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Ch. 14 Notes Energy Mrs. Sealy APES.

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1 Ch. 14 Notes Energy Mrs. Sealy APES

2 I. Mining Law of 1872 – encouraged mineral exploration and mining.
1. First declare your belief that minerals on the land. Then spend $500 in improvements, pay $100 per year and the land is yours 2. Domestic and foreign companies take out $2-$3 billion/ year 3. Allows corporations and individuals to claim ownership of U.S. public lands. 4. Leads to exploitation of land and mineral resources.

3 "This archaic, 132-year-old law permits mining companies to gouge billions of dollars worth of minerals from public lands, without paying one red cent to the real owners, the American people.  And, these same companies often leave the unsuspecting taxpayers with the bill for the billions of dollars required to clean up the environmental mess left behind." -- Senator Dale Bumpers (D-AR, retired)

4 Nature and Formation of Mineral Resources
A. Nonrenewable Resources – a concentration of naturally occurring material in or on the earth’s crust that can be extracted and processed at an affordable cost. Non-renewable resources are mineral and energy resources such as coal, oil, gold, and copper that take a long period of time to produce.

5 Nature and Formation of Mineral Resources
1. Metallic Mineral Resources – iron, copper, aluminum 2. Nonmetallic Mineral Resources – salt, gypsum, clay, sand, phosphates, water and soil. 3. Energy resource: coal, oil, natural gas and uranium

6 Nature and Formation of Mineral Resources
B.  Identified Resources – deposits of a nonrenewable mineral resource that have a known location, quantity and quality based on direct geological evidence and measurements C.  Undiscovered Resources– potential supplies of nonrenewable mineral resources that are assumed to exist on the basis of geologic knowledge and theory (specific locations, quantity and quality are not known) D.  Reserves – identified resources of minerals that can be extracted profitably at current prices. Other Resources – resources that are not classified as reserves.

7 Ore Formation 1. Magma (molten rock) – magma cools and crystallizes into various layers of mineral containing igneous rock.

8 Ore Formation Hydrothermal Processes: most common way of mineral formation A. Gaps in sea floor are formed by retreating tectonic plates B. Water enters gaps and comes in contact with magma C. Superheated water dissolves minerals from rock or magma D. Metal bearing solutions cool to form hydrothermal ore deposits. E. Black Smokers – upwelling magma solidifies. Miniature volcanoes shoot hot, black, mineral rich water through vents of solidified magma on the seafloor. Support chemosynthetic organisms.

9 Ore Formation Manganese Nodules (pacific ocean)– ore nodules crystallized from hot solutions arising from volcanic activity. Contain manganese, iron copper and nickel.

10 Ore Formation 3.      Sedimentary Processes – sediments settle and form ore deposits. A. Placer Deposits – site of sediment deposition near bedrock or course gravel in streams B. Precipitation: Water evaporates in the desert to form evaporite mineral deposits. (salt, borax, sodium carbonate) C. Weathering – water dissolves soluble metal ions from soil and rock near earth’s surface. Ions of insoluble compounds are left in the soil to form residual deposits of metal ores such as iron and aluminum (bauxite ore).

11 Methods For Finding Mineral Deposits
A. Photos and Satellite Images B. Airplanes fly with radiation equipment and magnetometers C. Gravimeter (density) D. Drilling E. Electric Resistance Measurement F. Seismic Surveys G. Chemical analysis of water and plants

12 Mineral Extraction Surface Mining: overburden (soil and rock on top of ore) is removed and becomes spoil.  1. open pit mining – digging holes 2. Dredging – scraping up underwater mineral deposits 3. Area Strip Mining – on a flat area an earthmover strips overburden 4. Contour Strip Mining – scraping ore from hilly areas

13 Subsurface Mining:  1. dig a deep vertical shaft,  blast underground tunnels to get mineral deposit, remove ore or coal and transport to surface      2. disturbs less land and produces less waste 3. less resource recovered, more dangerous and expensive 4. Dangers: collapse, explosions (natural gas), and lung disease

