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					     Energy
By: Amanda Lotspike and Jaclyn
         Jacobson
                     Energy

• Energy is the ability to do work and transfer heat
• Types of energy:
   - Electrical- from flow of electrons
   - Mechanical- used to move or lift matter
   - Electromagnetic- light
   - Heat
   - Chemical- stored in bonds holding matter together
   - Nuclear- stored in nuclei of atoms
   - Electromagnetic Radiation- energy travels as a
  wave as a result of changes in magnetic and electric
  fields
Electromagnetic Spectrum
                Two major types of energy
     Moving masses of air, flowing streams, flowing electrons
   (electricity), heat, and electromagnetic radiation are examples
     of   Kinetic Energy. Kinetic energy is possessed by matter
                because of its mass and speed/velocity.


A rock held in your hand, and unlit match, still water behind a
   dam, and nuclear energy stored in the nuclei of atoms are
   examples of Potential Energy. Potential energy is stored
   and potentially available for use, and can be changed to
                         kinetic energy.
             Energy Laws
• 1st Law of Thermodynamics- In all physical
  and chemical changes, energy is neither
  created nor destroyed, but may be
  converted form one form to another
  - Energy input always equals energy
  output
  - We cannot get more energy out of a
  system than we put in
             Energy Laws
• 2nd Law of Thermodynamics- When energy
  changes form one form to another, some
  useful energy is always degraded to lower-
  quality, more dispersed, less useful energy
  - Degraded energy usually takes the form
  of waste heat
  - We can never recycle or reuse high-
  quality energy for useful work
  - Example: Only 5% of the energy used for
  incandescent bulbs becomes light energy, the
  rest is waste heat
     2nd Law of Thermodynamics


                    Chemical                                   Mechanical
                                            Chemical
 Solar                energy                                     energy
                                             energy
                                                                (moving,
energy           (photosynthesis)            (food)
                                                                thinking,
                                                                 living)
         Waste                      Waste              Waste                Waste
         Heat                       Heat               Heat                 Heat
Energy flow in ecosystems




All organisms are potential energy
       because they are potential
            sources of food.
A FOOD CHAIN determines how energy and nutrients
move from one organism to another through an
ecosystem.

Within a food chain, ecologists
assign each organism in an
ecosystem to a TROPHIC LEVEL,
or feeding level, by asking

• Is it a producer or a consumer?
• What does it eat or decompose?
               Solar Energy

• The sun is a giant nuclear fusion reactor
• Flow of high-quality energy- The sun’s energy
  flows to earth and through materials and living
  things (food webs and trophic levels), to the
  environment as waste heat, and back to space
  - No round-trips, energy cannot be recycled
  - 80% of the energy that reaches Earth
  warms the troposphere and cycles water
  through the biosphere
  - 1% creates wind
  - 0.01% used for photosynthesis
              Photosynthesis
• The process by which
  photoautotrophic organisms
  convert light energy into
  carbohydrates
• Overall reaction:
6CO2+ 6H20+ Light Energy 6O2+
  C6H12O6
Respiration
      • The process by which
        heterotrophic
        organisms convert
        carbohydrates and
        oxygen gas to energy
      • Overall reaction:
      6O2+ C6H12O6 6CO2+ 6H20+
        Energy
         Greenhouse Effect
• Infrared radiation reaches the troposphere
  and causes greenhouse gasses to vibrate
  and release longer infrared waves
  - Radiation interacts with air molecules and
  heats the troposphere through kinetic energy
  - Greenhouse gasses- H2O vapor, CO2,
  methane, nitrous oxide, ozone
  - Without this natural greenhouse effect,
  the earth would be too cold for today’s life
  forms to exist
                                                                     Energy Flow To and From Earth
      Solar
    radiation
                                     Energy in = Energy out
                                       Energy in =
                                       Energy out

