BIO320 Chapter 9

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Non-Renewable Energy Sources
Chapter 9
15th Edition
A Study of Interrelationships
ENVIRONMENTAL
SCIENCE
1

Outline
• 9.1 Major Energy Sources
• 9.2 Resources and
Reserves
• 9.3 Fossil-Fuel Formation
• 9.4 Issues Related to the
Use of Fossil Fuels
• 9.5 Nuclear Power
2

Outline
• 9.6 The Nature of Nuclear Energy
• 9.7 Nuclear Chain Reaction
• 9.8 Nuclear Fission Reactors
• 9.9 The Nuclear Fuel Cycle
• 9.10 Issues Related to the Use of Nuclear Fuels
3

9.1 Major Energy Sources
• Nonrenewable energy sources are those whose
resources are being used faster than can be replenished.
• Coal, oil, and natural gas
• Renewable energy sources replenish themselves or are
continuously present as a feature of the environment.
• Solar, geothermal, tidal, etc.
• They currently provide about 12% of the energy used worldwide,
primarily from hydroelectricity and firewood.
4

9.2 Resources and Reserves
• A resource is a naturally occurring
substance of use to humans that
can potentially be extracted using
current technology.
• A reserve is a known deposit that
can be economically extracted
using current technology, under
certain economic conditions.
• Reserves are smaller than
resources.
• Reserve levels change as
technology advances, new
discoveries are made, and
economic conditions vary.
5

9.3 Fossil-Fuel Formation
• Coal
• 300 million years ago, plant material began
collecting underwater, initiating decay,
forming a spongy mass of organic material.
• Due to geological changes, some of these
deposits were covered by seas, and
covered with sediment.
• Pressure and heat over time transformed
the organic matter into coal.
6

Different Kinds of Coal
7

Oil and Natural Gas
• Oil and natural gas
probably originated from
microscopic marine
organisms that
accumulated on the ocean
floor and were covered by
sediments.
• Muddy rock gradually formed
shale containing dispersed
oil.
• Natural gas often forms on
top of oil.
8

Crude Oil and Natural Gas Deposits
9

Changes in Oil Reserves
10
• The proved oil reserves have been on
an upward slope since the 1980’s.
• The increase in the 1980s was mostly
due to more accurate reporting.

9.4 Issues Related to the Use of Fossil Fuels
• Fossil fuels supply 80% of world’s commercial energy.
Fossil
Fuels
11

Coal Use
• Coal is most abundant fossil fuel.
• Primarily used for generating electricity.
• There are four categories of coal: Lignite, Sub-bituminous,
Bituminous, and Anthracite.
• Lignite
• High moisture, low energy, crumbly, least desirable form.
• Sub-bituminous
• Lower moisture, higher carbon than lignite.
• Used as fuel for power plants.
12

Coal Use
• Bituminous
• Low moisture, high carbon content
• Used in power plants and other industry such as steel making.
• Most widely used because it is easiest to mine and the most
abundant.
• Anthracite
• Has the highest carbon content, and is relatively rare.
• It is used primarily in heating buildings and for specialty uses.
13

Coal Use: Extraction
• There are two extraction methods:
• Surface mining (strip mining), which is the process of removing
material on top of a vein, is efficient but destructive.
• Underground mining minimizes surface disturbance, but is costly
and dangerous.
• Many miners suffer from black lung disease, a respiratory condition that
results from the accumulation of fine coal-dust particles in the miners’
lungs.
14

Coal Use: Transportation & Pollution
• Coal is bulky and causes some transport problems.
• Mining creates dust pollution.
• Burning coal releases pollutants (e.g., carbon and sulfur).
• Millions of tons of material are released into atmosphere annually.
• Sulfur leads to acid mine drainage and acid deposition.
• Mercury is released into the air when coal is burned.
• Increased amounts of atmospheric carbon dioxide are implicated in
global warming.
15

Coal Mining Methods
16

Surface-Mine Reclamation
17

Environmental Issues: Subsidence
18

Environmental Issues:Acid Mine Drainage
19
• Acid mine drainage occurs when the
combined action of oxygen, water,
and certain bacteria causes the
sulfur in coal to form sulfuric acid.