14 Environmental Impacts of Mineral Resources
A. Scarring and disruption of land, B. Collapse or subsidence C. Wind and water erosion of toxic laced mine waste D. Air pollution – toxic chemicals E. Exposure of animals to toxic waste F. Acid mine drainage: seeping rainwater carries sulfuric acid ( acid comes from bacteria breaking down iron sulfides) from the mine to local waterway Google earth

15 Environmental Effects
Steps Environmental Effects Disturbed land; mining accidents; health hazards; mine waste dumping; oil spills and blowouts; noise; ugliness; heat Mining exploration, extraction Processing Solid wastes; radioactive material; air, water, and soil pollution; noise; safety and health hazards; ugliness; heat transportation, purification, manufacturing Use Noise; ugliness thermal water pollution; pollution of air, water, and soil; solid and radioactive wastes; safety and health hazards; heat transportation or transmission to individual user, eventual use, and discarding Fig. 14.6, p. 326

16 Percolation to groundwater Leaching of toxic metals
Subsurface Mine Opening Surface Mine Runoff of sediment Acid drainage from reaction of mineral or ore with water Spoil banks Percolation to groundwater Leaching of toxic metals and other compounds from mine spoil Leaching may carry acids into soil and ground water supplies Fig. 14.7, p. 326

17 Scattered in environment
Smelting Separation of ore from gangue Melting metal Conversion to product Metal ore Recycling Surface mining Discarding of product Fig. 14.8, p. 327 Scattered in environment

18 A. Life Cycle of Metal Resources (fig. 14-8)
Mining Ore A. Ore has two components: gangue(waste) and desired metal B. Separation of ore and gangue which leaves tailings C. Smelting (air and water pollution and hazardous waste which contaminates the soil around the smelter for decades) D. Melting Metal E. Conversion to product and discarding product

19 Economic Impact on Mineral Supplies
A. Mineral prices are low because of subsidies: depletion allowances and deduct cost of finding more B. Mineral scarcity does not raise the market prices C. Mining Low Grade Ore: Some analysts say all we need to do is mine more low grade ores to meet our need 1. We are able to mine low grade ore due to improved technology 2. The problem is cost of mining and processing, availability of fresh water, environmental impact 

20 Recycle; increase reserves by improved mining
Mine, use, throw away; no new discoveries; rising prices Recycle; increase reserves by improved mining technology, higher prices, and new discoveries B Production Recycle, reuse, reduce consumption; increase reserves by improved mining technology, higher prices, and new discoveries C Present Depletion time A Depletion time B Depletion time C Fig. 14.9, p. 329 Time

21 Fig , p. 329

22 A.     Mining Oceans 1. Minerals are found in seawater, but occur in too low of a concentration 2. Continental shelf can be mined 3. Deep Ocean are extremely expensive to extract (not currently viable)

23 A. Substitutes for metals
1. Materials Revolution 2. Ceramics and Plastics 3. Some substitutes are inferior (aluminum for copper in wire) 4. Will be difficult to find substitutes for helium, manganese, phosphorus and copper

24 Evaluating Energy Sources
What types of energy do we use? 1. 99% of our heat energy comes directly from the sun (renewable fusion of hydrogen atoms) 2. Indirect forms of solar energy (renewable) wind hydro biomass

25 Oil and Natural Gas Coal Geothermal Energy Contour strip mining
Hot water storage Floating oil drilling platform Oil storage Geothermal power plant Oil drilling platform on legs Pipeline Area strip mining Oil well Pipeline Mined coal Drilling tower Gas well Valves Pump Water penetrates down through the rock Underground coal mine Water is heated and brought up as dry steam or wet steam Impervious rock Natural gas Coal seam Oil Hot rock Water Water Magma Fig , p. 332

26 Kilocalories per Person per Day
Society Kilocalories per Person per Day Modern industrial (United States) 260,000 Modern industrial (other developed nations) 130,000 Early industrial 60,000 Advanced agricultural 20,000 Early agricultural 12,000 Hunter– gatherer 5,000 Primitive 2,000 Fig , p. 333