                             Reflected by by
                                Reflected
                             atmosphere (34% )       Radiated by
    radiation
UV UV                           atmosphere              Radiated
                                                     atmosphere
                                (34% )                  by
   radiation                                         as heat (66%)
                                                        atmospher
                          Lower Stratosphere
                                  Lower                 e as heat
     Absorbed               (ozone layer)
                              Stratosphere
        Absorb                                          (66%)
     by ozone Visible      Troposphere
                              Troposph  Greenhouse
                              (ozone layer) Greenhou
        ed         Visibl
               Light          ere            effect
                                                 se
        by         e
        ozone      Light               Heat effect
                                          He
               Absorbed                   at
                  Absorb                         Heat radiated
               by the                               Heat
                  ed                             by the earth
               earth                                radiated
                  by the
                  earth                             by the earth
               Energy Efficiency
• Energy efficiency (energy productivity)
  - A measure of how much useful work is accomplished by input of
  energy into a system
 Energy Efficiency and Renewable
               Energy
• Amory Lovins
  - Built a solar-
  heated, solar-
  powered, super-
  insulated, earth-
  sheltered home
    Reducing Energy Waste and
    Improving Energy Efficiency
• Energy Conservation- Reducing or
  eliminating unnecessary waste of energy
  - 84% of U.S. commercial energy is
  wasted
  - 41% from waste heat or energy
  degradation (2nd law of thermodynamics)
  - 43% from inefficient vehicles, power
  plants, motors, and poorly designed
  buildings
    Reducing Energy Waste and
    Improving Energy Efficiency
• Energy Efficiency- Getting more work from
  each unit of energy we use
• Net Energy Efficiency- how much useful
  energy we get from a source after
  subtracting energy used to obtain the
  source
• Reducing energy waste is the quickest,
  cheapest, cleanest way to provide more
  energy, reduce pollution and
  environmental degradation, and slow
  global warming
    Reducing Energy Waste and
    Improving Energy Efficiency
• Energy Wasting Devices:
  - Incandescent light bulb- 5% efficient
  - Internal combustion engine- 6%
  efficient
  - Nuclear power plant- 8-14% efficient
  - Coal-burning power plant- 33% efficient
   Improving Energy Efficiency in
             Industry
• Combined Heat and Power (CHP) System or
  Cogeneration- industries obtaining two forms
  of energy from same fuel source
  - Example: In a power plant the steam
  produced by generating electricity is used as
  a heat source for the plant or nearby
  buildings
• Replace energy-wasting electric motors
• Switch from incandescent to fluorescent
  lighting
   Improving Energy Efficiency in
             Vehicles
• Increase Corporate Average Fuel
  Economy (CAFE) standards for
  motor vehicles
• Drive a Prius (or some other hybrid
  or hydrogen fuel-cell car)
• Pay the full cost of fuel that is
  hidden by subsidies
• Tax breaks for efficient vehicles
• Redesign urban mass
  transportation
               Efficient Cars

• Hybrids- have small gasoline-powered motor and
  electric motor for acceleration
  - Engine stops when coasting, emits less CO2,
  and gets 50mpg
• Plug-in Hybrids- have second rechargeable
  battery
• Energy-efficient diesel cars
• Fuel-Cell Vehicle- combines hydrogen gas with
  oxygen to produce energy and water vapor
  - Good: twice as efficient as internal
  combustion, no CO2 emitted
  - Bad: currently expensive, can produce NOx
    Improving Energy Efficiency in
              Buildings
• Superinsulation
  -Strawbale houses- use agricultural waste as insulating
  material
  -Green roofs- covered with plants that absorb and store heat
  energy
• Insulate and plug leaks
• Energy efficient windows
  -Face windows south in northern hemisphere for maximum
  passive solar energy use
• Heat water more efficiently
  -Tankless water heater fired by natural gas runs water
  through small burner chamber only when needed
• Use energy efficient appliances
  -Energy Star
• Use fluorescent lighting
 Using Renewable Solar Energy to
    Provide Heat and Electricity
             Source
• Direct source- sun
• Indirect source- moving water, wind,
  biomass, geothermal energy
    Heating With Solar Energy
• Passive solar heating- absorbs and stores heat
  from the sun directly within a structure
  - Energy efficient windows
  - Walls and floors of concrete, adobe, brick or
  stone store and release heat
• Active solar heating- absorbs energy from the sun
  by pumping heat-absorbing fluid through collectors
  - Collectors are dark colored flat-plates covered
  with glass
  - Energy can be stored in an insulated container
  for later use
Solar Heating
             Efficient Cooling
•   Use fans and outdoor breeze to cycle air
•   Block sun with balcony or overhang
•   Light-colored roof reflects light
•   Earth tubes underground with fans pipe
    cool underground air inside
Cooling Systems
 Using Solar Energy for Electricity

