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Bio 105 Chapter 15

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Bio 105 Chapter 15

  1. 1. MILLER/SPOOLMAN LIVING IN THE ENVIRONMENT 17TH Chapter 15 Nonrenewable Energy
  2. 2. Energy Use: World and United States Fig. 15-1, p. 370
  3. 3. Basic Science: Net Energy Is the Only Energy That Really Counts (1)• First law of thermodynamics: • It takes high-quality energy to get high-quality energy • Pumping oil from ground, refining it, transporting it• Second law of thermodynamics • Some high-quality energy is wasted at every step
  4. 4. Basic Science: Net Energy Is the Only Energy That Really Counts (2)• Net energy • Total amount of useful energy available from a resource minus the energy needed to make the energy available to consumers• Net energy ratio: ratio of energy produced to energy used to produce it• Conventional oil: high net energy ratio
  5. 5. It Takes Energy to Pump Petroleum Fig. 15-2, p. 372
  6. 6. Net Energy Ratios Fig. 15-3, p. 373
  7. 7. Energy Resources With Low/Negative Net Energy Yields Need Marketplace Help• Cannot compete in open markets with alternatives that have higher net energy yields• Need subsidies from taxpayers• Nuclear power as an example
  8. 8. Reducing Energy Waste Improves Net Energy Yields and Can Save Money• 84% of all commercial energy used in the U.S. is wasted • 43% after accounting for second law of thermodynamics• Drive efficient cars, not gas guzzlers• Make buildings energy efficient
  9. 9. We Depend Heavily on Oil (1)• Petroleum, or crude oil: conventional, or light oil• Fossil fuels: crude oil and natural gas• Peak production: time after which production from a well declines
  10. 10. We Depend Heavily on Oil (2)• Oil extraction and refining • By boiling point temperature• Petrochemicals: • Products of oil distillation • Raw materials for industrial organic chemicals • Pesticides • Paints • Plastics
  11. 11. Science: Refining Crude Oil Fig. 15-4, p. 375
  12. 12. How Long Might Supplies of Conventional Crude Oil Last? (1) • Rapid increase since 1950 • Largest consumers in 2009 • United States, 23% • China, 8% • Japan, 6%
  13. 13. How Long Might Supplies of Conventional Crude Oil Last? (2) • Proven oil reserves • Identified deposits that can be extracted profitably with current technology • Unproven reserves • Probable reserves: 50% chance of recovery • Possible reserves: 10-40% chance of recovery • Proven and unproven reserves will be 80% depleted sometime between 2050 and 2100
  14. 14. World Oil Consumption, 1950-2009 Figure 1, Supplement 2
  15. 15. Crude Oil in the Arctic National Wildlife Refuge Fig. 15-5, p. 376
  16. 16. The United States Uses Much More Oil Than It Produces• Produces 9% of the world’s oil and uses 23% of world’s oil• 1.5% of world’s proven oil reserves• Imports 52% of its oil• Should we look for more oil reserves? • Extremely difficult • Expensive and financially risky
  17. 17. U.S. Energy Consumption by Fuel Figure 6, Supplement 9
  18. 18. Proven and Unproven Reserves of Fossil Fuels in North America Figure 18, Supplement 8
  19. 19. Trade-Offs: Conventional Oil Fig. 15-6, p. 377
  20. 20. Bird Covered with Oil from an Oil Spill in Brazilian Waters Fig. 15-7, p. 377
  21. 21. Case Study: Heavy Oil from Tar Sand• Oil sand, tar sand contains bitumen• Canada and Venezuela: oil sands have more oil than in Saudi Arabia• Extraction • Serious environmental impact before strip-mining • Low net energy yield: Is it cost effective?
  22. 22. Strip Mining for Tar Sands in Alberta Fig. 15-8, p. 378
  23. 23. Will Heavy Oil from Oil Shales Be a Useful Resource? • Oil shales contain kerogen • After distillation: shale oil • 72% of the world’s reserve is in arid areas of western United States • Locked up in rock • Lack of water needed for extraction and processing • Low net energy yield
  24. 24. Oil Shale Rock and the Shale Oil Extracted from It Fig. 15-9, p. 379
  25. 25. Natural Gas Is a Useful and Clean-Burning Fossil Fuel • Natural gas: mixture of gases • 50-90% is methane -- CH4 • Conventional natural gas • Sits above oil
  26. 26. Natural Gas Burned Off at Deep Sea Oil Well Fig. 15-11, p. 380
  27. 27. Is Unconventional Natural Gas the Answer? • Coal bed methane gas • In coal beds near the earth’s surface • In shale beds • High environmental impacts or extraction • Methane hydrate • Trapped in icy water • In permafrost environments • On ocean floor • Costs of extraction currently too high
  28. 28. Trade-Offs: Conventional Natural Gas Fig. 15-12, p. 381
  29. 29. Methane Hydrate Fig. 15-13, p. 381
  30. 30. Coal Is a Plentiful but Dirty Fuel (1)• Coal: solid fossil fuel• Burned in power plants; generates 42% of the world’s electricity • Inefficient• Three largest coal-burning countries • China • United States • Canada
