultural waste
Figure 5 ̈ Paper makes up most of includes crop wastes and manure. Because agricultural waste is
the municipal solid waste in the biodegradable, it can be broken down and returned to the soil.
United States. How much of the However, the increasing use of fertilizers and pesticides may cause
waste shown in this graph could agricultural waste to become more difficult to dispose of. If this
be recycled? waste is returned to the soil, it could harm plants and animals. It
could also contaminate groundwater in the area.
MATHPRACTICE Solid Waste Management
Municipal Solid Waste Most of our municipal waste in the United States is sent to land-
The United States gener- fills such as the one shown in Figure 6. However, some of our
ated approximately 236 waste is incinerated, and more than 30 percent of our waste is
million tons of municipal solid recycled. By comparison, in 1970, we recycled only 6.6 percent of
waste in 2003. In 1998, the United our waste.
States generated approximately
223 million tons of municipal solid
waste. What was the percent
increase in municipal solid waste
generation from 1998 to 2003?
Figure 6 ̈ Modern landfills are lined
with clay and plastic and have a sys-
tem for collecting and treating liquid
that passes through the compacted
solid waste.
520 Chapter 19 Waste
Landfills More than 50 percent of the municipal and manufac- Table 1 ̄
turing solid waste created in the United States ends up in landfills
as shown in Table 1. A landfill is a permanent waste-disposal Where Municipal Solid Waste
facility where wastes are put in the ground and covered each day in the United States Goes
with a layer of soil, plastic, or both. The parts of a modern land-
fill are shown in Figure 7. The most important function of a Percentage of
landfill is to contain waste so that it does not pollute the environ-
ment. The waste must be prevented from leaching toxins into the Waste-disposal waste by
soil and groundwater.
method weight
Problems with Landfills One problem with landfills is
leachate. Leachate is a liquid that has passed through com- Stored in 57
pacted solid waste in a landfill. Leachate forms when water landfills
seeps down through a landfill and collects dissolved chemicals 28
from decomposing garbage. Leachate may contain chemicals Recycled 15
from paints, pesticides, cleansers, cans, batteries, and appli-
ances. Landfills typically have monitoring wells and storage Incinerated
tanks to measure and store leachate. Stored leachate can then
be treated as waste water. However, if landfills are not moni- Figure 7 ̈ This landfill generates
tored properly, leachate can flow into groundwater supplies electricity by burning methane gas
and make water from nearby wells unsafe to drink. that is produced by decomposing
garbage.
Another problem with landfills is methane. Decomposing
organic waste may produce methane, a highly flammable gas.
Methane gas is usually pumped out of landfills and used as fuel.
However, if methane gas production is not monitored safely, it
may seep through the ground and into basements of homes up
to 300 m from a landfill. If the methane is ignited by a spark, it
can cause dangerous explosions.
■✓● Reading Check How can leachate in a landfill affect drinking water
in nearby wells?
Section 1 Solid Waste 521
Figure 8 ̈ Biodegradable materials Safeguarding Landfills The Resource Conservation and
do not degrade quickly in modern Recovery Act, passed in 1976 and updated in 1984, requires
landfills. This newspaper was put in a that new landfills be built with safeguards to reduce pollution
Tempe, Arizona landfill in 1971 and problems. New landfills must be lined with clay and a plastic
was removed in 1989. liner and must have systems for collecting and treating leachate.
Vent pipes must be installed to carry methane out of the land-
Figure 9 ̈ The map below shows fill, where the methane can be released into the air or burned to
the number of years until landfill produce energy.
capacity is reached in each state.
Adding these safeguards to landfills increases the cost of
building them. Also, finding acceptable places to build landfills
is difficult. The landfills must be close to the city producing the
waste but must be far enough from residents who object to
having a landfill near their homes. Any solution is likely to be
expensive, either because of the legal fees a city must pay to
fight residents’ objections or because of the cost of transporting
garbage to a distant site.
Building More Landfills Although we can build safer landfills,
we are currently running out of space that we are willing to
develop for new landfills. The materials we bury in landfills
are not decomposing as fast as we can fill landfills. Even
biodegradable materials, such as the newspaper in Figure 8,
take several years to decompose. The total number of active
landfills in the United States in 1988 was 8,000. By 2005, the
total number of active landfills was less than 1,700 because
many landfills had been filled to capacity. The U.S. Environ-
mental Protection Agency (EPA) estimates that the active land-
fills in 20 states will be filled to capacity within 10 years as
shown in Figure 9.
