LIVING IN THE ENVIRONMENT, 18e
G. TYLER MILLER • SCOTT E. SPOOLMAN
15
Nonrenewable Energy
©©Cengage
CengageLearning
Learning2015
2015
Core Case Study: Is the United States
Entering a New Oil and Natural Gas Era?
• Oil and natural gas
– Two most widely used natural resources in
the U.S.
• Oil consumption is increasing
– New extractions from oil shale cause
environmental harm
– Burning oil and natural gas will continue
adding greenhouse gases to the atmosphere
© Cengage Learning 2015
Natural gas
28%
Nuclear power
8%
Coal
22%
Hydropower
3%
Oil
37%
Geothermal,
solar, wind
biomass
2%
Fig. 15-1a, p. 374
Fig. 15-1b, p. 374
15-1 What is Net Energy and Why Is It
Important?
• Energy resources vary greatly in their net
energy yields
© Cengage Learning 2015
Net Energy Is the Only Energy That Really
Counts
• Net energy yield
– Total amount of useful, high-quality energy
available from a resource minus the energy
needed to make the energy available to
consumers
– Related to:
• Energy return on investment (EROI)
– Energy obtained per unit of energy used to
obtain it
© Cengage Learning 2015
Net Energy Is the Only Energy That Really
Counts (cont’d.)
• First law of thermodynamics (law of
conservation of energy):
– It takes high-quality energy to get high-quality
energy
• Pumping oil from ground, refining it, and
transporting it
• Second law of thermodynamics (High
qualitylow quality)
– Some high-quality energy is wasted at every
step
© Cengage Learning 2015
Some Energy Resources Need Help to
Compete in the Marketplace
• An energy resource with a low or negative
net yield cannot compete in open markets
with alternatives that have higher net energy
yields
– Need subsidies from taxpayers
• For example: nuclear power
– Has a low net energy yield because a great deal
of high quality energy is needed
– The uranium fuel cycle is costly
– Heavily subsidized
© Cengage Learning 2015
15-2 What Are the Advantages and
Disadvantages of Oil?
• Conventional crude oil is abundant and
has a medium net energy yield, but using
it causes air and water pollution and
releases greenhouse gases to the
atmosphere
– Unconventional heavy oil from oil shale rock
and tar sands exists in potentially large
supplies but has a low net energy yield and a
higher environmental impact than
conventional oil
© Cengage Learning 2015
We depend heavily on oil
• Oil is the world’s most widely used energy
resource.
• Used to:
– heat our homes
– grow most of our food
– transport people and goods
– make other energy resources available for use
– manufacture most of the things we use everyday
from plastics to cosmetics to asphalt on roads.
© Cengage Learning 2015
We Depend Heavily on Oil
• Crude oil (petroleum)
– Black, gooey liquid consisting mostly of a mix of
different combustible hydrocarbons along with
small amounts of sulfur, oxygen, and nitrogen
impurities.
– Formed from decayed remains of ancient
organisms that were crushed beneath layers of
rock for millions of years.
– Oil companies use huge machines to drill holes
and remove rock cores to extract oil.
© Cengage Learning 2015
• Peak production –
– After a decade or so, the pressure in the well
drops and the oil production declines
– Global peak production for all world oil occurs
when conventional oil declines faster than new
oil field are found
• Crude oil cannot be used as it comes out of
the ground
– Must be refined into:
– Petrochemicals
© Cengage Learning 2015
Lowest Boiling Point
Gases
Gasoline
Aviation fuel
Heating oil
Diesel
oil
Naphtha
Grease and wax
Heated
crude oil
Furnace
Asphalt
Highest Boiling Point
Fig. 15-4a, p. 377
Fig. 15-4b, p. 377
Are We Running Out of Conventional Oil?
• How much oil is there?
• Availability determined by:
– 1.Demand
– 2.Technology
– 3. Rate at which we remove the oil
– 4. Cost of making oil available
– 5. Market price
• Proven oil reserves –
– available deposits from which oil can be
extracted
© Cengage
Learning 2015 profitably; not fixed.
Are We Running Out of Conventional Oil?
(cont’d.)
