Energy Sources
Fossil Fuels
• Formed from the remains of organisms
that lived long ago
– Ex. oil, coal, and natural gas.
• Most of the energy we use comes from
fossil fuels.
– We use fossil fuels to run cars, ships, planes,
and factories and to produce electricity.
Fossil Fuels
• Two main problems with fossil fuels.
• Limited Supply
• Environmental consequences.
• Societies try to fix problems two ways:
– Explore alternatives to fossil fuels
– Develop better ways to use fossil fuels
Fossil Fuels
• Fuel is used for four main purposes:
• Transportation
• Manufacturing
• Heating and cooling buildings
• Generating electricity to run machines and appliances
• Different fuels are used for different purposes.
• The suitability of a fuel for each application
depends on the fuel’s energy content, cost,
availability, safety, and byproducts.
Fossil-Fuel Deposits
• Not distributed evenly
• Abundance of oil in Texas and Alaska
• Eastern United States produces more coal
than other areas.
• Differences result from the geologic history
of the areas.
How fossil fuel deposits form
• Coal forms from the remains of plants that lived
in swamps hundreds of millions of years ago.
• As ocean levels rose and fell, swamps were
repeatedly covered with sediment.
• Layers of sediment compressed the plant
remains, and heat and pressure within the
Earth’s crust caused coal to form.
• Much of the coal in the United States formed
about 300 to 250 million years ago.
How fossil fuel deposits form
• Oil and natural gas result from the decay of tiny
marine organisms that accumulated on the
bottom of the ocean millions of years ago.
• Remains were buried by sediments and then
heated until they became complex energy-rich
carbon molecules.
• Molecules move into porous rock formations
Coal
• Most of the world’s fossil-fuel reserves are
made up of coal.
• Coal is relatively inexpensive and needs
little refining after being mined (sulfur may
need to be removed).
• Asia and North America are particularly
rich in coal deposits.
Did you know?
• The United States produces about 20%, or 1.1 billion tons, of the world's coal supply—second only to China.
• Coal generates about half of the electricity used in the United States.
• More than 2 million acres of mined land have been reclaimed over the past 25 years—that's an area larger
than the state of Delaware.
• The United States has about a 245-year supply of coal, if it continues using coal at the same rate at which it
uses coal today.
• Montana is the state with the most coal reserves (119 billion tons). But Wyoming is the top coal-producing
state—it produced about 400 million tons in 2004.
• Texas is the top coal-consuming state. It uses about 100 million tons each year.
• The average coal miner is 50 years old and has 20 years of experience.
• Coal ash, a byproduct of coal combustion, is used as filler for tennis rackets, golf balls, and linoleum.
• U.S. coal deposits contain more energy than that of all the world's oil reserves.
• Each person in the United States uses 3.8 tons of coal each year.
4 types of coal
• Lignite
• soft
• contains a lot of moisture and breaks apart easily
• contains the least amount of carbon
• used mainly at electricity-generating plants
• Subbituminous
• medium-soft
• less moisture than lignite
• used to produce steam for electricity generation
• found mostly in the western United States and
Alaska
4 Types of Coal cont.
• Bituminous
• medium-hard
• contains very little moisture
• high heat value
• used to generate electricity and to produce coke—a coal
residue used in the steel industry
• Bituminous coal is the most plentiful type in the United States
• Anthracite
• hard
• highest carbon content
• burns slowly
• makes a good heating fuel for homes
• most can be found in Pennsylvania.
Coal and the Environment
Underground mining can have a minimal
effect on the environment at the surface
Surface coal-mining operations sometimes
remove the top of an entire mountain to
reach the coal deposit.
Coal
• Dirtiest of all fossil fuels
• Emissions result in
– Acid rain
– Global warming
– Polluted water
Underground Mining
• Include drift, slope, and shaft mining
– Drift mines enter horizontally into the side of a
hill.
– Slope mines usually begin in a valley bottom,
and a tunnel slopes down to the coal to be
mined.
– Shaft mines a vertical shaft with an elevator is
made from the surface down to the coal.
Surface Mining
• Include area, contour, mountaintop removal,
and auger mining.
– Area mines remove shallow coal over a broad
area where the land is fairly flat.
– Contour mines pull coal from steep, hilly, or
mountainous terrain.
Surface Mining
– Mountaintop removal mines are used where
several thick coal seams occur near the top of
a mountain. The top of the mountain is
removed.
– Auger mines are operated on surface-mine
benches. The coal in the side of the hill that
can't be reached by contour mining is drilled
(or augured) out.
Clean-burning Coal Technology
• Coal washing
– Mixes crushed coal with liquid, impurities settle out
• Scrubbers
– Control the emissions of sulfur and nitrogen
– Limestone and water in flue becomes gypsum—part
of drywall
• Carbon Capture
– Capture CO2 and store it in rocks or under the ocean
floor
• Gasification
– Avoids burning coal, uses the vapors to turn the
turbine
Oil
• Oil has many nicknames:
– Dinosaur juice
– Devil’s blood
– Earth’s blood
– Black gold
Petroleum/Crude Oil
• Petroleum is a liquid mixture of
hydrocarbons.
• Petroleum, aka crude oil.
• Petroleum accounts for 45% of the world’s
commercial energy use.
Oil
• Oil is found in and around major geologic
features, such as folds and faults, that trap oil as
it moves in the Earth’s crust.
• Most of the world’s oil reserves are in the Middle
East. Large deposits also exist in the United
States, Venezuela, the North Sea, Siberia, and
Nigeria.
• Geologists use many different methods to locate
the rock formations that could contain oil.
