Chapter 12
Energy
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We are not only responsible for what we
do, but also for what we do not do.
–Moliere
12-2
CASE STUDY: Renewable Energy in China
12-3
12.1 Energy Resources and Uses
• Currently, fossil fuels
(petroleum, natural gas,
and coal) supply about
88% of the world’s
commercial energy
needs.
• The U.S. spends about
$400 billion every year
on imported oil.
12-4
How Do We Measure Energy?
12-5
Fossil Fuels Supply Most of
Our Energy
• Like most other
industrialized nations, the
U.S. gets a vast majority
of its energy from fossil
fuels.
• 20 richest countries
consume 80% of natural
gas, 65% of the oil, and
50% of the coal.
• Renewables make up
only 7% of U.S. power.
12-6
How Do We Use Energy?
• The largest share of the
energy used in the U.S.
is consumed by
industry.
• Residential and
commercial customers
use roughly 41%.
• Transportation
consumes the
remaining 28%
7
12.2 Fossil Fuels
• Fossil fuels are organic
(carbon-based) compounds
derived from decomposed
plants, algae, and other
organisms buried in rock layers
for hundreds of millions of
years.
12-8
Coal Resources Are Vast
• World coal deposits are vast, ten times greater than
conventional oil and gas resources combined.
• The total resource is estimated to be 10 trillion metric tons.
If all this coal could be extracted, this would amount to
several thousand years’ supply.
• But coal mining is a dirty, dangerous activity. Underground
mines are notorious for cave-ins, explosions, and lung
diseases, such as black-lung suffered by miners. Surface
mines leave huge holes where coal has been removed and
vast piles of discarded rock and soil.
12-9
Mountain Top Removal in Appalachia
12-10
Coal Burning Releases Huge
Amounts of Air Pollution
• Every year the roughly one billion tons of coal burned
in the U.S. releases close to a trillion metric tons of
carbon dioxide (CO2). This is about half of the
industrial CO2 released by the United States each year.
• Coal also contains toxic impurities, such as mercury,
arsenic, chromium, and lead, which are released into
the air during combustion.
12-11
New Plants Could Be Cleaner
12-12
Have We Passed Peak Oil?
• We have already used
more than half of all the
oil estimated on the
planet. almost half of
proven oil reserves.
• Competition has
already raised oil prices,
from around $15 per
barrel in 1993 to more
than $150 per barrel in
2008.
12-13
Domestic Oil Supplies are Limited
• The U.S. has used more than half of its
technically recoverable petroleum
resources.
• At 2010 rates of consumption, that’s
enough for about 4.2 years, if we were
to stop all imports. Opening the Arctic
National Wildlife Refuge to drilling
would only add enough for another 4–
10 months, according to the U.S.G.S.
• Other U.S. regions with potential for
new oil discoveries include the
continental shelf on the coast of
California, the Arctic Ocean, and the
Grand Banks.
14
Oil Shales and Tar Sands Contain
Huge Amounts of Petroleum
• The World Energy Council estimates that oil shales,
tar sands, and other unconventional deposits contain
ten times as much oil as liquid petroleum reserves.
• However, this costly, energy-intensive extraction only
becomes economically justified when oil prices rise
above about $50 per barrel.
• There are severe environmental costs, though. A
typical plant creates about 15 million m3 of toxic
sludge, releases 5,000 tons of greenhouse gases, and
consumes billions of liters of water each year.
12-15
Natural Gas is the World’s
Third Largest Commercial Fuel
• The total ultimately recoverable natural gas
resources in the world are estimated to be 10,000
trillion ft3. Current gas reserves represent roughly a
60-year supply at present usage rates.
• Because natural gas produces only half as much CO2
as an equivalent amount of coal, substitution could
help reduce global warming.
12-16
Special Refrigerated Ships Transport
Liquefied Natural Gas (LNG)
12-17
12.3 Nuclear Power
• In 1953 President Dwight Eisenhower presented his
“Atoms for Peace” speech to the United Nations.
• He announced that the United States would build
nuclear-powered electrical generators to provide
clean, abundant energy.
• Today there are about 440 reactors in use worldwide,
104 of these in the United States.
• Half of the U.S. plants (52) are more than 30 years
old and are thus approaching the end of their
expected operational life.