• To avoid running out of oil:
• 1. Use unconventional heavy oil
– Higher environmental cost; production cost
• 2. Rely on three major options:
– 1. Live with much higher oil prices
– 2. Extend oil supplies (for example, improve
vehicle efficiency)
– 3. Use other energy sources
© Cengage Learning 2015
Barrels of oil per year (billions)
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Projected U. S.
oil consumption
Arctic refuge oil output
over 50 years
Year
Fig. 15-5a, p. 379
© Cengage Learning 2015
Fig. 15-5b, p. 379
Use of Conventional Oil Has
Environmental Costs
• Land disruption, greenhouse gas
emission, air pollution, water pollution, and
loss of biodiversity
• Burning oil accounts for 43% of global CO2
emissions
© Cengage Learning 2015
Trade-Offs
Conventional Oil
Advantages
Disadvantages
Ample supply for
several decades
Water pollution from
oil spills and leaks
Net energy yield
is medium but
decreasing
Environmental costs
not included in
market price
Low land
disruption
Releases CO2 and
other air pollutants
when burned
Efficient
distribution
system
Vulnerable to
international supply
interruptions
© Cengage Learning 2015
Fig. 15-6, p. 380
Case Study: Oil Production and
Consumption in the United States
• The U.S.:
– Produces 9% of the world’s oil and uses 23%
of world’s oil
– Has about 2% of world’s proven oil reserves
– Imports 52% of its oil
• Should we look for more oil reserves?
– Extremely difficult
– Expensive and financially risky
© Cengage Learning 2015
Heavy Oil From Oil Shale Rock
• A potential supply of heavy oil is shale oil
• Oil shale rock contains kerogen that can be
distilled to produce shale oil
• 72% of the world’s reserve is in arid areas
of western United States
– Locked up in rock; requires lots of energy,
money, and water
– Lots of pollution, in air and water
– Low net energy yield
© Cengage Learning 2015
© Cengage Learning 2015
Fig. 15-7, p. 381
Heavy Oil from Tar Sands
• Another soil of heavy oil is tar sands, or oil
sands, which are a mixture of clay, sand,
water, and contains bitumen ( a thick, sticky,
tarlike heavy oil)
• Extensive deposits in Canada and
Venezuela
– Oil sands have more oil than in Saudi Arabia
• Problems with extraction
– Serious environmental impacts
– Low net energy yield
© Cengage Learning 2015
© Cengage Learning 2015
Fig. 15-8, p. 381
Trade-Offs
Heavy Oils from Oil Shale and Tar Sand
Advantages
Disadvantages
Large potential
supplies
Low net energy yield
Easily
transported
within and
between
countries
Releases CO2 and
other air pollutants
when produced and
burned
Efficient
distribution
system in place
Severe land disruption
and high water use
Fig. 15-10, p. 382
15-3 What Are the Advantages and
Disadvantages of Using Natural Gas?
• Conventional natural gas:
– Is more plentiful than oil
– Has a medium net energy yield and a fairly
low production cost
– Is a clean-burning fuel
• However, producing it has created
environmental problems
© Cengage Learning 2015
Natural Gas Is a Useful, Clean-Burning,
but Not Problem-Free Fossil Fuel
• Natural gas –
– mixture of gases, 50-90% methane CH4
– Medium net energy yield
– Widely used for cooking, heating space and
water, industrialized purposes
– Provides 28% of energy consumed in US
– Burns cleaner than oil and much cleaner than
coal.
© Cengage Learning 2015
• Conventional natural gas
– Often found in deposits above conventional oil,
as well as in shale rock.
– When a natural gas deposit is tapped, propane
and butane gases can be liquefied under high
pressure and removed as:
– 1. Liquefied petroleum gas (LPG)
• Stored in tanks
© Cengage Learning 2015
– 2. Liquefied natural gas (LNG)
• Way by which to transport across oceans
• Low net energy yield
© Cengage Learning 2015
Natural Gas Is a Useful, Clean-Burning,
but Not Problem-Free Fossil Fuel (cont’d.)
