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Lecture Presentation
Chapter 17
Capturing Energy
Bradley Sieve
Northern Kentucky University
Highland Heights, KY
© 2014 Pearson Education, Inc.
17.1 Electricity Is a Convenient Form
of Energy
• Electricity can easily be transported to
many sites
– The energy originates in other forms of energy
– Losses are associated with the transfer
of types
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17.1 Electricity Is a Convenient Form
of Energy
• Electricity
– Flow of electric charge
– Generated when a metal wire is moved
through an electric field
• Electric Generator
– Armature—loops of wire wrapped around
an iron core
– Turbine—paddle wheel that turns
the armature
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17.1 Electricity Is a Convenient Form
of Energy
© 2014 Pearson Education, Inc.
17.1 Electricity Is a Convenient Form
of Energy
• Steam Turbines
– Use steam to turn the turbine and produce
the electricity
– Boiling the water requires an energy source
• Gas Turbines
– Driven by combustion products
– Require energy for the combustion reaction
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Concept Check
Is electricity more accurately thought of as a
source of energy or as a carrier of energy?
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Concept Check
Electricity is energy that is readily
transported through wires. In this sense, it is
best thought of as a carrier of energy. The
energy of electricity is used to run a
lightbulb, true, but the source of this energy
is not the electricity. Rather, the electricity is
merely delivering the energy that was
generated by some electric generator, which
received energy from some nonelectric
source, such as a fossil fuel or a waterfall.
© 2014 Pearson Education, Inc.
17.1 Electricity Is a Convenient Form of
Energy
• Power
– The rate electrical energy is expended
– Measured in watt, 1 watt = 1 joule/second
– Average house uses 800 watts
– Peak usage is much higher
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17.1 Electricity Is a Convenient Form of
Energy
Sources of Power in the United States
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17.2 Fossil Fuels Are Widely Used but
Limited Fuel Source
• Fossil Fuels
– Are a nonrenewable energy source
• Some types may be depleted in 100 years
– Are available in many regions of the world
– Gram for gram store more chemical energy
than other sources
– Are portable and make excellent fuels
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17.2 Fossil Fuels Are Widely Used but
Limited Fuel Source
• Gases from fossil fuels have negative
environmental effects and are
– Acid rain sources
– Components of smog
– Causes of global warming
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17.2 Fossil Fuels Are Widely Used but
Limited Fuel Source
• Fossil fuels exhibit many physical phases
– Coal is a solid
– Petroleum (crude oil) is a liquid
– Natural gas is a gas
• The different phases allow for a wide
variety of uses and transport methods
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17.2 Fossil Fuels Are Widely Used but
Limited Fuel Source
• Methane Hydrate
– Methane gas captured in frozen water
– Found in the ocean floor
– No shortage of this material but difficult
to extract
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17.2 Fossil Fuels Are Widely Used but
Limited Fuel Source
• Coal
– Energy available is estimated 10 times larger
than petroleum and natural gas
– Filthiest fossil fuel due to materials contained
within the solid
– Burning of coal releases sulfur dioxide,
nitrogen oxides, and carbon dioxide
– Provides 45% of electric power in the
United States
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17.2 Fossil Fuels Are Widely Used but
Limited Fuel Source
• Extracting coal is harmful to humans and
the environment
– Underground mines are dangerous to miners
– Strip mining destroys the entire ecosystem in
the area
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17.2 Fossil Fuels Are Widely Used but
Limited Fuel Source
• Minimizing Environmental Impact
– Flotation—separating impurities from coal by
using density differences
– Scrubber—capturing the by-products of
combustion as they are released
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Concept Check
What is the major advantage of using coal
as an energy source?
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Concept Check
Coal is relatively abundant, which means it
can be used as an energy source for many
years to come.
© 2014 Pearson Education, Inc.
17.2 Fossil Fuels Are Widely Used but
Limited Fuel Source
• Petroleum
– Liquid form of fossil fuels allowing for easy
transport and storage
– Contains all of the commercially important
hydrocarbons for many different fuels
– Contains fewer impurities than coal
– Used to produce organic chemicals
and polymers
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17.2 Fossil Fuels Are Widely Used but
Limited Fuel Source
• Natural Gas
– Burns cleaner than petroleum and coal
– Must be stored in storage tanks
– Difficult to transport and isolate
– Produces less carbon dioxide than other
forms of fossil fuels
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Concept Check
Of the three forms of fossil fuels, which is
most abundant worldwide? Which burns
most cleanly? Which is easiest to transport?
