1. Chapter 17 EnergyEfficiencyandRenewableEnergy

2. Chapter Overview Questions  How can we improve energy efficiency and what are the advantages of doing so?  What are the advantages and disadvantages of using solar energy to heat buildings and water and to produce electricity?  What are the advantages and disadvantages of using flowing water to produce electricity?

3. Chapter Overview Questions (cont’d)  What are the advantages and disadvantages of using wind to produce electricity?  What are the advantages and disadvantages of burning plant material (biomass) to heat buildings and water, produce electricity, and propel vehicles?

4. Chapter Overview Questions (cont’d)  What are the advantages and disadvantages of extracting heat from the earth’s “interior” (geothermal energy) and using it to heat and cool buildings, heat water, and produce electricity?  What are the advantages and disadvantages of producing hydrogen gas and using it in fuel cells to produce electricity, heat buildings and water, and propel vehicles?

5. Chapter Overview Questions (cont’d)  How can we make a transition to a more sustainable energy future?

6. Core Case Study: The Coming Energy- Efficiency and Renewable-Energy Revolution  It is possible to get electricity from solar cells that convert sunlight into electricity. Can be attached like shingles on a roof. Can be attached like shingles on a roof. Can be applied to window glass as a coating. Can be applied to window glass as a coating. Can be mounted on racks almost anywhere. Can be mounted on racks almost anywhere.

7. The Coming Energy-Efficiency and Renewable-Energy Revolution  The heating bill for this energy-efficient passive solar radiation office in Colorado is $50 a year (built in 1984 by energy analyst Amory Lovins)

8. Core Case Study: The Coming Energy- Efficiency and Renewable-Energy Revolution Australia will construct the world’s largest solar power plant, in Victoria state. It will have a capacity of 154 megawatts, with a completion date set for 2013. It will cost $320 million US dollars.

9. REDUCING ENERGY WASTE AND IMPROVING ENERGY EFFICIENCY  84% of all commercial energy (energy “produced” by humans) used in the U.S. is wasted. Therefore we currently have an overall energy efficiency of 16%. Therefore we currently have an overall energy efficiency of 16%.  41% will always be wasted due to 2 nd law of thermodynamics. So we could more than triple our efficiency to 59% So we could more than triple our efficiency to 59%

10. International Energy Efficiency  Unnecessary energy waste costs the US $300 billion per year. $570,000 per minute $570,000 per minute  Globally, $1 trillion per year is wasted Canada is less efficient than the US Canada is less efficient than the US Developing nations are 3x less efficient than the US. Developing nations are 3x less efficient than the US.  Japan, Germany, & France are 2-3x more energy efficient than the US

11. International Energy Efficiency  In 2004, China announced an energy strategy built around using “leapfrog technologies” to improve the energy efficiency of its cars, factories, buildings, and consumer products.

12. International Energy Efficiency  “Focusing the United States on greater energy efficiency and conservation is the most tough-minded, geostrategic, pro-growth, and patriotic thing we can do…Living green is not just a personal virtue, it is a national security imperative. Green is the new red, white, and blue.” -Thomas L. Friedman author, geopolitical expert

13. Fig. 17-2, p. 385 Energy Inputs System Outputs 9% 7% 41% 85% U.S. economy and lifestyles 8% 43% 4% Nonrenewable nuclear Petrochemicals (plastics, etc.) Nonrenewable fossil fuels Useful energy Hydropower, geothermal, wind, solar Unavoidable energy waste Unnecessary energy waste Biomass 3%

14. REDUCING ENERGY WASTE AND IMPROVING ENERGY EFFICIENCY  Four widely used devices waste large amounts of energy: Incandescent light bulb: 95% is lost as heat. Incandescent light bulb: 95% is lost as heat. Internal combustion engine (cars, etc.): 94% of the energy in its fuel is wasted. Internal combustion engine (cars, etc.): 94% of the energy in its fuel is wasted. Nuclear power plant: 92% of energy is wasted through the nuclear fuel cycle and energy needed for waste management. Nuclear power plant: 92% of energy is wasted through the nuclear fuel cycle and energy needed for waste management. Coal-burning power plant: 66% of the energy released by burning coal is lost. Coal-burning power plant: 66% of the energy released by burning coal is lost.

15. First Things First  To most energy analysts, reducing energy waste is the quickest, cheapest, cleanest way to: provide more energy provide more energy reduce pollution reduce pollution reduce environmental degradation reduce environmental degradation slow global warming. slow global warming.

