Transcript Document

Nonrenewable Energy
Chapter 15
Core Case Study:
How Long Will Supplies of Conventional Oil Last?
 Saudi Arabia could supply the world with oil for
about 10 years.
 The Alaska’s North Slope could meet the world oil
demand for 6 months. (U.S.: 3 yrs.)
 Alaska’s Arctic National Wildlife Refuge (ANWR)
would meet the world demand for 1-5 months.
(U.S.: 7-24 months)
Core Case Study:
How Long Will Supplies of Conventional Oil Last?
 We have three options:
• Look for more oil
• Use or waste less oil
• Use other energy sources
15-1 What Major Sources
of Energy Do We Use?
 Concept 15-1A About three-quarters of the world’s
commercial energy comes from nonrenewable
fossil fuels and the rest comes from nonrenewable
nuclear fuel and renewable sources.
 Concept 15-1B Net energy is the amount of highquality usable energy available from a resource
after the amount of energy needed to make it
available is subtracted.
Fossil Fuels Supply Most of
Our Commercial Energy
SOURCE : DEPARTMENT OF ENERGY
Fossil Fuels Supply Most of
Our Commercial Energy
 About 80% of global commercial
energy comes from nonrenewable
fossil fuels with the remainder
coming from renewable sources.
Commercial Energy Use by Source for the
World and the United States
Natural Capital:
Important Nonrenewable Energy Resources
Case Study:
A Brief History of Human Energy Use
 A Brief History of Human Energy Use – p. 372-373
• Muscle power: early humans
• Discovery of fire
• Agriculture
• Use of wind and flowing water
• Machines powered by wood, then coal
• Internal combustion engine
• Nuclear energy
• Energy crisis
15-2 What Are the Advantages and
Disadvantages of Oil?
 Concept 15-2A Conventional oil is currently
abundant, has a high net energy yield, and is
relatively inexpensive, but using it causes air and
water pollution and releases greenhouse gases to
the atmosphere.
 Concept 15-2B Heavy oils from oil sand and oil
shale exist in potentially large supplies but have
low net energy yields and higher environmental
impacts than conventional oil has.
OIL / PETROLEUM
We Depend Heavily on Oil
 Crude oil (petroleum) is a thick liquid containing
hydrocarbons that we extract from underground
deposits and separate into products such as
gasoline, heating oil and asphalt.
 Only 35-50% can be
economically recovered
from a deposit.
Science: Refining Crude Oil
 An oil refinery uses
distillation to separate crude
oil into it’s components:
• Based on boiling points,
components are removed at
various layers in a giant
distillation column.
• The components with the
lowest boiling points are
removed at the top.
OPEC Controls Most of the World’s Oil Supplies
 Twelve OPEC countries have 60% of the world’s
proven oil reserves and most of the world’s
unproven reserves.
• Organization of Petroleum Exporting Countries
Rising Oil Prices
 Global oil production peaked around 2005
 Sharp increases in oil prices could threaten the
economies of countries that have not shifted to
new energy alternatives.
 Possible effects of steeply rising oil prices:
•
•
•
•
•
•
•
Higher food prices
Airfares higher
Reduce energy waste
Upgrade of public transportation
Smaller more fuel-efficient vehicles
Shift to non-carbon energy sources
Higher prices for products made with petrochemicals
The United States Uses Much More Oil
Than It Produces
 The U.S. – the world’s largest oil user – has only
2.4% of the world’s proven oil reserves.
 The U.S. uses 24% of worldwide crude oil.
 The U.S. imports 50% of the oil it uses.
Case Study:
Oil and the U.S. Arctic National Wildlife Refuge
 The Arctic National Wildlife Refuge (ANWR)
• Not open to oil and gas development
• Fragile tundra biome
 Decrease dependence on foreign oil??
• “Drill baby, drill!”
Trade-Offs:
Conventional Oil, Advantages and Disadvantages
 Burning oil for
transportation accounts
for 43% of global CO2
emissions.
 About 60% of U.S oil
imports go through
refineries in hurricaneprone regions of the
Gulf Coast.
Will Heavy Oil from Oil Sand or Shale Oil
Be Viable Options?
 Heavy and tarlike oils from oil sand and shale oil
could supplement conventional oil, but there are
environmental problems.
•
•
•
•
High sulfur content
Extracting and processing produces toxic sludge
Uses and contaminates larges volumes of water
Requires large inputs of energy which reduces net energy
 Canada has 75% of the world’s oil sand.
 The Western U.S. has 72% of the
world’s shale oil.