• The U.S. produces natural gas
conventionally and from shale rock
– US does not have to rely on natural gas
imports
– Increasing environmental problems with shale
rock extraction
© Cengage Learning 2015
Trade-Offs
Conventional Natural Gas
Advantages
Disadvantages
Ample supplies
Low net energy yield
for LNG
Versatile fuel
Production and
delivery may emit
more CO2 and CH4 per
unit of energy
produced than coal
Medium net
energy yield
Emits less CO2
and other air
pollutants than
other fossil fuels
when burned
Fracking uses and
pollutes large
volumes of water
Potential groundwater
pollution from fracking
Fig. 15-11, p. 383
Case Study: Natural Gas Production and
Fracking in the U.S.
• Fracking
– Drilling wells; using huge amounts of water,
sand, and chemicals; dealing with toxic
wastewater; transporting the natural gas
• Drinking water contaminated with natural
gas can catch fire
• Fracking has several harmful
environmental effects
© Cengage Learning 2015
© Cengage Learning 2015
Fig. 15-12, p. 384
© Cengage Learning 2015
Fig. 15-13, p. 385
Unconventional Natural Gas
• 1.Coal bed methane gas
– Found in coal beds near the earth’s surface;
in shale beds
– High environmental impacts of extraction
• 2. Methane hydrate
– Trapped in icy water; in permafrost
environments; on ocean floor
– Costs of extraction is currently too high
© Cengage Learning 2015
15-4 What Are the Advantages and
Disadvantages of Coal?
• Conventional coal is plentiful and has a
high net energy yield at low costs, but
using it results in a very high
environmental impact
– We can produce gaseous and liquid fuels
from coal, but they have lower net energy
yields and using them would result in higher
environmental impacts than those of
conventional coal
© Cengage Learning 2015
Coal Is a Plentiful but Dirty Fuel
• Coal
– 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
millions of years
• Burned in power plants
– Generates 42% of the world’s electricity
Abundant fossil fuel– world’s largest coal
reserves United States, Russia, China
© Cengage Learning 2015
Coal Is a Plentiful but Dirty Fuel (cont’d.)
• Environmental costs of burning coal
– Dirtiest of all fossil fuels
– Severe air pollution
• Sulfur released as SO2
• Large amount of soot
• CO2
• Trace amounts of mercury and radioactive
materials
© Cengage Learning 2015
Increasing moisture content
Peat
Lignite
(not a coal)
(brown coal)
Heat
Pressure
Partially decayed plant
matter in swamps and
bogs; low heat content
Increasing heat and carbon content
Bituminous
(soft coal)
Heat
Heat
Pressure
Low heat content; low
sulfur content; limited
supplies in most areas
Anthracite
(hard coal)
Extensively used as a
fuel because of its high
heat content and large
supplies; normally has
a high sulfur content
Pressure
Highly desirable fuel
because of its high heat
content and low sulfur
content; supplies are
limited in most areas
© Cengage Learning 2015
Fig. 15-14, p. 386
Waste heat
Coal bunker
Cooling tower
transfers waste
heat to
atmosphere
Turbine
Generator
Cooling
loop
Stack
Pulverizing
mill
Boiler
Condenser
Filter
Ash disposal
Fig. 15-15a, p. 387
Fig. 15-15b, p. 387
The Clean Coal Campaign
• To keep their profits, coal companies and
energy companies has fought:
– Classifying carbon dioxide as a pollutant
– Classifying coal ash as hazardous waste
– Air pollution standards for emissions
• The 2008 clean coal campaign
– Note: there is no such thing as clean coal
© Cengage Learning 2015
Coal-fired
electricity
286%
Synthetic oil and
gas produced
from coal
150%
Coal
100%
Tar sand
92%
Oil
86%
58%
Natural gas
Nuclear power
fuel cycle
Geothermal
17%
10%
© Cengage Learning 2015
Fig. 15-17, p. 388
Trade-Offs
Coal
Advantages
Disadvantages
Ample supplies in
many countries
Severe land
disturbance and
water pollution
Medium to high
net energy yield
Fine particle and
toxic mercury
emissions threaten
human health
Low cost when
environmental
costs are not
included
Emits large amounts
of CO2 and other air
pollutants when
produced and burned
© Cengage Learning 2015
Fig. 15-20, p. 389
We Can Convert Coal into Gaseous and
Liquid Fuels
• Conversion of solid coal to:
– Synthetic natural gas (SNG) by coal gasification
to remove sulfur and impurities from coal
– Methanol or synthetic gasoline by coal
liquefaction, synfuels, cleaner version of coal
• Are there benefits to using these synthetic
fuels?
