1. Earth’s Resources
Chapter 4

2. Energy and Mineral Resources
Renewable – replenished over fairly short time spans (months, years, decades)
Plants, animals, natural fibers trees, water, wind, sun
Nonrenewable – takes millions of years to form and accumulate
Coal, oil, natural gas, iron, copper, uranium, gold

3. Fossil Fuels Any hydrocarbon that may be used as a source of energy
Coal, oil, natural gas
Coal – forms when heat and pressure transform plant material over millions of years.
Stages:
Peat
Lignite
Bituminous coal
anthracite

4. Coal Continued Uses: Disadvantages Power plants Enormous reserves
Surface mining - scars land
Underground mining - dangerous
Burning – produces sulfuric acid

5. Coal in the United States

6. Petroleum and Natural Gas
Form from remains of plants and animals that were buried in ancient seas
Steps:
Large # of plants & animals buried in ocean-floor sediments
Continual sediment build-up causes organic remains to transform into petroleum and natural gas
Oil and gas move into nearby rock beds
Less dense than water – so migrate upwards through water-filled spaces

7. Petroleum and Natural Gas
Oil trap – structure that allows large amounts of fluid to accumulate
Anticline – uparched series of sedimentary rock layers

8. Tar Sands
Tar sands – mixtures of clay and sand combined with water and black tar
Can be refined into oil
Disadvantages:
Causes huge land disturbance
Requires large amounts of water
Contaminated water and sediment accumulate in toxic disposal ponds

9. Oil Shale
Oil Shale – rock that contains waxy mixture of hydrocarbons called kerogen
Processes:
Can be mined and heated to vaporize kerogen
Vapor processed to remove impurities
Disadvantages:
Heat energy 1/8 that of crude oil
More expensive to mine, process, and dispose of

10. Formation of Mineral Deposits
Ore – useful metallic mineral that can be mined at a profit
Natural concentration of many minerals is small

11. Mineral Resources and Igneous Processes
Igneous Processes produce deposits of:
Gold
Silver
Copper
Mercury
Lead
Platinum
Nickel

12. Hydrothermal Solutions
Most form from hot, metal-rich fluids left during late stages of movement and cooling of magma
Examples:
Gold deposits in Homestake Mine, South Dakota
Lead, zinc, silver ores in Idaho

13. Placer Deposits
Formed when eroded heavy minerals settle quickly from moving water while less dense particles remain suspended and continue to move
Common sites: inside bends of streams, cracks, depressions
Sparked California gold rush

14. Nonmetallic Mineral Resources
All are used for specific chemical elements or compounds
Divided into two broad groups:
Building materials
Crushed stone, sand, and gravel)
Industrial minerals
Limestone
Not nearly as abundant
Require considerable processing before use

15. Alternate Energy Sources
Solar Energy
Nuclear Energy
Wind Energy
Hydroelectric Energy
Geothermal Energy
Tidal Power

16. Solar Energy
Direct use of the sun’s rays to supply heat or electricity
Two advantages
“fuel” is free
Non-polluting
Draw-backs
Equipment and installation is not free
Supplemental energy is needed on cloudy days, in winter, and at night
Example: Solar collector
Passive or active

17. Nuclear Energy
Fuel for nuclear plants comes from radioactive materials that release energy through nuclear fission:
Heavy atoms bombarded with neutrons;
split into smaller nuclei and emit neutrons and heat energy
Produces a chain reaction
Energy drives steam turbines that turn electrical generator

18. Nuclear Energy Obstacles: Cost of building safe facilities
Hazards associated with disposal of nuclear wastes
Possibility of a serious accident could allow radioactive materials to ascape
Three Mile Island; 1979
Substantial damage to reactor; little harm to public
Chernobyl; 1986
Reactor out of control; 10 days to put out fire
High levels of radioactive material as far as Norway

19. Wind Energy
Estimate – all winds of N. and S. Dakota could provide 80% electrical energy in U.S.
Wind turbines used to collect wind energy
Experiments by U.S. Department of Energy since 1980
Altamont Pass near San Fransisco
Next years: 5-10% of country’s demand
Needs:
technical advances
Noise pollution
Cost of land

20. Hydroelectric Power Drives turbines that produce electricity
Produce about 5% of the country’s electricity
Dams – allow for controlled flow of water
Water held in a reservoir behind a dam is a form of stored energy that can be released through the dam to produce electric power
Disadvantages:
Sediment is deposited behind dam and builds up – eventually fills reservoir
Availability of suitable sites

22. Geothermal Energy
Harnessed by tapping natural underground reservoirs of steam and hot water
Used directly for heating and to turn turbines to generate electric power
First one in U.S. built in 1960
Disadvantages
Clean, but not inexhaustible
Cannot be recharged

23. Tidal Power
Harnessed by constructing a dam across mouth of a bay or estuary in coastal areas with a large tidal range
Strong in-and-out flow that results drives turbines and electric generators
Is not economical if tidal range is too big or too small

24. Renewable Energy Some of the renewable energies we will look at:
Biomass
Wind
Hydroelectric
Solar
Geothermal
Which is the most advantageous???...