27 Hydropower, geothermal,
Nuclear power 6% Hydropower, geothermal, Solar, wind 7% Natural Gas 23% Biomass 12% Coal 22% Oil 30% Fig a, p. 333 World

28 Nuclear power 7% Hydropower geothermal, solar, wind 5% Natural Gas 22%
Coal 22% Biomass 4% Oil 40% Fig b, p. 333 United States

29 20th Century Trends 1. Coal use decreases from 55% to 22% 2. Oil increased from 2% to 30% 3. Natural Gas increased from 0% to 25% 4. Nuclear increased from 0% to 6%

30 100 Wood Coal 80 60 Natural gas Oil 40 Hydrogen Solar 20 Nuclear 1800
Contribution to total energy consumption (percent) Oil 40 Hydrogen Solar 20 Nuclear 1800 1875 1950 2025 2100 Year Fig , p. 334

31 Evaluating Energy Sources
Evaluating Energy Resources; Take into consideration the following: Availability net energy yield Cost environmental impact

32 Electric resistance heating (coal-fired plant) 0.4
Space Heating Passive solar 5.8 Natural gas 4.9 Oil 4.5 Active solar 1.9 Coal gasification 1.5 Electric resistance heating (coal-fired plant) 0.4 Electric resistance heating (natural-gas-fired plant) 0.4 Electric resistance heating (nuclear plant) 0.3 Fig a, p. 335

33 High-Temperature Industrial Heat
28.2 Surface-mined coal Underground-mined coal 25.8 Natural gas 4.9 Oil 4.7 Coal gasification 1.5 Direct solar (highly concentrated by mirrors, heliostats, or other devices) 0.9 Fig b, p. 335

34 Gasoline (refined crude oil) 4.1
Transportation Natural gas 4.9 Gasoline (refined crude oil) 4.1 Biofuel (ethyl alcohol) 1.9 Coal liquefaction 1.4 Oil shale 1.2 Fig c, p. 335

35 Net Energy Net Energy – total amount of energy available from a given source minus the amount of energy used to get the energy to consumers (locate, remove, process and transport) G. Net Energy Ratio - ratio of useful energy produced to the useful energy used to produce it.

36 Oil A. Petroleum/Crude Oil – thick liquid consisting of hundreds of combustible hydrocarbons and small concentrations of nitrogen, sulfur, and oxygen impurities. B. Produced by the decomposition of dead plankton that were buried under ancient lakes and oceans. It is found dispersed in rocks.

37 Oil Life Cycle 1:14 1. Primary Oil Recovery a. drill well
b. pump out light crude oil 1:14

38 Secondary Oil Recovery
a. pump water under pressure into a well to force heavy crude oil toward the well b. pump oil and water mixture to the surface c. separate oil and water d. reuse water to get more oil

39 Tertiary Oil Recovery a. inject detergent to dissolve the remaining heavy oil b. pump mixture to the surface c. separate out the oil d. reuse detergent

40 Transport oil to the refinery (pipeline, truck, boat)

41 Oil refining – heating and distilling based on boiling points of the various petrochemicals found in the crude oil. (fractional distillation in a cracking tower) 

42 Gases Gasoline Aviation fuel Heating oil Heated crude oil Diesel oil
Naphtha Grease and wax Furnace Fig , p. 337 Asphalt

43 Conversion to product a. Industrial organic chemicals b. Pesticides c. Plastics d. Synthetic fibers e. Paints f. Medicines g. Fuel

44 . Location of World Oil Supplies
1. 64% Middle East (67% OPEC – 11 countries) a. Saudi Arabia (26%) b. Iraq, Kuwait, Iran, (9-10% each) 2. Latin America (14%) (Venezuela and Mexico) 3. Africa (7%) 4. Former Soviet Union (6%) 5. Asia (4%) (China 3%) 6. United States (2.3%) we import 52% of the oil we use 7. Europe (2%)

