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576 Chapter 18 • Study Guide

Lesson 3 Solar and Wind energy• The sun’s energy can be used to heat buildings and gener-

ate electricity. • Solar power has many benefits, such as its limitless supply,

but it depends on weather and is expensive.• Wind turbines convert wind’s kinetic energy to electricity.• Wind power is nonpolluting and efficient, but its supply is

unpredictable, and it may damage landscape and wildlife.

passive solar heating (562) active solar heating (562) flat-plate solar collector (562) photovoltaic (PV) cell (562) concentrating solar power (CSP) (564) wind turbine (567) wind farm (567)

Lesson 4 energy From hydrogen• Hydrogen fuel can be produced from the breakdown of

water or methane.• Fuel cells are used to generate electricity.

electrolysis (571) fuel cell (572)

InquIry LABs And ActIvItIes• Regional Renewable Energy Think of a logical source of renewable energy in your

region. Then, research a local provider of this type of energy.

• Compare Biofuels Research the advantages and disadvantages of vari-

ous biofuels to replace petroleum-based fuels. Make a recommendation.

• Energy From Wind Design the rotor and blades for a model wind turbine

and test its efficiency at lifting weights.

Lesson 1 Biomass and Geothermal energy• Alternative energy resources are needed to replace fos-

sil fuels, reduce air pollution, and reduce the emission of greenhouse gases.

• Energy derived from biomass is used for cooking, heating, powering motor vehicles, and generating electricity.

• Liquid fuels made from biomass, known as biofuels, help to power millions of vehicles. Ethanol is used in gasoline engines, and biodiesel is used in diesel engines.

• Biopower is electricity generated from the combustion of biomass.

• Steam and hot water produced by geothermal energy can be used for generating electricity and for heating.

• A ground source heat pump uses underground soil tem-perature to heat and cool buildings.

biomass energy (551) biofuel (552) biopower (552) geothermal energy (553) ground source heat pump (554)

Lesson 2 hydropower and Ocean energy• The movement of river water can be used to generate

electricity. Electricity can be generated by using water stored behind a dam in a reservoir or by using the natural movement of a river.

• Hydropower is nonpolluting and relatively inexpensive, but dams can alter ecosystems and disrupt people’s lives.

• The movement of tides and ocean thermal energy can be used to generate electricity. Harnessing tidal energy works best where there is a large difference between the height of the water at low and high tides.

• Ocean thermal energy conversion (OTEC) is a process that converts thermal energy in ocean water to electrical energy.

hydropower (557) tidal energy (559) ocean thermal energy conversion (OTEC) (560)

What are the potential uses and limitations of

renewable energy sources?

Lesson 3 How can we rely on the sun

and wind for power?

Lesson 4 How can we use hydrogen

as a source of energy?

Lesson 1 How can we use biomass

energy and geothermal energy?

Lesson 2 How can water be used to

address energy needs?

STUDY RESOURCES

Chapter 18 Self Test • Chapter 18 Worksheets • Chapter 18 Overview Presentation (for PowerPoint)

Renewable Energy Alternatives 577

Germany‘s Renewable Energy Law specifies that Germany has to obtain at least 10 percent of its energy from renewable energy resources by 2020. Write a paragraph explaining the benefits and costs of the law.

6. Concentrating solar power uses a. a building’s design to capture solar energy. b. a heat-absorbing metal plate to capture solar

energy. c. passive solar heating techniques to generate

electricity. d. mirrors that focus sunlight to generate

electricity.

7. Offshore wind turbines are useful because a. they do not need gearboxes. b. they are easier to build than wind turbines on

land. c. average wind speeds are greater over water

than land. d. they do not require a generator to produce

electricity.

8. Which of the following is NOT an advantage of hydrogen as a source of energy?

a. It usually produces few pollutants. b. Hydrogen is the most abundant element in the

universe. c. It can be stored and transported. d. It is inexpensive to produce.

Modified True/False Write true if the statement is true. If it is false, change the underlined word or words to make the statement true.

9. Tidal energy works best in places where the dif-ferences in height between low and high tides are small.

10. Active solar heating uses devices such as pumps to move heat derived from the sun.

11. PV cells can be incorporated into roof tiles. 12. In a fuel cell, water molecules split to release

hydrogen ions. 13. Hydropower uses the potential energy of water to

generate electricity.

Review Concepts and Terms 1. Which of the following is NOT a renewable

source of energy? a. wind c. coal b. sunlight d. wood

2. Energy produced from material that comes from living organisms is known as

a. geothermal energy. c. electrical energy. b. biomass energy. d. wood energy.

3. The plant shown below can be a source of

a. ethanol. c. hydropower. b. ground source heat. d. photovoltaic power.

4. Geothermal energy is obtained by harnessing a. sunlight. b. wind energy. c. energy from tides. d. hot underground water or steam.

5. The run-of-the-river approach to generating hydroelectric power

a. requires construction of a dam. b. takes advantage of a river’s natural flow. c. causes more extensive habitat destruction than

the reservoir storage method does. d. involves burning fossil fuels.

