Earth’s Resources

Chapter 4

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

Fossil Fuels

• Any hydrocarbon that may be used as a source of energy

– Coal, oil, natural gas1. Coal – forms when heat and pressure transform

plant material over millions of years. a. Stages:

i. Peatii. Ligniteiii. Bituminous coaliv. anthracite

Coal Continued

b. Uses:a. Power plantsb. Enormous

reserves

c. Disadvantagesa. Surface mining -

scars landb. Underground

mining - dangerous

c. Burning – produces sulfuric acid

Coal in the United States

Petroleum and Natural Gas

• Form from remains of plants and animals that were buried in ancient seas

• Steps:1. Large # of plants & animals buried in ocean-floor

sediments2. Continual sediment build-up causes organic

remains to transform into petroleum and natural gas

3. Oil and gas move into nearby rock beds4. Less dense than water – so migrate upwards

through water-filled spaces

Petroleum and Natural Gas

5. Oil trap – structure that allows large amounts of fluid to accumulate– Anticline –

uparched series of sedimentary rock layers

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

Oil Shale• Oil Shale – rock that

contains waxy mixture of hydrocarbons called kerogen

• Processes:1. Can be mined and heated

to vaporize kerogen2. Vapor processed to remove

impurities

– Disadvantages:– Heat energy 1/8 that of

crude oil– More expensive to mine,

process, and dispose of

Formation of Mineral Deposits

• Ore – useful metallic mineral that can be mined at a profit– Natural

concentration of many minerals is small

Mineral Resources and Igneous Processes

• Igneous Processes produce deposits of:– Gold– Silver– Copper– Mercury– Lead– Platinum– Nickel

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

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

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

Alternate Energy Sources

• Solar Energy• Nuclear Energy• Wind Energy• Hydroelectric Energy• Geothermal Energy• Tidal Power

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

Nuclear Energy

• Fuel for nuclear plants comes from radioactive materials that release energy through nuclear fission:

1. Heavy atoms bombarded with neutrons;2. split into smaller nuclei and emit neutrons and heat

energy3. Produces a chain reaction

– Energy drives steam turbines that turn electrical generator

Nuclear Energy• Obstacles:

1. Cost of building safe facilities2. Hazards associated with disposal of nuclear wastes3. 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

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 50-60 years: 5-10% of country’s demand

• Needs:– technical advances– Noise pollution– Cost of land

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

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

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

Renewable Energy

• Some of the renewable energies we will look at:– Biomass– Wind– Hydroelectric– Solar– Geothermal

• Which is the most advantageous???...