16. Fig. 17-3, p. 386 Solutions Reducing Energy Waste Prolongs fossil fuel supplies Reduces oil imports Very high net energy Low cost Reduces pollution and environmental degradation Buys time to phase in renewable energy Less need for military protection of Middle East oil resources Creates local jobs

17. Net Energy Efficiency: Honest Accounting  Comparison of net energy efficiency for two types of space heating. next

18. Fig. 17-4, p. 387 Uranium mining (95%) Uranium processing and transportation (57%) Power plant (31%) Transmission of electricity (85%) Resistance heating (100%) Uranium 100% 95%54% 17% 14% Waste heat Electricity from Nuclear Power PlantWindow transmission (90%) Sunlight 100% 90% Waste heat Passive Solar Heat

19. WAYS TO IMPROVE ENERGY EFFICIENCY  Industry accounts for about 42% of U.S. energy consumption.  Industry can greatly improve energy efficiency by using cogeneration cogeneration more efficient electric motors more efficient electric motors

20. WAYS TO IMPROVE ENERGY EFFICIENCY  Cogeneration- combined heat and power (CHP) systems. Steam used to produce electric power is used to heat the plant or nearby buildings rather than wasted Steam used to produce electric power is used to heat the plant or nearby buildings rather than wasted Efficiency is 80% instead of 20-40% for coal-fired or nuclear power plants. Efficiency is 80% instead of 20-40% for coal-fired or nuclear power plants. Used in Western Europe for years, use is growing rapidly in the US and China. Used in Western Europe for years, use is growing rapidly in the US and China.

21. WAYS TO IMPROVE ENERGY EFFICIENCY  Energy wasting electric motors consume one fourth of the electricity in the US. Run only at full speed with their output mechanically throttled to match the task. Run only at full speed with their output mechanically throttled to match the task. Like driving a car by always running the motor at top speed and controlling the car’s speed with the brakes!Like driving a car by always running the motor at top speed and controlling the car’s speed with the brakes! Each year a heavily used electric motor consumes 10x it’s purchase cost in electricity. Each year a heavily used electric motor consumes 10x it’s purchase cost in electricity. Like using $200,000 worth of gas in a $20,000 car.Like using $200,000 worth of gas in a $20,000 car. The cost of replacing with adjustable speed motors would be paid back in 1 year in energy savings. The cost of replacing with adjustable speed motors would be paid back in 1 year in energy savings.

22. WAYS TO IMPROVE ENERGY EFFICIENCY  Transportation accounts for one fourth of US energy consumption, 74% of this by motor vehicles.  Between 1973 and 1985, average fuel efficiency rose due to CAFE standards (Corporate Average Fuel Economy).  Between 1988 and 2006, US vehicle fuel efficiency dropped 6%, due to SUVs and trucks that do not have to meet CAFE standards. A 2002 Roper poll showed that only 17% of Americans were aware of this, most thought that fuel economy had increased A 2002 Roper poll showed that only 17% of Americans were aware of this, most thought that fuel economy had increased

23. WAYS TO IMPROVE ENERGY EFFICIENCY  Average fuel economy of new vehicles sold in the U.S. between 1975-2006.  The government Corporate Average Fuel Economy (CAFE) has not increased after 1985. next

24. Fig. 17-5, p. 388 Cars Both Average fuel economy (miles per gallon, or mpg) Model year Pickups, vans, and sport utility vehicles

25. WAYS TO IMPROVE ENERGY EFFICIENCY  Inflation adjusted price of gasoline (in 2006 dollars) in the U.S.  US gas is still cheap compared to most of the rest of the world  Motor vehicles in the U.S. use 40% of the world’s gasoline. Next

26. Fig. 17-6, p. 388 Dollars per gallon (in 2006 dollars) Year

27. WAYS TO IMPROVE ENERGY EFFICIENCY  A possible (likely?) progression of vehicle technology: hybrids 50 mpg- dominate by 2025 plug-in hybrids 100 mpg, 1000 mpg short trips →eventually, most electricity from wind & solar ultralight, ultrastrong plug-in hybrids 300-1000+ mpg →nanotech materials for construction →nanotech materials for construction hydrogen fuel-cell zero emissions if fueled with H 2 instead of CH 4 →some by 2020, could dominate by 2050

28. WAYS TO IMPROVE ENERGY EFFICIENCY  General features of a car powered by a hybrid- electric engine.  “Gas sipping” cars account for less than 1% of all new car sales in the U.S.  Current hybrids get about 50 MPG Next

