Conventional Energy
Chapter 21
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Outline:
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Energy History
How Energy Is Used
Coal
Oil
Natural Gas
Nuclear Power
 Fission
 Reactors
 Waste Management
 Fusion
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
WHAT IS ENERGY
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Work - Application of force through a
distance.
Energy - The capacity to do work.
Power - Rate at which work is done.
 Calorie - Amount of energy necessary to
heat 1 gram of water 1oC.
 Joule - Amount of work done when a force
of 1 newton is exerted over 1 meter.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Energy History
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Muscle power provided by domestic animals
has been important since dawn of agriculture
10,000 years ago.
World Oil Use peaked in 1979.
 Oil prices rose ten-fold in 1970’s.
Early 1980’s saw increased interest in
conservation and renewable energy.
 Oil glut in mid 1980’s caused prices to fall.
US now imports over half annual oil supply.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Current Energy Sources
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Fossil Fuels currently provide about 85% of
all commercial energy in the world.
 Biomass fuels contribute about 6% of
commercial energy.
 Other renewable sources make up 4-5% of
commercial power.
 Nuclear power makes up 4-5% of
commercial power.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Worldwide Commercial Energy Production
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Per Capita Consumption
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Richest 20 countries consume nearly 80% of
natural gas, 65% of oil, and 50% of coal
production annually.
 On average, each person in the US and
Canada uses more than 300 GJ of energy
annually.
- In poorest countries of the world, each
person generally consumes less than
one GJ annually.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Per Capita Energy Use and GNP
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
HOW ENERGY IS USED
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Largest share of energy used in the US is
consumed by industry (36.5%).
Residential and Commercial buildings use
34% of primary energy consumed in US.
Transportation consumes about 26% of all
energy used in the US.
 Three trillion passenger miles and 600
billion ton miles of freight carried annually
by motor vehicles in the US.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
How Energy Is Used
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About half of all energy in primary fuels is
lost during conversion to more useful forms
while being shipped, or during use.
 Nearly two-thirds of energy in coal being
burned to generate electricity is lost during
thermal conversion in the power plant.
- Another 10% is lost during transmission
and stepping down to household
voltages.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
COAL
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Fossilized plant material preserved by burial
in sediments and compacted and condensed
by geological forces into carbon-rich fuel.
 Most laid down during Carboniferous
period (286 million to 360 million years
ago).
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Coal
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Resources and Reserves
 World coal deposits are ten times greater
than conventional oil and gas resources
combined.
- Under current consumption rates, this
could last several thousand years.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Proven-In-Place Coal Reserves
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Coal
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Mining
 Between 1870 and 1950, more than
30,000 coal miners died of accidents and
injuries in Pennsylvania alone.
- Several thousands have died of
respiratory diseases.
 Black Lung Disease - Inflammation
and fibrosis caused by accumulation
of coal dust in the lungs or airways.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Coal
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Air Pollution
 Coal burning releases radioactivity and
toxic metals into the atmosphere.
- Coal combustion is responsible for 25%
of all atmospheric mercury pollution in
the US.
 Coal contains up to 10% sulfur by weight.
- Unless removed by washing or flue-gas
scrubbing, sulfur is released and
oxidizes to sulfur dioxide or sulfate.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
OIL
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Petroleum is formed very similar to oil Organic material buried in sediment and
subjected to high pressure and temperature.
 Oil Pool usually composed of individual
droplets or thin film permeating spaces in
porous sandstone or limestone.
- At least half of total deposit is usually
uneconomical to pump out.
 Secondary oil recovery techniques.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Oil Recovery Process
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
OIL
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Resources and Reserves
 Total amount of oil in the world is
estimated at 4 trillion barrels. (Half is
thought to be ultimately recoverable)
- In 1999, proven reserves were estimated
at 1 trillion barrels.
 As oil becomes depleted and prices
rise, it will likely become more
economical to find and bring other
deposits to market.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Proven Recoverable Oil Reserves
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Oil
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Imports and Domestic Supplies
 The US has used about 40% of its original
recoverable petroleum resource.
- Of the 120 billion barrels thought to
remain, 58 billion are proven-in-place.
 Until 1947, the US was the world’s leading
oil export country.
- By 1998, the US was importing 10
million barrels per day - Half of total
consumption.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Oil
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Oil Shales and Tar Sands
 Estimates of total oil supply usually do not
reflect large potential from unconventional
oil sources such as shale oil and tar sand.
- Could potentially double total reserve.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
NATURAL GAS
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World’s third largest commercial fuel.
 23% of global energy consumption.
 Produces half as much CO2 as equivalent
amount of coal.
 Most rapidly growing energy source.
- Difficult to ship long distances, and to
store in large quantities.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Natural Gas
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Resources and Reserves
 Proven world reserves of natural gas are
3,200 trillion cubic feet.
- Current reserves represent roughly 60
year supply at present usage rates.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Proven-In-Place Natural Gas Reserves
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Unconventional Gas Sources
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Methane hydrate - Small individual
molecules of natural gas trapped in a
crystalline matrix of frozen water.
 Thought to hold 10,000 gigatons of carbon,
or twice as much as combined amount of
all traditional fossil fuels combined.
- Difficult to extract, store, and ship.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
NUCLEAR POWER
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President Dwight Eisenhower, 1953, “Atoms
for Peace”speech.
 Nuclear-powered electrical generators
would provide power “too cheap to meter.”
