Chapter 13: Energy
Fuel Cells 2000
American Wind Energy Association
Trade group for wind power providers.
http://www.awea.org/
OPEC
The Organization of the Petroleum Exporting Countries
http://www.opec.org/opec_web/en/
World Coal Institute
Coal trade association’s page about the environmental impacts of coal.
http://www.worldcoal.org/pages/content/index.asp?PageID=126
Digital Integration
Correlation to Global Environment Watch
Biofuel Energy Natural Gas Energy
Climate Change Nuclear Energy
Coal Energy Nuclear Waste
Correlation to Explore More
Batteries Coal Natural Gas
Biofuels Energy Nuclear Power
China Environmental History Water Pollution
Climate Change Fossil Fuels
Instructor’s Manual for Environmental Science, 15th edition
Suggested Answers to End of Chapter Questions
Answers will vary but these represent phrases from this chapter. The following are examples of the material
that should be contained in possible student answers to the end of chapter questions. They represent only a
Review
Core Case Study
1. Describe the potential for using renewable energy from the wind (wind power) to produce most of the
electricity used in the United States.
• Because wind is an indirect form of solar energy, relying more on wind is one way to apply the
solar energy principle of sustainability. Using wind to produce electricity has advantages and
Section 13-1
2. What is the Key Concept for this section? What is net energy yield and why is it important for
evaluating energy resources? Use the net energy concept to explain why some energy resources need
to be subsidized, and give an example of such a resource.
See pages 300-302.
• CONCEPT 13-1 Energy resources vary greatly in their net energy yields, the amount of high-
quality energy available from each resource minus the amount of energy needed to make it
available.
• The usable amount of high-quality, useful energy available from a given quantity of an energy
resource is its net energy yield: the total amount of useful energy available from an energy
resource minus the energy needed to make it available to consumers.
• T he net energy yield for any source of energy is calculated by estimating the total amount of
Chapter 13: Energy
Section 13-2
3. What is the Key Concept for this section? What is the earth’s main source of energy? What are three
forms of indirect solar energy? What is commercial energy and where does most of it come from in the
world and in the United States? What is crude oil (petroleum) and how is it extracted from the earth?
Define peak production for an oil well or field. What is refining? What are petrochemicals and why are
they important? What are proven oil reserves? Describe the process of removing tightly held oil and
natural gas through horizontal drilling and hydraulic fracturing, or fracking. What three countries have
the world’s largest proven oil reserves and what three countries are the largest users of oil? What
percentage of the world’s proven oil reserves do the United States and China have? Summarize the
story of oil production and consumption in the United States. What are the major advantages and
disadvantages of using crude oil as an energy resource? What is shale oil and how is this heavy oil
produced? What are tar sands, or oil sands? What is bitumen, and how is it extracted and converted to
heavy oil? What are the major advantages and disadvantages of using shale oil and heavy oils
produced from tar sands as energy resources?
See pages 302-312.
• CONCEPT 13.2 Oil, natural gas, and coal are currently abundant and relatively inexpensive, but
using them causes air and water pollution, degrades large areas of land, and releases climate–
changing greenhouse gases to the atmosphere.
• The energy that heats the earth and makes it livable for us comes from the sun.
• Three forms of indirect solar energy are: wind (moving air masses heated by the sun, flowing
water (made possible by solar energy, which evaporates water that returns to the earth as rain and
flows in rivers), and biomass (solar energy converted to chemical energy and stored in the tissues
of trees and other plants that can be burned as a source of energy).
Instructor’s Manual for Environmental Science, 15th edition
• Figure 13–8 lists the advantages and disadvantages of using heavy oils from oil shale and tar sand
as energy resources. Advantages include: large potential supplies, easy transportation within and
between countries, and efficient distribution system in place. Disadvantages include: low net
energy yield, releases CO2 and air pollutants when produced and burned. and severe land
disruption and high water use.
