Chapter 19 Energy resources 19.1 Electricity is a convenient form of energy

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Chapter 19 Energy resources19.1 Electricity is a
convenient form of energy
electron
Metal ion
turbine
steam
armature
Energy source
Multiple wire loops
water
magnet
Fig 19.1 basic anatomy of an electric generator.
Electricity is generated in a looped wire as the
wire rotates through a magnetic field. This
motion causes electrons in the wire to slosh back
and forth. Because the electrons are moving, they
possess kinetic energy and so have the capacity
to do work
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19.2 Fossil fuels are a widely used but limited
energy source38 from petroleum, 30 from coal,
20 from natural gas
Former Soviet Union coal 23.4 petroleum 6.3
natural gas 38.7
North America coal 26.1 petroleum 6.2 natural
gas 5.0
Europe coal 12.4 petroleum 2.0 natural gas
3.5
Asia Pacific coal 29.7 petroleum 4.3 natural
gas 7.0
Africa coal 6.2 petroleum 7.2 natural gas 7.7
Middle East coal 6.2 petroleum 65.4 natural
gas 33.8
South and central America coal 2.2 petroleum
8.6 natural gas 4.3
Fig 19.2 fossil-fuel deposits are not distributed
evenly throughout the world, for instance, as
percent of the worlds recoverable petroleum
deposits are in the middle east, along with 34
percent of recoverable natural-gas deposits.
North America is relatively poor in petroleum and
natural gas but has a bit more than one-fourth of
the worlds supply of coal
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Natural gas
Coal
petroleum
Fig 19.3 typical molecular structure of coal,
petroleum and natural gas
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Coal is the filthiest fossil fuelCoal contains
sulfur, toxic heavy metals, and radioactive
isotopes.Extracting coal from the ground is
harmful to human health and to the
environment.The coal can be purified by
floatation (??).Sulfur dioxide produced from the
burning of coal can be removed by scrubber
(?????).
Scrubbed gas to atmosphere
Spray tower
CaCO3
CaSO4 to solid-waste disposal site
Effluents from coal-fired power plant containing
SO2
Fig 19.7 a scrubber is used to remove most of the
sulfur dioxide created when coal is burned
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• Petroleum is the king of fossil coal.
• Natural gas is the purest fossil fuel.
• Natural gas contains little amount of sulfur. It
  burns at lower temperature, producing less NO.
• The efficiency to generate electricity by using
  gas turbine can be as high as 47.
• Natural gas can be methane, which is safer, and
  propane.

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19.3 There are two forms of nuclear energy
(Nuclear fission, ???Nuclear fusion, ???)
Nuclear fission
Fig 19.11 nuclear fission involves the splitting
apart of large atomic nuclei. Nuclear fusion
involves the coming together of small nuclei
Nuclear fusion
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Nuclear fission generates some of our electricity
Fig 19.12 percentage of electricity generated
from nuclear fission reactors in selected
countries (April, 2001)
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Nuclear wastes Storage is a problem.AccidentThe
number of nuclear power station has been
decreasing.
Fig 19.14 in 1986, a meltdown occurred at this
nuclear power plant in Chernobyl, Ukraine.
Because there was no containment building, large
amounts of radioactive material were released
into the environment, three people died outright
and dozens more died from radiation sickness
within a few weeks . Thousands who were exposed
to high levels of radiation stand an increased
risk of cancer. Today, 10,000 square kilometers
of land remains contaminated with high levels of
radiation
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Nuclear fusion is a potential source of clean
energyMagnetic field and laser are used to the
fusion reaction.Cost to build the power station
is very high.
Fig 19.16 a fusion reactor called the Large
Helical Device is being built and tested by
researchers in Japan. These coils create a
magnetic field that contain the hot ionized gas
within which nuclear fusion takes place
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19.5 Water can be used generate
electricityHydroelectric power comes from the
kinetic energy of flowing waterTemperature
differences in the ocean can generate
electricityGeothermal energy comes from the
Earths interiorThe energy of ocean tides can be
harnessed
Fig 19.22 about 50 percent of the electricity
generated in iceland is from geothermal sources.
This is the blue lagoon, a warm pool created from
the effluent of the hydrothermal power plant
visible in the background
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19.6 Biomass is chemical energy
Fig 19.23 Gasohol is gasoline containing an
alcohol additive. The alcohol provides an octane
boost, allowing an engine to run more efficiently
with less pollution. If the alcohol is produced
from biomass grown within a nation, there is the
added benefit of a reduced dependence on foreign
oil
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19.7 Energy can be harnessed from sunlightSolar
energy can be easily collected.
Glass plate
Warm water
Black interior
Cold water
Fig 19.25 (a) a solar energy collector is covered
with glass to provide a greenhouse effect
sunlight passing into the box is converted to
infrared radiation, which cannot escape. (b)
most solar energy collectors are located on
rooftops. The collectors are painted black to
maximize the absorption of solar heat. The
rooftop collector shown here is used for warming
an outdoor swimming pool
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Wind power is cheap
Fig 19.29 about 4000 wind turbines at the
Tehachapi site in Southern California supply 626
megawatts of electricity
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Photovoltaics convert sunlight directly to
electricity
Arsenics extra valence electron
Borons missing valance electron
Fig 19.33 (a) the four valence electrons in a
silicon atom can form four bonds. The fifth
valence electron of arsenic is unable to
participate in bonding in the silicon lattice,
and so remains free. Silicon that contains trace
amounts of arsenic (or any other element whose
atoms have five valence electrons) is called
n-type silicon. (b) boron has only three valence
electrons for bonding with four silicon atoms.
One boron-silicon pair therefore lacks an
electron for covalent bonding. Silicon containing
trace amounts of boron (or any other elements
whose atoms have three valence electrons) is
called p-type silicon.
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p-type wafer
n-type wafer
Fig 19.36 sunlight is converted to electrical
energy as it pushes electrons through the
external wire from the n-type silicon to the
p-type silicon
sunlight
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• 19.8 Our future economy should be based on
  hydrogen
• Fuel cells produce electricity from fuel
• Photovoltaic cells can be used to produce
  hydrogen from water