522 Chapter 19 Waste
Incinerators One option for reducing the amount of solid waste Figure 10 ̈ A solid-waste incinera-
sent to landfills is to burn it in incinerators, as shown in Figure 10. tor reduces the amount of trash that
In 1999, the United States had 102 operational incinerators that goes to landfills and can be used to
were capable of burning up to 94,000 metric tons of municipal generate electricity. However, the
solid waste per day. However, the waste that is burned does not dis- material that is created by the incin-
appear. Although incinerators can reduce the weight of solid waste erator can be toxic.
by 75 percent, they cannot separate materials that should not be
incinerated before burning the waste. So, some materials that
should not be burned, such as cleansers, batteries, and paints, end
up in the air as polluting gases. The rest of the solid waste is con-
verted into ash that must be disposed of in a landfill.
Incinerated material takes up less space in landfills, but the
incinerated material can be more toxic than it was before being
incinerated. Even incinerators that have special air pollution control
devices release small amounts of poisonous gases and particles of
toxic heavy metals into the air.
S E C T I O N 1 Review
1. Explain what makes a material biodegradable. CRITICAL THINKING
5. Identifying Relationships Name two non-
2. Compare municipal solid waste and manufacturing
solid waste. biodegradable products that you use. What makes
these products nonbiodegradable? Name two
3. Describe how a modern landfill works. Write a short biodegradable products that you can use instead.
paragraph to explain your answer. List two environ-
mental problems that can be caused by landfills. 6. Identifying Alternatives What can you do to
help reduce the amount of solid waste that you
WRITING SKILLS throw away? What can you do to help people in your
neighborhood reduce the amount of solid waste that
4. Describe one advantage and one disadvantage of is thrown away?
incinerating solid waste.
Section 1 Solid Waste 523
SECTION 2
Reducing Solid Waste
EARTH SCIENCE CONNECTION
Objectives If landfills and incinerators can pollute the environment and are
expensive to operate, what else can we do to safely reduce solid
̈ Identify three ways you can pro- waste? This section examines ways to reduce solid waste through
duce less waste. producing less waste, recycling, and changing the materials and
products we use. All of these techniques help reduce waste before
̈ Describe how you can use your it is delivered to landfills or incinerators. This method of reducing
consumer buying power to reduce solid waste is known as source reduction. Source reduction is
solid waste. any change in design, manufacture, purchase, or use of materials
or products to reduce their amount or toxicity before they
̈ List the steps that an item must go become municipal solid waste.
through to be recycled.
Reducing Solid Waste
̈ List two benefits of composting.
̈ Name one advantage and one dis- If we produce less waste, we will reduce the expense and difficulty
of collecting and disposing of it. Many ideas for reducing waste are
advantage to producing degrad- common sense, such as using both sides of a sheet of paper and not
able plastic. using unneeded bags, napkins, or utensils at stores and restaurants.
Key Terms Buying Less As a consumer, you can influence manufacturers to
reduce solid waste. If you buy products that have less packaging,
source reduction products that last longer, or reusable products, you will encourage
recycling manufacturers to produce more of those products. For example,
compost you can buy products such as dish towels instead of paper towels,
as shown in Figure 11. You can also buy rechargeable batteries
instead of regular batteries to help reduce solid waste.
Until about 1965, nearly all bottled beverages were sold in
bottles that were designed to be returned to stores when empty.
The empty bottles were then collected, washed, and refilled at
bottling plants. Today, there is a demand for disposable bot-
tles rather than for refillable bottles. If consumers began
to use more refillable bottles similar to those used in
the past, beverage manufacturers would begin
producing the refillable bottles.
Lasting Longer Manufacturers could also
reduce waste and conserve resources by
redesigning products to use less material.
A return to products that last longer and
that are designed to be easily repaired
would both save resources and reduce
waste disposal problems.
Figure 11 ̈ You can help reduce solid waste by purchasing
items that have less packaging. Purchasing items that last
longer, such as dish towels, can also reduce solid waste.
524 Chapter 19 Waste
Recycling FIELD ACTIVITY
In addition to reducing waste, we need to find ways to make the Is It Really Recyclable?