• Solar Thermal System- collects energy from
  sun and converts it to heat which can be
  changed into electricity or used directly
  - Central receiver system- power tower
  uses computer-controlled mirrors (heliostats)
  to focus sunlight on collector
  - Solar thermal plant- sunlight focused on
  oil-filled pipes running through area of solar
  collectors
  - Solar cookers- focus sunlight to cook food
                    Trade-Offs

        Solar Energy for High-Temperature
               Heat and Electricity

Advantages                       Disadvantages

Moderate net                     Low efficiency
energy
                                 High costs
Moderate
environmental                    Needs backup or
impact                           storage system

No CO2 emissions
                                 Need access to sun
Fast construction                most of the time
(1–2 years)
                                 High land use
Costs reduced
with natural gas                 May disturb desert
turbine backup                   areas
          Photovoltaic Cells
• Thin wafers of silicon with trace metals like
  cadmium to function as semiconductors
  - Emit electrons that flow and create an
  electrical current
                           Trade-Offs
                           Solar Cells

            Advantages                  Disadvantages
Fairly high net energy                   Need access to sun

Work on cloudy days
                                         Low efficiency
Quick installation

Easily expanded or moved                 Need electricity storage
                                         system or backup
No CO2 emissions
                                         High land use (solar-cell
Low environmental impact                 power plants) could disrupt
                                         desert areas
Last 20–40 years

Low land use (if on roof                 High costs (but should
or built into walls or                   be competitive in 5–15
windows)                                 years)

Reduces dependence on
fossil fuels                             DC current must be converted
                                         to AC
 Producing Electricity Through the
           Water Cycle
• Hydropower
  - Using the flow of water to produce
  electricity
                                Dam It.
•   Large-scale dam- high walled across a river
•   Advantages:
    - Allows water to flow through pipes and spin turbines and produce
    electricity
    - Highly efficient
    - Low-cost
    - Long life span
    - No carbon dioxide emissions
    - Provides recreation
•   Disadvantages:
    - Floods land
    - Displaces people and animals
    - Danger of collapse
    - Obstructs fish migration
    - Thermal pollution
    - Decreases flow of silt below dam
  More Hydro-Electric Options
• Micro-hydro Generators- small scale dam
  that can be removed and has little
  environmental impact
• Tidal Energy- dam across mouth of bay or
  estuary with turbines spun by rising tides
   Producing Electricity with Wind

• Wind- flow of air caused by difference in solar
  heating between the equator and poles along with
  earth’s rotation
• Wind Energy
  - Cheapest energy source (with environmental
  impact included)
  - Can be built quickly
  - Turbines can be controlled with a single
  computer source
  - Off-shore wind farms are even more efficient
  - Some people find wind turbines visually
  polluting
 Producing Energy From Biomass

• Biomass
  - Organic plant materials or animal
  wastes that can be burned directly or
  converted to gaseous or liquid biofuels
  - Biomass used for heating and cooking
  supply 10% of the world’s energy
  - Many developing countries are
  harvesting fuel wood faster than it is being
  produced
        Producing Biomass
• Biomass plantation- plant and harvest fast
  growing species
  - Poplars, sycamores, cottonwoods, water
  hyacinth
  - Repeatedly planting one species depletes
  soil of nutrients
• Crop residue or animal wastes can also be
  burned
  - Burning biomass releases the CO2 locked
  in plants
        Producing Liquid Biofuels

• Brazil already runs 40% of its cars on ethanol
• Advantages:
  -Crops can be grown almost anywhere
  -Reduces independence on foreign fuel
  -No net increase in CO2 with continued sustainable use
  -They are available now
  -Switchgrass can be grown on marginal land quickly, and has
  high-net energy yield
• Disadvantages:
  -Industrialized agriculture lends itself to unsustainable
  harvesting
  -Using land for farming decreases biodiversity
  -Competes with farm land for food crops
                      Grass to Gas

