Transcript Earth’s Energy Sources - Piedra Vista High School

Earth’s Energy Sources
Chapter 22 Pearson, 16 Glenco
Energy uses
• List all of the energy sources you have used
today
Solar Energy
• Heating with solar energy
• Passive Solar energy
• Active Solar energy
Passive
Active
Transforming Energy
• Law of conservation of Energy: energy is
neither created nor destroyed only
transformed.
• Some energy transformation is not useful for
us.
– Example: Power lines transform energy into heat.
Published January 27, 2011 | By Amanda Kaufmann
Energy Usage in the United States
Energy Usage in the United States
Fossil Fuels
• Formed by decay of ancient plants and
animals
• When burned they produce carbon dioxide
and water
• Petroleum,
• Natural Gas, and coal
Petroleum
• Fossil Fuel made of Hydrocarbons
• Produced by separating the liquid oil in a
process called Fractional distillation.
– Oil is pumped into the bottom of a tower and
heated. Materials rise to the top depending on
boiling point and are collected. Some are pulled
from the bottom, like asphalt.
– Other uses: Plastics, lubricants, asphalt
Petroleum and by-products
• List four things in the class room made from
petroleum.
http://www.msnbc.msn.com/id/37637353/ns/technology_and_science-science/t/just-pelicans-people-cant-avoid-oil-either/#.T2NP8M3SOJo
Natural Gas
• Composed mainly of Methane.
• Natural gas contains more energy per kilogram
than either petroleum or coal.
• Produces fewer pollutants than other fossil fuels
Coal
• Solid fossil fuel found underground
• One fourth of our energy comes from coal.
• Coal is formed from organic material
deposited in ancient swamps.
• Burning coal results in more pollutants
Generating Electricity
Coal generation
Electricity Generation
• Fuel is burned to heat a boiler of water
• Steam is produced and causes the turbine to
spin
• Turbine is connected to an electric generator
– Electric current is produced when the spinning
turbine shaft rotates magnets inside the
generator.
Simple Electric Generator
• When the coil is turned, the magnets cause
movement in the electrons within the coil.
The movement of
electrons causes
an electric current.
Efficiency of Power plants
Process
Chemical Thermal
Water steam
Steam turn turbine
Turbine generator
Tranmission through
power lines
Over all efficiency
Efficiency %
60 %
90%
75%
95%
90%
35%
65% is converted to thermal( unusable energy)
Nonrenewable Resources
• Cannot be replaced by natural processes as
quickly as they are used.
• All fossil fuels are nonrenewable.
http://www.theoildrum.com/story/2006/12/13/44528/872
Carbon dioxide
1. According to the graph by how many parts
per million (ppm) did the concentration of
CO2 increase from 1958 to 2000?
Nuclear Energy
Nuclear Power
• Energy is released when the nucleus of an
atom breaks apart.
• Nuclear power plants produced 8% of all
power in 2003.
• There were 104 nuclear reactors at 65 power
plants in the US.
Core of the Nuclear Reactor
Nuclear power
• Only certain elements
– Uranium 235
– Naturally occurring at 0.7% so it is enriched to 35%
Inside the reactor core fuel pellets are placed
in a tube the core contains 100,000 Kg of
uranium in fuel rods
Energy released by 1 gram = 3 million kg of
coal
Nuclear fission
• A neutron hits a U-235 nucleaus and splits it
apart into two smaller nuclei and energy is
released
Risks of Nuclear power
• Mining of Uranium causes enviornmental
damage.
• Coolant water must be cooled before
discharge
• The most serious is the release of radioactivity
Disposal of Nuclear waste
• Low-level waste:
– Have low radioactivity
– Short half-lives
– Can be released into the air when diluted.
• High-Level Waste:
– The spent fuel rods
– Stored in water
– Will remain radioactive for for tens of thousands
of years
– Can be sealed in glass and buried in salt mines.
Renewable Energy Resources
• A Renewable resource is an energy source
that is replaced nearly as quickly as it is used
Solar
• Use Photovoltaic cell that converts radiant
energy from the Sun directly into electrical
energy. Also called solar cells
How a photovoltaic cell works
• Only about 7 to
• 11% efficient
Uses of Solar energy
• More expensive in 2003 than burning fossil
fuels
• Another method is to use the sun to heat a
fliud that then heats steam toturn a turbin to
generate power.
Hydroelectric power
• Electricity is produced by the energy of
moving water
• http://www.energygreen.net/blog/catalog.asp?tags=hydro-power
http://www.energy-green.net/blog/catalog.asp?tags=hydro-power
Advantages of Hydro power
• 8% of all US power is made this way
• Efficient: because no heat is involved that can
take away from the energy used to turn the
turbines
• Without any pollution
• Dams form lakes that can be used for drinking
water and irrigation
Disadvantages
• Have to have a place to build the dam near
the regions that need to power
• Destroys the area around the dam
• Fish cannot migrate
– Fish ladders are added to dams but still reduce the
fish.
Tidal Energy
• Gravity from the sun and moon bulge the
earths oceans (tides)
• Hydroelectric power can be generated by the
tides. As the tide comes in and out it turns a
turbine
• Pollution free
• Only a few places have large enough tides to
produce electricity
Wind Energy
• Windmills historically pump water, grind grain.
• For electricity they are 20% efficient( and
improving)
• Only a few places have enough wind
• Noisy
• Change landscape appearance, disrupt bird
migrations.
• They do not consume any nonrenewable
resource and do not pollute
Geothermal energy
• Energy from the earth.
• 16% efficient
• Can release gases and bring brine to the
surface
• Only can be used where magma is close to the
surface.
Alternative fuels
• Biomass fuels; burned in the presence of
oxygen: wood sugarcane, fibers, rice hulls,
animal manure.
• Hydrogen gas fuel cells