12-18
Nuclear Reactors in Southern California
12-19
How Do Nuclear
Reactors Work?
• Radioactive uranium
atoms are unstable—
that is, when struck by a
high-energy subatomic
particle called a
neutron, they undergo
nuclear fission
(splitting), releasing
energy and more
neutrons.
12-20
Pressurized Water Nuclear Reactor
12-21
We Lack Safe Storage for
Radioactive Waste
• One of the most difficult
problems associated with
nuclear power is the
disposal of wastes produced
during mining, fuel
production, and reactor
operation.
• How these wastes are
managed may ultimately be
the overriding obstacle to
nuclear power.
12-22
We Lack Safe Storage for
Radioactive Waste
• In 1987 the U.S. Department of Energy announced
plans to build the first high-level waste repository on a
barren desert ridge under Yucca Mountain, Nevada.
• President Obama cut off funding for the project in
2009 after 20 years of research and $100 billion in
exploratory drilling and development.
12-23
12.4 Energy Conservation
• Our ways of using energy are so inefficient that most
potential energy in fuel is lost as waste heat.
• Conservation involves technology innovation as well
as changes in behavior, but we have met these
challenges in the past.
• In 2010, however, the Obama administration
mandated an average fleet fuel efficiency of 35.5
mpg (14.6 km/l) for cars and light trucks by 2016.
12-24
Per Capita Energy Consumption in
the U.S. Since the 1950s
12-25
What Can You Do?
Steps to Save Energy and Money
1. Live close to work and school, or near transit routes, so you can minimize
driving.
2. Ride a bicycle, walk, and use stairs instead of elevators.
3. Keep your thermostat low in winter and high in summer. Fans are cheaper
to run than air conditioners.
4. Buy fewer disposable items; producing and shipping them costs energy.
5. Turn off lights, televisions, computers, and other appliances when not
needed.
6. Line-dry your laundry.
7. Recycle.
8. Cut back on meat consumption; if every American ate 20 percent less
meat, we would save as much energy as if everyone used a hybrid car.
9. Buy some of your food locally, to reduce energy in shipping.
12-26
Green Building Can Cut
Energy Costs by Half
12-27
12.5 Energy From Biomass
• Firewood is our original source of fuel. For more than
a billion people in developing countries, burning
biomass remains the principal energy source for
heating and cooking.
• In developed countries, where we depend on fossil
fuels for most energy, wood burning is a minor heat
source.
12-28
A Charcoal Market in Ghana
12-29
Power Generation from Wood Chips
12-30
Ethanol and Biodiesel can
Contribute to Fuel Supplies
• Biofuels, ethanol and biodiesel, are by far the biggest
recent news in biomass energy.
• Globally, production of these two fuels is booming,
from Brazil to Southeast Asia to the U.S. and Europe.
• Small amounts of ethanol have been added to
gasoline for years, but it takes about 3 to 5 liters of
water for every liter of fuel produced.
12-31
Effects on Food and
Environment are Uncertain
• Will biofuel production affect food costs? Yes, but
the seriousness of the problem depends on where
you look.
• In developing countries, more than 50% of
household income may be spent on food. Higher
costs of cooking oil and grain can be devastating for
family budgets.
• In Indonesia, conversion to oil palm plantations has
become an important threat to primary rainforest
habitat.
12-32
12.6 Wind and Solar Energy
• In China’s efforts to reduce dependence on fossil fuel
imports, wind power has been the principal focus.
• Relative to other alternative sources, wind is cheap
and available almost everywhere.
• Wind turbines have a small footprint, so they don’t
displace farming and other land uses.
• How people feel about a wind farm depends on their
views about energy alternatives, whether it earns
money for their community, and which particular
view is obstructed by the turbines.
12-33
U.S. Wind Resources by Region
12-34
Wind Energy is Our
Fastest Growing Renewable
• U.S. is the world leader of
installed wind generating
capacity.
• Wind farms are large
concentrations of wind
generators producing
commercial electricity.
• The key to making wind
energy successful is reliable
energy storage technology,
so we can grab it when it is
available and release it when
it is needed.
12-35
Solar Energy is Abundant
• The Sun is a giant nuclear furnace in space,
constantly bathing our planet with a free energy
supply.