best use of all the materials we throw away. Recycling is the Conduct a survey of the plastic
process of reusing materials or recovering valuable materials containers in your household that
from waste or scrap. Making products from recycled materials are recyclable. Note the number
usually saves energy, water, and other resources. For example, of plastic containers found in your
95 percent less energy is needed to produce aluminum from household. Now look at the num-
recycled aluminum than from ore. About 70 percent less energy ber printed on the bottom of
is needed to make paper from recycled paper than from trees. each container. The plastics indus-
try has established a system of
Recycling: A Series of Steps When most people think about recy- designating which plastics are
cling, they probably think about only the first step — bringing recyclable. Types 1 and 2 are
their bottles, cans, and newspapers to a recycling center or putting most commonly recycled by most
these things at the curb. However, as shown in Figure 12, a series communities. Type 4 is less com-
of steps is needed for recycling to work. monly recycled, and types 3, 5, 6,
and 7 are most likely not to be
First, the discarded materials must be collected and sorted by recycled. In your EcoLog, record
type. Next, each type of material must be taken to a facility the total number of plastic con-
where it can be cleaned and made ready to be used again. For tainers for each type of plastic
example, glass is sorted by color and is crushed, and paper is that you find in your household.
sorted by type and made into a pulp with water. Then the materi- How many Type 1 and Type 2
als are used to manufacture new products. Finally, the new prod- plastic containers did you find in
ucts are sold to consumers. If more people buy products made your household?
from recycled materials, there will be an increase in the demand
for these products. This demand encourages manufacturers to Figure 12 ̈ The steps of recycling
build facilities to make recycled products. When such facilities are include collecting and sorting dis-
built, it becomes easier for communities to sell the materials they carded materials by type, taking
collect from residents for recycling. the materials to a recycling facility,
■✓● Reading Check How can consumer demand influence the packaging cleaning the discarded materials
so that they can be shredded or
of bottled beverages? crushed, and reusing the shred-
ded or crushed materials to manufac-
ture new products.
525
Table 2 ̄ Composting Yard waste often makes up more than 15 percent of a
community’s solid waste. None of this waste has to go to a landfill.
Benefits of Composting Because yard waste is biodegradable, it will decompose in a com-
post pile. Fruit and vegetable trimmings and table scraps will also
• keeps organic wastes out of decompose in a compost pile. The more oxygen and moisture there
landfills are in a compost pile, the more rapidly microorganisms will break
down the biodegradable waste. Eventually the material becomes
• provides nutrients to the soil compost, a dark brown, crumbly material made from decomposed
plant and animal matter that is spread on gardens and fields to
• increases beneficial soil enrich the soil. Compost is rich in the nutrients that help plants
organisms, such as worms and grow. More benefits of composting are listed in Table 2.
centipedes
Some cities collect yard waste from homes and compost it at a
• suppresses some plant diseases large, central facility. Composting can also be an effective way of
handling waste from food-processing plants and restaurants,
• reduces the need for fertilizers manure from animal feedlots, and municipal sewage sludge. If all
and pesticides biodegradable wastes were composted, the amount of solid waste
going to landfills could be reduced.
• protects soil from erosion
■✓● Reading Check What conditions help biodegradable material break
down rapidly?
Paper or Plastic?
The following question may sound Upon closer examination, how- ̈ Making an educated decision
familiar: Do you want paper or plas- ever, the decision may not be as at the grocery store will help
tic? If you have ever stood in the simple as it seems. Removing large reduce solid waste.
checkout line of a grocery store, it numbers of trees from forests to
probably is. Many grocery stores manufacture paper can disrupt • Can recycled materials be used in
offer a choice between either paper woodland ecosystems. Plus, a the manufacture of the bag? If
or plastic bags for sacking grocery tremendous amount of energy is so, to what degree will the use of
items. Many people make their required to convert trees into pulp recycled materials reduce the
choice based on convenience. But and then manufacture paper from amount of raw materials, energy,
what is the best choice for some- the pulp.
one who is concerned about the
environment? To make the best decision
about which product is better for
On the surface, it may seem the environment, the following
that paper is the better choice. questions should be considered.
Paper comes from a renewable
resource—trees—and is biodegrad- • How much raw material, energy,
able. Plastic, on the other hand, and water is needed to manufac-
comes from petroleum or natural ture each bag?
gas, which are usually considered
nonrenewable resources. In addi- • What waste products will result
tion, plastic bags are not from the manufacture of each
biodegradable. bag, and what effect will those
wastes have on water, the
atmosphere, and the land?
526 Chapter 19 Waste
Changing the Materials We Use www.scilinks.org
Simply changing the materials we use could eliminate much of Topic: Waste
the solid waste we produce. For example, single-serving drink Prevention
boxes are made of a combination of foil, cardboard, and plas-
tic. The drink boxes are hard to recycle because there is no Code: HE81623
easy way to separate the three components. More of our
waste could be recycled if such products were no longer made
and if all drinks came in recyclable glass, cardboard, or alu-
minum containers.