Arctic Ocean Prudhoe Bay Coal Beaufort Sea ALASKA Gas Trans Alaska oil pipeline Arctic National Wildlife Refuge Oil Prince William Sound High potential areas Gulf of Alaska Valdez CANADA Grand Banks Pacific Ocean UNITED STATES Atlantic Ocean Fig , p. 338 MEXICO

46 Oil price per barrel ($)
70 60 50 40 Oil price per barrel ($) 30 20 (1997 dollars) 10 1950 1960 1970 1980 1990 2000 2010 Year Fig , p. 339

47 40 2,000 x 109 barrels total 30 (x 109 barrels per year)
Annual production 20 10 1900 1925 1950 1975 2000 2025 2050 2075 2100 Year World Fig a, p. 339

48 4 200 x 109 barrels total 1975 3 Undiscovered: 32 x 109 barrels
(x 109 barrels per year) Annual production Proven reserves: 34 x 109 barrels 2 1 1900 1920 1940 1960 2080 2000 2020 2040 Year United States Fig b, p. 339

49 286% Coal-fired electricity Synthetic oil and 150% gas produced
from coal 150% 100% Coal 86% Oil 58% Natural gas 17% Nuclear power Fig , p. 339

50 Advantages Disadvantages
Ample supply for 42–93 years Need to find substitute within 50 years Low cost (with huge subsidies) Artificially low price encourages waste and discourages search for alternatives High net energy yield Easily transported within and between countries Air pollution when burned Low land use Releases CO2 when burned Moderate water pollution Fig , p. 340

51 How long will the oil last
1. Identified Reserve will last 53 years at current usage rates 2. Known and projected supplies are likely to be 80% depleted within 42 to 93 years depending on usage rate US oil supplies are expected to be depleted within 15 to 48 years depending on the annual usage rate

52 Heavy Oils Oil Shale – fine grained sedimentary rock containing solid organic combustible material called kerogenShale Oil – kerogen distilled from oil shale. a. could meet U.S. crude oil demand for 40 years at current usage rates (Colorado, Utah and Wyoming public lands) Tar Sand – mixture of clay sand and water containing bitumen (high sulfur heavy oil)

53 Fig , p. 340

54 Shale oil pumped to surface
Mined oil shale Retort Conveyor Spent shale Above Ground Conveyor Pipeline Shale oil storage Impurities removed Hydrogen added Crude oil Refinery Air compressors Sulfur and nitrogen compounds Air injection Shale layer Shale oil pumped to surface Underground Shale heated to vaporized kerogen, which is condensed to provide shale oil Fig , p. 341

55 Tar sand is mined. Tar sand is heated until bitumen floats to the top.
Bitumen vapor Is cooled and condensed. Pipeline Impurities removed Hydrogen added Synthetic crude oil Refinery Fig , p. 341


57 Advantages Disadvantages
Moderate existing supplies High costs Low net energy yield Large potential supplies Large amount of water needed to process Severe land disruption from surface mining Water pollution from mining residues Air pollution when burned CO2 emissions when burned Fig , p. 342

58 XI. Natural Gas Natural Gas is a mixture of 50-90% methane (CH4) by volume; contains smaller amounts of ethane, propane, butane and toxic hydrogen sulfide. B. Conventional natural gas - lies above most reservoirs of crude oil C. Unconventional deposits - include coal beds, shale rock, deep deposits of tight sands and deep zones that contain natural gas dissolved in hot hot water

59 Oil and Natural Gas Coal Geothermal Energy Contour strip mining
Hot water storage Floating oil drilling platform Oil storage Geothermal power plant Oil drilling platform on legs Pipeline Area strip mining Oil well Pipeline Mined coal Drilling tower Gas well Valves Pump Water penetrates down through the rock Underground coal mine Water is heated and brought up as dry steam or wet steam Impervious rock Natural gas Coal seam Oil Hot rock Water Water Magma Fig , p. 332