– Eh…—requires mining of 50% more coal;
produces and burning synfuels leads to more
CO2 in atmosphere; lots of water; lots energy;
© Cengage Learning 2015
high cost for low yield
Trade-Offs
Synthetic Fuels
Advantages
Disadvantages
Large potential
supply in many
countries
Low to medium
net energy yield
Vehicle fuel
Lower air
pollution than
coal
Requires mining
50% more coal
with increased
land disturbance,
water pollution
and water use
Higher CO2
emissions than
coal
Fig. 15-21, p. 389
15-5 What Are the Advantages and
Disadvantages of Using Nuclear Power?
• 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, and long-lived radioactive wastes
– Its role in spreading nuclear weapons
technology
© Cengage Learning 2015
Nuclear Power Plant
• Nuclear Power Plant
– A highly complex and costly system designed
to perform a relatively simple task: to boil
water and produce steam that spins a turbine
and generates electricity.
© Cengage Learning 2015
How Does a Nuclear Fission Reactor
Work?
• Uses complex and costly controlled nuclear
fission reaction
• Takes place in a reactor
– Light-water reactors; Very inefficient
– Fueled by uranium ore and packed as pellets in
fuel rods and fuel assemblies in the core of a
reactor
– Control rods absorb neutrons generated in
fission, regulating the rate of fission and
amount o power produced
© Cengage Learning 2015
How Does a Nuclear Fission Reactor
Work? (cont’d.)
• Takes place in a reactor (continued)
– Water is the usual coolant; keeps components
from melting and releasing radioactivity into
the environment.
– Containment shell around the reactor core to
ensure radioactive materials do not escape
into the environment.
– Water-filled pools or dry casks for storage of
radioactive wastes and spent fuel rod
assemblies
© Cengage Learning 2015
Small amounts of
radioactive gases
Uranium fuel
input (reactor
core)
Control rods
Containment shell
Heat exchanger
Waste heat
Steam Turbine
Generator
Hot
coolant
Hot
water
output
Coolant
Cool
water
input
Moderator
Shielding
Pressure Coolant
vessel
passage
Periodic removal and
storage of
radioactive wastes
and spent
fuel assemblies
Periodic
removal and
storage
of radioactive
liquid wastes
Water
Useful electrical
energy
about 25%
Waste heat
Condenser
Water source
(river, lake, ocean)
Fig. 15-22a, p. 390
Fig. 15-22b, p. 390
What Is the Nuclear Fuel Cycle?
• 1. Mine the uranium
• 2. Process and enrich the uranium to
make the fuel
• 3. Use it in the reactor
• 4. Safely store the radioactive waste
• 5. Decommission the reactor
© Cengage Learning 2015
Decommissioning
of reactor
Fuel assemblies
Enrichment
of UF6
Reactor
Fuel fabrication
(conversion of enriched UF6
to UO2 and fabrication of
fuel assemblies)
Conversion
of U3O8
to UF6
Uranium-235 as UF6
Plutonium-239 as
PuO2
Temporary storage
of spent fuel
assemblies underwater
or in dry casks
Spent fuel
reprocessing
Low-level radiation
with long half-life
Mining uranium
ore (U3O8)
Open fuel cycle today
Recycling of nuclear fuel
Geologic
disposal of
moderate
and high-level
radioactive
wastes
Fig. 15-23, p. 392
Trade-Offs
Conventional Nuclear Fuel Cycle
Advantages
Disadvantages
Low environmental
impact (without
accidents)
Low net energy yield
Emits 1/6 as
much CO2 as coal
Produces long-lived,
harmful radioactive
wastes
Low risk of
accidents in
modern plants
High overall cost
Promotes spread of
nuclear weapons
© Cengage Learning 2015
Fig. 15-24, p. 392
Storing Radioactive Spent-Fuel Rods
Presents Risks
• Uranium fuel in a nuclear reactor lasts for 34 years; reactors are shut down for
refueling
• Extremely hot spent-fuel rods must be
replaced, and are stored and cooled in
water-filled pools
• Placed in dry casks made of heat-resistant
metal alloys and concrete filled with Helium
• Must be stored for thousands of years
•© Cengage
Vulnerable
to terrorist attack
Learning 2015
© Cengage Learning 2015
Fig. 15-25, p. 393
Dealing with Radioactive Nuclear Wastes
Is a Difficult Problem
• High-level radioactive wastes
– Must be stored safely for 10,000–240,000
years; too expensive to reprocess
• Where can it be stored?