Recycling other common household products into new, use-
able products could also help eliminate solid waste. For example,
newspapers can be recycled to make cardboard, egg cartons, and
building materials. Telephone books, magazines, and catalogs can
also be recycled to make building materials. Used aluminum bev-
erage cans can be recycled to make new beverage cans, lawn
chairs, aluminum siding for houses, and cookware. Used glass
jars and bottles can be recycled to make new glass jars and bot-
tles. Finally, plastic beverage containers can be recycled to make
nonfood containers, insulation, carpet yarn, textiles, fiberfill,
scouring pads, toys, plastic lumber, and crates.
EARTH SCIENCE CONNECTION
and water used and wastes pro- ̈ A reusable canvas shopping bag CRITICAL THINKING
duced in making the bag? may be the best response to the
• How will the bag decompose, paper-or-plastic question. 1. Identifying Relationships
and what will the environmental Explain how environmentally con-
impact be if it is incorrectly dis- stronger, better for reusing or recy- scious shoppers have helped
posed of? cling, and less harmful in a landfill. improve paper and plastic bag
manufacturing in this country.
Although several studies have Then, new technology allowed
analyzed these questions, most have the plastics industry to gain a larger 2. Understanding Concepts
been conducted by parties with a market share. By incorporating Why should a person care which
vested interest, such as plastic or recycled plastic into the bags, manu- bag he or she is given at the gro-
paper manufacturing companies. As facturers improved the image of cery store?
you might expect, the studies done plastic bags.
by plastic manufacturers conclude
that plastic bags have the least envi- Therefore, the debate continues
ronmental impact, while the studies and environmentally conscious peo-
done by paper producers conclude ple are still wondering which is bet-
that paper bags have the least envi- ter. Right now there seems to be no
ronmental impact. Often, the right answer. However, the follow-
researchers fail to study all of the ing are environmentally sound
important factors listed above. options.
But the plastic versus paper • Carry your groceries in bags
debate has caused both industries to brought from home (paper, plas-
improve the way their products tic, or canvas bags).
affect the environment. For example,
paper bags recently outsold plastic • Choose the bag you are most
bags because they were considered likely to reuse in the future.
• If you have only one or two small
items do not use a bag.
Section 2 Reducing Solid Waste 527
Chain-of- Degradable Plastics As you read earlier, most plastics are not
Events Chart biodegradable. To make plastic products more appealing to peo-
ple who are concerned about the environment, several companies
Create the Graphic Organizer have developed new kinds of plastics that they say are degrad-
entitled “Chain-of-Events Chart” able. One type, called photodegradable plastic, is made so that
described in the Appen- when it is left in the sun for many weeks, it becomes weak and
dix. Then, fill in the chart brittle and eventually breaks into pieces.
with details about each
step of the degradation Another type of degradable plastic, called green plastic, is
of degradable plastics. made by blending the sugars in plants with a special chemical
agent to make plastic. Green plastics are labeled as green because
they are made from living things and are considered to be more
environmentally friendly than other plastics. The production of
green plastics requires 20 to 50 percent less fossil fuel than the
production of regular plastics does. The fork in Figure 13 is made
of green plastic. This plastic has been engineered to degrade
within 45 days of being thrown away. When this plastic is buried,
the bacteria in the soil eat the sugars and leave the plastic weak-
ened and full of microscopic holes. The chemical agent then grad-
ually causes the long plastic molecules to break into shorter
molecules. These two effects combine to cause the plastic to even-
tually fall apart into small pieces.
Figure 13 ̈ Green plastics made Problems with Degradable Plastics The main problem with
from living things are biodegradable.
The plastic fork below has been engi- these so-called degradable plastics is that although they do break
neered to degrade within 45 days
of disposal. apart and the organic parts can degrade, the plastic parts are
only reduced to smaller pieces. This
type of plastic can help reduce the
harmful effects that plastic litter has
on animals in the environment,
because the plastic pieces will be too
small to get caught in their throats
or around their necks. However, the
small pieces of plastic will not disap-
pear completely. Instead, the pieces
of plastic will be spread around. So,
these biodegradable plastics can
remain in landfills for many years,
DAY 0 DAY 12 DAY 33 DAY 45 just as regular plastics can.
S E C T I O N 2 Review
1. Name three things you could do each day to pro- CRITICAL THINKING
duce less waste.
5. Analyzing Methods What are the advantages and
2. Explain how buying certain products can help disadvantages to producing degradable plastics?
reduce solid waste.
6. Demonstrating Reasoned Judgement Read the
3. Describe the steps it takes to recycle a piece Case Study in this section and decide which type of
of plastic. bag you would choose the next time you go shop-
ping. Explain why you made this choice. What are
4. List two benefits of composting. other uses of the bag you chose? READING SKILLS
528 Chapter 19 Waste
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