60 XI. Natural Gas Gas Hydrates - an ice-like material that occurs in underground deposits (globally)  Liquefied Petroleum Gas (LPG) - propane and butane are liquefied and removed from natural gas fields. Stored in pressurized tanks. Liquefied Natural Gas (LNG) - natural gas is converted at a very low temperature (-184oC)

61 Where is the world’s natural gas?
Russia and Kazakhstan - 40% Iran - 15% Qatar - 5% Saudi Arabia - 4% Algeria - 4% United States - 3% Nigeria - 3% Venezuela - 3%

62 Advantages: 1. Cheaper than Oil 2. World reserves - >125 years
3. Easily transported over land (pipeline) 4. High net energy yield 5. Produces less air pollution than other fossil fuels 6. Produces less CO2 than coal or oil 7. Extracting natural gas damages the environment much less that either coal or uranium ore 8. Easier to process than oil 9. Can be used to transport vehicles 10. Can be used in highly efficient fuel cells

63 Advantages Disadvantages
Ample supplies (125 years) Releases CO2 when burned High net energy yield Methane (a greenhouse gas) can leak from pipelines Low cost (with huge subsidies) Shipped across ocean as highly explosive LNG Less air pollution than other fossil fuels Sometimes burned off and wasted at wells because of low price Lower CO2 emissions than other fossil fuels Moderate environ- mental impact Easily transported by pipeline Low land use Good fuel for fuel cells and gas turbines Fig , p. 342

64 Disadvantages: 1. When processed, H2S and SO2 are released into the atmosphere 2. Must be converted to LNG before it can be shipped (expensive and dangerous) 3. Conversion to LNG reduces net energy yield by one-fourth 4. Can leak into the atmosphere; methane is a greenhouse gas that is more potent than CO2.

65 XII. Coal Coal is a solid, rocklike fossil fuel; formed in several stages as the buried remains of ancient swamp plants that died during the Carboniferous period (ended 286 million years ago); subjected to intense pressure and heat over millions of years. Coal is mostly carbon (40-98%); small amount of water, sulfur and other materials

66 Three types of coal lignite (brown coal) bituminous coal (soft coal) anthracite (hard coal) Carbon content increases as coal ages; heat content increases with carbon content

67 Increasing heat and carbon content Increasing moisture content
Peat (not a coal) Lignite (brown coal) Bituminous Coal (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 , p. 344

68 Coal Extraction Subsurface Mining - labor intensive; world’s most dangerous occupation (accidents and black lung disease Surface Mining - three types 1. Area strip mining 2. contour strip mining 3. open-pit mining

69 Oil and Natural Gas Coal Geothermal Energy Contour strip mining
Hot water storage Floating oil drilling platform Oil storage Geothermal power plant Oil drilling platform on legs Pipeline Area strip mining Oil well Pipeline Mined coal Drilling tower Gas well Valves Pump Water penetrates down through the rock Underground coal mine Water is heated and brought up as dry steam or wet steam Impervious rock Natural gas Coal seam Oil Hot rock Water Water Magma Fig , p. 332

70 Why we need coal Coal provides 25% of world’s commercial energy (22% in US). Used to make 75% of world’s steel Generates 64% of world’s electricity

71 Coal-Fired Electric Power Plant
Coal is pulverized to a fine dust and burned at a high temperature in a huge boiler. Purified water in the heat exchanger is converted to high-pressure steam that spins the shaft of the turbine. The shaft turns the rotor of the generator (a large electromagnet) to produce electricity.

72 . Coal-Fired Electric Power Plant
Air pollutants are removed using electrostatic precipitators (particulate matter) and scrubbers (gases). Ash is disposed of in landfills. Sulfur dioxide emissions can be reduced by using low-sulfur coal.