29. Fig. 17-7, p. 389 Regulator: Controls flow of power between electric motor and battery bank. Fuel tank: Liquid fuel such as gasoline, diesel, or ethanol runs small combustion engine. Transmission: Efficient 5-speed automatic transmission. Battery: High-density battery powers electric motor for increased power. Combustion engine: Small, efficient internal combustion engine powers vehicle with low emmissions; shuts off at low speeds and stops. Electric motor: Traction drive provides additional power for passing and acceleration; excess energy recovered during braking is used to help power motor. FuelElectricity

30. Hybrid Vehicles, Sustainable Wind Power, and Oil imports  Hybrid gasoline-electric engines with an extra plug- in battery could be powered mostly by electricity produced by wind and get twice the mileage of current hybrid cars. Currently plug-in batteries would be charged by coal and nuclear power plants…eventually wind and solar. Currently plug-in batteries would be charged by coal and nuclear power plants…eventually wind and solar. According to U.S. Department of Energy, a network of wind farms in North Dakota, South Dakota, Texas, and Kansas could meet all U.S. electricity demands. According to U.S. Department of Energy, a network of wind farms in North Dakota, South Dakota, Texas, and Kansas could meet all U.S. electricity demands. No more oil imports! No more oil imports!

31. Fuel-Cell Vehicles

34.  Fuel-efficient vehicles powered by a fuel cell that runs on hydrogen gas are being developed.  Combines hydrogen gas (H 2 ) and oxygen gas (O 2 ) fuel to produce electricity and water vapor 2H 2 +O 2  2H 2 O  Emits no air pollution or CO 2 if the hydrogen is produced from renewable-energy sources such as splitting water into H and O by using wind- generated electricity. 2H 2 O  2H 2 +O 2

35. Fuel-Cell Basics Protons “go through”, so electrons “flow around” (make electric current) One hydrogen atom

36. Fig. 17-8, p. 390 Body attachments Mechanical locks that secure the body to the chassis Air system management Universal docking connection Connects the chassis with the drive-by-wire system in the body Fuel-cell stack Converts hydrogen fuel into electricity Rear crush zone Absorbs crash energy Drive-by-wire system controls Cabin heating unit Side-mounted radiators Release heat generated by the fuel cell, vehicle electronics, and wheel motors Hydrogen fuel tanks Front crush zone Absorbs crash energy Electric wheel motors Provide four-wheel drive; have built-in brakes

37. WAYS TO IMPROVE ENERGY EFFICIENCY  We can save energy in existing buildings by insulating them insulating them plugging leaks plugging leaks using energy-efficient heating and cooling systems, appliances, and lighting. using energy-efficient heating and cooling systems, appliances, and lighting.

38. WAYS TO IMPROVE ENERGY EFFICIENCY  We can save energy in new buildings by getting heat from the sun getting heat from the sun superinsulating them superinsulating them using plant covered green roofs. using plant covered green roofs. using energy-efficient heating and cooling systems, appliances, and lighting. using energy-efficient heating and cooling systems, appliances, and lighting.

39. Strawbale House  Strawbale construction is a superinsulator that is made from bales of low-cost straw covered with plaster or adobe.  Insulation is measured in “R-values” (resistance to heat flow) Standard home insulation is R-12 to R-19 Standard home insulation is R-12 to R-19 Strawbale construction is R-35 to R-60. Strawbale construction is R-35 to R-60. Figure 17-9

40. Strawbale House  Depending on the thickness of the bales, its strength exceeds standard construction. Workshop in Eastern France

41. Living Roofs

42.  Roofs covered with plants have been used for decades in Europe and Iceland.  These roofs are built from a blend of light- weight compost, mulch and sponge-like materials that hold water.  They must first be carefully waterproofed Figure 17-10

43. Living Roofs

44. Figure 17-10

45. “City of Living Roofs” proposed for London (artist conception)

46. Saving Energy in Existing Buildings  About one-third of the heated air in typical U.S. homes and buildings escapes through closed windows and holes and cracks. Thermal imaging “takes a picture” of heat loss Thermal imaging “takes a picture” of heat loss

47. Why Are We Still Wasting So Much Energy?  Heavily subsidized, low-priced fossil fuels and few government tax breaks or other financial incentives for saving energy promote energy waste.

48. How Would You Vote?  Should the United States (or the country where you live) greatly increase its emphasis on improving energy efficiency? No. The free market already encourages investments in energy efficiency. Yes. Without government participation, there is little incentive to improve energy efficiency until a crisis occurs.