Oil Use
• Oil is more concentrated than coal, burns cleaner, and is
easily transported through pipelines.
• These qualities make it ideal for automobile use.
• It is difficult to find.
• It causes less environmental damage than coal mining.
20

Oil Use
• Once a source of oil has been located, it must be
extracted and transported to the surface.
• Primary Recovery methods
• If water or gas pressure associated with the oil is great enough, the
oil is forced to the surface when a well is drilled.
• If water and gas pressure is low, the oil is pumped to the surface.
• 5–30% of the oil is extracted depending on viscosity and geological
characteristics.
21

Oil Use
• Secondary Recovery
• Water or gas is pumped into a well to drive the oil out of the pores
in the rock.
• This technique allows up to 40% of the oil to be extracted.
• Tertiary Recovery
• Steam is pumped into a well to lower the viscosity of the oil.
• Aggressive pumping of gas or chemicals can be pumped into a
well.
• These methods are expensive and only used with high oil prices.
22

Oil Use
• Processing
• As it comes from the ground, oil is not in a form suitable for use,
and must be refined.
• Multiple products can be produced from a single barrel of crude oil.
• Oil Spills
• Accidental spills only account for about 10% of oil pollution
resulting from shipping.
• The effects are still poorly understood.
23

Extraction Methods
Offshore Drilling Secondary Recovery
24

Transportation of Oil
25

Environmental Issues
Oil Spills From Tankers Sources of Marine Oil Pollution
26
It is estimated that
worldwide only about
10% of human-caused
oil pollution comes
from tanker accidents.

Natural Gas Use
• The drilling operations to obtain natural gas are similar to
those used for oil.
• It is hard to transport and in many places is burned off at
oil fields, but new transportation methods are being
developed.
• Liquefaction at -126o F (1/600 volume of gas)
• The public is concerned about the safety of LNG loading facilities
so they are located off shore.
• It is the least environmentally damaging fossil fuel.
• It causes almost no air pollution.
27

9.5 Nuclear Power
• Although nuclear power does not come from a fossil fuel,
it is fueled by uranium, which is obtained from mining and
is non-renewable.
• As of July 2017, there were 447 nuclear power reactors in
operation and 59 nuclear power plants under construction
in 14 countries.
• Of the 160 nuclear power plants currently being planned,
most are in Asian countries such as China, India, Japan,
and South Korea.
28

Nuclear Reactor Statistics
29

Distribution of Nuclear Power Plants
in North America
30

9.6 The Nature of Nuclear Energy
• The nuclei of certain atoms are unstable and
spontaneously decompose. These isotopes are
radioactive.
• Neutrons, electrons, protons, and other larger particles
are released during nuclear disintegration, along with a
great deal of energy.
• Radioactive half-life is the time it takes for half the
radioactive material to spontaneously decompose.
31

Half-Lives and Significance
of Some Radioactive Isotopes
32

9.6 The Nature of Nuclear Energy
• Nuclear disintegration releases energy from the nucleus
as radiation, of which there are three major types:
• Alpha radiation consists of moving particles composed of two
neutrons and two protons.
• It can be stopped by the outer layer of skin.
• Beta radiation consists of electrons from the nucleus.
• It can be stopped by a layer of clothing, glass, or aluminum.
• Gamma radiation is a form of electromagnetic radiation.
• It can pass through your body, several centimeters of lead, or a meter of
concrete.
33

9.7 Nuclear Chain Reaction
• Nuclear fission occurs when neutrons impact and split
the nuclei of certain other atoms.
• In a nuclear chain reaction, splitting nuclei release
neutrons, which themselves strike more nuclei, in turn
releasing even more neutrons.
34

35

• Only certain kinds of atoms are suitable for development
of a nuclear chain reaction.
• The two most common are uranium-235 and plutonium-
239.
• There also must be a certain quantity of nuclear fuel
(critical mass) for the chain reaction to occur.
36

9.8 Nuclear Fission Reactors
• A nuclear reactor is a device that permits a controlled
fission chain reaction.
• When the nucleus of a U-235 atom is struck by a slowly moving
neutron from another atom, the nucleus splits into smaller particles.
• More rapidly-moving neutrons are released, which strike more
atoms.
• The chain reaction continues to release energy until the fuel is
spent or the neutrons are prevented from striking other nuclei.
37

• Control rods made of a non-fissionable material (boron,
graphite) are lowered into the reactor to absorb neutrons
and control the rate of fission.
• When they are withdrawn, the rate of fission increases.
• A moderator is a substance that absorbs energy, which
slows neutrons, enabling them to split the nuclei of other
atoms more effectively.
• Water and graphite are the most commonly used.
• Coolant, usually water, manages the heat produced.
38

