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 plantsProcess Efficiency %Chemical Thermal 60 %Water steam 90%Steam turn turbine 75%Turbine generator 95%Tranmission through power lines

90%

Over all efficiency 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 3-

5%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.energy-green.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