49. USING RENEWABLE SOLAR ENERGY TO PROVIDE HEAT AND ELECTRICITY  A variety of renewable-energy resources are available but their use has been hindered by a lack of government support compared to nonrenewable fossil fuels and nuclear power. Solar Solar Moving water (hydropower) Moving water (hydropower) Wind Wind Geothermal Geothermal

50. USING RENEWABLE SOLAR ENERGY TO PROVIDE HEAT AND ELECTRICITY  The European Union aims to get 22% of its electricity from renewable energy by 2010.  Costa Rica already gets 92% of its energy from renewable resources.  China aims to get 10% of its total energy from renewable resources by 2020.  In 2004, California got about 12% of its electricity from wind and plans to increase this to 50% by 2030.

51. USING RENEWABLE SOLAR ENERGY TO PROVIDE HEAT AND ELECTRICITY  Denmark now gets 20% of its electricity from wind and plans to increase this to 50% by 2030.  Brazil gets 20% of its gasoline from sugarcane residues called bagasse.  In 2004, the world’s renewable-energy industries provided 1.7 million jobs.

52. Heating Buildings and Water with Solar Energy  We can heat buildings by orienting them toward the sun or by pumping a liquid such as water through rooftop collectors. Next

53. Fig. 17-12, p. 395 Summer sun Heat to house (radiators or forced air duct) Pump Heavy insulation Superwindow Hot water tank Winter sun Super window Heat exchanger Stone floor and wall for heat storage PASSIVE SOLAR HEAT ACTIVE SOLAR HEAT

54. Passive Solar Heating  Passive solar heating system absorbs and stores heat from the sun directly within a structure without the need for pumps to distribute the heat. Next

55. Fig. 17-13, p. 396 Direct Gain Summer sun Hot air Warm air Super- insulated windows Winter sun Cool air Earth tubes Ceiling and north wall heavily insulated

56. Fig. 17-13, p. 396 Greenhouse, Sunspace, or Attached Solarium Summer cooling vent Warm air Insulated windows Cool air

57. Fig. 17-13, p. 396 Earth Sheltered Reinforced concrete, carefully waterproofed walls and roof Triple-paned or superwindows Earth Flagstone floor for heat storage

58. Fig. 17-14, p. 396 Trade-Offs Passive or Active Solar Heating AdvantagesDisadvantages Energy is freeNeed access to sun 60% of time Net energy is moderate (active) to high (passive) Sun blocked by other structures Need heat storage system Quick installation No CO 2 emissions Very low air and water pollution High cost (active) Very low land disturbance (built into roof or window) Active system needs maintenance and repair Moderate cost (passive) Active collectors unattractive

59. Cooling Houses Naturally  We can cool houses by: Superinsulating them. Superinsulating them. Taking advantages of breezes. Taking advantages of breezes. Shading them. Shading them. Having light colored or green roofs. Having light colored or green roofs. Using geothermal cooling. Using geothermal cooling.

60. Cooling Houses Naturally: Geothermal Cooling Can also be reversed for heat in the winter.

61. Cooling Houses Naturally

62. Geothermal heat pumps cost $1000 to $2000 more than conventional heat pumps like many have in Georgia, but this cost is recovered in 1-2 years as energy bills can be cut in half.

63. Using Solar Energy to Generate High- Temperature Heat and Electricity Solar Thermal Systems: Large arrays of solar collectors in sunny deserts can produce high-temperature heat to spin turbines for electricity, but costs are high.

64. Fig. 17-15, p. 397 Trade-Offs Solar Thermal Systems: Solar Energy for High-Temperature Heat and Electricity Advantages Disadvantages Moderate net energy Low efficiency High costs Moderate environmental impact Needs backup or storage system No CO 2 emissions Need access to sun most of the time Fast construction (1–2 years) High land use Costs reduced with natural gas turbine backup May disturb desert areas

65. Producing Electricity with Solar Cells  Solar cells convert sunlight to electricity.  Their costs are high, but expected to fall. Figure 17-16

66. Producing Electricity with Solar Cells  Photovoltaic (PV) cells can provide electricity for a house of building using solar-cell roof shingles. Next

67. Fig. 17-17, p. 398 Single solar cell Solar-cell roof – Boron enriched silicon + Junction Phosphorus enriched silicon Roof options Panels of solar cells Solar shingles

68. Producing Electricity with Solar Cells  Solar cells can be used in rural villages with ample sunlight who are not connected to an electrical grid. Figure 17-18

69. Producing Electricity with Solar Cells  Solar cells are currently 15% efficient.  It has been calculated that when their efficiency reaches 20%, a sunny desert area equivalent to the states of Connecticut and Rhode Island could supply the US with ALL of our electricity. Figure 17-18

70. Fig. 17-19, p. 399 Trade-Offs Solar Cells AdvantagesDisadvantages Fairly high net energyNeed access to sun Work on cloudy days Low efficiency Quick installation Need electricity storage system or backup Easily expanded or moved No CO 2 emissions High land use (solar-cell power plants) could disrupt desert areas Low environmental impact Last 20–40 years Low land use (if on roof or built into walls or windows) High costs (but should be competitive in 5–15 years) Reduces dependence on fossil fuels DC current must be converted to AC

71. Producing Electricity with Solar Cells

72. How Would You Vote? Should the world greatly increase its dependence on solar cells for producing electricity? No. Solar cells are too expensive and cannot substantially meet our electricity needs. Yes. Solar cells are environmentally friendly and could supplement our energy needs.