• In the production of electricity, a nuclear reactor serves
the same function as a fossil-fuel boiler: it produces heat,
which converts water to steam, which turns a turbine,
generating electricity.
• The 3 most common types of reactors are:
• Pressurized-Water (60%)
• Boiling-Water (20%)
• Heavy-Water (10%)
• Gas-Cooled Reactors are not popular, and no new plants
of this type are being constructed.
39

Pressurized-Water Reactor
40

• Breeder reactors produce nuclear fuel as they produce
electricity.
• Liquid sodium efficiently moves heat away from the reactor
core.
• Hence they are called Liquid Metal Fast Breeder Reactors.
• A fast moving neutron is absorbed by Uranium-238 and produces
Plutonium-239
• P239 is fissionable fuel.
• Most breeder reactors are considered experimental.
• Because P239 can be used in nuclear weapons, breeder reactors are
politically sensitive.
41

9.9 The Nuclear Fuel Cycle
• The nuclear fuel cycle begins with the mining of low-grade
uranium ore primarily from Australia, Kazakhstan, Russia,
South Africa, Canada, and the United States.
• It is milled, and crushed and treated with a solvent to
concentrate the uranium.
• Milling produces yellow-cake, a material containing 70-90%
uranium oxide.
42

• Naturally occurring uranium contains about 99.3% non-
fissionable U238, and .7% fissionable U235.
• It must be enriched to 3% U235 to be concentrated enough for most
nuclear reactors.
• Centrifuges separate the isotopes by their slight differences in
mass.
• Material is fabricated into a powder and then into pellets.
• The pellets are sealed into metal rods (fuel rods) and lowered into
the reactor.
43

• As fission occurs, U-235 concentration decreases.
• After about three years of operation, fuel rods don’t have
enough radioactive material remaining to sustain a chain
reaction, thus spent fuel rods are replaced by new ones.
• Spent rods are still very radioactive, containing about 1%
U-235 and 1% plutonium.
44

• Spent fuel rods are radioactive, and must be managed
carefully to prevent health risks and environmental
damage.
• Rods can be reprocessed.
• U-235 and plutonium are separated from the spent fuel and used to
manufacture new fuel rods.
• Less than half of the world’s fuel rods are reprocessed.
• Rods can undergo long-term storage.
• At present, India, Japan, Russia, France, and the United
Kingdom operate reprocessing plants as an alternative to
storing rods as waste.
45

Steps in the Nuclear Fuel Cycle
46

• All of the processes involved in the nuclear fuel cycle
have the potential to generate waste.
• Each step in the nuclear fuel cycle involves the transport
of radioactive materials.
• Each of these links in the fuel cycle presents the
possibility of an accident or mishandling that could
release radioactive material.
47

9.10 Issues Related to the Use of Nuclear
Fuels
• Most of the concerns about the use of nuclear fuels relate
to the danger associated with radiation.
• The absorbed dose is the amount of energy absorbed by
matter. It is measured in grays or rads.
• The damage caused by alpha particles is 20 times greater
than that caused by beta particles or gamma rays.
• The dose equivalent is the absorbed dose times a quality
factor.
48

The Biological Effects of Ionizing Radiation
• When alpha or beta particles or gamma radiation interact
with atoms, ions are formed. Therefore, it is known as
ionizing radiation.
• Ionizing radiation affects DNA and can cause mutations.
• Mutations that occur in some tissues of the body may manifest
themselves as abnormal tissue growths known as cancers.
49

The Biological Effects of Ionizing Radiation
• Large doses of radiation are clearly lethal.
• Demonstrating known harmful biological effects from
smaller doses is much more difficult.
• The more radiation a person receives, the more likely it is
that there will be biological consequences.
• Time, distance, and shielding are the basic principles of
radiation protection.
• Water, lead, and concrete are common materials used for shielding
from gamma radiation.
50

Protective Equipment
51

Radiation Effects
52

Reactor Safety
• The Three Mile Island nuclear plant in Pennsylvania
experienced a partial core meltdown on March 28, 1979.
• It began with pump and valve malfunction, but operator error
compounded the problem.
• The containment structure prevented the release of radioactive
materials from the core, but radioactive steam was vented into the
atmosphere.
• The crippled reactor was defueled in 1990 at a cost of about $1
billion.
• Placed in monitored storage until its companion reactor reaches the
end of its useful life.
53