4. Define natural gas, liquefied petroleum gas (LPG), and liquefied natural gas (LNG). What are two
sources of unconventional natural gas? What two countries are the world’s largest producers of natural
gas and what two countries are the world’s largest users of natural gas? Describe the potential for
greatly increasing natural gas production in the United States by fracking. List four problems that have
resulted from this trend. What are the major advantages and disadvantages of using natural gas as an
energy resource? What is coal, how is it formed, and how do the various types of coal differ? How
does a coal-burning power plant work? What three countries are the largest producers of coal and what
two countries are the largest users of coal? Explain why there is no such thing as clean coal.
Summarize the major environmental and health problems caused by the use of coal. What are the
major advantages and disadvantages of using coal as an energy resource?
Natural gas is a mixture of gases of which 50–90% is methane (CH4).
• Natural gas is a mixture of gases of which 50–90% is methane (CH4). Conventional natural gas
lies above most reservoirs of crude oil.
• When a natural gas field is tapped, propane and butane gases are liquefied and removed as
liquefied petroleum gas (LPG). LPG is stored in pressurized tanks for use mostly in rural areas not
served by natural gas pipelines.
Chapter 13: Energy
holds, such wells could be producing 50% of the country’s natural gas by 2040, up from 30% in
2012.
• Problems of fracking:
o Fracking requires enormous volumes of water
Leaks of methane, along with exhaust fumes from heavy truck traffic and electrical generators on fracking
sites, have raised local levels of air pollution.
• Figure 13–11: advantages and disadvantages of using conventional natural gas as an energy
resource. Advantages include ample supplies, high net energy yield, and emits less CO2 and air
pollutants than other fossil fuels. Disadvantages include low net energy yield for LNG, releases
CO2 and air pollutants when burned and difficult and costly to transport from one country to
another.
• Coal is a solid fossil fuel formed from the remains of land plants that were buried 300–400 million
years ago and exposed to intense heat and pressure over those millions of years
• Figure 13-16: advantages and disadvantages of using coal as an energy resource. Advantages
harmful chemicals in coal ash waste ponds have contaminated groundwater used by 63
communities in 26 U.S states. In 2009, the EPA estimated that there are 44 coal ash waste ponds
in several states that are highly hazardous.
• There is no such thing as clean coal because:
o Air pollution resulting from inadequate regulation of coal-burning power and industrial
Section 13-3
5. What is the Key Concept for this section? How does a nuclear fission reactor work and what are its
major safety features? Describe the nuclear fuel cycle. Explain how highly radioactive spent fuel rods
are stored and what risks this presents. How has the United States dealt with the nuclear waste
problem? What can we do with worn-out nuclear power plants? What would the nuclear industry have
to do in order to play an effective role in slowing projected climate change during this century?
Summarize the arguments of experts who disagree over the future of nuclear power. What is the
relationship between nuclear power plants and the spread of nuclear weapons? What are five criteria
that any new design for a nuclear power plant should meet, according to some analysts? Describe the
Fukushima Daiichi nuclear power plant accident and its effects on the environment. What is nuclear
fusion and what is its potential as an energy resource?
Instructor’s Manual for Environmental Science, 15th edition
• CONCEPT 13-3 Nuclear power has a low environmental impact and a very low accident risk, but
its use has been limited by a low net energy yield, high costs, fear of accidents, long-lived
radioactive wastes, and the potential for spreading nuclear weapons technology.
• Nuclear power plants have several levels of safety features.
o Control rods are moved in and out of the reactor core to absorb neutrons, thereby
regulating the rate of fission and amount of power produced.
o A coolant, usually water, circulates through the reactor’s core to remove heat, and this
• The nuclear fuel cycle includes the mining of uranium, processing and enriching the uranium to
make fuel, using it in a reactor, safely storing the resulting highly radioactive wastes for thousands
of years until their radioactivity falls to safe levels and retiring the highly radioactive plant by
taking it apart and storing its high- and moderate-level radioactive material safely for thousands of
years.
• After 3–4 years in a reactor, spent fuel rods are removed and stored in a deep pool of water
contained in a steel-lined concrete basin (left) for cooling. After about 5 years of cooling, the fuel
rods can be stored upright on concrete pads (right) in sealed dry-storage casks made of heat-
resistant metal alloys and concrete. The intensely radioactive waste storage pools and dry casks
are vulnerable to sabotage or terrorist attack. Most of these pools and casks are located outside of
reactor buildings and thus are not protected nearly as well as the reactor core is from accidents or
acts of terrorism.