73. PRODUCING ELECTRICITY FROM THE WATER CYCLE  Water flowing in rivers and streams can be trapped in reservoirs behind dams and released as needed to spin turbines and produce electricity.  There is little room for expansion in the U.S. – Dams and reservoirs have been created on 98% of suitable rivers. Provides 7% of US electricity, 50% on the West coast Provides 7% of US electricity, 50% on the West coast

74. Trade-Offs Large-Scale Hydropower AdvantagesDisadvantages Moderate to high net energyHigh construction costs Large untapped potential (global) High environmental impact from flooding land to form a reservoir High efficiency (80%) High CO 2 emissions from biomass decay in shallow tropical reservoirs Low-cost electricity Long life span (until dam silts up) No CO 2 emissions during operation in temperate areas Floods natural areas behind dam May provide flood control below dam Converts land habitat to lake habitat Danger of collapse Provides water for year-round irrigation of cropland Uproots people Decreases fish harvest below dam Reservoir is useful for fishing and recreation Decreases flow of natural fertilizer (silt) to land below dam

75. How Would You Vote? Should the world greatly increase its dependence on large-scale dams for producing electricity? No. Large hydroelectric dams harm the environment and should be replaced by renewable energy. Yes. We need large dams to meet power demands, protect areas from flooding, and provide water.

76. PRODUCING ELECTRICITY FROM THE WATER CYCLE  Ocean tides and waves and temperature differences between surface and bottom waters in tropical waters are not expected to provide much of the world’s electrical needs. High costs, storm damage, and salt water corrosion are problems High costs, storm damage, and salt water corrosion are problems  Only two large tidal energy dams are currently operating: one in La Rance, France and Nova Scotia’s bay of Fundy where the tidal amplitude can be as high as 16 meters (63 feet).

77. ELECTRICITY FROM WIND One Blade

78. ELECTRICITY FROM WIND  Wind power is the world’s most promising energy resource because it is abundant, inexhaustible, widely distributed, cheap, clean, and emits no greenhouse gases.  Much of the world’s potential for wind power remains untapped.  Capturing only 20% of the wind energy at the world’s best energy sites could meet all the world’s energy demands.

79. Wind Turbine

80. PRODUCING ELECTRICITY FROM WIND  Wind turbines can be used individually to produce electricity. They are also used interconnected in arrays on wind farms. Figure 17-21

82. Fig. 17-21, p. 402 Gearbox Electrical generator Power cable Wind turbineWind farm

83. PRODUCING ELECTRICITY FROM WIND  The United States once led the wind power industry, but Europe now leads this rapidly growing business. The U.S. government lacked subsidies, tax breaks and other financial incentives. The U.S. government lacked subsidies, tax breaks and other financial incentives.  European companies manufacture 80% of the wind turbines sold in the global market The success has been aided by strong government subsidies. The success has been aided by strong government subsidies.

84. Wind Turbine Bird Mortality  Wind turbines kill about 40,000 birds per year in the US  Other sources of US bird mortality per year: Cars & trucks: 50-100 million Cars & trucks: 50-100 million Hunters: 100 million Hunters: 100 million Electric transmission lines: 175 million Electric transmission lines: 175 million Glass windows, buildings, & electric transmission towers: 100-900 million Glass windows, buildings, & electric transmission towers: 100-900 million

85. How Would You Vote?  Should the United States greatly increase its dependence on wind power? No. Wind turbines need research and mass- production before they will be competitive in the energy market. Yes. Wind power is becoming competitive and produces more clean energy than most other energy sources.