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Concept Check
Coal is the most abundant. Because it
contains few impurities, natural gas burns
most cleanly. Because it is a liquid,
petroleum is easiest to transport.
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17.3 Issues of the Nuclear Industry
• Two Forms of Nuclear Energy
– Fission is the splitting apart of large nuclei
– Fusion is the combining of two small nuclei
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17.3 Issues of the Nuclear Industry
• Nuclear Fission
– Used in commercial energy production since
the 1950s
– Produces roughly 20% of electrical energy
– Worldwide about 436 fission reactions
are used
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17.3 Issues of the Nuclear Industry
• Expanded use of nuclear energy can
reduce dependence on fossil fuels
• Nuclear energy plants do not release
atmospheric waste but do produce
nuclear wastes
• This nuclear waste must be stored in a
safe location
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17.3 Issues of the Nuclear Industry
• Nuclear energy plants also pose the
risk of releasing nuclear waste into
the environment
– Three Mile Island in 1979
– Chernobyl meltdown in 1986
– Fukushima reactors in 2011
• Design of the facility has a large
effect on the overall damage to
the environment
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Concept Check
What is the major disadvantage of nuclear
fission as an energy source?
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Concept Check
Nuclear fission reactors generate large
amounts of radioactive wastes that require
permanent large-scale storage facilities.
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17.4 What Are Sustainable Energy Sources
• Sustainable Energy Source
– Ideally is an inexhaustible source along with
being environmentally benign
– Ultimate sustainable source is the Sun
– Other astronomical sources include
• Warm interior of Earth
• Tidal forces
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Concept Check
What is a sustainable energy source?
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Concept Check
A sustainable energy source has the
potential to be available indefinitely. The
technologies that take advantage of these
sources should be environmentally benign.
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17.5 Water Can Be Used to Generate
Electricity
• Hydroelectric Power
– Power from the kinetic energy of flowing water
– One example is a hydroelectric dam
• Supplies 10% of energy in the
United States
• 2400 dams of the roughly 80,000 dams are
outfitted to produce electricity
• Many are built with inefficient technology by
today’s standards
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17.5 Water Can Be Used to Generate
Electricity
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17.5 Water Can Be Used to Generate
Electricity
• Drawbacks to Hydroelectric Dams
– No pollutants released, but local
environments are affected
– Flow of traffic blocked in the waterway
– Buildup of silt behind the dam
– Downstream cropland can be lost
– Upstream flooding occurs
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17.5 Water Can Be Used to Generate
Electricity
• Ocean Thermal Energy Conversion (OTEC)
– Uses differences in water temperature to
create electricity
– Low-boiling liquid is vaporized and pushes
a turbine
– Condenses when exposed to cooler water
– Limited to regions where large differences in
water temperature occur
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17.5 Water Can Be Used to Generate
Electricity
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17.5 Water Can Be Used to Generate
Electricity
• Geothermal Energy
– Energy from the Earth’s interior
– Hydrothermal energy uses this energy to
pump hot water or steam from the ground
– Energy costs are competitive to fossil fuels
– Disadvantages include emission of
pollutants, disposal of extracted waters,
and geological effects of withdrawing water
in unstable regions
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17.5 Water Can Be Used to Generate
Electricity
© 2014 Pearson Education, Inc.
17.5 Water Can Be Used to Generate
Electricity
• Tidal Power
– Use of ocean tides to create power
– Tidal waters move through a dam,
creating power
– Large-scale prospects are not good due to
limited locations and destruction of the sites
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Concept Check
Of the forms of water power discussed in
this section, which are solar in origin? Which
is lunar? Which is derived from the Earth’s
hot interior?
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Concept Check
The energy obtained from dams, from ocean
thermal energy conversion, and from a
geothermal heat exchanger is solar because
they all involve water’s being warmed by the
Sun. Tidal energy is lunar, and other forms
of geothermal energy are derived from the
Earth’s hot interior.
