World Energy and Their Sources

1. World Energy and Their Sources Nonrenewable Energy Sources

5. Solar Radiation drives • Where do fossil fuels come from?

6. Where Does the Energy Go?

7. ENERGY TO MAKE ENERGY! • To get fossil fuels and extract the energy from them, one must • Net Energy = Energy returned – Energy invested

8. EROI: Energy Returned On Investment EROI = Energy returned Energy invested • ↑ EROI: • Presently, fossil fuels have: • EROI can change over time:

9. Where Our Energy Comes From

10. coal

11. Coal Formation

12. Coal • Most abundant fossil fuel • It is the remains of mostly woody plant material from 300-400 MYA; little decomposition has occurred • ¼ of coal in US • Coal provides ¼ of world’s energy • US & China are main producers and consumers

13. Coal: Impurities • Sulfur → can lead to acid rain • Mercury → can bioaccumulate

14. Coal: Mining Subsurface - shafts and tunnels into ground • Dangerous to miners • Collapse of tunnels • Black lung disease

15. Coal: Mining Strip Mining – machines removes soil to expose coal • Habitat destruction • Soil erosion • Acid drainage: sulfide minerals in rock react with O2 and H2O → sulfuric acid • Acid leaches out metals from rocks

16. Coal: Mining Mountaintop removal is an extreme form of surface mining • Loss of habitat • Big soil erosion

17. Pros and Cons of Coal

19. Coal-fired Power Plant

20. Natural gas

21. Natural Gas • Commercial energy • Provides ¼ of global energy • “Cleaner” than coal • Longevity: 60 years

22. Biogenic Gas • Also known as swamp gas – shallow water decomposition • Pure methane • Landfill gas – now is collected and used

23. Thermogenic Gas • Formed through heat and compression deep underground • Coalbed methane is now being collected • With oil – too expensive to capture; burned at the source • LNG liquefied natural gas – easier to ship, but very dangerous

24. Environmental Impacts • Infrastructure – roads, housing, pipelines, soil removal, ponds to collect toxic sludge • Most drilling occurs in sensitive ecosystems – arctic & semi-arid tundra • Exploratory work • Hydraulic fracturing has its own sets of problems

25. Pros and Cons of Natural Gas

26. Crude oil

28. Oil • What it is: a mixture of hydrocarbons with varying numbers of carbon atoms • Refineries separate the hydrocarbons based upon differing boiling points (fractional distillation)

29. Fractional Distillation

30. Oil: Prospecting • Drilling rock cores, all kinds of surveys • Assess “technically recoverable” oil • Assess “economically recoverable” oil • Proven Recoverable Reserve – amt of fuel in a deposit that is technically & economically feasible

31. Oil: Drilling Primary extraction • Initial drilling and pumping • Gets out about 1/3 of the oil Secondary Extraction • Gets out the remaining 2/3 of oil • Solvents are needed • ↑$

32. Oil: Impacts • Same impacts as with NG • ANWR is a big debate

33. Pros and Cons of Oil

34. Other Fossil Fuels Oil sands • Tar-like heavy oil in sand, clay; bitumen Oil shale • Sedimentary rock full of kerogen, a waxy mixture of HCs Methane hydrate • Methane in ice; difficult to extract

35. nuclear

36. Nuclear Fission

37. Fission • Nuclear energy = energy holding protons and neutrons together • Nuclear energy → thermal energy → electricity • In fission, a large, unstable nucleus (U-235 or U-238), is made to break apart, releasing energy • Radioisotopes are atoms of a certain element that emit subatomic particles and radiation to become stable

39. Fission • Each radioisotope has a certain half-life of decay • Half-life is the time it takes for half of the original amount of radioactive isotope to decay • After several years, rods must be replaced due to decay and consumption • Fuel rods can be processed to extract more energy, but they are usually disposed of as radioactive waste

40. Nuclear Reactor Design

41. Fusion • Fusion involves the synthesis of heavier elements from lighter ones under high temperature and pressure • Hydrogen isotopes (deuterium and tritium) are fused to form helium • Have not achieved break-even energy • Energy is cleaner, resources are plentiful (water)

44. Small Risks of Large Accidents • 1979 – Three Mile Island in Pennsylvania • Metal surrounding the fuel rods melted down, releasing radiation • It did not escape containment (some gases were vented) • Clean-up lasted years • No significant health risks

46. Small Risks of Large Accidents • 1986 – an explosion at the Chernobyl plant (Ukraine) caused most severe nuclear pp disaster in the world • Clouds of radioactive debris spewed into the atmosphere • Fallout carried over most of northern hemisphere • 30-km radius contaminated

48. Waste Disposal & Other Problems • Waste remains dangerous for thousands of years (remember half-life?) • Currently, waste is held in temporary storage on-site • Yucca mountain in Nevada has been chosen for storage beginning in 2010 • More expensive than expected • Plants have aged more quickly • Shutting down plants more expensive than the original construction

49. Pros and Cons of Nuclear