86. Trade-Offs Wind Power AdvantagesDisadvantages Moderate to high net energySteady winds needed Backup systems needed when winds are low High efficiency Moderate capital cost Low electricity cost (and falling) High land use for wind farm Very low environmental impact No CO 2 emissions Visual pollution Quick construction Noise when located near populated areas Easily expanded Can be located at sea Land below turbines can be used to grow crops or graze livestock May interfere in flights of migratory birds and kill birds of prey

87. PRODUCING ENERGY FROM BIOMASS  Plant materials and animal wastes can be burned to provide heat or electricity burned to provide heat or electricity converted into gaseous or liquid biofuels. converted into gaseous or liquid biofuels. Next

88. Solid Biomass Fuels Wood logs and pellets Charcoal Agricultural waste (stalks and other plant debris) Timbering wastes (branches, treetops, and wood chips) Animal wastes (dung) Aquatic plants (kelp and water hyacinths) Urban wastes (paper, cardboard), And other combustible materials Direct burning Conversion to gaseous and liquid biofuels Gaseous Biofuels Synthetic natural gas (biogas) Wood gas Liquid Biofuels Ethanol Methanol Gasonol Biodiesel Stepped Art

89. PRODUCING ENERGY FROM BIOMASS  The scarcity of fuelwood causes people to make fuel briquettes from cow dung in India.  This deprives soil of plant nutrients. Figure 17-24

90. Trade-Offs Solid Biomass AdvantagesDisadvantages Large potential supply in some areas Nonrenewable if harvested unsustainably Moderate costs Moderate to high environmental impact No net CO 2 increase if harvested and burned sustainably CO 2 emissions if harvested and burned unsustainably Low photosynthetic efficiency Plantation can be located on semiarid land not needed for crops Soil erosion, water pollution, and loss of wildlife habitat Plantation can help restore degraded lands Plantations could compete with cropland Often burned in inefficient and polluting open fires and stoves Can make use of agricultural, timber, and urban wastes

91. How Would You Vote?  Should we greatly increase our dependence on burning solid biomass to provide heat and produce electricity? No. Increased utilization of solid biomass may result in net greenhouse gas emissions, deforestation, and competition for valuable farmland. Yes. Biomass incineration would decrease the landfilling of wastes.

92. Converting Plants and Plant Wastes to Liquid Biofuels: An Overview  Motor vehicles can run on ethanol, biodiesel, and methanol produced from plants and plant wastes.  The major advantages of biofuels are: Crops used for production can be grown almost anywhere. Crops used for production can be grown almost anywhere. There is no net increase in CO 2 emissions (why?) There is no net increase in CO 2 emissions (why?) Widely available and easy to store and transport. Widely available and easy to store and transport.

93. Case Study: Producing Ethanol  Crops such as sugarcane, corn, and switchgrass and agricultural, forestry and municipal wastes can be converted to ethanol.  Switchgrass can remove CO 2 from the troposphere and store it in the soil. Figure 17-26

94. Disadvantages of Biofuels  Sustainable?...industrialized agriculture has a larger harmful environmental impact than any other industry.  Expanding agricultural lands for biofuel crops degrades land and decreases biodiversity  Competition with crops grown for food. In 2007-2008, globalfood prices have increased 40% In 2007-2008, globalfood prices have increased 40% There have been food riots in Haiti and Egypt There have been food riots in Haiti and Egypt

95. Corn vs Sugarcane  Net energy efficiency = energy out / energy in Brazilian sugarcane “bagasse” = 8.3 Brazilian sugarcane “bagasse” = 8.3 US corn = 1.5 US corn = 1.5 Switchgrass = 4 Switchgrass = 4

96. Case Study: Producing Ethanol  10-23% pure ethanol makes gasohol which can be run in conventional motors.  85% ethanol (E85) must be burned in flex- fuel cars.  Processing all corn grown in the U.S. into ethanol would cover only about 55 days of current driving.  Biodiesel is made by combining alcohol with vegetable oil made from a variety of different plants such as soybeans and palm oils

97. Fig. 17-27, p. 407 Trade-Offs Ethanol Fuel AdvantagesDisadvantages High octaneLarge fuel tank needed Some reduction in CO 2 emissions Lower driving range Low net energy (corn) High net energy (bagasse and switchgrass) Much higher cost Corn supply limited Reduced CO emissions May compete with growing food on cropland Can be sold as gasohol Higher NO emissions Corrosive Potentially renewable Hard to start in cold weather

98. Case Study: Producing Biodiesel  Biodiesel has the potential to supply about 10% of the country’s diesel fuel needs. Figure 17-28

99. How Would You Vote?  Do the advantages of using liquid ethanol as fuel outweigh its disadvantages? No. Liquid ethanol is costly to produce and reduces vehicle performance. Yes. Liquid ethanol is a renewable fuel and can reduce carbon dioxide and carbon monoxide emissions and our dependence on imported petroleum.

