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Wind Energy
• Wind energy is a form of indirect solar energy
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The atmosphere is warmed by the radiant
energy of the sun.
Wind is caused by the uneven warming of the
atmosphere, the varying topography of the
earth, and the rotation of the earth.
The flow of the wind is modified by the earth’s
terrain, obstacles (such as trees and buildings),
bodies of water, etc.
• A wind turbine converts the kinetic energy in
wind into electricity.
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Source:
Wind Energy Program, U.S. Department of Energy
(http://www.eren.doe.gov/wind/)
The kinetic energy of the wind rotates the
blades of a wind turbine.
The blades rotate a shaft and convert the
kinetic energy of wind into mechanical energy.
The shaft of the turbine is connected to a
generator, which converts the mechanical
energy to electrical energy.
Hydropower
• Hydropower is a form of indirect solar energy
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Water constantly moves through a global
hydrological cycle driven by the sun.
Water evaporates from the surfaces of lakes
and oceans and rises into the atmosphere.
The moist warm air rises, cools, and
condenses to forms clouds.
Water is transported through the atmosphere in
clouds and as water vapor.
Water precipitates to the surface of the earth in
the form of rain, snow, sleet, or freezing rain.
Water flows into lakes, rivers and streams and
is carried back to the oceans.
• Hydropower plants convert the kinetic energy
of falling water into electricity.
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Source:
Hydropower Program, U.S. Department of Energy
(http://hydropower.inel.gov/more.htm)
A dam is built to control the flow of water,
increase the elevation, and form a reservoir to
harness the potential energy of elevated water.
As water is released, gravity causes water to
flow through the penstock.
The moving water turns a turbine at the base of
the dam, converting the kinetic energy of water
into mechanical energy.
The shaft of the turbine is connected to a
generator, which converts the mechanical
energy to electrical energy.
Source: USGS (http://wwwga.usgs.gov/edu/hyhowworks.html)
Fossil Fuels
• Fossil Fuels are the remnants of organisms
that lived 300 million years ago.
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The sun provides energy which plants use
to produce energy through photosynthesis.
Plants accumulate energy throughout life
and eventually die.
Plant life decays and is buried under water
and rock at very high pressures.
These ancient seas recede, exposing fossil
fuels such as coal and petroleum buried in
the rock.
For every ten feet of plant matter, there is
roughly one foot of coal.
• Fossil Fuel burning plants convert chemical
energy into thermal energy, thermal energy
into mechanical energy, and mechanical
energy into electrical energy.
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Source:
Fossil Fuel Program, U.S. Department of Energy
(http://fossil.energy.gov)
A boiler combusts fuel, and uses the
resulting heat to boil water.
This high pressure steam processes
through the plant, powering a turbine.
The shaft of the turbine is connected to a
generator, which converts the mechanical
energy to electrical energy.
Solar Power
• On the sun, fusion reactions continually
occur, releasing energy – solar radiation.
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Two pairs of protons fuse, and the two
products of these reactions fuse with an
additional proton.
The three proton nuclei then fuse together
to form beryllium-6, which is highly
unstable.
The beryllium-6 decays into a helium
nucleus (alpha particle) and two protons.
Along the way, gamma rays, or solar
radiation (γ), is released.
• Some of this solar radiation reaches the
earth and strikes a photovoltaic cell.
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Source:
Fusion Energy Sciences Program and Photovoltaics Program,
U.S. Department of Energy (http://wwwofe.er.doe.gov,
http://www.eren.doe.gov/)
Light that is not reflected and has a
specific amount of energy is absorbed by
the cell.
The energy absorbed from the light frees
electrons from the semiconducting layers,
generating an electric current.
This power can then be used at the source,
or stored until a later time when it is
needed.
Nuclear Power
• Nuclear fission occurs inside what is
known as a reactor.
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A neutron collides with a uranium nucleus
and is absorbed
The nucleus is induced to split into two
smaller nuclei (fission products) and other
neutrons.
The mass that is lost in the process is
released in the form of thermal energy.
The other neutrons cause further fission
reactions.
• The energy released from fission is used to
generate electrical energy.
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Source:
Nuclear Energy Program, U.S. Department of Energy
(http://www.eia.doe.gov)
Water surrounding the reactor is boiled by
the thermal energy released in fission.
The thermal energy of the newly produced
steam powers a turbine.
The mechanical energy of the turbine
generates electrical energy in the same
way as a wind turbine, or the turbine in a
fossil fuel plant.
Geothermal Power
• Thermal energy from molten rock heats
water below the surface of the earth.
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Source:
Geothermal Energy Program, U.S. Department of Energy
(http://www.eren.doe.gov/RE/geothermal.html)
Underground water, stored under high
pressure, is heated by molten rock.
A heat pump takes this warm water, which
either boils under the lower pressure, is
already steam, or is used to boil a second
liquid with a lower boiling point than
water.
The resulting steam then powers a turbine,
and electrical energy is generated.
Water is pumped back into the ground,
where it is again heated and placed under
high pressure.
Biomass Power
• Energy from the sun is absorbed by trees
and other organic life forms.
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Source:
Biomass Fuels Program, ONRL
(http://www.ornl.gov)
Solar radiation, the product of fusion, is
absorbed by plants and converted to
energy by a process known as
photosynthesis.
Plants grow, and are eventually used for
industrial or agricultural purposes.
Organic material left over from these
primary uses are collected by combustion
plants.
Biomass fuel is used in the same way as
fossil fuel, to convert chemical energy
into thermal energy, thermal energy into
mechanical energy, and finally
mechanical energy into electrical energy.
Generation, Transmission, & Distribution
1. Power Plant
2. Transmission
Substation
steps the voltage up to
69,000 - 765,000 V
generates 3-phase AC power
6. Distribution
Power Lines
3. High Voltage
Transmission Lines
moves power over long distances
on the transmission grid
5. Distribution Substation
4. Subtransmission
Steps the voltage down
to 22,000 – 69,000 V
Moves power over distribution
grid to points-of-use
steps the voltage down
to 4160 -36,000V
Small Substation
Distribution Power Lines
Industrial Uses
2400 – 15,000 Volts
Distribution
6. Distribution
Power Lines
1200 A
Commercial Uses
480Y/277 Volts
Residential Uses
120/240 Volts