1. Energy Efficiency and Renewable Energy
Chapter

2. 16-3 What Are the Advantages and Disadvantages of Solar Energy?
Concept Passive and active solar heating systems can heat water and buildings effectively, and the costs of using direct sunlight to produce high-temperature heat and electricity are coming down.

3. We Can Heat Buildings and Water with Solar Energy
Passive solar heating system
Active solar heating system
Countries using solar energy to heat water

4. Solutions: Passive and Active Solar Heating for a Home

5. Vent allows hot air to escape in summer
Summer sun
Heavy insulation
Winter sun
Superwindow
Superwindow
Figure 16.10
Solutions: passive and active solar heating for a home.
Stone floor and wall for heat storage
PASSIVE
Fig a, p. 411

6. Heat to house (radiators or forced air duct)
Solar collector
Heat to house (radiators or forced air duct)
Pump
Heavy insulation
Super- window
Hot water tank
Heat exchanger
Figure 16.10
Solutions: passive and active solar heating for a home.
ACTIVE
Fig b, p. 411

7. TRADE-OFFS Passive or Active Solar Heating Advantages Disadvantages
Energy is free
Need access to sun 60% of time
Net energy is moderate (active) to high (passive)
Sun can be blocked by trees and other structures
Quick installation
Environmental costs not included in market price
No CO2 emissions Very low air and water pollution
Figure 16.11
Advantages and disadvantages of heating a house with passive or active solar energy (Concept 16-3). Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Need heat storage system
Very low land disturbance (built into roof or windows)
High cost (active)
Active system needs maintenance and repair
Moderate cost (passive)
Active collectors unattractive
Fig , p. 412

8. Rooftop Solar Hot Water on Apartment Buildings in Kunming, China

9. Case Study: The Rocky Mountain Institute—Solar Powered Office and Home
Location: Snowmass, CO (U.S.)
No conventional heating system
Heating bills: <$50/year
How is this possible?

10. Sustainable Energy: Rocky Mountain Institute in Colorado, U.S.

11. We Can Cool Buildings Naturally
Technologies available
Superinsulation and high-efficiency windows
Overhangs or awnings on windows
Light-colored roof
Reflective insulating foil in an attic
Geothermal pumps
Plastic earth tubes underground

12. We Can Use Sunlight to Produce High-Temperature Heat and Electricity
Solar thermal systems
Central receiver system
Other collecting systems
Unfeasible for widespread use
High cost
Low new energy yields
Limited suitable sites
Sunny, desert sites

13. Trade-Offs: Solar Energy for High-Temperature Heat and Electricity

14. Commercial Solar Power Tower Plant Near Seville in Southern Spain

15. Solutions: Woman in India Uses a Solar Cooker

16. We Can Use Solar Cells to Produce Electricity (1)
Photovoltaic (PV) cells (solar cells)
Convert solar energy to electric energy
Design of solar cells
Benefits of using solar cells
Solar-cell power plants
Near Tucson, AZ (U.S.)
2007: Portugal

17. We Can Use Solar Cells to Produce Electricity (2)
Solar-cell systems being built or planned in
Leipzig, Germany
South Korea
South California (U.S.)
China

18. We Can Use Solar Cells to Produce Electricity (3)
Key problem
High cost of producing electricity
Will the cost drop with
Mass production
New designs
Nanotechnology

19. Solutions: Solar Cells Can Provide Electricity Using Solar-Cell Roof Shingles

20. Boron- enriched silicon
Single solar cell
Boron- enriched silicon
Junction
Roof options
Phosphorus- enriched silicon
Panels of solar cells
Solar shingles
Figure 16.17
Solutions: Photovoltaic (PV) or solar cells can provide electricity for a house or other building using solar-cell roof shingles, as shown in this house in Richmond Surrey, England. Solar-cell roof systems that look like a metal roof are also available. In addition, new thin-film solar cells can be applied to windows and outside walls.
Fig a, p. 415

21. Solutions: Solar Cells Used to Provide Electricity for a Remote Village in Niger

22. Total Costs of Electricity from Different Sources in 2004

23. The Solar Power Industry Is Expanding Rapidly
Solar cells: 0.2% of the world’s electricity
2040: could solar cells produce 16%?
Nanosolar: California (U.S.)
Germany: huge investment in solar cell technology
General Electric: entered the solar cell market