100. Trade-Offs Biodiesel AdvantagesDisadvantages Slightly increased emissions of nitrogen oxides Reduced CO 2 emissions (78%) Higher cost than regular diesel Reduced hydrocarbon emissions Low yield for soybean crops Better gas mileage (40%) May compete with growing food on cropland Loss and degradation of biodiversity from crop plantations High yield for oil palm crops Moderate yield for rapeseed crops Hard to start in cold weatherPotentially renewable

101. Case Study: Biodiesel and Methanol  Growing crops for biodiesel could potentially promote deforestation.  Methanol is made mostly from natural gas but can also be produced at a higher cost from CO 2 from the atmosphere which could help slow global warming. Can also be converted to other hydrocarbons to produce chemicals that are now made from petroleum and natural gas (petrochemicals) Can also be converted to other hydrocarbons to produce chemicals that are now made from petroleum and natural gas (petrochemicals)

102. Fig. 17-30, p. 408 Trade-Offs Methanol Fuel AdvantagesDisadvantages High octaneLarge fuel tank needed Some reduction in CO 2 emissions Half the driving range Lower total air pollution (30–40%) Corrodes metal, rubber, plastic Can be made from natural gas, agricultural wastes, sewage sludge, garbage, and CO 2 High CO 2 emissions if made from coal Expensive to produce Can be used to produce H 2 for fuel cells Hard to start in cold weather

103. GEOTHERMAL ENERGY  Geothermal energy consists of heat stored in soil, underground rocks, and fluids in the earth’s mantle.  We can use geothermal energy stored in the earth’s mantle to heat and cool buildings and to produce electricity. A geothermal heat pump (GHP) can heat and cool a house by exploiting the difference between the earth’s surface and underground temperatures. A geothermal heat pump (GHP) can heat and cool a house by exploiting the difference between the earth’s surface and underground temperatures.

104. Geothermal Heat Pump  The house is heated in the winter by transferring heat from the ground into the house.  The process is reversed in the summer to cool the house. Figure 17-31

105. Fig. 17-31, p. 409 Basement heat pump

106. GEOTHERMAL ENERGY  Deeper more concentrated hydrothermal reservoirs can be used to heat homes and buildings and spin turbines: Dry steam: water vapor with no water droplets. Dry steam: water vapor with no water droplets. Wet steam: a mixture of steam and water Wet steam: a mixture of steam and waterdroplets. Hot water: is trapped in fractured or porous rock. Hot water: is trapped in fractured or porous rock.

107. Fig. 17-32, p. 410 Trade-Offs Hydrothermal Energy Advantages Disadvantages Very high efficiency Scarcity of suitable sites Moderate net energy at accessible sites Depleted if used too rapidly Lower CO 2 emissions than fossil fuels Moderate to high local air pollution Low cost at favorable sites CO 2 emissions Noise and odor (H 2 S) Low land use Low land disturbance Cost too high except at the most concentrated and accessible sources Moderate environmental impact

108. How Would You Vote?  Should the United States (or the country where you live) greatly increase its dependence on geothermal energy to provide heat and to produce electricity? No. Most sites in the U.S. would not benefit from geothermal power. Yes. Geothermal energy has environmental advantages. Potentially suitable sites for geothermal power plants exist in Hawaii, Alaska, California, and several other states.

109. HYDROGEN  Some energy experts view hydrogen gas as the best fuel to replace oil during the last half of the century, but there are several hurdles to overcome: Hydrogen is chemically locked up in water an organic compounds. Hydrogen is chemically locked up in water an organic compounds. It takes energy and money to produce it (net energy is low). It takes energy and money to produce it (net energy is low). Fuel cells are expensive. Fuel cells are expensive. Hydrogen may be produced by using fossil fuels. Hydrogen may be produced by using fossil fuels.

110. Converting to a Hydrogen Economy  Iceland plans to run its economy mostly on hydrogen (produced via hydropower, geothermal, and wind energy), but doing this in industrialized nations is more difficult. Must convert economy to energy farming (e.g. solar, wind) from energy hunter-gatherers seeking new fossil fuels. Must convert economy to energy farming (e.g. solar, wind) from energy hunter-gatherers seeking new fossil fuels. No infrastructure for hydrogen-fueling stations (12,000 needed at $1 million apiece). No infrastructure for hydrogen-fueling stations (12,000 needed at $1 million apiece). High cost of fuel cells. High cost of fuel cells.