  31. 31. Coal Is a Plentiful but Dirty Fuel (2)• World’s most abundant fossil fuel • U.S. has 28% of proven reserves• Environmental costs of burning coal • Severe air pollution • Sulfur released as SO2 • Large amount of soot • CO2 • Trace amounts of Hg and radioactive materials
  32. 32. Air Pollution from a Coal-Burning Industrial Plant in India Fig. 15-16, p. 383
  33. 33. CO2 Emissions Per Unit of Electrical Energy Produced for Energy Sources Fig. 15-17, p. 383
  34. 34. World Coal and Natural Gas Consumption, 1950-2009 Figure 7, Supplement 9
  35. 35. Coal Consumption in China and the United States, 1980-2008 Figure 8, Supplement 9
  36. 36. Coal Deposits in the United States Figure 19, Supplement 8
  37. 37. Trade-Offs: Coal Fig. 15-18, p. 384
  38. 38. The Clean Coal and Anti-Coal Campaigns• Coal companies and energy companies fought • Classifying carbon dioxide as a pollutant • Classifying coal ash as hazardous waste • Air pollution standards for emissions• 2008 clean coal campaign • But no such thing as clean coal
  39. 39. How Does a Nuclear Fission Reactor Work? (1)• Controlled nuclear fission reaction in a reactor • Very inefficient• Fueled by uranium ore and packed as pellets in fuel rods and fuel assemblies• Control rods absorb neutrons
  40. 40. How Does a Nuclear Fission Reactor Work? (2)• Water is the usual coolant• Containment shell around the core for protection• Water-filled pools or dry casks for storage of radioactive spent fuel rod assemblies
  41. 41. Fission of Uranium-235 Fig. 2-9b, p. 43
  42. 42. What Happened to Nuclear Power?• Slowest-growing energy source and expected to decline more• Why? • Economics • Poor management • Low net yield of energy of the nuclear fuel cycle • Safety concerns • Need for greater government subsidies • Concerns of transporting uranium
  43. 43. Global Energy Capacity of Nuclear Power Plants Figure 10, Supplement 9
  44. 44. Nuclear Power Plants in the United States Figure 21, Supplement 8
  45. 45. Case Study: Chernobyl: The World’s Worst Nuclear Power Plant Accident • Chernobyl • April 26, 1986 • In Chernobyl, Ukraine • Series of explosions caused the roof of a reactor building to blow off • Partial meltdown and fire for 10 days • Huge radioactive cloud spread over many countries and eventually the world • 350,000 people left their homes • Effects on human health, water supply, and agriculture
  46. 46. Trade-Offs: Conventional Nuclear Fuel Cycle Fig. 15-22, p. 389
  47. 47. Storing Spent Radioactive Fuel Rods Presents Risks• Rods must be replaced every 3-4 years• Cooled in water-filled pools• Placed in dry casks• Must be stored for thousands of years• Vulnerable to terrorist attack
  48. 48. Dealing with Spent Fuel Rods Fig. 15-24, p. 390
  49. 49. Dealing with Radioactive Wastes Produced by Nuclear Power Is a Difficult Problem • High-level radioactive wastes • Must be stored safely for 10,000–240,000 years • Where to store it • Deep burial: safest and cheapest option • Would any method of burial last long enough? • There is still no facility • Shooting it into space is too dangerous
  50. 50. What Do We Do with Worn-Out Nuclear Power Plants?• Decommission or retire the power plant• Some options 1. Dismantle the plant and safely store the radioactive materials 2. Enclose the plant behind a physical barrier with full-time security until a storage facility has been built 3. Enclose the plant in a tomb • Monitor this for thousands of years
  51. 51. Can Nuclear Power Lessen Dependence on Imported Oil & Reduce Global Warming?• Nuclear power plants: no CO2 emission• Nuclear fuel cycle: emits CO2• Need high rate of building new plants, plus a storage facility for radioactive wastes
  52. 52. Will Nuclear Fusion Save Us?• “Nuclear fusion • Fuse lighter elements into heavier elements • No risk of meltdown or large radioactivity release• Still in the laboratory phase after 50 years of research and $34 billion dollars• 2006: U.S., China, Russia, Japan, South Korea, and European Union • Will build a large-scale experimental nuclear fusion reactor by 2018
  53. 53. Nuclear Fusion Fig. 2-9c, p. 43
  54. 54. Experts Disagree about the Future of Nuclear Power• Proponents of nuclear power • Fund more research and development • Pilot-plant testing of potentially cheaper and safer reactors• Opponents of nuclear power • Fund rapid development of energy efficient and renewable energy resources
  55. 55. Three Big Ideas1. A key factor to consider in evaluating the usefulness of any energy resource is its net energy yield.2. Conventional oil, natural gas, and coal are plentiful and have moderate to high net energy yields, but using any fossil fuel, especially coal, has a high environmental impact.3. Nuclear power has a low environmental impact and a very low accident risk, but high costs, a low net energy yield, long-lived radioactive wastes, and the potential for spreading nuclear weapons technology have limited its use.

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