73 I. World’s Coal Supplies
US - 66% of worlds proven reserves Identified reserves should last 220 years at current usage rates. Unidentified reserves could last about 900 years

74 . Pros and Cons of Solid Coal
Advantages World’s most abundant and dirtiest fossil fuel, High net energy yield

75 Advantages Disadvantages
Ample supplies (225–900 years) Very high environmental impact High net energy yield Severe land disturbance, air pollution, and water pollution Low cost (with huge subsidies) High land use (including mining) Severe threat to human health High CO2 emissions when burned Releases radioactive particles and mercury into air Fig , p. 344

76 Disadvantages: harmful environmental effects -mining is dangerous (accidents and -black lung disease) -harms the land and causes water pollution -Causes land subsidence -Surface mining causes severe land disturbance and soil erosion -Surface mined land can be restored - involves burying toxic materials, returning land to its original contour, and planting vegetation (Expensive and not often done) -Acids and toxic metals drain from piles of water materials -Coal is expensive to transport -Cannot be used in sold form in cars (must be converted to liquid or gaseous form) -Dirtiest fossil fuel to burn releases CO, CO2, SO2, NO, NO2, particulate matter (flyash), toxic metals and some radioactive elements. -Burning Coal releases thousands of times more radioactive particles into the atmosphere per unit of energy than does a nuclear power plant -Produces more CO2 per unit of energy than other fossil fuels and accelerates global warming. -A severe threat to human health (respiratory disease)

77 Clean Coal Technology . Fluidized-bed combustion - developed to burn coal more cleanly and efficiently. Use of low sulfur coal - reduces SO2 emission Coal gasification – uses coal to produce synthetic natural gas (SNG) . Coal liquefaction - produce a liquid fuel - methanol or synthetic gasoline

78 Flue gases Coal Limestone Steam Fluidized bed Water Air nozzles Air
Calcium sulfate and ash Fig , p. 345

79 Raw coal Remove dust, tar, water, sulfur Recover sulfur Air or oxygen
Steam Raw gases Clean Methane gas 2C Coal + O2 2CO Pulverizer Recycle unreacted carbon (char) CO + 3H2 CH4 + H2O Methane (natural gas) Slag removal Pulverized coal Fig , p. 345

80 Advantages Disadvantages
Large potential supply Low to moderate net energy yield Higher cost than coal Vehicle fuel High environmental impact Increased surface mining of coal High water use Higher CO2 emissions than coal Fig , p. 346

81 Clean Coal Technology Synfuels - can be transported by pipeline inexpensively; burned to produce electricity; burned to heat houses and water; used to propel vehicles.

82 XIII. Nuclear Energy A. Three reasons why nuclear power plants were developed in the late 1950s: 1. Atomic Energy Commission promised electricity at a much lower cost than coal 2. US Gov’t paid ~1/4 the cost of building the first reactors 3. Price Anderson Act protected nuclear industry from liability in case of accidents

83 Gigawatts of electricity
375 300 225 Gigawatts of electricity 150 75 1960 1970 1980 1990 2000 2010 2020 Year Fig a, p. 348

84 Gigawatts of electricity
35 30 25 20 Gigawatts of electricity 15 10 5 1960 1970 1980 1990 2000 2010 Year Fig b, p. 348

85 Why is nuclear power on the decline?
B. Globally, nuclear energy produces only 17% of world’s electricity (6% of commercial energy) -huge construction overruns -high operating costs -frequent malfunctions -false assurances -cover-ups by government and industry -inflated estimates of electricity use -poor management -Chernobyl -Three Mile Island -public concerns about safety, cost and disposal of radioactive wastes

86 C. How a Nuclear Reactor Works
Nuclear fission of Uranium-235 and Plutonium-239 releases energy that is converted into high-temperature heat. This rate of conversion is controlled. The heat generated can produce high-pressure steam that spins turbines that generate electricity.