111. Trade-Offs Hydrogen Advantages Disadvantages Not found in nature Energy is needed to produce fuel Negative net energy (so far) Renewable if from renewable resources CO 2 emissions if produced from carbon-containing compounds No CO 2 emissions if produced from water Nonrenewable if generated by fossil fuels or nuclear power Good substitute for oil Competitive price if environmental & social costs are included in cost comparisons High costs (but may eventually come down) 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 High efficiency (45–65%) in fuel cells Excessive H 2 leaks may deplete ozone in the atmosphere Can be produced from plentiful water Low environmental impact

112. A SUSTAINABLE ENERGY STRATEGY  Shifts in the use of commercial energy resources in the U.S. since 1800, with projected changes to 2100. Next

113. Fig. 17-34, p. 413 Wood Coal Natural gas Oil Hydrogen Solar Nuclear Contribution to total energy consumption (percent) Year

114. A SUSTAINABLE ENERGY STRATEGY  A more sustainable energy policy would: improve energy efficiency improve energy efficiency rely more on renewable energy rely more on renewable energy reduce the harmful effects of using fossil fuels and nuclear energy (our current strategy) reduce the harmful effects of using fossil fuels and nuclear energy (our current strategy)

115. A SUSTAINABLE ENERGY STRATEGY  There will be a gradual shift from: large, centralized macropower systems large, centralized macropower systems coal & nuclear power plantscoal & nuclear power plants huge refinerieshuge refineriesto: smaller, decentralized micropower systems smaller, decentralized micropower systems See next slideSee next slide

116. Fig. 17-35, p. 414 Small solar-cell power plants Bioenergy power plants Wind farm Rooftop solar cell arrays Fuel cells Solar-cell rooftop systems Transmission and distribution system Commercial Small wind turbine Residential Industrial Microturbines

117. Fig. 17-36, p. 415 More Renewable Energy Increase renewable energy to 20% by 2020 and 50% by 2050 Provide large subsidies and tax credits for renewable energy Use full-cost accounting and life-cycle cost for comparing all energy alternatives Encourage government purchase of renewable energy devices Greatly increase renewable energy R&D Reduce Pollution and Health Risk Cut coal use 50% by 2020 Phase out coal subsidies Levy taxes on coal and oil use Phase out nuclear power or put it on hold until 2020 Phase out nuclear power subsidies Improve Energy Efficiency Increase fuel-efficiency standards for vehicles, buildings, and appliances Mandate govern- ment purchases of efficient vehicles and other devices Provide large tax credits for buying efficient cars, houses, and appliances Offer large tax credits for invest- ments in energy efficiency Reward utilities for reducing demand for electricity Encourage indepen- dent power producers Greatly increase energy efficiency research and development

118. Economics, Politics, Education, and Energy Resources  Governments can use a combination of subsidies, tax breaks, rebates, taxes and public education to promote or discourage use of various energy alternatives: Can keep prices artificially low to encourage renewable energy resources. Can keep prices artificially low to encourage renewable energy resources. Can keep prices artificially high to discourage nonrenewable energy resources. Can keep prices artificially high to discourage nonrenewable energy resources. Emphasize consumer education. Emphasize consumer education.

119. How Would You Vote? Should the government increase taxes on fossil fuels and offset this by reducing income and payroll taxes and providing an energy safety net for the poor and lower middle class? No. The government should stay out of this issue. Yes. This plan will slow our consumption of fossil fuels while not overburdening the poor.

120. Fig. 17-37, p. 416 What Can You Do? Energy Use and Waste Get an energy audit at your house or office. Drive a car that gets at least 15 kilometers per liter (35 miles per gallon) and join a carpool. Use mass transit, walking, and bicycling. Superinsulate your house and plug all air leaks. Turn off lights, TV sets, computers, and other electronic equipment when they are not in use. Wash laundry in warm or cold water. Use passive solar heating. For cooling, open windows and use ceiling fans or whole- house attic or window fans and geothermal heat pumps Turn thermostats down in winter, up in summer. Buy the most energy-efficient homes, lights, cars, and appliances available. Turn down the thermostat on water heaters to 43–49°C (110–120°F) and insulate hot water heaters and pipes.

121. Updates Online The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles.  InfoTrac: Plants, grass on the rooftop? No longer an oddity. The Christian Science Monitor, July 10, 2006 p02.  InfoTrac: Thinking globally, acting locally on energy use. Patrick Tucker. The Futurist, July-August 2006 v40 i4 p8(2).  InfoTrac: The Energy. Tom Clynes. Popular Science, July 2006 v269 i1 p47.  InfoTrac: San Francisco's 360. Paul Fenn; Michael Paulo Kuchkovsky. Architecture, May 2006 v95 i5 p31(3).  California Solar Center: Solar Evolution  National Wind Technology Center  Union of Concerned Scientists: Renewable Energy Basics

122. Video: Solar Energy  This video clip is available in CNN Today Videos for Environmental Science, 2004, Volume VII. Instructors, contact your local sales representative to order this volume, while supplies last.