• Ethanol- can be made by fermentation and distillation of plant
  sugars
• Gasohol= gasoline+ (10-23%) pure ethanol
• Brazil uses bagasse (sugarcane residue) to create ethanol
• Corn is not the answer- it is highly subsidized and has low-net
  energy yield
• Cellulosic ethanol- use bacteria to convert cellulose and lignin in
  plants to starches that can be turned into ethanol by other
  bacteria
• Biodiesel- uses alcohol in combination with vegetable oils
  -40% more efficient than gas
  -Produces 78% less carbon dioxide than conventional diesel
  -Can produce high amounts of photochemical smog
• Methanol- produced with natural gas, coal, or wood, garbage
              Solid Biomass Fuels

            Wood logs and pellets

                   Charcoal
       Agricultural waste (plant debris)

          Timbering wastes (wood)

            Animal wastes (dung)
   Aquatic plants (kelp and water hyacinths)
Urban wastes (paper, cardboard, combustibles)




                    Conversion to
    Direct          gaseous and
    burning         liquid biofuels




      Gaseous Biofuels        Liquid Biofuels
                              Ethanol
      Synthetic natural
                              Methanol
      gas (biogas)
                              Gasohol
      Wood gas
                              Biodiesel
                                Trade-Offs

                                Biodiesel

                 Advantages                  Disadvantages

Reduced CO emissions                         Slightly increased emissions
                                             of nitrogen oxides
Reduced CO2 emissions (78%)
                                             Higher cost than regular
                                             diesel
Reduced hydrocarbon
emissions
                                             Low yield for soybean
                                             crops
Better gas mileage (40%)
                                             May compete with growing
                                             food on cropland
High yield for oil palm crops

                                             Loss and degradation of
Moderate yield for                           biodiversity from crop
rapeseed crops                               plantations

Potentially                                  Hard to start in cold weather
renewable
                      Trade-Offs

                     Methanol Fuel

  Advantages                         Disadvantages
High octane                          Large fuel tank
                                     needed
Some reduction in
CO2 emissions                        Half the driving
                                     range
Lower total air
pollution (30–40%)
                                     Corrodes metal,
                                     rubber, plastic
Can be made from
natural gas,
agricultural                         High CO2 emissions
wastes, sewage                       if made from coal
sludge, garbage,
and CO2                              Expensive to
                                     produce
Can be used to
produce H2 for                       Hard to start in cold
fuel cells                           weather
                Geothermal Energy

• Consists of heat stored in soil, underground rocks, and fluids in the
  earth’s mantle
• Geothermal heat pump (GHP)- can heat and cool a house by using
  the difference in underground temperatures and the earth’s surface
• Usually a loops of buried pipes filled with fluid that extracts heat from
  the ground and carries it to a heat pump
• Hydrothermal reservoirs- deep and concentrated underground and
  can be used to spin turbines
• Dry steam reservoir- has water vapor but no droplets
• Wet steam reservoir- mixture of steam and water droplets
• Hot water reservoir- trapped in porous rock
• U.S. is the largest producer of geothermal energy
• Currently high cost to produce
• Steam reservoirs can be depleted if used unsustainably
            Geothermal Heating and
                   Cooling



Basement
heat pump
                     Trade-Offs

                  Geothermal Energy

Advantages                        Disadvantages
Very high                         Scarcity of suitable
efficiency                        sites
Moderate net
                                  Depleted if used
energy at
                                  too rapidly
accessible sites
Lower CO2                         CO2 emissions
emissions than
fossil fuels                      Moderate to high
                                  local air pollution
Low cost at
favorable sites
                                  Noise and odor
Low land use                      (H2S)
Low land
disturbance                       Cost too high
                                  except at the most
Moderate                          concentrated and
environmental impact              accessible sources
                Hydrogen

• Releases more energy per gram than any
  other fuel
• Challenges:
  - Hydrogen is chemically locked up in H2O
  or organic compounds
  - It takes energy and money to produce
  hydrogen
  - Current fuel cells are expensive
  - We have to use fossil fuels to make
  hydrogen
                                        Trade-Offs
                                        Hydrogen
                           Advantages            Disadvantages
Can be produced from plentiful                   Not found in nature
water
                                                 Energy is needed to produce fuel
Low environmental impact
                                                 Negative net energy
Renewable if from renewable
resources                                        CO2 emissions if produced from
                                                 carbon-containing compounds
No CO2 emissions if produced
from water                                       Nonrenewable if generated by fossil
                                                 fuels or nuclear power
Good substitute for oil
                                                 High costs (but may eventually
Competitive price if environmental               come down)
& social costs are included in cost
comparisons                                      Will take 25 to 50 years to phase in