Trade-Offs:
Heavy Oils from Oil Shale and Oil Sand
15-3 What Are the Advantages and
Disadvantages of Natural Gas?
 Concept 15-3 Conventional natural gas is more
plentiful than oil, has a high net energy yield and
a fairly low cost, and has the lowest
environmental impact of all fossil fuels.
NATURAL GAS
Natural Gas Is a Useful and
Clean-Burning Fossil Fuel
 Natural gas, consisting mostly of methane (CH4),
is often found above reservoirs of crude oil.
• Coal beds, bubbles of methane trapped under the
arctic permafrost and beneath deep-ocean
sediments, and landfills are unconventional sources
of natural gas.
Natural Gas Is a Useful and
Clean-Burning Fossil Fuel
 Russia, Iran, and Qatar have about 3/4 of the
world’s reserves of conventional gas, and global
reserves should last 62-125 years.
Natural Gas Is a Useful and
Clean-Burning Fossil Fuel
Produces
electricity X 2
Fuel burning in a combustion chamber produces hot gases that pass directly
through the turbine, which spins a generator to produce electricity. Then these
hot gases are used to turn water to steam, which pushes a second turbine
producing more electricity.
Natural Gas Is a Useful and
Clean-Burning Fossil Fuel
 Natural gas is transported through
dense networks of pipelines
 Liquefied petroleum gas (LPG)
• Pressurized tanks used in rural areas
 Liquefied natural gas (LNG)
• Gas is cooled and pressurized in
order to ship across the ocean
Trade-Offs:
Conventional Natural Gas
 Natural gas is versatile
and cleaner-burning
fuel, but it releases the
greenhouse gases
carbon dioxide (when
burned) and methane
(from leaks) into the
troposphere.
 Some analysts see
natural gas as the best
fuel to help us make the
transition to improved
energy efficiency and
greater use of
renewable energy.
15-4 What Are the Advantages and
Disadvantages of Coal?
 Concept 15-4A Conventional coal is very plentiful
and has a high net energy yield and low cost, but it
has a very high environmental impact.
 Concept 15-4B Gaseous and liquid fuels
produced from coal could be plentiful, but they have
lower net energy yields and higher environmental
impacts than conventional coal has.
COAL
Coal Comes in Several Forms and Is Burned
Mostly to Produce Electricity
 Coal is a solid fossil fuel that is formed in several
stages as the buried remains of land plants that
lived 300-400 million years ago.
 Burned in 2100 power plants, generates 40% of the
world’s electricity (49% in the U.S.)
• Inefficient process that burns coal to boil water which
produces steam that turns a turbine
Stages in Coal Formation over Millions of Years
Science: Coal-Burning Power Plant
Coal Is a Plentiful but Dirty Fuel
 World’s most abundant fossil fuel
 Coal reserves in the United States, Russia, and
China could last hundreds to over a thousand years.
 In 2005, China
and the U.S.
accounted for
53% of the global
coal consumption
 By 2025, China is
expected to burn
TWICE as much
as the U.S.
Coal Is a Plentiful but Dirty Fuel
 Environmental costs of burning coal:
• Single biggest air polluter in coal-burning countries
•
•
•
•
•
CO2 – one-fourth of the annual global emissions
Sulfur released as SO2 (acid rain)
Large amount of soot
Mercury (Hg)
Radioactive materials
 Environmentalists call for:
• Taxation on CO2 production by power plants
• Cleaner coal-burning plants
Trade-Offs:
Coal, Advantages and Disadvantages
 Coal is the most
abundant fossil
fuel, but compared
to oil and natural
gas it is not as
versatile, has a
high environmental
impact, and
releases much
more CO2 into the
troposphere.
15-5 What Are the Advantages and
Disadvantages of Nuclear Energy?
 Concept 15-5 Nuclear power has a low
environmental impact and a very low accident
risk, but high costs, a low net energy yield, longlived radioactive wastes, vulnerability to sabotage,
and the potential for spreading nuclear weapons
technology have limited its use.
NUCLEAR FISSION
The blue glow is known as Čerenkov radiation – when charged particles
(electrons) passes through an insulator (water).
How Does a Nuclear Fission
Reactor Work?
 Nuclear Fission is the splitting of atoms to release
the energy they contain.
 E = MC2
• E = energy
• M = mass
• C = speed of light 3.0x108 m/s
How Does a Nuclear Fission
Reactor Work?
 Isotopes of uranium and plutonium undergo
controlled nuclear fission, the resulting heat produces
steam that spins turbines to generate electricity.
