Classroom presentations to accompany Understanding Earth , 3rd edition

1. Classroom presentations to accompany Understanding Earth, 3rd edition prepared by Peter Copeland and William Dupré University of Houston Chapter 22 Energy and Material Resources from the Earth

2. Part IV Conserving Earth’s Bounty

3. Energy and Material Resources Thomas Kitchin/Tom Stack

4. Fig. 22.1

5. Natural resources • Most geologists are employed in looking for some kind of resource. • Resources range from petroleum to precious metals to water.

6. Resource • A material that is both useful and available in useable quantities. • A renewable resource is one that is produced faster than it is depleted.

7. Reserves • Resources that are identifiable and recoverable under today's economic conditions • Conditional resources: not economic at the moment.

8. Energy Mix in the U.S. 1850–1997 Fig. 22.2

9. Photosynthesis and Fossil Fuels The Carbon Cycle Fig. 22.3

10. Fossil fuels • Decayed organic material (plants) • Must have relatively rapid burial FOSSIL FUELS ARE A NONRENEWABLE RESOURCE

11. Hydrocarbons—oil and gas Oil formation 1) Relatively large quantity of organic matter 2) Rapid burial (before oxidation) 3) Subsequent chemical reactions [f(P,T)] transform decaying organic matter into hydrocarbons.

12. How do oil and gas deposits form? • Production of large amounts of organic material (mainly microscopic plants and bacteria) • Preservation in a reducing (oxygen-poor) depositional environment (e.g., restricted ocean basin) • Burial causes increased heat and pressure, resulting in maturation (the physical and chemical breakdown of organic matter into a liquid or gaseous hydrocarbon compounds) in a source rock.

13. There’s more: • Migration of fluids out of the source rock into a more permeable reservoir rock. • Trapping of fluids must occur by encountering an impermeable seal. • In short, you need • Production • Preservation • Maturation • Migration • Trapping

14. Thermal conditions of oil formation • Relatively narrow temperature range: ≈50–200°C (also depends on time) • Temperature and duration determine type of hydrocarbon: oil wet gas dry gas gone • Duration of process could last millions of years

15. Environments of oil formation • Continental shelf • Continental rise • Some nonmarine basins

16. Reservoirs • For oil to be useful, it must accumulate in concentrated and accessible areas. Such spots are called reservoirs. • Accumulation is possible because oil and gas are low-density fluids that can migrate through the pore space in rocks.

17. Reservoirs To create a reservoir, the migration of the fluids is retarded by cap rock. Cap rocks Reservoir rocks shalesandstone gypsum limestone salt limestone

18. Trap Combination of cap rock and reservoir rock favorable for petroleum accumulation • Stratigraphic trap • Structural trap

19. Anticlinal Trap Fig. 22.4a

20. Fault Trap Fig. 22.4b

21. Stratigraphic Trap Fig. 22.4c

22. Salt Dome Trap Fig. 22.4d

23. Dry Holes • Many potential reservoirs exist that are free of hydrocarbons. • Source rocks may have enough organic matter but may never have been hot enough.

24. Oil distribution Most oil is found in Cenozoic rocks, which have the best chance of preservation (erosion, metamorphism).

25. How do we explore for oil? • Map surface geology (use surface geometry to interpret subsurface conditions) • Seismic exploration (good way to get lots of information but subject to interpret) • Drilling, coring (more detailed information from smaller area—like seismic, very expensive)

26. How much oil is left? • Proven reserves: 700 billion barrels (over half in Middle East) • Petroleum resources: 2 trillion barrels • 1997 consumption: ~70 million barrels per day • At this rate reserves will last between 25 and 80 years.

27. This assumes no increase in the rate of consumption, but • Between 1985 and 1995, consumption of oil in the world increased by 16%. • The increase in Latin America was 30%. • The increase in Africa was 40%. • The increase in Asia was 50%.

28. Estimated World Reserve of Crude Oil Fig. 22.5

29. Total World Reserves Fig. 22.7

30. Coal • Coal is usually formed in swamps • 1st stage - peat (high C, high H20) • P,T  loss of gases, toward higher C Ranks of coal: Anthracite Bituminous Subbituminous Lignite

31. Coal • High sulfur is bad—H2SO4 is produced during burning. • Principle coal producing areas in United States are Appalachia, Wyoming, New Mexico, and Colorado.

32. Formation of Coal Fig. 22.8

33. Coalfields of the United States Fig. 22.9

34. Strip Mining Coal in Pennsylvania Fig. 22.10a Peter Kresan

35. Reclaimed Land in Pennsylvania Fig. 22.10b Peter Kresan

36. Alternatives to fossil fuels 1. Nuclear energy Advantage: virtually inexhaustible supply Disadvantage: dangerous waste

37. Possible Nuclear Waste Contamination After R.E. Gephart, 1998

38. Alternatives to fossil fuels 2. Solar energy Advantage: virtually inexhaustible supply Disadvantage: very expensive with current technology

39. Solar Cells Fig. 22.11 Ned Gallate/The Stock Market

40. Alternatives to fossil fuels 3. Geothermal energy Advantage: cheap and clean Disadvantages: cannot be transported long distances

41. Geothermal energy • Must have a concentrated heat source near the surface: magma chamber with porous rocks above • Cool water pumped into hot rocks, hot water or steam extracted (rocks may be as cool as 80°C) • Producing: Iceland, France • Experimenting: New Mexico, California

42. Geothermal Energy to Electricity Fig. 22.12 Pacific Gas and Electric

43. World Energy Demand1971-2010 Fig. 22.13

44. Mineral deposits • If deposited in concentrated volume, we get veins or lodes. • If deposited in large volume, we get disseminated deposit. • grade: The relative quantity of ore in an ore body (gold ≈0.05 oz/ton)

45. Mineral deposits • hydrothermal deposits: minerals deposited from hot waters usually associated with igneous intrusions • These fluids carry “low temperature ions”; when the fluids cool off (near surface) the solubility goes down and minerals with Pb, Fe, Hg, Cu, Zn, Ag, Au, etc. are precipitated.

47. Iron Ores Siderite Pyrite Magnetite Hematite Fig. 22.14 Chip Clark

48. Native Gold on a Quartz Crystal Fig. 22.15 Chip Clark

49. Hydrothermal Ore Deposits Fig. 22.18

50. Vein Deposit of Gold and Silver Quartz Fig. 22.19 Peter Kresan