ANSWERS

Chapter Assessment For answers to the Chapter Assessment, see page A–30 at the back of the book.

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578 Chapter 18 • Assessment

Reading Comprehension Read the following selection and answer the questions that follow.In Idaho, resource planners decided that the state’s power future lies in generating electricity from wind. Idaho has turned its citizens into “wind prospectors,” asking them to identify potential areas for wind farms. People who join the program collect data on wind speed and direction, and share those data with the state.

To obtain wind data, Idaho lends landowners devices called anemometers. Anemometers mea-sure wind speed and direction. To measure wind speed, anemometers have three or four hollow cups that catch the wind and rotate around a vertical rod. The greater the wind speed, the faster the cups rotate.

14. Which of the following is the BEST title for the selection?

a. “Anemometers and Barometers” b. “Collecting Wind Data” c. “Idaho’s Weather” d. “Alternative Energy”

15. Which of the following is the BEST description of what people use an anemometer for?

a. to find a potential location for a wind farm b. to convert wind energy into electrical energy c. to measure wind speed and direction d. to collect information about how frequently

the wind blows

16. On one day, the same anemometer was used to measure wind speed in two different locations. In Location A, the anemometer’s cups rotated faster than they did in Location B. How did the wind speeds compare in the two locations?

a. Wind speed was greater in Location A. b. Wind speed was greater in Location B. c. Wind speed was the same in both locations. d. An anemometer’s cups are not used to measure

wind speed.

Short Answer 17. List four benefits of renewable energy resources. 18. Explain what biodiesel is and why biodiesel is a

form of biomass energy. 19. What is biopower? Give an example of how it can

be produced. 20. What are the costs of hydropower? 21. Explain what ocean thermal energy conversion

(OTEC) is. 22. Describe the construction of a wind turbine.

Alternatively, make a diagram with labels and captions.

23. What is a photovoltaic cell? How does it work? 24. What are two problems associated with solar

power? 25. What are the products of the electrolysis of water?

Critical Thinking 26. Predict In ten years, do you think there will be

more jobs in renewable energy industries than there are now? Explain your answer.

27. Apply Concepts A greenhouse such as the one below uses glass panes to trap heat inside. Is this an example of passive solar heating or active solar heating? Explain your answer.

28. Relate Cause and Effect Why is the production of electricity from geothermal energy practical only in certain parts of the world?

29. Pose Questions You and your family are think-ing of building a home that uses both active and passive solar heating. What questions should you ask the building contractor before you make the decision?

30. Apply Concepts Besides solar energy itself, what forms of alternative energy can trace their origin to energy from the sun? Explain your answer.

Ecological Footprints

Data from International Energy Agency Statistics, 2007.

Growth Rate, Energy Sources

Total e

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productio

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BiomassHydro

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20

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1

Area of Photovoltaic Cells Needed (m2)

Population Cost of Photovoltaic Cells Needed

Renewable Energy Alternatives 579

3. The cost of a photovoltaic system is high. Besides cost, what else would you consider when thinking about installing photovoltaic cells for your home?

Read the information below. Copy the table into your notebook and record your calcula-tions. Then answer the questions that follow.

Assume that in the United States, photovoltaic cells cost $800 per square meter to install. Also assume that the average person needs 25 square meters of photovoltaic cells to supply the electric-ity that he or she needs. Use this information to fill in the footprint table. 1. The actual number of PV cells needed per

person depends on where the person lives. Why is this true?

2. Find the area where you live on the map in Figure 16. Do you think that you would need more than the average number of PV cells, an average number, or fewer? Explain.

Analyze DataThe graph shows how different sources of energy grew annually worldwide from 1971 to 2004. Use the graph to answer the questions.

31. Interpret Graphs Which source of energy had the most rapid growth rate for the years shown?

32. Relate Cause and Effect Which two forms of renewable energy had the lowest growth rate? What is the probable reason? (Hint: Before the period shown on the graph, what renewable energy sources were already widely used?)

33. Interpret Graphs Taken as a whole, did renew-able energy resources grow slower or faster than nonrenewable energy resources? How does the graph show this?

34. Infer Do you think the overall trend shown for the growth of renewable energy sources has con-tinued? Explain your answer.

Write About It 35. Creative Writing Suppose you are writing a

magazine article about the Three Gorges Dam in China. Your article will focus on the effects the dam has had on people’s lives. Plan interviews that you might conduct with two people: one person whose job depends on the dam, and one person who had to move because the dam has flooded his or her town. Write a list of questions you might ask each person.

36. Explanation Explain how a ground source heat pump regulates the temperature in a building.

37. Apply the BIGQUESTION A community that bor-ders the ocean is deciding whether to construct an offshore wind farm that can be seen from the community. Write a letter to the editor of the local newspaper. Your letter should either support the development of the wind farm or be against it. Support your opinion with facts and reasons.