ENVIRONMENTAL SCIENCE

1. 13e ENVIRONMENTALSCIENCE CHAPTER 13:Energy

2. Core Case Study: Amory Lovins and the Rocky Mountain Institute (1) • 1984: home and office building in Snowmass, CO • Heat: • Sun • Heavy roof insulation • Thick stone walls • Energy-efficient windows • Waste-heat recovery

3. Core Case Study: Amory Lovins and the Rocky Mountain Institute (2) • Sun • 99% of heat and hot water • 95% of daytime lighting • 90% of household electricity • Energy-efficient electrical appliances and computers • Rocky Mountain Institute • Promotes energy-efficient buildings and transportation

4. Fig. 13-1, p. 296

5. 13-1 What Major Sources of Energy Do We Use? • Concept 13-1AAbout three-quarters of the world’s commercial energy comes from nonrenewable fossil fuels, and the rest comes from nonrenewable nuclear fuel and renewable sources. • Concept 13-1BNet energy is the amount of high-quality energy available from a resource minus the amount of energy needed to make it available.

6. What do we need to consider when evaluating energy resources?

7. Evaluating Energy Resources • The supply • The environmental impact • How much net useful energy they provide

8. Commercial energy use by source What can be said about renewable vs non-renewable? Fig. 13-2, p. 298

9. Science Focus: Net Energy • It takes energy get energy. • What steps are involved in the oil industry that require energy? • Second law of thermodynamics (what happens to the energy at each step?) • Net energy: The usable amount of high quality energy available from a given quantity of an energy resource minusthe energy needed to find, extract, process, and get that energy to consumers • Net energy ratio • Ex. Nuclear fuel cycle, how much energy we get out vs how much energy we put in

10. 13-2 What Are the Advantages and Disadvantages of Fossil Fuels? • Concept 13-2 Oil, natural gas, and coal are currently abundant and relatively inexpensive, but using them causes air and water pollution, degrades large areas of land, and releases greenhouse gases to the atmosphere.

11. Dependence on Oil (1) • Petroleum (crude oil) • Also called light oil • Trapped underground or under ocean with natural gas • Fossil fuels • Extraction • U.S. peak production • Global peak production: the point in time when we reach the maximum overall rate of crude oil production for the whole world. Once we pass this point, what will happen to global oil production?

12. Dependence on Oil (2) • Transportation • Refining • Petrochemicals

13. Lowest Boiling Point Gases Gasoline Aviation fuel Heating oil Diesel oil Naphtha Grease and wax Heated crude oil Asphalt Furnace Highest Boiling Point Fig. 13-3, p. 300

14. Fig. 13-3, p. 300

15. Supplement 9, Fig. 3, p. S40

16. How Long Will Crude Oil Supplies Last? • Crude oil is the single largest source of commercial energy in world and U.S.

17. How Long Will Crude Oil Supplies Last? • Crude oil is the single largest source of commercial energy in world and U.S. • Proven oil reserves • Identified deposits that can be extracted profitably at today’s prices with today’s technology

18. How Long Will Crude Oil Supplies Last? • Crude oil is the single largest source of commercial energy in world and U.S. • Proven oil reserves • Identified deposits that can be extracted profitably at today’s prices with today’s technology • Geologists predict known and projected global reserves of crude oil will be 80% depleted between 2050 and 2100 depending on consumption rates

19. What are our options?

20. What are our options? • Look for more oil • Use and waste less oil • Use other energy options • Yes, yes, and yes!

21. 14 13 12 11 10 Projected U.S. oil consumption 9 8 7 Barrels of oil per year (billions) 6 5 4 3 2 Arctic refuge oil output over 50 years 1 0 2000 2010 2020 2030 2040 2050 Year Fig. 13-4, p. 301

22. *United States Oil Production and Use (1) • U.S. • 93% of energy from fossil fuels • 39% from crude oil • Produces 9% of world’s crude oil • Uses 25% of world production • Has 2% of proven crude oil reserves

23. United States Oil Production and Use (2) • Domestic oil production • Off-shore drilling • Alaska • Future U.S. production • Consumption versus production • Oil imports • 2008: imported 58% of crude oil

24. Trade-Offs Conventional Oil Advantages Disadvantages Ample supply for 42–93 years Need to find substitutes within 50 years Low cost Large government subsidies High net energy yield Environmental costs not included in market price Easily transported within and between countries Artificially low price encourages waste and discourages search for alternatives Low land use Pollutes air when produced and burned Technology is well developed Releases CO2 when burned Can cause water pollution Efficient distribution system Fig. 13-5, p. 301

25. Oil Sand • Oil sand (tar sand): mixture of clay, water and bitumen • Bitumen: thick, sticky, tar like heavy oil with high sulfur content • Northeastern Alberta in Canada has ¾ world’s tar sands resources • Under boreal forest • Huge environmental cost

26. Tar sands • http://www.good.is/post/think-nuclear-or-coal-is-bad-tar-sands-mining-is-coming-to-utah/ • http://www.youtube.com/watch?v=YkwoRivP17A&feature=related

27. Oil shale • Contain kerogen • Shale Oil • About 72% of world’s estimated oil shale reserves buries in government owed land in US states of Colorado, Wyoming, and Utah in Green River formation • What are the problems? Low net energy, requires huge amount of water to produce (Colorado River System), severe water pollution, air pollution, CO2 emission …

28. Fig. 13-6, p. 303

29. Trade-Offs Heavy Oils from Oil Shale and Tar Sand Advantages Disadvantages High cost (oil shale) Moderate cost (tar sand) Low net energy yield Large potential supplies, especially tar sands in Canada Environmental costs not included in market price Large amounts of water needed for processing Easily transported within and between countries Severe land disruption Efficient distribution system in place Severe water pollution Technology well-developed (tar sand) Air pollution and CO2 emissions when produced and burned Fig. 13-7, p. 303