– Deep burial: safest and cheapest option
– There is still no facility
– Shooting it into space is too dangerous
© Cengage Learning 2015
Dealing with Radioactive Nuclear Wastes
Is a Difficult Problem (cont’d.)
• Plans in the U.S. to build a repository for
high-level radioactive wastes in the Yucca
Mountain desert region (Nevada)
• Many problems including:
– Cost of $96 billion
– Rock fractures
– Earthquake zone
– Decrease national security
© Cengage Learning 2015
Dealing with Radioactive Nuclear Wastes
Is a Difficult Problem (cont’d.)
• Dealing with old nuclear power plants:
– Nuclear power plants reach the end of useful
life after 40-60 years and must close
– Decommission or retire the power plant
– Dismantle the plant and safely store the
radioactive materials
– Enclose the plant behind a physical barrier with
full-time security until a storage facility has
been built
– Enclose the plant in a tomb
• Monitor this for thousands of years
© Cengage Learning 2015
Can Nuclear Power Help Reduce Climate
Change?
• Nuclear power plants – no CO2 emission
• However, building plants as well as the
nuclear fuel cycle – emits CO2
• Need high rate of building new plants, and
a storage facility for radioactive wastes
© Cengage Learning 2015
Experts Disagree about the Future of
Nuclear Power
• Proponents of nuclear power:
– Fund more research and development on
safer and lest costly type of reactions
– Pilot-plant testing of potentially cheaper and
safer reactors
• Opponents of nuclear power:
– Very expensive; does not save on oil
– Questions of safety
– Fund rapid development of energy efficient
and renewable energy resources
© Cengage Learning 2015
Experts Disagree about the Future of
Nuclear Power (cont’d.)
• New technologies
– Advanced Light Water Reactors (ALWRs)
• Safer
– Thorium based reactors in place of uranium
• Less costly and safer
© Cengage Learning 2015
© Cengage Learning 2015
Fig. 15-26, p. 395
Case Study: The 2011 Nuclear Power
Plant Accident in Japan
• Triggered by a major offshore earthquake
and resulting tsunami
• Four key human-related factors:
– No worst-case scenarios
– Seawalls too short
– Design flaws
– Relationship between plant owners and
government
© Cengage Learning 2015
Fig. 15-27, p. 396
Is Nuclear Fusion the Answer?
• Fusion
– Two isotopes (hydrogen) fused together at
extremely high temperatures to form a heavier
nucleus; Releases energy in the process
– Scientists think it could form a limitless source
of energy
– No risk of a meltdown or release of large
amounts of radioactive material;little risk of
nuclear weapons.
– Could also destroy toxic wastes and supply
electricity to desalinate water!
© Cengage Learning 2015
Is Nuclear Fusion the Answer?
• Technology is very difficult to develop; 50
years of research and we’re still in the
laboratory stage.
© Cengage Learning 2015
Three Big Ideas
• A key factor to consider in evaluating the
long-term usefulness of any energy
resource is its net energy yield
• Conventional oil, natural gas, and coal:
– Plentiful and have moderate to high net
energy yields
– Use of these fossil fuels, especially coal, has
a high environmental impact
© Cengage Learning 2015
Three Big Ideas (cont’d.)
• The nuclear power fuel cycle has a low
environmental impact and a very low
accident risk, but limited use because of:
– High costs
– A low net energy yield
– Long-lived radioactive wastes
– Its role in spreading nuclear weapons
technology
© Cengage Learning 2015
Tying It All Together: A New U.S. Oil and
Natural Gas Era and Sustainability
• Conventional fossil fuels have high net
energy yields
• We cannot recycle energy
– Recycling materials can help reduce energy
needs
• Relying on a diversity of energy resources
– Will reduce environmental impacts
© Cengage Learning 2015