24. Solar-Cell Power Plant in Arizona, U. S
Solar-Cell Power Plant in Arizona, U.S., Is the Largest Solar-Cell Power Plant

25. TRADE-OFFS Solar Cells Advantages Disadvantages Need access to sun
Fairly high net energy yield
Low efficiency
Work on cloudy days
Need electricity storage system or backup
Quick installation
Easily expanded or moved
Environmental costs not included in market price
No CO2 emissions
High costs (but should be competitive in 5–15 years)
Low environmental impact
Figure 16.20
Advantages and disadvantages of using solar cells to produce electricity (Concept 16-3). Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Last 20–40 years
High land use (solar-cell power plants) could disrupt desert areas
Low land use (if on roof or built into walls or windows)
Reduces dependence on fossil fuels
DC current must be converted to AC
Fig , p. 417

26. 16-4 Advantages and Disadvantages of Producing Electricity from the Water Cycle
Concept Water flowing over dams, tidal flows, and ocean waves can be used to generate electricity, but environmental concerns and limited availability of suitable sites may limit the use of these energy resources.

27. We Can Produce Electricity from Falling and Flowing Water
Hydropower
World’s leading renewable energy source used to produce electricity
Hydroelectric power: Iceland
Advantages
Disadvantages
Micro-hydropower generators

28. TRADE-OFFS Large-Scale Hydropower Disadvantages Advantages
High construction costs
Moderate to high net energy
High environmental impact from flooding land to form a reservoir
High efficiency (80%)
Large untapped potential
Environmental costs not included in market price
Low-cost electricity
Long life span
High CO2 emissions from rapid biomass decay in shallow tropical reservoirs
No CO2 emissions during operation in temperate areas
Figure 16.21
Advantages and disadvantages of using large dams and reservoirs to produce electricity (Concept 16-4). Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Danger of collapse
Can provide flood control below dam
Uproots people
Decreases fish harvest below dam
Provides irrigation water
Decreases flow of natural fertilizer (silt) to land below dam
Reservoir useful for fishing and recreation
Fig , p. 418

29. Tides and Waves Can Be Used to Produce Electricity (1)
Produce electricity from flowing water
Ocean tides and waves
So far, power systems are limited
Norway
New York City

30. Tides and Waves Can Be Used to Produce Electricity (2)
Disadvantages
Few suitable sites
High costs
Equipment damaged by storms and corrosion

31. 16-5 Advantages and Disadvantages of Producing Electricity from Wind
Concept When environmental costs of energy resources are included in market prices, wind energy is the least expensive and least polluting way to produce electricity.

32. Using Wind to Produce Electricity Is an Important Step toward Sustainability (1)
Wind: indirect form of solar energy
Captured by turbines
Converted into electrical energy
Second fastest-growing source of energy
What is the global potential for wind energy?
Wind farms: on land and offshore

33. Using Wind to Produce Electricity Is an Important Step toward Sustainability (2)
“Saudi Arabia of wind power”
North Dakota
South Dakota
Kansas
Texas
How much electricity is possible with wind farms in those states?

34. Solutions: Wind Turbine and Wind Farms on Land and Offshore

35. Gearbox Electrical generator Power cable Wind turbine Figure 16.22
Solutions: A single wind turbine (left) can be used to produce electricity. But increasingly, they are being used in interconnected arrays of ten to hundreds of turbines. These wind farms or wind parks can be located on land (middle and front cover of this book) or offshore (right). Land lying under these turbines can still be used to grow crops and raise cattle. Question: Would you object to having a wind farm located near where you live? Why or why not?
Wind turbine
Fig a, p. 420

36. Figure 16.22
Solutions: A single wind turbine (left) can be used to produce electricity. But increasingly, they are being used in interconnected arrays of ten to hundreds of turbines. These wind farms or wind parks can be located on land (middle and front cover of this book) or offshore (right). Land lying under these turbines can still be used to grow crops and raise cattle. Question: Would you object to having a wind farm located near where you live? Why or why not?
Wind farm
Fig b, p. 420

37. Wind farm (offshore) Figure 16.22
Solutions: A single wind turbine (left) can be used to produce electricity. But increasingly, they are being used in interconnected arrays of ten to hundreds of turbines. These wind farms or wind parks can be located on land (middle and front cover of this book) or offshore (right). Land lying under these turbines can still be used to grow crops and raise cattle. Question: Would you object to having a wind farm located near where you live? Why or why not?
Wind farm (offshore)
Fig c, p. 420