30. Natural Gas Is a Useful and Clean-burning Fossil Fuel (1) • Natural gas • Conventional natural gas • Unconventional natural gas • Liquefied petroleum gas (LPG) • Less carbon dioxide emitted per unit of energy than with crude oil, tar sand, shale oil

31. Natural Gas Is a Useful and Clean-burning Fossil Fuel (2) • Liquefied natural gas (LNG) • World supply of conventional natural gas – 62-125 years • Unconventional natural gas • Coal-bed methane gas • Methane hydrate

32. Trade-Offs Conventional Natural Gas Advantages Disadvantages Ample supplies Nonrenewable resource High net energy yield Releases CO2 when burned Low cost Government subsidies Less air pollution than other fossil fuels Environmental costs not included in market price Lower CO2 emissions than other fossil fuels Methane (a greenhouse gas) can leak from pipelines Easily transported by pipeline Difficult to transfer from one country to another Low land use Can be shipped across ocean only as highly explosive LNG Good fuel for fuel cells, gas turbines, and motor vehicles Fig. 13-8, p. 304

33. Coal Is a Plentiful But Dirty Fuel (1) • Used in electricity production • World’s most abundant fossil fuel • U.S. reserves should last about 250 years • Sulfur and particulate pollutants • Mercury and radioactive pollutants

34. Coal Is a Plentiful But Dirty Fuel (2) • Heavy carbon dioxide emissions • Pollution control and environmental costs • China major builder of coal plants

35. Increasing heat and carbon content Increasing moisture content Peat (not a coal) Lignite (brown coal) Bituminous (soft coal) Anthracite (hard coal) Heat Heat Heat Pressure Pressure Pressure Partially decayed plant matter in swamps and bogs; low heat content Low heat content; low sulfur content; limited supplies in most areas Extensively used as a fuel because of its high heat content and large supplies; normally has a high sulfur content Highly desirable fuel because of its high heat content and low sulfur content; supplies are limited in most areas Fig. 13-9, p. 305

36. Waste heat Coal burning power plant Cooling tower transfers waste heat to atmosphere Coal bunker Turbine Generator Cooling loop Stack Pulverizing mill Filter Condenser Boiler Toxic ash disposal Fig. 13-10, p. 306

37. TVA Coal fired power plant • http://www.tva.com/power/coalart.htm • http://www.newsweek.com/photo/2009/07/21/photos--the-worst-man-made-environmental-disasters.html

38. Fig. 13-10, p. 306

39. Coal-fired electricity 286% Synthetic oil and gas produced from coal 150% Coal 100% Tar sand 92% Oil 86% Natural gas 58% Nuclear power fuel cycle 17% Geothermal 10% CO2 Emissions per unit of electrical energy Stepped Art Fig. 13-11, p. 306

40. Trade-Offs Coal Advantages Disadvantages Ample supplies (225–900 years) Severe land disturbance, air pollution, and water pollution Severe threat to human health when burned High net energy yield Environmental costs not included in market price Low cost Large government subsidies Well-developed technology High CO2 emissions when produced and burned Air pollution can be reduced with improved technology Radioactive particle and toxic mercury emissions Fig. 13-12, p. 307

41. Case Study: The Growing Problem of Coal Ash • Highly toxic • Often stored in ponds • Ponds can rupture • Groundwater contamination • EPA: in 2009 called for classifying coal ash as hazardous waste • Opposed by coal companies

42. TVA coal ash spill • http://earthfirst.com/americas-top-10-worst-man-made-environmental-disasters/

43. Clean Coal Campaign • Coal industry • Rich and powerful • Fought against labeling carbon dioxide a greenhouse gas • “Clean coal” touted by coal industry • Mining harms the environment • Burning creates carbon dioxide and toxic chemicals • Plan to capture and store carbon dioxide

44. Converting Coal into Gaseous and Liquid Fuels • Synfuels • Coal gasification • Synthetic natural gas (SNG) • Coal liquefaction • Methanol or synthetic gasoline • Extracting and burning coal more cleanly

45. Trade-Offs Synthetic Fuels Advantages Disadvantages Low to moderate net energy yield Large potential supply Higher cost than coal Requires mining 50% more coal Vehicle fuel Environmental costs not included in market price High environmental impact Moderate cost Large government subsidies High water use Lower air pollution than coal when burned Higher CO2 emissions than coal Fig. 13-13, p. 309

46. 13-3 What Are the Advantages and Disadvantages of Nuclear Energy? • Concept 13-3 The nuclear power fuel cycle has a low environmental impact and a very low accident risk, but its use has been limited because of high costs, a low net energy yield, long-lived radioactive wastes, vulnerability to sabotage, and the potential for spreading nuclear weapons technology.

47. How Does a Nuclear FissionReactor Work? • Nuclear fission • Light-water reactors • Boil water to produce steam to turn turbines to generate electricity • Radioactive uranium as fuel • Control rods, coolant, and containment vessels

48. TVA • http://www.tva.gov/power/nuclear/wattsbar_howworks.htm • http://www.tvakids.com/videos/pressurized_water_animation.htm

49. Small amounts of radioactive gases Uranium fuel input (reactor core) Control rods Containment shell Waste heat Heat exchanger Steam Turbine Generator Hot coolant Useful electrical energy About 25% Hot water output Pump Pump Pump Coolant Waste heat Pump Cool water input Moderator Pressure vessel Coolant passage Shielding Condenser Water Periodic removal and storage of radioactive wastes and spent fuel assemblies Periodic removal and storage of radioactive liquid wastes Water source (river, lake, ocean) Fig. 13-14, p. 310

50. Fig. 13-14, p. 310