• After 25 years of research and testing, and over $8 billion of U.S. government (taxpayer) subsidy
payments, no scientifically and politically acceptable site for such storage has been established in
the United States. Meanwhile these deadly wastes are building up.
• Scientists have proposed three ways to safely store high-level radioactive materials from worn-out
nuclear plants for thousands of years.
o
One strategy is to store the highly radioactive parts in a permanent, secure repository,
which so far, no country has built and tested.
Chapter 13: Energy
• Some claim nuclear power will help reduce the U.S. dependence on imported crude oil. Others say
that it will not do so because oil-burning power plants provide only about 1% of the electricity in
most other countries that use nuclear power.
• Nuclear power advocates contend that increased use of nuclear power will greatly reduce or
eliminate CO2 emissions and, reduce atmospheric warming. However, building a plant emits large
amounts of CO2, and every other step in the nuclear power fuel cycle involves CO2 emissions. For
nuclear power to play an effective role in slowing projected climate change over the next 50 years,
the world would need to build some 2,000 nuclear reactors, or one about every 2 weeks. Typically,
it takes a decade or more to build a nuclear power plant at a cost of up to $10 billion.
• Opposition to Nuclear Power.
o The nuclear power industry could not exist without support from governments and
taxpayers, because of the extraordinarily high costs and the low net energy yield of the
nuclear fuel cycle. The U.S. government has provide huge subsidies, tax breaks, and loan
guarantees, as well as accident insurance guarantees, because insurance companies have
refused to fully insure any nuclear reactor.
• Support for Nuclear Power.
o Governments should continue funding research, development, and pilot-plant testing of
potentially safer and less expensive second-generation reactors.
o Hundreds of new advanced light-water reactors (ALWRs) could be build in just a few
years. ALWRs have built-in safety features designed to make explosions and releases of
• A major accident occurred on March 11, 2011, at the Fukushima Daiichi Nuclear Power Plant on
the northeast coast of Japan. A strong offshore earthquake that caused a severe tsunami (see Figure
12.19, p. 000) devastated coastal communities and triggered the worst nuclear accident since the
Chernobyl explosion in 1986. An immense wave of seawater washed over the nuclear plant’s
protective seawalls and knocked out the circuits and backup diesel generators of the emergency
core cooling systems for three of the reactors. Then, explosions (presumably from the buildup of
hydrogen gas) blew the roofs off three of the reactor buildings and released radioactivity into the
Instructor’s Manual for Environmental Science, 15th edition
Section 13-4
6. What is the Key Concept for this section? What is energy efficiency? What percentage of the energy
used in the United States is unnecessarily wasted? Briefly describe two widely used energy-inefficient
technologies. What are the major benefits of improving energy efficiency? Define and give an example
of cogeneration. List three other ways to save energy and money in industry. How could an energy
efficient smart electrical grid help us to save energy and money? List three ways to save energy and
money in transportation. Explain why the true cost of gasoline is much higher than what consumers
pay at the pump. Distinguish among hybrid, plug-in hybrid, all-electric, and fuel-cell motor vehicles.
Summarize the story of the search for better batteries. List four ways to save energy and money (a) in
new buildings, and (b) in existing buildings. List three ways in which you can save energy and money.
Give three reasons why we are still wasting so much energy and money.
• CONCEPT 13-4 Improving energy efficiency could save the world at least a third of the energy it
uses, and it could save the United States up to 43% of the energy it uses.
• Energy efficiency is the measure of how much work we can get from each unit of energy we use.
• Roughly 84% of all commercial energy used in the United States is wasted.
• Two widely used devices waste large amounts of energy unnecessarily:
o The internal combustion engine, which propels most motor vehicles and wastes about 80% of
the energy in its fuel.
Chapter 13: Energy
• A smart grid would use smart meters to monitor the amount of electricity used and the patterns of
use for each customer then use this information to deliver electricity as efficiently as possible.