Easier to store than electricity                 Short driving range for current
                                                 fuel-cell cars
Safer than gasoline and natural gas
                                                 No fuel distribution system in place
Nontoxic
                                                 Excessive H2 leaks may deplete
High efficiency (45–65%) in                      ozone in the atmosphere
fuel cells
    Sustainable Energy Strategy

• Gradual shift from large, centralized
  macropower systems to smaller,
  decentralized micropower systems
• The best alternatives combine improved
  energy efficiency with natural gas and
  biofules to transition to renewable sources
• The government can keep prices artificially
  low to encourage selected energy sources
NONRENEWABLE ENERGY
About 99% of the energy we use for heat comes from
   the sun and the other 1% comes from commercial
    energy (76% of which comes from the burning of
  carbon-containing fossil fuels—oil, natural gas, and
                         coal).
                           CRUDE OIL
                          Also called petroleum and conventional/light oil is
                             a thick and gooey liquid consisting of
                             combustible hydrocarbons and small amounts of
                             sulfur, oxygen, and nitrogen impurities.

                          Geologists use satellite data, conduct ground, air,
                            and seismic surveys, and drill rock cores and
                            wells in order to find oil.



Deposits of crude oil and natural gas are trapped
together underneath a dome deep within the earth’s crust.

Crude oil is dispersed in pores and cracks in underground
rock formations.
1. Oil is EXTRACTED (drawn by gravity into the bottom of a well
   which is then pumped to the surface and only 35-50% is
   retrieved)

2. Oil is then TRANSPORTED to a refinery (by way of truck,
   pipeline, or oil tanker).

3. At the REFINERY, oil is heated and distilled to separate its
   components (which decreases its energy yield)




Products from oil distillation include petrochemicals (used as
   industrial organic chemicals, pesticides, plastics, synthetic
   fibers, paints, medicines, etc.)
     RESERVES OF WORLD OIL (OPEC Countries)
                               Saudi Arabia (25%)
                                  Canada (15%)
                                    Iraq (11%)
                           United Arab Emirates (9.3%)
                                  Kuwait (9.2%)
                                   Iran (8.6%)

                 And the three largest consumers:

                                 1.United States
                              (29% from offshore drilling)
                                     2. China
                                      3.Japan

It costs about $7.50 to $10.00 per barrel to produce oil in the US and $1.00 to $2.00
per barrel to produce oil in Saudi Arabia.

(This is why the US imported 60% of its oil in 2005)
                           Trade-Offs
                         Conventional Oil
           Advantages                Disadvantages
Ample supply for
                                      Need to find
42–93 years
                                      substitutes within 50
                                      years
Low cost (with huge
subsidies)
                                      Artificially low price
                                      encourages waste and
High net energy yield                 discourages search for
                                      alternatives

Easily transported within
and between countries
                                      Air pollution when
                                      burned
Low land use

Technology is well                    Releases CO2 when
developed                             burned
Efficient distribution
system                                Moderate water
                                      pollution
                                                               Fig. 16-7, p. 363
       A CRUDE AWAKENING
• Burning oil accounts for 43% of
• global carbon dioxide emissions

• Supplies about 1/3 of the world’s
  energy (plastics, asphalt,
  transportation).

• Reserves are projected to be 80% depleted by 2050 to
  2100

• Production rate is dropping 5% per year while
  consumption rate has a 2-5% exponential growth.
                              OIL SAND
Oil sand, or tar sand, is a mixture of clay, sand, water, and a combustible
   organic material called bitumen (a thick and sticky heavy oil with a high
   sulfur content).