Three Mile Island
54

Reactor Safety
• Chernobyl is a small city in Ukraine, north of Kiev.
• It is the site of the world’s largest nuclear accident, which
occurred April 26, 1986.
• Experiments were being conducted on reactor.
• Operators violated six important safety rules.
• They shut off all automatic warning systems, automatic shutdown
systems, and the emergency core cooling system for the reactor.
55

Reactor Safety
• In 4.5 seconds, the energy level of the reactor increased
2000 times.
• The cooling water converted to steam and blew the 1102-
ton concrete roof from the reactor.
• The reactor core caught fire.
• It took 10 days to bring the burning reactor under control.
56

Reactor Safety
• There were 37 deaths; 500 people hospitalized (237 with
acute radiation sickness); 116,000 people evacuated.
• 24,000 evacuees received high doses of radiation.
• Children or fetuses exposed to fallout are showing increased
frequency of thyroid cancer because of exposure to radioactive
iodine 131 released from Chernobyl.
57

The Accident at Chernobyl
58

Reactor Safety
• The Fukushima nuclear power plant was damaged on
March 11, 2011 following a magnitude 9 earthquake and
tsunami.
• Heat exchangers were damaged, power to the site was cut off, and
the diesel generators designed to provide power in an emergency
were flooded and stopped operating.
• Explosions, fires, and leaks in the cooling system released
radiation into the atmosphere and sea water.
59

Terrorism
• After Sept. 11, 2001, fear arose regarding nuclear plants
as potential targets for terrorist attacks.
• Nuclear experts feel aircraft wouldn’t significantly damage
the containment building or reactor, and normal
emergency and containment functions would prevent the
release of radioactive materials.
• Probably the greatest terrorism-related threat is from
radiological dispersal devices (RDDs), or dirty bombs.
They cause panic, not numerous deaths.
60

Decommissioning Nuclear Power Plants
• The life expectancy of most electrical generating plants
(fossil fuel or nuclear) is 30-40 years.
• Unlike other plants, nuclear plants are decommissioned,
not demolished.
• Decommissioning is a 2-step process.
• Stage 1 includes removing, properly disposing of or storing fuel
rods and water used in the reactor.
• Stage 2 is the final disposition of the facility.
61

• There are three options to this second stage of the
decommissioning process:
• 1. Decontaminate and dismantle the plant as soon as it is shut
down.
• 2. Secure the plant for many years to allow radioactive materials
that have a short half-life to disintegrate and then dismantle the
plant. (However, this process should be completed within 60
years.)
• 3. Entomb the contaminated portions of the plant by covering the
reactor with reinforced concrete and placing a barrier around the
plant. (Currently this option is only considered suitable for small
research facilities.)
62

• Today, about 160 commercial nuclear power plants and
about 48 experimental reactors in the world have been
shut down and are in various stages of being
decommissioned.
• Recent experience indicates that the cost for decommissioning a
large plant will be between $200 million and $400 million, about 5
percent of the cost of generating electricity. Although the
mechanisms vary among countries, the money for
decommissioning is generally collected over the useful life of the
plant.
63

Summary
• Resources are naturally occurring substances of use to
humans.
• Reserves are known deposits from which materials can
be extracted profitably with existing technology under
present economic conditions.
• Coal is the world’s most abundant fossil fuel.
• The supply of oil, like all fossil fuels, is limited.
• Natural gas is another major source of fossil-fuel energy,
but transport of natural gas to consumers is problematic.
64

Summary
• Nuclear fission is the splitting of the nucleus of an atom.
• All reactors contain a core with fuel, a moderator to
control the rate of the reaction, and a cooling mechanism
to prevent the reactor from overheating.
• The nuclear fuel cycle involves mining and enriching the
original uranium ore, fabricating it into fuel rods, using the
fuel in reactors, and reprocessing or storing the spent fuel
rods.
• Fuel and wastes must also be transported.
• Each step in the process presents a danger of exposure.
65

Summary
• Although accidents at Three Mile Island and Chernobyl
raised safety concerns for a time, rising energy prices
have stimulated increased building of nuclear power
plants in many countries.
• Disposal of waste is expensive and controversial.
• Long-term storage in geologically stable regions is supported.
• Russia, Japan, and the UK operate nuclear reprocessing facilities
to reduce future long-term storage needs.
66

BIO320 Chapter 9

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