Transcript Renewable Energy

Renewable Energy
Why is Renewable Energy Used?
• Renewable Energy is used to replace nonrenewable energy sources.
• Unlike non-renewable energy sources,
renewable energy can easily be replaced.
Types of Renewable Energy
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Hydroelectricity
Solar
Wind
Tidal
Geothermal
Myths of Renewable Energy
• Not all renewable
Energy is perfect, each
still has its problems.
• Some types of
renewable energy can
damage the
environment
Hydroelectricity
• About 8% of the US
energy is currently
being produced from
Hydroelectric power
plants.(Glenco)
• Hydroelectric plants
tend to disrupt the
natural ecosystem.
Solar Energy
• When the sun is shining, the energy must be
stored in batteries so it can be used when the
sun is not shining….that is a major
disadvantage of solar cells.
• Photovoltaic cells (solar cells) is what is used
to convert solar energy into electricity.
• Calulators (solar)
Photovoltaic Cell (Solar Cell)
• Made of 2 layers of semiconductor materials
sandwiched between 2 layers of metal. (One
layer is rich in elctrons (has a lot)/one layer is
poor (lacks electrons)
• When sunlight strikes the surface of the solar
cell, electrons flow through an electrical
circuit from the electron rich semiconductor
to the electron poor semiconductor. (7-11%
efficient)
Wind Energy
• Windmills use the
energy of the wind to
pump water.
• Only around 20%
efficient…..needs windy
areas.
• Windmills can also use
the energy of the wind
to generagte electricity.
• Can affect the migration
patterns of birds…..can
also affect military
equipment.
• Wind spins a propeller
that is connected to a
generator.
Tides
• The gravity of the Moon and the sun causes
bulges in the Earth’s oceans. As Earth rotates,
the two bulges moves westward.
• Each day, the levels of the ocean rises rises
and falls…..producing tides…which can be
used to generate electricity.
Tidal Energy
• As the tide comes in, the moving water spins a
turbine amd at low tide when the waters
reced, the water can be used to spin the
turbines again. (Annapolis Royal – Nava
Scotia)
Geothermal Energy
• Geothermal Energy can be used when magma
is close to the earth since if it is close, the
surrounding rocks are hot.
• A well is drilled and water is pumped into the
ground. The water hits the hot rocks and
makes steam.
• The steam returns to the surface and rotates
turbines that spin electric generators. (16%)
efficient.
Limitations
• One major limitation of Renewable Energy is
that it is often limited to certain areas.
• Hydroelectricity is limited to areas where
dams can be built.
• Wind energy (turbines) – must be built in
places that have lots of wind.
Alternative Fuels
• Biomass is an alternative fuel that has been
used for thousands of years.
• Other alternative fuels is hydrogen gas which
produces only water vapor when burned …so
no pollution.
Hydrogen Gas
• The hydrogen in water can be released by
passing electricity through it….but it takes
more energy to get the hydrogen out that way
than hydrogen gas provides as it burns.