12-36
Passive Solar Absorbs Heat;
Active Solar Pumps Heated Fluids
• Passive Solar uses thick adobe or stone walls to
absorb daytime heat and release it gradually at night.
• Active solar pumps a heat-absorbing fluid medium
through a relatively small collector and then transfers
the heat to create hot water or heat the air in the
home.
12-37
Concentrating Solar Energy
Generates Electricity
• Solar thermal energy can also be used to generate
electricity.
• Concentrating trough systems use long rows of
parabolic mirrors to heat a transfer fluid to
temperatures as high as 400°C.
• The hot liquid is pumped to a central plant, where it
heats water to produce steam that spins a turbine to
produce electricity.
12-38
Solar Thermal Electric Plant
in California Desert
12-39
Solar Thermal Electric
Plant Using Heliostats
12-40
Photovoltaic Cells Generate
Electricity Directly
• Photovoltaic cells capture solar energy and convert it
directly to electrical current
• Over the past 25 years, the efficiency of energy
captured by photovoltaic cells has increased from
less than 1% of incident light to more than 10%.
• New Amorphous silicon collectors can be made into
lightweight, paper-thin sheets that require much less
material than traditional crystalline silicon pv cells.
12-41
How a Photovoltaic Cell Operates
12-42
12.7 Water Power
• Much of the hydropower development since the
1930s has focused on enormous dams because of
their efficiency of size.
• Water power is only one-quarter of total electrical
generation.
12-43
Environmental Issues
• Flooding of large
tracts of land
• Dams block the
migration of fish,
such as salmon
• Sediment trapping
• Conversion of river
ecosystems to lakes
• Increased loss of
water to
evaporation
Unconventional Hydropower
Comes from Tides and Waves
• Ocean tides and waves also contain
enormous amounts of energy that
can be harnessed to do useful
work.
• A tidal station works like a
hydropower dam, with its turbines
spinning as the tide flows through
them. A high-tide/low-tide
differential of several meters is
required to spin the turbines.
• Unfortunately, variable tidal
periods often cause problems in
integrating this energy source into
the electric utility grid.
12-45
The Pelamis Wave-Power Generator Now in
Operation Off the Coast of Portugal
12-46
Geothermal Heat Could Supply
Substantial Amounts of Energy
• The Earth’s internal temperature can
provide a useful source of energy in
some places.
• This geothermal energy is expressed in
the form of hot springs, geysers, and
fumaroles.
• Iceland, which sits on a midocean
ridge, has abundant geothermal
energy.
• Iceland has ambitious plans to be the
first carbon-neutral country, largely
because the Earth’s heat provides
steam for heat and electric energy.
12-47
Geothermal Heat Pumps Can
Heat and Cool Efficiently
• While few places have
geothermal steam, the
Earth’s stable subsurface
temperatures can help
reduce energy costs
nearly everywhere.
• Pumping fluids through
deeply buried pipes can
exchange temperatures
with the soil to efficiently
heat or cool a home. 12-48
12.8 Fuel Cells
• Fuel cells are devices
that use ongoing
electrochemical
reactions to produce an
electrical current.
12-49
Fuel Cells in Long Island, NY
12-50
Utilities are Promoting Renewable Energy
• Utility restructuring currently being planned in the
U.S. could include policies to encourage conservation
and alternative energy sources. Among the proposed
policies are:
– (1) “distributional surcharges” in which a small tax is levied
on all utility customers to help finance renewable energy.
– (2) “renewables portfolio” standards to require power
suppliers to obtain a minimum percentage of their energy
from sustainable sources.
– (3) green pricing that allows utilities to charge premium
prices for energy from renewable sources.
12-51
Potential Renewable Energy Mix
for a Typical Day in California
12-52
Practice Quiz
1. Where is Rizhao, and how does it supply its energy
needs?
2. Define energy, power, and kilowatt-hour (kWh).
3. What are the major sources of global commercial
energy?
4. How does energy consumption in the United States
compare to that in other countries?
5. Why don’t we want to use all the coal in the ground?
12-53
Practice Quiz
6. Where is most liquid oil located? How long are
supplies likely to last?
7. What are tar sands and oil shales? What are the
environmental costs of their extraction?
8. How are nuclear wastes now being stored?
9. Explain active and passive solar energy.
10.How do photovoltaic cells work?
12-54