38. Producing Electricity from Wind Energy Is a Rapidly Growing Global Industry
Countries with the highest total installed wind power capacity
Germany
United States
Spain
India
Denmark
Installation is increasing in several other countries

39. Wind Energy Is Booming but Still Faces Challenges
Advantages of wind energy
Drawbacks
Windy areas may be sparsely populated
Winds die down; need back-up energy
Storage of wind energy
Kills migratory birds
“Not in my backyard”

40. TRADE-OFFS Wind Power Advantages Disadvantages
Moderate to high net energy yield
Steady winds needed
Backup systems needed when winds are low
High efficiency
Moderate capital cost
Plastic components produced from oil
Low electricity cost (and falling)
Environmental costs not included in market price
Very low environmental impact
High land use for wind farm
No CO2 emissions
Figure 16.23
Advantages and disadvantages of using wind to produce electricity (Concepts 16-5). With sufficient and consistent incentives, wind power could supply more than 10% of the world’s electricity and 10–25% of the electricity used in the United States by Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Quick construction
Visual pollution
Easily expanded
Noise when located near populated areas
Can be located at sea
Land below turbines can be used to grow crops or graze livestock
Can kill birds and interfere with flights of migratory birds
Fig , p. 421

41. 16-6 Advantages and Disadvantages of Biomass as an Energy Source (1)
Concept 16-6A Solid biomass is a renewable resource, but burning it faster than it is replenished produces a net gain in atmospheric greenhouse gases, and creating biomass plantations can degrade soil biodiversity.

42. 16-6 Advantages and Disadvantages of Biomass as an Energy Source (2)
Concept 16-6B Liquid biofuels derived from biomass can be used in place of gasoline and diesel fuels, but creating biofuel plantations could degrade soil and biodiversity and increase food prices and greenhouse gas emissions.

43. We Can Get Energy by Burning Solid Biomass
Biofuels
Production of solid mass fuel
Plant fast-growing trees
Biomass plantations
Collect crop residues and animal manure
Advantages
Disadvantages

44. TRADE-OFFS Solid Biomass Advantages Disadvantages
Large potential supply in some areas
Nonrenewable if harvested unsustainably
Moderate to high environmental impact
Moderate costs
Environmental costs not included in market price
No net CO2 increase if harvested, burned, and replanted sustainably
Increases CO2 emissions if harvested and burned unsustainably
Plantation can be located on semiarid land not needed for crops
Low photosynthetic efficiency
Figure 16.24
General advantages and disadvantages of burning solid biomass as a fuel (Concept 16-6A). Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Soil erosion, water pollution, and loss of wildlife habitat
Plantation can help restore degraded lands
Plantations could compete with cropland
Can make use of agricultural, timber, and urban wastes
Often burned in inefficient and polluting open fires and stoves
Fig , p. 422

45. We Can Convert Plants and Plant Wastes to Liquid Biofuels (1)
Biodiesel
Ethanol
Biggest producers of biofuel
Brazil
The United States
The European Union
China

46. We Can Convert Plants and Plant Wastes to Liquid Biofuels (2)
Major advantages over gasoline and diesel fuel produced from oil
Biofuel crops can be grown almost anywhere
No net increase in CO2 emissions if managed properly
Available now

47. We Can Convert Plants and Plant Wastes to Liquid Biofuels (3)
Studies warn of problems:
Decrease biodiversity
Increase soil degrading, erosion, and nutrient leaching
Push farmers off their land
Raise food prices

48. Case Study: Is Biodiesel the Answer?
Biodiesel production from vegetable oil from various sources
95% produced by The European Union
Jatropha shrub: promising new source
Advantages
Disadvantages

49. TRADE-OFFS Biodiesel Advantages Disadvantages Reduced CO emissions
Increased NOx emissions and more smog
Reduced CO2 emissions (78%)
Higher cost than regular diesel
High net energy yield for oil palm crops
Environmental costs not included in market price
Low net energy yield for soybean crops
Moderate net energy yield for rapeseed crops
May compete with growing food on cropland and raise food prices
Figure 16.25
General advantages and disadvantages of using biodiesel as a vehicle fuel, compared to gasoline. Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Reduced hydrocarbon emissions
Loss and degradation of biodiversity from crop plantations
Better gas mileage (40%)
Can make engines hard to start in cold weather
Potentially renewable
Fig , p. 424

50. Case Study: Is Ethanol the Answer? (1)
Ethanol converted to gasohol
Brazil: “Saudi Arabia of sugarcane”
Saved $50 billion in oil import costs since the 1970s
United States: ethanol from corn
Reduce the need for oil imports?
Slow global warming?
Reduce air pollution?