• dug up from the earth’s surface
• ¾ of reserves found in Northeastern Alberta, Canada
• reserves In Canada and Venezuela contain more oil than Saudi Arabia


EXTRACTING AND PROCESSING

•   produces huge amounts of toxic sludge
•   uses and contaminates a large volume of water
•   requires large inputs of natural gas (which reduces energy yield from the
    oil)

New developments include underground mining which leaves land
undisturbed but requires huge amounts of natural gas and releases as much
carbon dioxide in the air as conventional oil.
                              OIL SHALE
Shale oil is extracted from oil shales which contain a solid combustible
mixture of hydrocarbons called krogen. It is extracted by heating crushed oil
shales and refined (removing sulfur, nitrogen, and other impurities) before
transporting


• about ½ of the world’s estimated oil shale reserves are buried deep in rock
formations in the western United States

• other large reserves include Russia, China, and Australia

• most deposits are of such low grade that it takes a lot of energy, water, and
money to mine and convert the krogen to crude oil
                  Trade-Offs
       Heavy Oils from Oil Shale
            and Oil Sand
 Advantages                    Disadvantages

Moderate cost                  High cost
(oil sand)                     (oil shale)

Large potential                Low net energy
supplies,                      yield
especially oil
sands in                       Large amount
Canada                         of water needed
                               for processing
Easily
transported
                               Severe land
within and
                               disruption
between
countries
                               Severe water
Efficient                      pollution
distribution
system in                      Air pollution
place                          when burned

Technology is                  CO2 emissions
well developed                 when burned
                                                 Fig. 16-10, p. 365
                     Natural Gas
: a mixture of gases which consists of 50-90% methane and small
    amounts of ethane, propane, butane, and hydrogen sulfide (very
    toxic)

Conventional natural gas lies above most reservoirs of crude oil.
Liquefied petroleum gas (LPG) consists of liquefied propane and
   butane (removed when the natural gas field is tapped).

• Supplies 23% of U.S. energy needs,12% of the nations electricity,
  and heats 52% of U.S. homes
• 20% is imported (95% of which comes from Canada)
• Russia has 31% of world’s proven reserves
               Natural Gas (cont’d)
• A versatile fuel that can be burned to heat space and water
  and to propel vehicles (with modifications)

• Releases less carbon dioxide into the troposphere than oil, oil
  sand, or coal

• Natural-gas-run turbines are 50-60% more energy efficient
  than coal and 24-35% more than nuclear power, are cheaper
  to build, require less time to install, and are easy and cheap to
  maintain

However, cost advantages are decreasing because of near
  tripling costs of natural gas prices.
      Unconventional Natural Gas
• Found in underground sources (ex. Coal bed
  methane gas)
• Results in roads, pipelines, and waste water pits
  that pollute the air and water (with salt and other
  minerals) and scar the land
• Can reduce U.S. alliance on natural gas imports

• Another example, Methane Hydrate, is trapped in
  water molecules
• Extraction releases methane into the troposphere
• Currently extraction is too expensive
                                 Trade-Offs
                           Conventional Natural Gas

                Advantages                    Disadvantages

Ample supplies (125 years)                    Nonrenewable resource

High net energy yield
                                              Releases CO2 when
                                              burned
Low cost (with huge
subsidies)
                                              Methane (a greenhouse gas)
Less air pollution than other                 can leak from pipelines
fossil fuels

Lower CO2 emissions than                      Difficult to transfer from
other fossil fuels                            one country to another

Moderate environmental
impact                                        Shipped across ocean as
                                              highly explosive LNG
Easily transported by pipeline
                                              Sometimes burned off and
Low land use                                  wasted at wells because of
                                              low price
Good fuel for fuel cells
and gas turbines
                                              Requires pipelines
                                                                           Fig. 16-11, p. 368
                       COAL
: A solid fossil fuel that is formed in several stages as the
   buried remains of land plants that lived 300 to 400
   millions of years ago
                  COAL (cont’d)
• Contains mostly carbon and small amounts of sulfur (which
  turns into sulfur dioxide when coal burns)

• Anthracite (95% carbon) is the most desirable type of coal
  because of its high heat content and low sulfur content

• Coal generates 62% of the world’s electricity and 50% of U.S.
  electricity

• Burned to create ¾ of the world’s steel

• Area strip mining is used to extract coal found close to the
  earth’s surface on flat terrain

• Contour strip mining is used on hilly or mountainous terrain
          COAL SUPPLIES
Coal is the world’s most abundant fossil fuel.

• The U.S. has 27% of the world’s proven
  coal reserves, Russia has 17%, China has
  13%, India has 10%, and Australia has 9%
• This supply of coal could last hundreds to
  thousands of years
EFFECTS OF COAL BURNING
• Single biggest polluter in the U.S.

