Geologic Resources: Nonrenewable Mineral and Energy Resources Chapter 15 G. Tyler Miller’s Living in the Environment 13th Edition

Key Concepts Types of mineral resources Formation and location of mineral resources Extraction and processing of mineral resources Increasing supplies of mineral resources Major types, acquisition, advantages, and disadvantages of fuel resources

Nature and Formation of Mineral Resources Metallic Iron, copper, aluminum Ore - rock containing one or more metallic minerals Non-metallic Salt, clay, sand, phosphates, soil Energy Resources Coal, oil, gas, uranium Non-renewable

Nature and Formation of Mineral Resources Magma Igneous rock Hydrothermal processes Hydrothermal ore deposits Black smokers Manganese nodules Weathering and sedimentary sorting Residual deposits Placer deposits Evaporite mineral deposits Black smoker White smoker Sulfide deposit Magma White clam Tube worms White crab

Finding Nonrenewable Mineral Resources Satellite imagery Aerial sensors (magnetometers) Gravity differences (gravimeter) Core sampling Seismic surveys Chemical analysis of water and plants

Removing Nonrenewable Mineral Resources Surface mining Overburden Layer of soil and rock overlaying mineral deposits Spoils Unwanted rock and other materials in with ore Open pit Strip mining Mountain removal Dredging Surface Mining Control and Reclamation Act of 1977 Restore surface land like it was prior to mining. Levied tax on mining companies to restore land disturbed before the law was passed.

Open Pit Mine

Area Strip Mining

Contour Strip Mining

Mountain Top Removal

Removing Nonrenewable Mineral Resources Subsurface mining Room and pillar Longwall Disturbs less land area Produces less waste More dangerous and expensive

Environmental Effects of Mining, Processing, and Using Mineral Resources

Environmental Effects of Extracting (Mining) and Processing Mineral Resources Ore Ore mineral Desired metal Gangue Waste material Tailings Separated waste Smelting Fig. 15-7 p. 344

Environmental Effects of Using Mineral Resources Disruption of land surface 500,000 mines Subsidence Erosion of solid mining waste Acid mine drainage H2SO4 Air pollution Mining produces more toxic emissions than any other industry Storage and leakage of liquid mining waste

Supplies of Mineral Resources Economic depletion Costs more to find, extract, transport, and process the remaining deposit than it is worth (10%) Options Recycle or reuse Waste less Use less Find a substitute Do without Fig. 15-9 p. 346

Evaluating Energy Resources Renewable energy Non-renewable energy Future availability Net energy yield Cost Environmental effects Fig. 15-12 p. 351

Important Nonrenewable Energy Sources Fig. 15-10 p. 350

Oil Crude Oil oil as it comes out of the ground thick liquid consisting of combustible hydrocarbons small amounts of sulfur, oxygen, and nitrogen impurities only 35% of the oil out of an oil deposit “heavy crude oil”

Oil Refinery Separation based on boiling points Petrochemicals Fig. 15-18 p. 355 Separation based on boiling points Petrochemicals Raw materials used in manufacturing such as organic chemicals, pesticides, plastics, synthetic fibers, paints, medicines…..

North American Energy Resources Fig. 15-20 p. 356

World’s Oil Supplies Organization of Petroleum Exporting Countries (OPEC) 67% of the world’s oil reserves Saudi Arabia : 26% Kuwait, Iran, United Arab Emirates : 9-10% Latin America : 9% Africa : 7% Former Soviet Union : 6% Asia : 4% US : 3%

Oil (million barrels per day) 60 History History Projections Projections 50 Consumption 40 Net Imports Oil (million barrels per day) 30 20 Domestic supply 10 1970 1980 1990 2000 2010 2020 Year U.S. supply, consumption, and imports

Oil Shale and Tar Sands Oil shale Keragen Tar sand Bitumen Fig. 15-28 p. 361

Natural Gas 50-90% Methane Conventional natural gas Lies above crude oil reservoirs Unconventional natural gas Found by itself Methyl hydrate 200 year supply Fig. 15-29 p. 362

Important Nonrenewable Energy Sources Fig. 15-10 p. 350

Coal Stages of coal formation

Coal Fig. 15-30 p. 363

Coal Stages of coal formation Primarily strip-mined. Used most for generating electricity 21% of the world’s energy Enough coal for about 1000 years Coal is the world’s most abundant fossil fuel Highest environmental impact! Coal gasification and liquefaction may reduce impact.

Burning Coal More Cleanly Fluidized-Bed Combustion Fig. 15-32 p. 364

NUCLEAR POWER President Dwight Eisenhower, 1953, “Atoms for Peace”speech. Nuclear-powered electrical generators would provide power “too cheap to meter.” Between 1970 and 1974, American utilities ordered 140 new reactors for power plants.

Nuclear Power After 1975, only 13 orders were placed for new nuclear reactors, and all of those were subsequently cancelled. In all, 100 of 140 reactors on order in 1975 were cancelled. Construction costs, declining demand for electrical power, safety fears Electricity from nuclear power plants was about half the price of coal in 1970, but twice as much in 1990.

Nuclear Power Plant History

How Do Nuclear Reactors Work Most commonly used fuel is U235, a naturally occurring radioactive isotope of uranium. Occurs naturally at 0.7% of uranium, but must be enriched to about of 3%. Formed in cylindrical pellets (1.5 cm long) and stacked in hollow metal rods (4 m long). About 100 rods and bundled together to make a fuel assembly. Thousands of fuel assemblies bundled in reactor core.

How Do Nuclear Reactors Work When struck by neutrons, radioactive uranium atoms undergo nuclear fission (splitting) releasing energy and more neutrons. Triggers nuclear chain reaction.

