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  1. 17-1

  2. Upon successfully completing this chapter, you will be able to • Discuss the reasons for seeking alternatives to fossil fuels • Summarize the contributions to world energy supplies of conventional alternatives to fossil fuels • Describe the scale, methods, and environmental impacts of hydroelectric power, nuclear power, and biomass energy • Outline the major “new renewable” alternative sources of energy and assess their potential for growth • Describe a variety of new biomass, solar, wind, geothermal, and ocean energy technologies, and outline their advantages and disadvantages • Explain the benefits of hydrogen and fuel cells and assess future options for energy storage and transportation 17-2

  3. Central Case: Harnessing Tidal Energy at the Bay of Fundy “Not only will atomic power be released, but someday we will harness the rise and fall of the tides and imprison the rays of the Sun.” —THOMAS A. EDISON, 1921 • Large tidal ranges makes the Bay of Fundy one of the most suitable locations in the world for generating power from ocean tides • Site of three tidal power plants • Tidal power does not entail negative impacts of traditional hydroelectric dams • Major impacts involve interference with normal currents and with marine life 17-3

  4. Alternatives to Fossil Fuels 17-4

  5. Hydropower, nuclear power, and biomass energy are conventional alternatives • They exert less environmental impact than fossil fuels but more impact than the “new renewable” energy sources • Each has benefits and drawbacks • These are best viewed as intermediates along a continuum of renewability 17-5

  6. Hydropower, nuclear power, and biomass energy are conventional alternatives (cont’d) • Fuelwood and other biomass sources provide 10% of the world’s energy, nuclear power provides 6.3%, and hydropower provides 2.2% • Nuclear energy and hydropower each account for nearly one-sixth of the world’s electricity generation • Canada relies heavily on hydropower 17-6

  7. 17-7

  8. Hydroelectric Power 17-8

  9. Modern hydropower uses two approaches • Hydroelectric power = uses the kinetic energy of moving water to turn turbines and generate electricity • Approaches: • Storage technique = impoundments harness energy by storing water in reservoirs behind dams • Run-of-river approaches generates energy without greatly disrupting the flow of river water 17-9

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  11. 17-11

  12. Hydropower generates relatively little air pollution • The great age of dam building began in the 1930s • Hydropower accounts for 2.2% of the world’s energy supply and 16% of the world’s electricity production • This is considerably higher in Canada 17-12

  13. Hydropower generates relatively little air pollution (cont’d) • Hydropower has advantages over fossil fuels for producing electricity: • It is renewable: as long as precipitation fills rivers we can use water to turn turbines • It is clean: no carbon dioxide is emitted • It is efficient: has an EROI of 10:1, as high as any modern-day energy source 17-13

  14. Hydropower has negative impacts, too • Dams: • Destroy habitats • Disrupt natural flooding cycles • Cause thermal pollution downstream and thermal shocks which can eliminate fish populations • Block passage of fish, fragmenting the river and reducing biodiversity • Have geological impacts (e.g. earthquakes) • Have other social and economic impacts on local communities 17-14

  15. Hydropower may not expand much more • China’s Three Gorges Dam is the world’s largest dam • Displaced over 3 million people, ecological impacts • Hydropower not likely to expand much more • Most of the world’s large rivers have already been dammed • People have grown aware of the ecological impact of dams • Developing nations will probably increase hydropower if they have rivers 17-15

  16. Nuclear Power 17-16

  17. Nuclear Power • Public safety concerns and the costs of addressing them have constrained the development and spread of nuclear power in the Canada, Sweden, and many other nations • 20% of U.S. electricity comes from nuclear sources • Canada generates 15% of its electricity with nuclear power • France receives 75% of its electricity from nuclear power 17-17

  18. Fission releases nuclear energy • Nuclear energy = the energy that holds together protons and neutrons within the nucleus of an atom • Nuclear fission = the splitting apart of atomic nuclei 17-18

