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Sources of Energy. pp.145-151. Nearly all the energy on Earth comes originally from the sun. Plants get energy for photosynthesis from sunlight. Animals get energy from food, including plants. Over time plant and animal remains changed into coal, oil and natural gas.

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nearly all the energy on earth comes originally from the sun
Nearly all the energy on Earth comes originally from the sun.
  • Plants get energy for photosynthesis from sunlight.
  • Animals get energy from food, including plants.
  • Over time plant and animal remains changed into coal, oil and natural gas.
  • Photovoltaics change solar power directly into electricity
  • Heat from sunlight creates wind, which windmills change into electricity or mechanical energy.
fossil fuels
Fossil Fuels

Coal, oil and natural gas are called fossil fuels because they take millions of years to be created, like fossils.

Fossil fuels are nonrenewable resources because we are using them much faster than they can be replaced.

They will run out!

Burning fossil fuels releases pollution into the air.

fossil fuels1
Fossil Fuels

Coal comes from plants alive millions of years ago.

Oil and natural gas come from animals and bacteria from millions of years ago.

nuclear energy
Nuclear Energy

Nuclear energy comes from releasing the energy that holds the nucleus of a uranium atom together.

This releases lots of heat (thermal energy).

The nuclear fuel is still radioactive for millions of years after it’s removed from the power plant.

hydroelectricity
Hydroelectricity

Uses the potential energy of water to generate electricity.

The water has to be stored by a dam. Then it passes through the dam’s generators.

Hydroelectricity is a renewable resource because the source can be replaced.

inexhaustible resources
Inexhaustible Resources

Inexhaustible means they can never run out!

Examples include solar power, wind power and geothermal energy.

These are also called alternative resources.

geothermal energy
Geothermal Energy
  • Underground temperature stays same year round
  • Power plants pump water deep down to be heated to steam to generate electricity.
  • Home Heat Pumps
    • In summer: underground cooler than house so pump water down to cool it, then pump through house
    • In winter: underground hotter than house so pump water down to heat it, then pump through house
inexhaustible resources1
Inexhaustible Resources

Solar Power

Wind Power

Geothermal

  • From sunlight
  • Depends on weather
  • Expensive
  • Passive solar uses light to heat water
  • Photovoltaics change light energy into electricity
  • From underground heat
  • No pollution
  • Expensive
  • From kinetic energy of wind
  • Depends on weather
  • No pollution
  • Not pretty to look at
  • Can kill birds that fly into windmill
notes
Notes
  • Nearly all the energy on Earth comes originally from the sun
  • Coal, oil and natural gas are called fossil fuels.
  • Nonrenewable resources are used faster than they can be replaced. (Examples: coal, oil, natural gas)
  • Renewable resources can be replaced. (Example: hydroelectricity)
  • Inexhaustible resources can never run out! (Examples: solar, wind, geothermal energy)
  • Photovoltaics change sunlight to electric energy.
fossil fuels2
Fossil Fuels

Advantages

  • We already use them
  • Portable
fossil fuels3
Fossil Fuels

Advantages

Disadvantages

Limited amounts left

Need large amounts of fuel

Releases lots of pollution

Leaves lots of ash/residue

  • We already use them
  • Portable
nuclear energy1
Nuclear Energy

Advantages

  • Uses small amounts of fuel
  • No air pollution
  • Releases large amounts of energy
nuclear energy2
Nuclear Energy

Advantages

Disadvantages

Limited amounts of uranium

Leaves radioactive waste

  • Uses small amounts of fuel
  • No air pollution
  • Releases large amounts of energy
hydroelectricity1
Hydroelectricity

ADVANTAGES

  • No pollution
  • Available on demand
hydroelectricity2
Hydroelectricity

ADVANTAGES

Disadvantages

Can harm fish swimming upstream

Drought can lower water level too low to generate power

Expensive to build

  • No pollution
  • Available on demand
solar power
Solar Power

Advantages

  • Inexhaustible
  • No pollution
solar power1
Solar Power

Advantages

Disadvantages

Need sunlight (night, clouds)

Expensive

Needs large spaces

  • Inexhaustible
  • No pollution
wind power
Wind Power

Advantages

  • No pollution
wind power1
Wind Power

Advantages

Disadvantages

Depends on weather

Needs large spaces

Can kill birds

Not pretty to look at

  • No pollution
geothermal energy1
Geothermal Energy

Advantages

  • Available 24/7
  • No pollution
geothermal energy2
Geothermal Energy

Advantages

Disadvantages

Not available everywhere

Expensive

  • Available 24/7
  • No pollution
sources of energy1
Sources of Energy
  • Nearly all the energy on Earth comes originally from the sun
  • Coal, oil and natural gas are called fossil fuels.
  • Nonrenewable resources are used faster than they can be replaced. (Examples: coal, oil, natural gas)
  • Renewable resources can be replaced. (Example: hydroelectricity)
  • Inexhaustible resources can never run out! (Examples: solar, wind, geothermal energy)
  • Photovoltaic cells change sunlight directly into electricity.