87 Small amounts of Radioactive gases Uranium fuel input (reactor core)
Containment shell Waste heat Electrical power Emergency core Cooling system Steam Control rods Useful energy 25 to 30% Turbine Generator Heat exchanger Hot coolant Hot water output Condenser Pump Pump Coolant Coolant passage Moderator Cool water input Black Pump Waste heat Pressure vessel Water Shielding Waste heat Water source (river, lake, ocean) Periodic removal and storage of radioactive wastes and spent fuel assemblies Periodic removal and storage of radioactive liquid wastes Fig , p. 346

88 Front end Back end Fuel assemblies Spent fuel assemblies Reactor
(conversion of enriched UF6 to UO2 and fabrication of fuel assemblies) Open fuel cycle today Prospective “closed” end fuel cycle Fuel fabrication Interim storage Under water Enriched UF6 Plutonium-239 as PuO2 Spent fuel assemblies Enrichment UF6 Spent fuel reprocessing Decommissioning of reactor Uranium-235 as UF6 High-level radioactive waste or spent fuel assemblies Conversion of U3O8 to UF6 Uranium tailings (low level but long half-life) Processed uranium ore Geologic disposal of moderate- and high-level radioactive wastes Uranium mines and mills Ore and ore concentrate (U3O8) Fig , p. 347 Front end Back end

89 D. Light-water reactors (LWR)
1. Core containing 35,000-40,000 fuel rods containing pellets of uranium oxide fuel. Pellet is 97% uranium-238 (nonfissionable isotope) and 3% uranium-235 (fissionable). 2. Control rods - move in and out of the reactor to regulate the rate of fission 3. Moderator - slows down the neutrons so the chain reaction can be kept going [ liquid water in pressurized water reactors; solid graphite or heavy water (D2O) ]. 4. Coolant - water to remove heat from the reactor core and produce steam

90 Decommissioning Power Plants
1/3 of fuel rod assemblies must be replaced every 3-4 years. They are placed in concrete lined pools of water (radiation shield and coolant). A. Nuclear wastes must be stored for 10,000 years B. After years of operation, the plant must be decommissioned by 1. dismantling it 2. putting up a physical barrier, or 3. enclosing the entire plant in a tomb (to last several thousand years)

91 Advantages Disadvantages
Large fuel supply High cost (even with large subsidies) Low environmental impact (without accidents) Low net energy yield High environmental impact (with major accidents) Emits 1/6 as much CO2 as coal Moderate land disruption and water pollution (without accidents) Catastrophic accidents can happen (Chernobyl) Moderate land use No acceptable solution for long-term storage of radioactive wastes and decommissioning worn-out plants Low risk of accidents because of multiple safety systems (except in 35 poorly designed and run reactors in former Soviet Union and Eastern Europe) Spreads knowledge and technology for building nuclear weapons Fig , p. 349

92 Coal Nuclear Ample supply Ample supply of uranium High net energy
yield Low net energy yield Low air pollution (mostly from fuel reprocessing) Very high air pollution High CO2 emissions Low CO2 emissions (mostly from fuel reprocessing) 65,000 to 200,000 deaths per year in U.S. About 6,000 deaths per year in U.S. High land disruption from surface mining Much lower land disruption from surface mining High land use Moderate land use Low cost (with huge subsidies) High cost (with huge subsidies) Fig , p. 349

93 F. Advantages of Nuclear Power:
1. Don’t emit air pollutants 2. Water pollution and land disruption are low

94 G. Nuclear Power Plant Safety
1. Very low risk of exposure to radioactivity 2. Three Mile Island - March 29, 1979; No. 2 reactor lost coolant water due to a series of mechanical failures and human error. Core was partially uncovered 3. Nuclear Regulatory Commission estimates there is a 15-45% chance of a complete core meltdown at a US reactor during the next 20 years. 4. US National Academy of Sciences estimates that US nuclear power plants cause 6000 premature deaths and 3700 serious genetic defects each year.