Smart meters would show consumers how much energy they are using by the minute and for each
appliance which would help them reduce their power consumption.
• The price of gasoline does not include hidden costs such as government subsidies and tax breaks
for oil companies, car manufacturers and road builders; costs of pollution control and cleanup;
costs of military protection of oil supplies in the Middle East; time wasted in traffic jams; and
costs of illness from air and water pollution in the form of higher medical bills and health
insurance premiums.
• Hybrids use more than one form of power. A plug-in hybrid electric vehicle is a hybrid with a
second and more powerful battery that can be plugged into a conventional electrical outlet and
recharged.
• Fuel-cell motor vehicles use hydrogen gas as fuel to produce electricity.
• Reasons for high levels of energy waste in the world:
o Energy resources such as fossil fuels and nuclear power are artificially cheap, primarily
Section 13-5
7. What is the Key Concept for this section? List four reasons for why renewable energy is not more
widely used than it is. Distinguish between passive solar heating and active solar heating systems and
discuss the major advantages and disadvantages of such systems for heating buildings. What are three
ways to cool houses naturally? Define solar thermal systems and give an example of a centralized
system and a smaller-scale system. List the major advantages and disadvantages of using centralized
systems. What is a solar cell (photovoltaic or PV cell) and what are the major advantages and
disadvantages of using such devices to produce electricity?
• CONCEPT 13.5 By using a mix of renewable energy resources, we can satisfy our energy needs
while drastically reducing pollution, greenhouse gas emissions, and biodiversity.
• First, since 1950, government tax breaks, subsidies, and funding for research and development of
renewable energy resources have been much lower than those for fossil fuels (especially oil) and
Instructor’s Manual for Environmental Science, 15th edition
• Three ways to keep cool:
o Block the high summer sun with window overhangs or awnings.
o Use a light-colored roof to reflect as much as 80% of the sun’s heat (compared to only 8% for
a dark colored roof).
o Use geothermal heat pumps for cooling (and heating in winter).
• Advantages and disadvantages of using solar energy to generate high-temperature heat and
8. Define hydropower and summarize the potential for expanding it. What are the major advantages and
disadvantages of using hydropower to produce electricity? What is the potential for using tides and
waves to produce electricity? Summarize the potential for using wind power (a) globally, and (b) in the
United States. What are the major advantages and disadvantages of using wind to produce electricity?
What is biomass and what are the major advantages and disadvantages of using it to provide heat and
electricity? What are the major advantages and disadvantages of using biodiesel fuel and ethanol to
power motor vehicles? What is geothermal energy and what are three major sources of such energy?
What are the major advantages and disadvantages of using geothermal energy as a source of heat and
to produce electricity? List the major advantages and disadvantages of using hydrogen as a fuel. Why
is it important to compare the various methods of producing hydrogen gas?
• Hydropower is any technology that uses the kinetic energy of flowing or falling water to produce
electricity. It is an indirect form of solar energy because it depends on the evaporation of water,
which is deposited as rain or snow at higher elevations where it can flow to lower elevations in
rivers as part of the earth’s solar-powered water cycle.
Chapter 13: Energy
systems needed when winds are low, visual pollution, noise when located near populated areas,
and can kill birds and bats if not properly designed and located.
• (Burning solid biomass as a fuel has advantages and disadvantages. Advantages include: widely
available in some areas, moderate costs, no net CO2 increase if harvested, burned and replanted
sustainably, and plantations can help restore degraded lands. Disadvantages include can lead to
deforestation, increases CO2 emissions if not harvested and burned sustainably, clear cutting can
cause soil erosion, water pollution and loss of wildlife habitat, and some biomass plants can be
invasive species.
• Advantages and disadvantages of using liquid biofuels. Advantages include: reduced CO2
emissions for some crops, high net energy yield for oil palm crops, and moderate net energy yield
for ethanol from sugarcane. Disadvantages include: fuel crops compete with growing food on
cropland, low net energy yield for corn ethanol and biodiesel from soybean, and higher CO2
emissions from corn ethanol.
