Conventional Energy

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Conventional Energy
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Outline

• Energy History
• How Energy Is Used
• Coal
• Oil
• Natural Gas
• Nuclear Power
• Fission
• Reactors
• Waste Management
• Fusion

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WHAT IS ENERGY

• 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 1o C.
• Joule - Amount of work done when a force of 1
  newton is exerted over 1 meter.

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Energy History

• 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 1970s.
• Early 1980s saw increased interest in
  conservation and renewable energy.
• Oil glut in mid 1980s caused prices to fall.
• U.S. now imports over half annual oil supply.

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Current Energy Sources

• Fossil fuels currently provide about 86 of all
  commercial energy in the world.
• Hydroelectric dams supply about 7 of commercial
  power.
• Nuclear power makes up about 6.5 of commercial
  power, but about 20 of electric power in
  more-developed countries.

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Worldwide Commercial Energy Production
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Per Capita Consumption

• Richest 20 countries consume nearly 80 of
  natural gas, 65 of oil, and 50 of coal
  production annually.
• On average, each person in the U.S. and Canada
  uses more than 300 GJ (equivalent to 60 barrels
  of oil) of energy annually.
• In poorest countries of the world, each person
  generally consumes less than one GJ annually.

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Per Capita Energy Use and GDP
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HOW ENERGY IS USED

• Largest share of energy used in the U.S. is
  consumed by industry (33).
• Residential and Commercial buildings use 20 of
  primary energy consumed in U.S..
• Transportation consumes about 27 of all energy
  used in the U.S..
• Three trillion passenger miles and 600 billion
  ton miles of freight carried annually by motor
  vehicles in the U.S..

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How Energy Is Used

• 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.

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U.S. Energy Flow
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COAL

• 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).

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Coal

• 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.

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Proven-In-Place Coal Reserves
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Coal

• 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.

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Coal

• 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 U.S..
• 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.

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OIL

• 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.

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Oil Recovery Process
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OIL

• Resources and Reserves
• Total amount of oil in the world is estimated at
  4 trillion barrels. (Half is thought to be
  ultimately recoverable)
• In 2003, 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.

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Proven Oil Reserves
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Oil

• Imports and Domestic Supplies
• The U.S. 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 U.S. was the worlds leading oil
  export country.
• By 1998, the U.S. was importing 10 million
  barrels per day - Half of total consumption.

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Oil

• 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.

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NATURAL GAS

• Worlds 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.

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Natural Gas

• Resources and Reserves
• Proven world reserves of natural gas are 5,500
  trillion ft3.
• Current reserves represent roughly 60 year supply
  at present usage rates.
• Proven reserves in North America are about 250
  trillion ft3.

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Proven Natural Gas Reserves
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Unconventional Gas Sources

• 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.

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NUCLEAR POWER

• 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.

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Nuclear Power

• 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.

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Nuclear Power Plant History
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How Do Nuclear Reactors Work ?

• 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 are bundled together to make a
  fuel assembly.
• Thousands of fuel assemblies bundled in reactor
  core.

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How Do Nuclear Reactors Work

• 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
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How Do Nuclear Reactors Work

• 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.

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Kinds of Reactors

• 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.

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Kinds of Reactors

• 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.

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PWR
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Kinds of Reactors

• 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.

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Alternative Reactor Designs

• 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.

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Breeder Reactors

• 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.

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Breeder Reactor Drawbacks

• 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.

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RADIOACTIVE WASTE MANAGEMENT

• Until 1970, the U.S., 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 U.S..

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Radioactive Waste Management

• About 100,000 tons of low-level waste (clothing)
  and about 15,000 tons of high-level (spent-fuel)
  waste in the U.S..
• 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.

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Radioactive Waste Management

• U.S. 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.

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Decommissioning Old Nuclear Plants

• 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.

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CHANGING FORTUNES OF NUCLEAR POWER

• 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 U.S..

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Changing Fortunes

• With natural gas prices soaring, and electrical
  shortages looming, many sectors are once again
  promoting nuclear reactors.
• Over the past 50 years, the U.S. government has
  provided 150 billion in nuclear subsidies, but
  less than 5 billion to renewable energy research.

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NUCLEAR FUSION

• 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.

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Summary

• Energy History
• How Energy Is Used
• Coal
• Oil
• Natural Gas
• Nuclear Power
• Fission
• Reactors
• Waste Management
• Fusion

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