http://www.kidwind.org/lessons/BBrenewableenergy.html

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http//www.kidwind.org/lessons/BBrenewableenergy.h
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Renewable Energy What is Renewable Energy? A
source of energy would be considered renewable if
it is a natural resource on earth and it can be
naturally replenished on a relatively short time
scale. Furthermore, producing electricity from
renewable sources will not produce harmful
pollutants or emissions and will not harm
ecosystems. Renewable Energy is also called
"clean" or "green" power.
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Fossil fuels like coal, oil, and natural gas are
nonrenewable, because they are finite resources
which will run out. Fossil fuels are also
environmentally harmful to extract and convert
into usable energy. They produce a lot of
hazardous emissions and pollutants that
contribute to climate change and can harm plants,
animals, and humans. Nuclear power is also
considered nonrenewable because of the toxic
waste it creates.
Renewable energy can be produced using sources
like the wind, sunlight, hydrogen, geothermal
energy (heat from inside the earth), biomass
(energy from plants), flowing rivers, and even
the power of the ocean!
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Believe it or not, the source of most forms of
renewable energy can be traced back to the sun!
Solar energy is the most direct use of the sun
sunlight is used to excite electrons and push
them through a circuit. Wind energy relies on the
sun too! Wind is created by uneven heating of the
earth's surface. When sun hits one part of the
earth more directly, it warms that part up. The
warm air rises and cooler air rushes in, creating
wind! So wind energy is actually a form of solar
energy too! Of course, energy from biomass relies
on the sun too, because plants cannot grow
without sunlight! Even hydropower would never
work without the power from the sun!
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Why Don't We Use More Renewable Energy?
The use of renewable energy is increasing at very
fast pace, but we cannot rely exclusively on
renewable energy to meet all of our demand for
electricity. Renewable energy is not easy to
store or save, because we can only get wind
energy when the wind is blowing or solar energy
when the sun is shining. Coal and natural gas
power plants can store the fuel and use more when
there is more demand or less when there is less
demand.
Renewable energy is also usually more expensive
than conventional energy sources. However, as
technology for renewables improves and the cost
of fossil fuels increases, renewables will become
competitive or cheaper than fossil fuels
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Wind Power Basics
A wind turbine is the modern advancement of the
windmill. Instead of using the wind to lift water
or move heavy rocks to grind seeds wind is used
to turn an electrical generator to make
electricity. Sometimes, students mistake our
model wind turbines for a fan. While a fan uses
electricity to produce wind, a wind turbine uses
the wind to produce electricity!
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How Wind Turbines Work
To put it simply, the wind turns the blades,
which spin a shaft, which connects to a generator
to make electricity. The electricity is sent
through transmission lines to a substation, then
on to homes, business and schools
Wind turbine blades spin because of lift, the
same force that allows airplanes to fly. If the
blades are all oriented in the same direction
they will start to spin, just as the wind spins a
pinwheel. The blades are attached to a hub, which
spins as the blades turn. Most modern wind
turbines have three blades. The blades and the
hub together are called the rotor. As the rotor
turns, it spins a drive shaft which is connected
to a generator inside the housing at the top of
the tower. This housing is called the nacelle.
The spinning generator produces electricity. The
generator inside of a wind turbine converts the
mechanical energy of moving wind into electrical
energy that we can use in our houses. Depending
on the size of the wind turbine there may be a
gearbox between the spinning rotor and the
generator. This is to help the generator spin
fast enough to make electricity for the grid.
Generators on the large grid connected turbines
spin at 1600 RPM. For more detailed information
on wind turbine technology,
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The amount of electricity that a turbine is able
to produce depends on the diameter of the rotor
and the speed of the wind that propels the rotor.
The wind turbines that are manufactured today
range greatly in their output capacity from as
little as 100 watts to as much as 5
Megawattsenough to power a small town! Wind
Turbines are often grouped together in wind farms
to produce large amounts of electricity. Some
wind farms have only a coupe turbines, but the
largest wind farms are made up of hundreds and
hundreds of wind turbines.
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Wind Energy Growth Wind energy is the fastest
growing energy source in the world. In 2007,
19,696 MW of new wind energy capacity were
installed, reaching a global installed capacity
of 93,849 MW by the end of 2007. This represents
a 26.6 growth rate in that year alone! Global
installed capacity exceeded 100,000 MW in early
2008. In the United States, the installed
capacity if wind energy grew by an incredible 45
in 2007 and another 50 in 2008. The United
States installed 8,358 MW of new wind energy in
2008. Wind energy is growing at this rate because
the cost of electricity produced by wind energy
is competitive with electricity produced by
natural gas, oil, coal, or nuclear power. Also,
wind energy is a clean, renewable technology that
does not contribute to global warming. This makes
it a healthier, more sustainable choice than
other forms of electricity generation.
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