95 Chernobyl Crane for moving fuel rods Steam generator Cooling pond
Almost all control rods were removed from the core during experiment. Automatic safety devices that shut down the reactor when water and steam levels fall below normal and turbine stops were shut off because engineers didn’t want systems to “spoil” experiment. Crane for moving fuel rods Emergency cooling system was turned off to conduct an experiment. Steam generator Cooling pond Turbines Radiation shields Reactor Water pumps Reactor power output was lowered too much, making it too difficult to control. Additional water pump to cool reactor was turned on. But with low power output and extra drain on system, water didn’t actually reach reactor. Chernobyl Fig , p. 350

96 H. Low-Level Radioactive Waste
1. Low-level waste gives off small amounts of ionizing radiation; must be stored for years before decaying to levels that don’t pose an unacceptable risk to public health and safety : low-level waste was put into drums and dumped into the oceans. This is still done by UK and Pakistan 3. Since 1970, waste is buried in commercial, government-run landfills. 4. Above-ground storage is proposed by a number of environmentalists. : the NRC proposed redefining low-level radioactive waste as essentially nonradioactive. That policy was never implemented (as of early 1999).

97 I. High-Level Radioactive Waste
1. Emit large amounts of ionizing radiation for a short time and small amounts for a long time. Must be stored for about 240,000 2. Spent fuel rods; wastes from plants that produce plutonium and tritium for nuclear weapons.

98 J. Possible Methods of Disposal and their Drawbacks
1. Bury it deep in the ground 2. Shoot it into space or into the sun 3. Bury it under the Antarctic ice sheet or the Greenland ice cap 4. Dump it into descending subduction zones in the deep ocean 5. Bury it in thick deposits of muck on the deep ocean floor 6. Change it into harmless (or less harmful) isotopes 7. Currently high-level waste is stored in the DOE $2 billion Waste Isolation Pilot Plant (WIPP) near Carlsbad, NM. (supposed to be put into operation in 1999)

99 Up to 60 deep trenches dug into clay. As many as 20 flatbed trucks
deliver waste containers daily. Barrels are stacked and surrounded with sand. Covering is mounded to aid rain runoff. Clay bottom Fig b, p. 351

100 What covers waste Grass Topsoil Gravel Soil Compacted clay Sand Gravel
Fig c, p. 351

101 Waste container 2 meters wide 2–5 meters high Several steel drums
holding waste Steel wall Steel wall Lead shielding Fig a, p. 351

102 Storage Containers Fuel rod Primary canister Overpack container sealed
Fig c, p. 352

103 Underground Buried and capped Fig d, p. 352

104 Ground Level Unloaded from train Lowered down shaft
Fig a, p. 352

105 2,500 ft. (760 m) deep Personnel elevator Air shaft
Nuclear waste shaft Fig b, p. 352

106 K. Worn-Out Nuclear Plants
1. Walls of the reactor’s pressure vessel become brittle and thus are more likely to crack. 2. Corrosion of pipes and valves

107 3. Decommissioning a power plant (3 methods have been proposed)
A. immediate dismantling B. mothballing for years C. entombment (several thousand years) 4. Each method involves shutting down the plant, removing the spent fuel, draining all liquids, flushing all pipes, sending all radioactive materials to an approved waste storage site yet to be built.

108 Connection between Nuclear Reactors and the Spread of Nuclear Weapons
1. Components, materials and information to build and operate reactors can be used to produce fissionable isotopes for use in nuclear weapons. Los Alamos Muon Detector Could Thwart Nuclear Smugglers

109 M. Can We Afford Nuclear Power?
1. Main reason utilities, the government and investors are shying away from nuclear power is the extremely high cost of making it a safe technology. 2. All methods of producing electricity have average costs well below the costs of nuclear power plants.

110 N. Breeder Reactors 1. Convert nonfissionable uranium-238 into fissionable plutonium-239 2. Safety: liquid sodium coolant could cause a runaway fission chain reaction and a nuclear explosion powerful enough to blast open the containment building. 3. Breeders produce plutonium fuel too slowly; it would take years to produce enough plutonium to fuel a significant number of other breeder reactors.

111 O. Nuclear Fusion 1. D-T nuclear fusion reaction; Deuterium and Tritium fuse at about 100 million degrees 2. Uses more energy than it produces

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