• Biofuels have three major advantages over gasoline and diesel fuel produced from oil.
o First, while oil resources are concentrated in a small number of countries, biofuel crops
• Disadvantages of large-scale biofuel crop farming include:
o decrease biodiversity by increasing the clearing of natural forests and grasslands
o increase soil degradation, erosion, and soil nutrient loss
o push small farmers off their land
o raise food prices if food producers can make more money growing corn and other crops
to fuel cars rather than to feed livestock and people
• Biofuels are renewable resources. Ethanol made from sugarcane yields 8 times the amount of
energy used to produce it—compared with a net energy ratio of 5 for gasoline. Use of ethanol
could enable a country such as Brazil to eliminate all oil imports. In the United States, most
ethanol is made from corn. Farmers profit from growing corn to produce ethanol because they
Instructor’s Manual for Environmental Science, 15th edition
Section 13-6
9. What is the Key Concept for this section? List three of the general conclusions of energy experts with
regard to possible energy futures. List five major strategies recommended by such experts for making
the transition to a more sustainable energy future.
• CONCEPT 13-6 We can make the transition to a more sustainable energy future by greatly
improving energy efficiency, depending more on a mix of renewable energy resources, and
including the environmental costs of energy resources in their market prices.
• Three general conclusions of experts who have evaluated energy alternatives:
o There will likely be a gradual shift from large, centralized power systems such as current
coal and nuclear power plants to smaller, decentralized power systems such as wind
• Governments can use three strategies to help stimulate or reduce the short-term and long-term use
of a particular energy resource.
o
First, they can keep the prices of selected energy resources artificially low to encourage
use of those resources. They do this by providing research and development subsidies,
tax breaks, and loan guarantees to encourage the development of those resources, and by
enacting regulations that favor them.
Chapter 13: Energy
availability, advantages, disadvantages, and hidden environmental costs of various energy
resources.
10. What are this chapter’s three big ideas? Explain how we can apply each of the six principles of
sustainability in working to make a transition to a more sustainable energy future.
• Here are this chapter’s three big ideas:
o
We should evaluate energy resources on the basis of their potential supplies, how much
net energy they provide, and the environmental impacts of using them.
o
Using a mix of renewable energy sources—especially solar, wind, flowing water,
sustainable biofuels, and geothermal energy—can drastically reduce pollution, greenhouse
gas emissions, and biodiversity losses.
o
Making the transition to a more sustainable energy future will require sharply reducing
energy waste, using a mix of environmentally friendly renewable energy resources, and
including the harmful environmental costs of energy resources in their market prices.
Critical Thinking
1. Suppose that a developer has proposed building a wind farm near where you live (Core Case Study).
Would you be in favor of the project or opposed to it? Write a letter to your local newspaper or a blog
for a website explaining your position and your reasoning. Include the concept of net energy yield in
your arguments. As part of your research, determine how the electricity you use now is generated and
where the power plant is located, and include this information in your arguments..
Answers will vary but could include:
2. Should governments give a high priority to considering net energy yields when deciding what energy
resources to support? What are other factors that should be considered? Which factor or factors should
get the most weight in decision-making? Explain your thinking.
3. Some analysts argue that in order to continue using oil at the current rate, we must discover and add to
global oil reserves the equivalent of two new Saudi Arabian reserves every 7 years. Do you think this
is possible? If not, what effects might the failure to find such supplies have on your life and on the
lives of any children and grandchildren that you might eventually have?
Answers will vary due to the inherent uncertainty of the question. Even if it is possible to discover and
4. During much of the time since the beginning of the Industrial Revolution, the United States and
European nations fueled their economic growth by burning coal, with little effort to control the resulting
air pollution. Eventually, as they became more affluent, they established air pollution standards and
sought cleaner energy sources. Now China, which has been fueling its rapid economic growth largely by
burning coal, says it is being asked to shift to cleaner energy resources before it becomes affluent
enough to do so. Do you think this is a fair expectation? Explain.
There may be a range of answers to this question depending on personal perspectives. One potential
5. List five ways in which you unnecessarily waste energy during a typical day, and explain how these
actions violate the three scientific principles of sustainability.