51. Case Study: Is Ethanol the Answer? (2)
Cellulosic ethanol: alternative to corn ethanol
Sources
Switchgrass
Crop residues
Municipal wastes
Advantages
Disadvantages

52. Natural Capital: Rapidly Growing Switchgrass in Kansas, U.S.

53. TRADE-OFFS Ethanol Fuel Advantages Disadvantages High octane
Lower driving range
Low net energy yield (corn)
Some reduction in CO2 emissions (sugarcane bagasse)
Higher CO2 emissions (corn)
Much higher cost
High net energy yield (bagasse and switchgrass)
Environmental costs not included in market price
Figure 16.27
General advantages and disadvantages of using ethanol as a vehicle fuel, compared to gasoline. (Concept 16-6B). Question: Which single advantage and which single disadvantage do you think are the most important? Why?
May compete with growing food and raise food prices
Reduced CO emissions
Can be sold as E85 or pure ethanol
Higher NOx emissions and more smog
Corrosive
Potentially renewable
Can make engines hard to start in cold weather
Fig , p. 426

54. ABC Video: MTBE pollution http://abclocal.go.com/kgo/video?id=7286080
Could not get the video to the left to play, so check out the website above. It tells you all about MTBE

55. 16-7 What Are the Advantages and Disadvantages of Geothermal Energy?
Concept 16-7 Geothermal energy has great potential for supplying many areas with heat and electricity and generally has a low environmental impact, but locations where it can be exploited economically are limited.

56. Getting Energy from the Earth’s Internal Heat (1)
Geothermal energy: heat stored in
Soil
Underground rocks
Fluids in the earth’s mantle
Geothermal heat pump system
Energy efficient and reliable
Environmentally clean
Cost effective to heat or cool a space

57. Getting Energy from the Earth’s Internal Heat (2)
Hydrothermal reservoirs
Iceland
Geothermal energy: two problems
High cost of tapping large-scale hydrothermal reservoirs
Dry- or wet-steam geothermal reservoirs could be depleted
Hot, dry rock: another potential source of geothermal energy?

58. Basement heat pump Figure 16.28
Natural capital: a geothermal heat pump system can heat or cool a house almost anywhere. It heats the house in winter by transferring heat from the ground into the house (shown here). In the summer, it cools the house by transferring heat from the house to the ground.
Fig , p. 427

59. TRADE-OFFS Geothermal Energy Advantages Disadvantages
Very high efficiency
Scarcity of suitable sites
Can be depleted if used too rapidly
Moderate net energy at accessible sites
Environmental costs not included in market price
Lower CO2 emissions than fossil fuels
CO2 emissions
Low cost at favorable sites
Figure 16.29
Advantages and disadvantages of using geothermal energy for space heating and for producing electricity or high-temperature heat for industrial processes (Concept 16-7). Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Moderate to high local air pollution
Low land use and disturbance
Noise and odor (H2S)
High cost except at the most concentrated and accessible sources
Moderate environmental impact
Fig , p. 428

60. 16-8 The Advantages and Disadvantages of Hydrogen as an Energy Source
Concept Hydrogen fuel holds great promise for powering cars and generating electricity, but to be environmentally beneficial, it would have to be produced without the use of fossil fuels.

61. Hydrogen Is a Promising Fuel but There Are Challenges (1)
Hydrogen as a fuel
Eliminate most of the air pollution problems
Reduce threats of global warming
Some challenges
Chemically locked in water and organic compounds
Fuel cells are the best way to use hydrogen
CO2 levels dependent on method of hydrogen production

62. Hydrogen Is a Promising Fuel but There Are Challenges (2)
Production and storage of H2
Hydrogen-powered vehicles: prototypes available
Can we produce hydrogen on demand?
Larger fuel cells