- Between 1970 and 1974, American
utilities ordered 140 new reactors for
power plants.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Nuclear Power
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After 1975, only 13 orders were placed for
new nuclear reactors, and all of those were
subsequently cancelled.
 In all, 100 of 140 reactors on order in 1975
were cancelled.
- Electricity from nuclear power plants was
about half the price of coal in 1970, but
twice as much in 1990.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Nuclear Power Plant History
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
How Do Nuclear Reactors Work
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Most commonly used fuel is U235, a naturally
occurring radioactive isotope of uranium.
- Occurs naturally at 0.7% of uranium, but
must be enriched to about of 3%.
Formed in cylindrical pellets (1.5 cm long)
and stacked in hollow metal rods (4 m long).
 About 100 rods and bundled together to
make a fuel assembly.
- Thousands of fuel assemblies bundled in
reactor core.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
How Do Nuclear Reactors Work
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When struck by neutrons, radioactive
uranium atoms undergo nuclear fission,
releasing energy and more neutrons.
 Triggers nuclear chain reaction.
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Nuclear Fission
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
How Do Nuclear Reactors Work
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Reaction is moderated in a power plant by
neutron-absorbing solution (Moderator).
 In addition, Control Rods composed of
neutron-absorbing material are inserted
into spaces between fuel assemblies to
control reaction rate.
- Water or other coolant is circulated
between the fuel rods to remove excess
heat.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Kinds of Reactors
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Seventy percent of nuclear power plants are
pressurized water reactors.
 Water circulated through core to absorb
heat from fuel rods.
- Pumped to steam generator where it
heats a secondary loop.
 Steam from secondary loop drives
high-speed turbine producing
electricity.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Kinds of Reactors
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Both reactor vessel and steam generator are
housed in a special containment building
preventing radiation from escaping, and
providing extra security in case of accidents.
 Under normal operating conditions, a PWR
releases very little radioactivity.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
PWR
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Kinds of Reactors
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Simpler, but more dangerous design is a
boiling water reactor.
 Water from core boils to make steam,
directly driving turbine generators.
- Highly radioactive water and steam
leave containment structure.
Canadian deuterium reactors - Operate with
natural, un-concentrated uranium.
Graphite moderator reactors - Operate with a
solid moderator instead of a liquid.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Alternative Reactor Designs
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High-Temperature, Gas-Cooled Reactors
 Uranium encased in tiny ceramic-coated
pellets.
Process-Inherent Ultimate Safety Reactors
 Reactor core submerged in large pool of
boron-containing water within a massive
pressure vessel.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Breeder Reactors
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Breeder reactors create fissionable
plutonium and thorium isotopes from stable
forms of uranium.
 Uses plutonium reclaimed from spent fuel
from conventional fission reactors as
starting material.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Breeder Reactors
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Breeder Reactor Drawbacks
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Reactor core must be at very high density,
thus liquid sodium used as a coolant.
 Corrosive and difficult to handle.
- Core will self-destruct within a few
seconds if primary coolant is lost.
Produces weapons-grade plutonium.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
RADIOACTIVE WASTE MANAGEMENT
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Until 1970, the US, Britain, France, and
Japan disposed of radioactive waste in the
ocean.
 Production of 1,000 tons of uranium fuel
typically generates 100,000 tons of tailings
and 3.5 million liters of liquid waste.
- Now approximately 200 million tons of
radioactive waste in piles around mines
and processing plants in the US.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Radioactive Waste Management
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About 100,000 tons of low-level waste
(clothing) and about 15,000 tons of high-level
(spent-fuel) waste in the US.
 For past 20 years, spent fuel assemblies
have been stored in deep water-filled pools
at the power plants. (Designed to be
temporary.)
- Many internal pools are now filled and a
number plants are storing nuclear waste
in metal dry casks outside.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Radioactive Waste Management
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US Department of Energy announced plans
to build a high-level waste repository near
Yucca Mountain Nevada in 1987.
 Facility may cost between $10 and 35
billion, and will not open until at least 2010.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Decommissioning Old Nuclear Plants
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Most plants are designed for a 30 year
operating life.
 Only a few plants have thus far been
decommissioned.
- General estimates are costs will be 2-10
times more than original construction
costs.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
CHANGING FORTUNES
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Public opinion has fluctuated over the years.
 When Chernobyl exploded in 1985, less
than one-third of Americans favored
nuclear power.
- Now, half of all Americans support
nuclear-energy.
Currently, 103 nuclear reactors produce
about 20% of all electricity consumed in the
US.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Changing Fortunes
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With natural gas prices soaring, and
electrical shortages looming, many sectors
are once again promoting nuclear reactors.
 Over the past 50 years, the US
government has provided $150 billion in
nuclear subsidies, but less than $5 billion
to renewable energy research.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
NUCLEAR FUSION
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Nuclear Fusion - Energy released when two
smaller atomic nuclei fuse into one large
nucleus. (Sun)
 Temperatures must be raised to
100,000,000o C and pressure must reach
several billion atmospheres.
- Magnetic Confinement
- Inertial Confinement
 Despite 50 years and $25 billion,
fusion reactors have never produced
more energy than they consume.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Summary:
•
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•
•
•
•
Energy History
How Energy Is Used
Coal
Oil
Natural Gas
Nuclear Power
 Fission
 Reactors
 Waste Management
 Fusion
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.