Fossil Fuels
• The remains of ancient organisms
that changed into coal, oil, or natural
gas
• Provide most of the energy used
today
• 2 main problems
• Supply is limited
• Obtaining and using them causes
environmental problems
Fuels for Different Uses
• Used for 5 main purposes:
•
•
•
•
•
Cooking
Transportation
Manufacturing
Heating & cooling buildings
Generating electricity to run machines &
appliances
• Suitability of a fuel for each
application depends on the fuel’s
energy content, cost, availability &
safety, and the byproducts of the
fuel’s use
Electricity – Power on Demand
• Energy in fuels is often converted
into electrical energy in order to
power machines because electricity
is more convenient to use
• Can be transported quickly across long
or short distances
• Disadvantages of electricity:
• Difficult to store
• Other energy sources have to be used to
generate it
How is Electricity Generated?
• Electric generator: converts
mechanical energy (motion) into
electrical energy
• convert the movement of a turbine into
electrical energy
• Uses a turbine (wheel that changes the
force of a moving gas or liquid into energy
that can do work)
• water is heated by burning a fuel (coal,
gas) or by fission of uranium (in nuclear
plants) to produce steam to that turns the
turbine
• The turbine spins a generator to produce
electricity
Energy Use in the U.S.
• People in developed societies use
much more energy than people in
developing countries do
• The U.S. uses more energy per
person than any other country in the
world except Canada & the United
Arab Emirates
• Uses more than 25% of its energy
resources to transport goods & people
(trucks & personal vehicles)
• Residents of U.S. & Canada have some
of the lowest gasoline taxes
Energy Use in the U.S.
World Energy Use
How Fossil-Fuel Deposits Form
• Coal
• Forms from the remains of plants that lived in
swamps hundreds of millions of years ago
• Much of the coal in the eastern U.S. formed
about 320 million to 300 million years ago
• Formation of coal:
• As ocean levels rose & fell, swamps were covered
with sediment
• Layers of sediment compressed the plant remains
• Heat & pressure within the Earth’s crust caused coal
to form
• Oil & Natural Gas
• Result from the decay of tiny marine
organisms that accumulated on the bottom of
the ocean millions of years ago
Coal
• Two major advantages of coal
• Relatively inexpensive
• Needs little refining after it has
been mined
How Electricity is
Generated in the U.S.
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•
•
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•
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Coal:
Nuclear:
Natural Gas:
Hydroelectricity
Oil:
Other
50%
20%
18%
7%
3%
2%
Coal Mining & the
Environment
• Surface mining has a bigger effect
on the environment
• Toxic chemicals can leach into
nearby streams
• A lot of research focuses on 2
things:
• Developing better methods of locating
• Developing less damaging methods
Air Pollution
• Higher-grade coals produce more
heat and less pollution than lowergrade coal
• Sulfur is a major source of pollution
when coal is burned
• Clean-burning coal technology has
dramatically reduced air pollution in
the U.S.
Petroleum
• Oil that is pumped from the ground
(also called crude oil)
• Petroleum product: anything that is
made from crude oil
• Accounts for 45% of the world’s
commercial energy use
• Most of the world’s oil reserves are
in the Middle East
Steps in the Oil-Drilling
Process
• Exploration wells are drilled
• If oil can be extracted at a profitable
rate, wells are drilled
• Oil is transported to a refinery to be
converted into fuels & other
petroleum products
Environmental Effects of
Using Oil
• When petroleum fuels are burned, they
release pollutants
• Contribute to the formation of smog and
cause health problems
• Sulfur: a pollutant that contributes to acid
rain
• The carbon dioxide released may
contribute to global warming
• 2 things that have reduced air pollution
from cars in many areas:
• Emission regulations
• Technology (catalytic converters)
Natural Gas
• Provides 20% of the world’s
nonrenewable energy
• Methane (CH4)
• Has become more common to use
because it produces fewer pollutants
than burning other fossil fuels
Fossil Fuels & the Future
• Supply about 90% of the energy used in
developed countries
• Cost will likely increase as the demand for
energy resources increases
• Oil reserves: oil deposits that can be
extracted profitably at current prices using
current technology
• The relative cost of obtaining fossil fuels
influences the amount of fossil fuels that
we extract from the Earth