63. Electrons Hydrogen gas (H2) in Anode Polymer Electrolyte Membrane
Cathode
Water
(H2O)
out
Figure 16.30
A fuel cell takes in hydrogen gas and separates the hydrogen atoms’ electrons from their protons. The electrons flow through wires to provide electricity, while the protons pass through a membrane and combine with oxygen gas to form water vapor (2H2 + O2 → 2H2O + energy). Note that this process is the reverse of electrolysis, which is used to produce hydrogen fuel (2H2O + energy → 2H2 + O2).
Protons
Air (O2) in
Fig , p. 429

64. TRADE-OFFS Hydrogen Advantages Disadvantages Fuel cell
Can be produced from plentiful water
Not found as H2 in nature
Energy is needed to produce fuel
Low environmental impact
Negative net energy
Renewable if produced from renewable energy resources
CO2 emissions if produced from carbon-containing compounds
No CO2 emissions if produced from water
Environmental costs not included in market price
Good substitute for oil
Nonrenewable if generated by fossil fuels or nuclear power
Competitive price if environmental and social costs are included in cost comparisons
High costs (that may eventually come down)
Figure 16.31
Advantages and disadvantages of using hydrogen as a fuel for vehicles and for providing heat and electricity (Concept 16-8). Question: Which single advantage and which single disadvantage do you think are the most important? Why?
Will take 25 to 50 years to phase in
Easier to store than electricity
Short driving range for current fuel-cell cars
Safer than gasoline and natural gas
No fuel distribution system in place
Nontoxic
Excessive H2 leaks may deplete ozone in the atmosphere
High efficiency (45–65%) in fuel cells
Fig , p. 430

65. 16-9 How Can We Make a Transition to a More Sustainable Energy Future?
Concept We can make a transition to a more sustainable future if we greatly improve energy efficiency, use a mix of renewable energy resources, and include environmental costs in the market prices of all energy resources.

66. Choosing Energy Paths (1)
How will energy policies be created?
Supply-side, hard-path approach
Demand-side, soft-path approach

67. Choosing Energy Paths (2)
General conclusions about possible energy paths
Gradual shift to smaller, decentralized micropower systems
Transition to a diverse mix of locally available renewable energy resources Improved energy efficiency
How?
Fossil fuels will still be used in large amounts
Why?

68. Small solar-cell power plants Bioenergy power plants Wind farm
Fuel cells
Rooftop solar-cell arrays
Solar-cell rooftop systems
Transmission and distribution system
Commercial
Figure 16.32
Solutions: decentralized power system in which electricity is produced by a large number of dispersed, small-scale micropower systems. Some such systems would produce power on site; others would feed the power they produce into an updated electrical distribution system. Over the next few decades, many energy and financial analysts expect a shift to this type of power system often based on locally available renewable energy resources. Question: Can you think of any disadvantages of a decentralized power system?
Small wind turbine
Residential
Industrial
Microturbines
Fig , p. 431

69. SOLUTIONS Making the Transition to a More Sustainable Energy Future
More Renewable Energy
Improve Energy Efficiency
Greatly increase use of renewable energy
Increase fuel-efficiency standards for vehicles, buildings, and appliances
Provide large subsidies and tax credits for use of renewable energy
Include environmental costs in prices for all energy resources
Mandate government purchases of efficient vehicles and other devices
Encourage government purchase of renewable energy devices
Greatly increase renewable energy research and development
Provide large tax credits or feebates for buying efficient cars, houses, and appliances
Reduce Pollution and Health Risk
Offer large tax credits for investments in energy efficiency
Figure 16.33
Suggestions of various energy analysts for helping us to make the transition to a more sustainable energy future (Concept 16-9). Question: Which five of these solutions do you think are the most important? Why?
Cut coal use 50% by 2020
Phase out coal subsidies
Reward utilities for reducing demand for electricity
Levy taxes on coal and oil use
Greatly increase energy efficiency research and development
Phase out nuclear power subsidies, tax breaks, and loan guarantees
Fig , p. 432

70. Economics, Politics, Education, and Sustainable Energy Resources
Government strategies:
Keep the prices of selected energy resources artificially low to encourage their use
Keep energy prices artificially high for selected resources to discourage their use
Consumer education

71. What Can you Do? Shifting to Sustainable Energy Use

72. Case Study: California’s Efforts to Improve Energy Efficiency
High electricity costs
Reduce energy waste
Use of energy-efficient devices
Strict building standards for energy efficiency