  19. Enriched uranium is used as fuel in nuclear reactors • Nuclear reactors = facilities within nuclear power plants • Nuclear fuel cycle = the process when naturally occurring uranium is mined from underground deposits • Radioisotopes = emit subatomic particles and high-energy radiation as they decay into lighter radioisotopes, ultimately becoming stable isotopes • Most spent fuel is disposed of as radioactive waste 17-19

  20. Fission takes place in nuclear power plants • The neutrons bombarding uranium fuel in a reactor are slowed down with a substance called a moderator (most often water) • Control rods = soak up excess neutrons produced and are placed into the reactor among the fuel rods • Some reactors (CANDU) make use of 238U an instead of 235 U-enriched fuels • Breeder reactors • Generate new fissile fuel at a faster rate than they are used up, less waste • More expensive and more susceptible to explosive accidents 17-20

  21. 17-21

  22. Nuclear power generates little air pollution • Generates electricity without creating air pollution from stack emissions • International Atomic Energy Agency – 150X lower than fossil fuel combustion • Took into account not only emissions but mining, transport of fuel, manufacturing of equipment, construction of power plants, disposal of wastes and decommissioning of plants 17-22

  23. Nuclear power generates little air pollution (cont’d) • Advantages of nuclear power over fossil fuels: • helps us avoid emitting 600 million metric tons of carbon each year • Less damage to landscapes and less waste than coal mining • Plants are safer for workers than coal-fired plants • Drawbacks of nuclear power: • Nuclear waste is radioactive • Accidents can be catastrophic 17-23

  24. Coal versus nuclear power 17-24

  25. Nuclear power poses small risks of large accidents • 1979: Near-miss at the Three Mile Island plant in Pennsylvania • Meltdown = coolant water drained from the reactor vessel, temperatures rose inside the reactor core, and metal surrounding the uranium fuel rods began to melt, releasing radiation • Most radiation remained trapped inside the containment building • Cleanup lasted for years • Residents have shown no significant health impacts 17-25

  26. Nuclear power poses small risks of large accidents (cont’d) • 1986: explosion at the Chernobyl plant in Ukraine caused the most severe nuclear power plant accident the world has ever seen • For 10 days, radiation escaped from the plant while crews tried to put out the fire • The Soviet Union evacuated more than 100,000 residents • The landscape around the plant for 19 miles remains contaminated • The accident killed 31 people directly and up to several thousand developed fatal cancers 17-26

  27. Nuclear power poses small risks of large accidents (cont’d) • Atmospheric currents carried radioactive fallout across much of Northern Hemisphere • Fallout was greatest where rainstorms brought radioisotopes down from the radioactive cloud • Parts of Sweden received the highest fallout 17-27

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  29. Nuclear power poses small risks of large accidents (cont’d) • March 11, 2011, a megathrust earthquake of magnitude 9.0 struck off the coast of Tōhoku, Japan • It generated a massive tsunami that killed more than 15,000 people and inundated the Fukushima Dai-ichi power plant • Nuclear reactors shut down automatically but fission continues in the reactor cores • Backup generators failed due to the flooding • Subsequent overheating set off fires, explosions, and core meltdowns – released radioactive materials 17-29

  30. Radioactive waste disposal remains problematic • The long half-lives of uranium, plutonium, and other radioisotopes will cause them to continue emitting radiation for thousands of years • Must be stored in unusually stable and secure locations and monitored for years • Currently nuclear waste from power generation is held in temporary storage at nuclear power plants in Canada and other places around the world 17-30

  31. Radioactive waste disposal remains problematic (cont’d) • Spent fuel rods sunken in pools of water to minimize radiation leakage • Some store wastes in thick casks of steel, lead, and concrete • In Lac du Bonnet, Manitoba, scientists are testing proposals for long-term storage deep underground in the stable, ancient crystalline rocks of the Canadian Shield • Geological isolation 17-31