• Releases 25% more carbon dioxide per unit of energy than burning
  oil

• Accounts for more than 1/3 of the world’s annual carbon dioxide
  emissions

• Each year, air pollutants from burning coal prematurely kill 23,500
  people

• Responsible for ¼ of atmospheric pollution from toxic mercury in the
  U.S.

• Releases more radioactive particles into the air than normally
  operating nuclear power plants
                  Trade-Offs
                     Coal
 Advantages                    Disadvantages
Ample supplies                 Severe land
(225–900 years)                disturbance, air
                               pollution, and
High net                       water pollution
energy yield
                               High land use
Low cost                       (including
(with huge                     mining)
subsidies)
                               Severe threat to
Well-developed                 human health
mining and
combustion
technology                     High CO2
                               emissions
                               when burned
Air pollution
can be
reduced with                   Releases
improved                       radioactive
technology                     particles and
(but adds to                   toxic mercury
cost)                          into air
                                                  Fig. 16-14, p. 370
         SYNTHETIC FUELS
Solid coal can be converted into synthetic natural
  gas by coal gasification or into a liquid such as
  methanol or synthetic gasoline by coal
  liquefaction

• Does not have large enough government
  subsidies

• Require mining 50% more coal

• Coal gasification plants can remove all carbon
  dioxide from their emissions and then pump it
  underground or in the ocean (which in turn
  leaves pure hydrogen)
                Trade-Offs
               Synthetic Fuels
Advantages                   Disadvantages
Large                        Low to
potential                    moderate net
supply                       energy yield

                             Higher cost
                             than coal
Vehicle fuel
                             Requires
                             mining 50%
                             more coal
Moderate cost                High
(with large                  environmental
government                   impact
subsidies)
                             Increased
                             surface
                             mining of coal
Lower air
pollution                    High water use
when
burned than                  Higher CO2
coal                         emissions than
                             coal
                                              Fig. 16-15, p. 371
             NUCLEAR ENERGY
: generated when isotopes of uranium and plutonium undergo
   controlled nuclear fission, and the heat produced spins turbines
In a nuclear fission chain reaction, neurons split the
nuclei of atoms such as uranium-235 and plutonium-239
and release energy mostly as high temperature heat.




In a nuclear power plant reactor, the rate of fission is
controlled and the heat generated is used to produce
high-pressure steam, which spins turbines that generate
electricity.
       LIGHT-WATER REACTORS
• Produce 85% of the world’s nuclear-generated electricity (100% in the U.S.)

• The core contains tens of thousands of long, thin fuel rods each packed with
fuel pellets. One hundred of these rods create a fuel assembly, and then
thousands of assemblies are bundled together.

• The uranium oxide fuel in each pellet contains 97% non-fissionable uranium-
238 and 3% fissionable uranium-235

• A neutron-absorbing material called a moderator slows down the neutrons
emitted by the fission process

• A coolant circulated through the reactor core to remove heat

• A containment vessel with strong and thick steel-reinforced concrete walls
surrounds the reactor core (in order to keep radioactive materials from escaping
into the environment)

• Water-filled pools store fuel rod assemblies that are removed when reactors are
refueled each year
               Small amounts of
               radioactive gases
Uranium fuel
                               Control rods
input (reactor
core)                             Containment shell
                                      Heat exchanger
                                              Steam    Turbine
                                                                       Generator             Electric
                                                          Waste heat                         power




                                                                                            Useful energy
                                                                            Hot               25%–30%
                                                                            water
                                                                            output


                           Coolant
                                                                            Cool         Waste heat
                      Moderator                                             water
                                                                            input
                      Coolant
Shielding    Pressure
                      passage
             vessel
                                           Water      Condenser
  Periodic removal and       Periodic removal
                                                                              Water source (river,
  storage of radioactive     and storage of
                                                                              lake, ocean)
  wastes and spent fuel      radioactive liquid
  assemblies                 wastes

                                                                                           Fig. 16-16, p. 372
     History of Nuclear Power
U.S. utilities began developing nuclear
power plants in the 1950s for three reasons:

1. The Atomic Energy Commission promised utility
   executives that nuclear energy would produce
   electricity at a much lower cost than alternatives
2. The government (taxpayers) paid about ¼ the cost of
   building the first group of commercial reactors and
   guaranteed there would be no overruns
3. After insurance companies refused to insure nuclear
   power, Congress passed the Price-Anderson Act to
   protect the U.S. nuclear industry from liability in case
   of acidents
Electricity production is the world’s slowest-growing energy source