Oil
• Petroleum fuel releases pollutants when
burned.
– contribute to smog and cause health
problems.
• Carbon dioxide released from burning
petroleum fuels contributes to global
warming.
Oil
• Oil spills from tankers are potential
environmental problems
• More oil pollution comes from everyday
sources—leaking cars.
• Measures to reduce everyday sources lag
behind the efforts to prevent large spills.
Oil
• No large oil reserves have been discovered in
the past decade.
• Geologists predict that oil production from land
will peak in about 2010.
• Additional oil reserves exist under the ocean, but
it is expensive to drill for oil in the deep ocean.
• Currently, oil platforms can be built to drill for oil
in the ocean, but much of the oil in the deep
ocean is currently inaccessible.
Octane in Gasoline
• Check the owner’s
manual of your car to
see which grade of
gasoline is
appropriate.
• The numbers: 87, 89,
91 refer to the
amounts of slow
burning octane present
in the gasoline.
• Branched octane
burns slower than
linear octane.
World Energy Use
• Other countries, such as Japan and
Switzerland, depend on extensive rail
systems and are smaller, compact
countries
• Residents of the United States and
Canada enjoy some of the lowest gasoline
taxes in the world. There is little incentive
to conserve gasoline when cost is so low.
Natural Gas
• About 20% of the world’s nonrenewable
energy comes from natural gas.
• Natural gas, or methane (CH4), produces
fewer pollutants than other fossil fuels
when burned.
• Electric power plants can also use this
clean-burning fuel.
Natural Gas Reserves
Electricity
• Because electricity is more convenient to use,
the energy in fuel is often converted before
used.
• Electricity can be transported quickly across
great distances.
– This makes it a good source of power for computers,
light switches, and more.
• Two disadvantages of electricity
– Difficult to store
– Other energy sources have to be used to generate it.
Electricity
• Move a piece of wire next to a magnet and
electricity is produced
• Why not let the wind or water do the work
for you?
– Windmills
– Hydroelectric dams
Nuclear Power
• Today, nuclear power accounts for 17% of
the world’s electricity.
Nuclear Power
• Nuclear power plants get their power from nuclear
energy.
– 1 lb. of highly enriched uranium is equal to about a million
gallons of gasoline
• Nuclear energy is the energy released by a fission or
fusion reaction. It represents the binding energy of the
atomic nucleus.
• The forces that hold together a nucleus of an atom are
more than 1 million times stronger than the chemical
bonds between atoms.
• Uranium-235 is the fuel.
Uranium
• Uranium-238 is present on Earth in fairly
large quantities.
– U-238 makes up 99 percent of the uranium on
Earth
• Uranium-235 makes up about 0.7 percent
of the remaining uranium found naturally.
Uranium
• Uranium-238 must be enriched so that it
contains 2 to 3 percent more U-235.
– Three-percent enrichment is ok for nuclear
power plants
– Weapons-grade uranium has at least 90
percent U-235.
Fission
• Nuclear fission is the splitting of the nucleus of a
large atom into two or more fragments.
• The nuclei of uranium atoms are bombarded
with atomic particles called neutrons. These
collisions cause the nuclei to split.
• Nuclear fission releases a tremendous amount
of energy and more neutrons, which in turn
collide with more uranium nuclei.
Fission
Fusion
• One possible future energy source is nuclear
fusion.
• Nuclear fusion is the combination of the nuclei
of small atoms to form a larger nucleus. Fusion
releases tremendous amounts of energy.
• It is potentially a safer energy source than
nuclear fission is because it creates less
dangerous radioactive byproducts.
Fusion
Fusion
• Although the potential for nuclear fusion is great, so is
the technical difficulty of achieving that potential.
• For fusion to occur, three things must occur
simultaneously:
• Atomic nuclei must be heated to extremely high temperatures
(about 100,000,000ºC or 180,000,000ºF).
• The nuclei must be maintained at very high conditions.
• The nuclei must be properly confined.
• The technical problems are so complex that building a
nuclear fusion plant may take decades or may never
happen.
Nuclear Power
• The heat released during nuclear
reactions is used to generate electricity in
the same way that power plants burn fossil
fuels to generate electricity.
Nuclear Power
Advantages of Nuclear Power
• Concentrated energy source.
• Does not produce air-polluting gases.
• Countries with limited fossil-fuel resources
can use nuclear plants to supply
electricity.
Disadvantages of Nuclear Power
• Building and maintaining a safe reactor is
very expensive.
– Makes nuclear plants no longer competitive
with other energy sources in many countries.
• Mining and purifying uranium is not a very
clean process.
• Transporting nuclear fuel to and from
plants poses a contamination risk.
Disadvantages of Nuclear Power
• Finding a safe place to store nuclear
waste.
– Storage sites for nuclear wastes must be
located in areas that are geologically stable
for tens of thousands of years.
Nuclear Waste
• Ave. nuclear waste= 20 metric tons a year
classified as high-level radioactive
waste.
• Nuclear power plants produce a great deal
of low-level radioactive waste
– radiated machinery
Nuclear Waste
• High level waste will decay to safe
levels—takes thousands of years
• Low-level radioactive waste—hundreds of
years
Dangers
• The Chernobyl reactor was destroyed in
1986 when an unauthorized test blasted
radioactive materials into the air.
• Hundreds of people in the Ukraine died
from radioactive exposure.
• Contaminated from this disaster remains.
Danger
• Nuclear accident in the US occurred in
1979 at the Three Mile Island nuclear
power plant in Pennsylvania.
– Human error, along with blocked valves and
broken pumps