People unnecessarily waste energy by having too many lights on in the home both during the day and
6. What do you think should be the top three energy resources? Explain. What do you think should be the
three least-used energy resources? Explain.
Answers will vary but one possible answer is:
The top three energy sources should be renewable. Different geographic areas favor different solutions,
7. Explain why you would support or oppose each of the following proposals made by various energy
analysts:
a. Government subsidies for all energy alternatives should be eliminated so that all energy choices can
compete on a level playing field in the marketplace.
b. All government tax breaks and other subsidies for conventional fossil fuels, synthetic natural gas
and oil, and nuclear power (fission and fusion) should be eliminated. They should be replaced with
subsidies and tax breaks for improving energy efficiency and developing renewable energy
8. Congratulations! You are in charge of the world. List the five most important features of your energy
policy and explain why each of them is important and how they relate to each other.
Five important features of my energy policy would be: promote energy conservation and efficiency;
phase-out the use of wasteful energy appliances in the home; improve the mpg of all vehicles on the
road and encourage more people to drive hybrids and/or similar fuel efficient cars; ensure that all new
Global Environment Watch Exercise
Search the term fracking and find information on the use of fracking to produce oil and natural gas from
shale rock in the United States. Try to answer the following questions: (1) In what areas are fracking for
either fuel on the rise? (2) In one area of your choice, how many fracking wells have been drilled in the
past year? (3) In that area, how much fuel has been produced in the past year? (4) In that area, has there
been any opposition to the use of fracking? (5) Has the opposition, if any, resulted in any changes to the
process or to regulations over the process? (6) Is fracking projected to continue in your chosen area, and to
what extent? Write a report on your findings.
First step in the process is to identify prospective gas reserves in the ground and obtaining required permits
for gas well construction. These permits are regulated by state agencies and requirements to qualify for the
permit vary from state to state. Next step in the process is the drilling and casing of the well. In this
Instructor’s Manual for Environmental Science, 15th edition
Massive hydraulic fracturing uses millions of gallons of water per treatment, raising concerns of
creating or aggravating water shortages.
There are environmental concerns, including contamination of ground water, risks to air quality, the
potential migration of gases and hydraulic fracturing chemicals to the surface, the potential
Ecological Footprint Analysis
1. Suppose a car has an average fuel efficiency of 8.5 kpl (20 mpg) and is driven 19,300 kilometers
(12,000 miles) a year. (a) How many liters (and gallons) of gasoline does this vehicle consume in a
year? (b) If gasoline costs 80¢ per liter ($3.00 per gallon), how much will the owner spend on fuel in a
year? (c) How many liters (and gallons) and of gasoline would be consumed by a U.S. fleet of 250
million such vehicles in a year? (1 liter = 0.265 gallons and 1 kilometer = 0.621 miles)
(a) Gas consumption per year per vehicle:
19,300 kilometers/8.50 kilometers/liter = 2,270 liters
2. Recalculate the values in Question 1, assuming that a car has an average fuel efficiency of 19.6 kpl (46
mpg).
(a) Gas consumption per year per vehicle:
3. Determine the number of metric tons of CO2 emitted annually by (a) the car described in Question 1
with a low fuel efficiency, (b) a fleet of 250 million vehicles with this same fuel efficiency, (c) the car
described in Question 2 with a high fuel efficiency, and (d) a fleet of 250 million vehicles with this
same high fuel efficiency. These calculations provide a rough estimate of the carbon footprints for
individual cars and for the entire U.S. fleet with low and high efficiency cars. (1 kilogram = 2.20
pounds; 1 metric ton = 1,000 kilograms = 2,200 pounds = 1.1 tons; 1 ton = 2,000 pounds).
(a) CO2 emissions per car with low fuel efficiency:
2,270 liters x 2.4 kilograms CO2/liter = 5,448 kilograms CO2
4. If the average fuel efficiency of the U.S. fleet increased from 8.5 kpl (20 mpg) to 19.6 kpl (46 mpg), by
what percentage would this reduce the CO2 emissions from the entire fleet per year? You can think of
this as the percentage reduction in the carbon footprint of the U.S. motor vehicle fleet.