No new nuclear power plants have been ordered since 1978 (all 120 plants
   ordered since 1973 have been canceled)

Reasons for failure to grow as projected:
• Multibillion-dollar construction cost overruns
• High operating costs and more malfunctions than expected
• Concerns over safety
• Vulnerability of terrorist attacks



                                 Chernobyl (Ukraine) is the site of the world’s
                                 most serious nuclear power plant accident. In
                                 1986, a series of explosions blew the roof off of
                                 the reactor building. This was caused by poor
                                 design and human error, and caused the deaths
                                 of 56 people (according to the government) and
                                 90,000 (according to Greenpeace).
High-level nuclear active wastes must be stored safely for 10,000
   years.




Proposed methods include:
• Bury it deep underground
• Shoot it into space
• Bury it under the Antarctic ice sheet or the Greenland Ice cap
• Dump it into descending subduction zones
• Bury it in thick deposits of mud on the ocean floor
• Change it into less harmful isotopes

(worn-out nuclear plants must be decommissioned when it reached the
   end of its useful life which includes dismantleing and storing its large
   volume of highly radioactive wastes in a high-level nuclear waste
   storage facility)
Advanced Light Water Reactors
• Have built in passive safety features
• Are high-temperature, gas-cooled reactors
  (used to decompose water to produce
  hydrogen fuel)
• However, do no eliminate threats and the
  expense and hazards of long-term
  radioactive waste storage
  Pebble Bed Modular Reactor
• No need for emergency core cooling
  system and an airtight containment dome
• Does not need to be shut down to add
  new fuel
• However, is an old design, can release
  massive amounts of radioactivity if cracks
  in reactor, would create ten times the
  volume of radioactive waste per unit of
  electricity compared to a conventional
  nuclear reactor
 Breeder Nuclear Fission Reactors
• Generate more nuclear fuel than they
  consume
• However, if safety system fails, the reactor
  could lose some of its coolant which is
  explosive when exposed to air and water
• Produce plutonium so slowly that it would
  take 300 to 200 years to produce enough
  plutonium to fuel a significant number of
  other breeder reactors
Nuclear energy has received 58% of all
federal energy and research development
 funds (compared to 22% for fossil fuels,
  11% for renewable energy, and 8% for
    energy efficiency and conservation
           Future Energy Policy
• Creating a future energy policy involves answering the
  following questions:
  -How much of the resource will be available in the near
  future?
  -What is the net energy yield?
  -How much will it cost to produce, develop, phase in and use
  the resource?
  -Are government subsidies and taxes necessary?
  -How will dependence on the resource affect global economic
  and military security?
  -Is the resource vulnerable to terrorism?
  -How will extracting, using, and transporting the resource
  affect the environment?
                                                       Small solar-cell
           Bioenergy power      Wind farm               power plants
           plants




Rooftop solar                                                   Fuel cells
cell arrays                                                               Solar-cell
                                                                            rooftop
                                                                           systems


                                          Transmission
                                          and distribution
                                          system

                                                                  Commercial
                 Small
Residential      wind
                turbine

                             Industrial               Microturbines
Improve Energy
Efficiency                More Renewable Energy
Increase                  Increase renewable energy to 20% by
fuel-efficiency           2020 and 50% by 2050
standards for
vehicles, buildings,      Provide large subsidies and tax
and appliances            credits for renewable energy
Mandate govern-           Use full-cost accounting and life-cycle
ment purchases            cost for comparing all energy
of efficient vehicles     alternatives
and other devices
                          Encourage government purchase of
Provide large tax         renewable energy devices
credits for buying
efficient cars, houses,   Greatly increase renewable energy
and appliances            R&D
Offer large tax
credits for invest-
ments in energy           Reduce Pollution and Health Risk
efficiency
                          Cut coal use 50% by 2020
Reward utilities for
reducing demand for       Phase out coal subsidies
electricity
                          Levy taxes on coal and oil use
Encourage indepen-
dent power producers      Phase out nuclear power or put it on
                          hold until 2020
Greatly increase energy
efficiency research and   Phase out nuclear power subsidies
development                                           Fig. 17-36, p. 415

				
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