• The uranium oxide consists of about:
• 97% non-fissionable U238
• 3% fissionable U235
• The concentration of U235 is increased through an
enrichment process (normally only 0.7%).
• Uranium enrichment is a difficult process
 An uncontrolled nuclear fission reaction is used in/for
atomic weapons.
How Does a Nuclear Fission
Reactor Work?
 The nuclear fission reaction takes place in a reactor
 Fueled by uranium dioxide and packed as pellets in
fuel rods and fuel assemblies
• Each eraser-sized pellet contains the energy of a TON of coal
 Control rods absorb neutrons
• Moved up/down to control the
speed of the reaction
 Water is the usual coolant
 Containment shell around the core for protection
Nuclear Power Plant:
Light-Water-Reactor
 Nuclear power plants are highly inefficient
• Lose as much as 83% of its energy as waste heat
How Does a Nuclear Fission
Reactor Work?
 After three or four years in a
reactor, spent fuel rods are
removed and stored in a deep
pool of water contained in a
steel-lined concrete container.
 After spent fuel rods have
cooled considerably, they are
sometimes moved to drystorage containers made of
steel or concrete.
• Typically stored on-site
What Is the Nuclear Fuel Cycle?





Mine the uranium
Process the uranium to make the fuel
Use it in the reactor
Safely store the radioactive waste
Decommission the reactor
• Safely shut it down and seal it up
Our Very Own Nuclear Power Plant!
 Duane Arnold Energy Center
• Located near Palo, Iowa approximately nine miles NW of
Cedar Rapids
• Generates about 592 million watts
of electricity - enough power to
supply the annual needs of more
than 600,000 homes
What Happened to Nuclear Power?
 After more than 50 years of development and
enormous government subsidies, nuclear power has
not lived up to its promise of “almost limitless energy
at a very small cost per kWh” because:
• Multi billion-dollar construction costs
• Higher operation costs and more
malfunctions than expected
• Poor management
• Public concerns about safety and
strict government safety regulations
• Low net yield of energy
Case Study:
Worst Commercial Nuclear Power Plant Accident in the U.S.
 The accident occurred at the Three Mile Island Unit 2
(TMI-2) nuclear power plant near Middletown, PA on
March 28, 1979.
• Human and mechanical errors lead to part of one of
the reactor cores melting (meltdown).
• Unknown amounts of radioactivity escaped
• People fled the area
Case Study:
Worst Nuclear Power Plant Accident in the World
 The world’s worst nuclear power plant accident
occurred on April 26, 1986 near Chernobyl, Ukraine.
• Poor reactor design and human error led to a series of
explosions causing the roof of a reactor building to blow off
• Partial meltdown and fire for 10 days
• Huge radioactive cloud spread over many countries and
eventually the world
• 350,000 people left their homes
Trade-Offs:
Conventional Nuclear Fuel Cycle
 In 1995, the World
Bank said nuclear
power is too costly
and risky.
 In 2006, it was found
that several U.S.
reactors were leaking
radioactive tritium into
groundwater.
Trade-Offs:
Coal versus Nuclear to Produce Electricity
 A 1,000 MW
nuclear plant is
refueled once a
year, whereas a
coal plant requires
80 rail cars a day.
Dealing with Radioactive Wastes Produced by
Nuclear Power Plants Is a Difficult Problem
 When a nuclear reactor reaches the end of its useful
life, its high-level radioactive wastes must be
stored safely for 10,000 – 240,000 years
• Deep burial: safest and cheapest option
• Change it into harmless or less harmful isotopes?
 At least 228 large commercial reactors worldwide
(20 in the U.S.) are scheduled for retirement by 2012.
• Many reactors are applying to extent their 40-year
license to 60 years
 What Do We Do with Worn-Out Nuclear Power Plants?
Case Study:
Experts Disagree about What to Do with
Radioactive Wastes in the U.S.
 1985: plans in the U.S. to build a repository for highlevel radioactive wastes in the Yucca Mountain
desert region (Nevada)
 Problems
• Cost: $58–100 billion
• Large number of shipments to the site
• protection from attack?
• Rock fractures
• Earthquake zone
• Decrease national security
Will Nuclear Fusion Save Us?
 Nuclear fusion is a nuclear change in which two
isotopes are forced together.
• No risk of meltdown or radioactive releases
• May also be used to breakdown toxic material
• Still in laboratory stages after 50 years of research
and $34 billion dollars
• So far, more energy is put in
than we get out