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17.6 Biomass Is Chemical Energy
• Biomass
– The energy contained within plant material
– Methods to use the energy
• Produce transportable fuels from the material
• Burn it at a power plant
– Biomass power generation if carbon-neutral
• Amount of carbon dioxide is equal growing and
burning it
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17.6 Biomass Is Chemical Energy
• Fuels from Biomass
– Ethanol has a higher octane rating than
gasoline and was once the preferred fuel
for cars
– Cars running on pure ethanol (E100) do
not add extra carbon dioxide than is used
in growing the biomass
– Ethanol is relatively expensive due to
gasoline price being held artificially low
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17.6 Biomass Is Chemical Energy
• Ethanol Sources
– Corn
• Primarily in the United States
• 49 billion liters produced in 2010
– Sugar cane
• Primarily in Brazil
• 28 billion liters produced in 2010
– Ideal material is cellulose found in all plants
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17.6 Biomass Is Chemical Energy
• Biomass can be burned
– Higher efficiency than when changing into
a fuel
– Most sources are wood and wood waste
– Cities experimenting with burning solid waste
– Energy is used to produce steam and turn a
traditional turbine
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Concept Check
What do biomass and fossil fuels have
in common?
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Concept Check
They both originate from solar energy.
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17.7 Energy Can Be Harnessed from
Sunlight
• Solar Heat
– Easily collected to heat water
– 15% of energy use is for heating water
– Water can then be used for washing
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17.7 Energy Can Be Harnessed from
Sunlight
• Solar Thermal Electric Generation
– Producing electricity from sunlight
– Heats a material that is then used to create
steam when needed
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17.7 Energy Can Be Harnessed from
Sunlight
• Wind Power
– Widely available and cheap
– Wind turbine turns in the wind to
create electricity
– Costs have been lowering over the years
– 239 gigawatts of capacity worldwide
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17.7 Energy Can Be Harnessed from
Sunlight
• Drawbacks to Wind Power
– Power generation is located far from largest
power needs
– Aesthetic issues for some people
– Hazards for wildlife, especially birds
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Concept Check
What do fossil fuels have in common with
the various forms of direct solar energy
just discussed?
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Concept Check
They all originate with the Sun.
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17.7 Energy Can Be Harnessed from
Sunlight
• Photovoltaics
– Convert sunlight directly to electricity
– Most direct manner to convert sunlight to
electrical energy
– Cost of electricity is tied to equipment cost
– Minimal maintenance and no water needed
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17.8 Solar Energy Can Be Stored as
Hydrogen
• Hydrogen is an ideal fuel
– Most energy per weight of all fuels
– Readily produced from water, which can be
run off solar power
– Burns cleanly, emitting only water vapor
– Easily transported through pipelines
– Can be used to power automobiles
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Concept Check
Why does the combustion of hydrogen
produce no carbon dioxide?
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Concept Check
There is no carbon with which to form
carbon dioxide. Hydrogen is an ideal fuel
that, when burned, produces almost nothing
but water vapor—no carbon dioxide, no
carbon monoxide, and no particulate matter.
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17.8 Solar Energy Can Be Stored as
Hydrogen
• Fuel Cells
– An efficient means to produce electricity
– Roughly 60% efficiency compared with
34% in coal-fired power plants
– One potential H source is treatment of coal
– Coal not burned directly creates
fewer pollutants
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17.8 Solar Energy Can Be Stored as
Hydrogen
• Photovoltaic Cells
– Can produce hydrogen directly from water
using sunlight
– 60% efficiencies are expected from research
– Materials are still being optimized for
the process
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17.8 Solar Energy Can Be Stored as
Hydrogen
• Distributed versus current centralized
energy sources
– Photovoltaic and wind turbines can be
distributed to points of use
– Avoids losses due to transport of the fuel
– Supplement current utilities to meet the everincreasing demand
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17.8 Solar Energy Can Be Stored as
Hydrogen
• Drawbacks to Hydrogen
– Fossil fuels will likely be the primary source
of hydrogen
– Major breakthroughs are need to make the
process cost effective
– Concentrating on hydrogen technologies may
leave other alternatives underfunded
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17.8 Solar Energy Can Be Stored as
Hydrogen
• Putting Things in Perspective
– Nearly 25% of all power plants will need major
renovations within the next few years
– Population growth and emerging nations are
demanding more and more energy
– Energy conservation and improved
technologies are helping
– Controlling population growth is likely easier
than providing electricity and basic needs
for everyone
© 2014 Pearson Education, Inc.
17.8 Solar Energy Can Be Stored as
Hydrogen
© 2014 Pearson Education, Inc.