  32. Waste storage by geological isolation 17-32

  33. Multiple dilemmas have slowed nuclear power’s growth • It is enormously expensive to build, maintain, operate, and ensure the safety of nuclear facilities • Electricity is more expensive than from coal and other sources • Nuclear power plants in Western Europe will be retired by 2030 • Asian nations are increasing nuclear capacity; 15 plants are under construction 17-33

  34. More Nuclear Power? weighingtheissues • Do you think Canada as a whole, or your province in particular, should expand its nuclear power program? • Why, or why not? 17-34

  35. Fusion remains a dream • Nuclear fusion = forcing together the small nuclei of lightweight elements under extremely high temperature and pressure • Have not yet developed “cold” fusion for commercial power generation • If we could control fusion, we could produce vast amounts of energy from water 17-35

  36. Traditional Biomass Energy 17-36

  37. Biomass energy means different things to different users • Biomass = organic material that makes up living organisms • People harness biomass energy from many types of plant matter • Wood from trees • Charcoal from burned wood • Matter from agricultural crops • Combustible animal waste products 17-37

  38. Traditional biomass sources are widely used in the developing world • Over 1 billion people still use wood from trees as their principal energy source • Fuelwood, charcoal, and manure account for 35% of energy use • In the poorest nations it may be up to 90% • Fuelwood and other biomass sources constitute 80% of all renewable energy used worldwide • By the year 2030, 2.6 billion people will be using traditional fuels for heating and cooking in unsustainable ways 17-38

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  40. Traditional biomass energy has environmental pros and cons • It is essentially carbon-neutral, releasing no net carbon into the atmosphere • Carbon released is carbon that was used in photosynthesis • Only if biomass sources are not overharvested • If overharvested leads to deforestation, soil erosion, and desertification • Damaging landscapes, diminishing biodiversity, and impoverishing human societies 17-40

  41. “New” Renewable Energy Sources 17-41

  42. “New” renewable energy sources • Energy from sunlight, wind, geothermal heat, ocean water, and hydrogen, as well as new technologies for biomass energy • Three major applications: • Power generation • Space heating • Fuel 17-42

  43. “New” renewable contributions are small but growing quickly • Globally, we obtain only 0.5% of our energy from new renewable energy sources • In Canada, only about 6% of electricity generation comes from renewable sources other than large hydro • Most in Canada comes from wind, followed by small hydro (run-of-river) installations and biomass • Wind power has grown by 50% each year from 1970s • Rapid growth is likely to continue as population and consumption grow 17-43

  44. The transition won’t happen overnight • Still technological, economic, and social barriers • Most remaining barriers are political and economic • Companies have not been eager to invest in the transition from fossil fuels to renewable energy due to limited profits and subsidies, tax breaks, and other incentives 17-44

  45. Biofuels and Biopower 17-45

  46. Biomass can be processed to make vehicle fuels • Biofuels = biomass sources converted into fuels to power vehicles • Corn, soybeans, plant matter • Biopower = produced when biomass sources are burned in power plants, generating heat and electricity • Crop residues, landfill gas, livestock waste 17-46

  47. Biomass can be processed to make vehicle fuels (cont’d) • Ethanol = produces as a biofuel by fermenting carbohydrate-rich crops (corn) • Any vehicle will run well on gasoline blended with up to 10% ethanol • Flexible fuel vehicles = run on 85% ethanol • Biodiesel = biofuel for diesel engines produced from vegetable oils (canola) 17-47

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  49. Electricity can be generated from biomass • Many sources of biomass can be used • Waste products of existing industries or processes • Woody debris from logging operations and sawmills • Crops can be specifically grown, such as fast-growing willow trees or bamboo • Co-firing combines biomass with coal • Bacterial breakdown of waste to produce methane and other gases (landfill gas) 17-49

  50. Biofuels have environmental and economic benefits • Adding biofuels helps fossil fuels combust more completely, reducing pollution • Replacing gasoline with biofuels reduces emissions of nitrogen oxides, greenhouse gases, and other pollutants • Reduces sulphur dioxide emissions when used instead of coal • Economic benefits such as supporting rural communities and help reducing dependence of fossil fuel imports 17-50