Nuclear Fission

How Do Nuclear Reactors Work Reaction is moderated in a power plant by neutron-absorbing solution (Moderator). In addition, Control Rods composed of neutron-absorbing material are inserted into spaces between fuel assemblies to control reaction rate. Cadmium or boron Water or other coolant is circulated between the fuel rods to remove excess heat.

Kinds of Reactors Seventy percent of nuclear power plants are pressurized water reactors (PWR). Water circulated through core to absorb heat from fuel rods. Pumped to steam generator where it heats a secondary loop. Steam from secondary loop drives high-speed turbine producing electricity.

Kinds of Reactors Both reactor vessel and steam generator are housed in a special containment building preventing radiation from escaping, and providing extra security in case of accidents. Under normal operating conditions, a PWR releases very little radioactivity.

PWR

Small amounts of radioactive gases Uranium fuel input (reactor core) Small amounts of radioactive gases 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

Kinds of Reactors Simpler, but more dangerous design is a boiling water reactor (BWR). Water from core boils to make steam, directly driving turbine generators. Highly radioactive water and steam leave containment structure. Canadian deuterium reactors - Operate with natural, un-concentrated uranium. Graphite moderator reactors - Operate with a solid moderator instead of a liquid.

Alternative Reactor Designs High-Temperature, Gas-Cooled Reactors Uranium encased in tiny ceramic-coated pellets. Process-Inherent Ultimate Safety Reactors Reactor core submerged in large pool of boron-containing water within a massive pressure vessel.

Breeder Reactors Breeder reactors create fissionable plutonium and thorium isotopes from stable forms of uranium. Uses plutonium reclaimed from spent fuel from conventional fission reactors as starting material.

Breeder Reactors

Breeder Reactor Drawbacks Reactor core must be at very high density, thus liquid sodium used as a coolant. Corrosive and difficult to handle. Core will self-destruct within a few seconds if primary coolant is lost. Produces weapons-grade plutonium.

RADIOACTIVE WASTE MANAGEMENT Until 1970, the US, Britain, France, and Japan disposed of radioactive waste in the ocean. Production of 1,000 tons of uranium fuel typically generates 100,000 tons of tailings and 3.5 million liters of liquid waste. Now approximately 200 million tons of radioactive waste in piles around mines and processing plants in the US.

Radioactive Waste Management About 100,000 tons of low-level waste (clothing) and about 15,000 tons of high-level (spent-fuel) waste in the US. For past 20 years, spent fuel assemblies have been stored in deep water-filled pools at the power plants. (Designed to be “temporary”.) Many internal pools are now filled and a number plants are storing nuclear waste in metal dry casks outside.

Radioactive Waste Management US Department of Energy announced plans to build a high-level waste repository near Yucca Mountain Nevada in 1987. Facility may cost between $10 and 35 billion, and will not open until at least 2015.

Decommissioning Old Nuclear Plants Most plants are designed for a 30 year operating life. Only a few plants have thus far been decommissioned. General estimates are costs will be 2-10 times more than original construction costs.

CHANGING FORTUNES Public opinion has fluctuated over the years. When Chernobyl exploded in 1985, less than one-third of Americans favored nuclear power. Now, half of all Americans support nuclear-energy. Currently, 103 nuclear reactors produce about 20% of all electricity consumed in the US.

Changing Fortunes With natural gas prices soaring, and electrical shortages looming, many sectors are once again promoting nuclear reactors. Over the past 50 years, the US government has provided $150 billion in nuclear subsidies, but less than $5 billion to renewable energy research.

NUCLEAR FUSION Nuclear Fusion - Energy released when two smaller atomic nuclei fuse into one large nucleus. (Sun) Duterium and tritium, two heavy isotopes of H Temperatures must be raised to 100,000,000o C and pressure must reach several billion atmospheres. Advantages: Production of few radioactive wastes Elimination of products that could be made into bombs Fuel supply that is larger and less hazardous than uranium.

NUCLEAR FUSION Despite 50 years and $25 billion, fusion reactors have never produced more energy than they consume!

US Energy Policy Oil, coal, and natural gas remain the United States’ primary energy resources. Support the use of nuclear power as an environmentally friendly way to increase energy supplies.

Nuclear Energy Fission reactors Uranium-235 Potentially dangerous Fig. 15-35 p. 366 Uranium-235 Potentially dangerous Radioactive wastes Refer to Introductory Essay p. 338

The Nuclear Fuel Cycle Fig. 15-36 p. 367

Dealing with Nuclear Waste Low-level waste High-level waste Underground burial Disposal in space Burial in ice sheets Dumping into subduction zones Burial in ocean mud Conversion into harmless materials Fig. 15-40 p. 370

Nuclear Alternatives Breeder nuclear fission reactors Nuclear fusion New reactor designs Storage Containers Fuel rod Primary canister Ground Level Overpack container sealed Unloaded from train Personnal elevator Air shaft Nuclear waste shaft Underground Buried and capped Lowered down shaft Fig. 15-42 p. 376

Some Energy Units 1 joule (J) = force exerted by a current of 1 amp through a resistance of 1 ohm 1 watt (W) = 1 joule per second 1 kilowatt-hour = 1 thousand (103) watts exerted for 1 hour 1 megawatt (MW) = 1 million (106) watts 1 British Thermal Unit (BTU) = energy to heat 1 lb. of water 1 °F 1 standard barrel (bbl) of oil = 42 gal (160 l) or 5.8 million BTUs 1 metric ton of coal = 27.8 million BTU or 4.8 bbl oil