readings with assessment in Alternative Energy -- Wind
Energy -- Geothermal Energy -- Hydropower -- Nuclear Energy
Alternative Energy Basics
simple air in motion. It is caused by the uneven heating of
the earth’s surface by the sun. Since the earth’s surface
is made of very different types of land and water, it absorbs
the sun’s heat at different rates.
the day, the air above the land heats up more quickly than
the air over water. The warm air over the land expands and
rises, and the heavier, cooler air rushes in to take its place,
creating winds. At night, the winds are reversed because the
air cools more rapidly over land than over water.
In the same
way, the large atmospheric winds that circle the earth are created
because the land near the earth's equator is heated more by the
sun than the land near the North and South Poles.
energy is mainly used to generate electricity. Wind is called a
renewable energy source because the wind will blow as long as the
times, people have harnessed the winds energy. Over 5,000 years
ago, the ancient Egyptians used wind to sail ships on the Nile River.
Later, people built windmills to grind wheat and other grains. The
earliest known windmills were in Persia (Iran). These early windmills
looked like large paddle wheels. Centuries later, the people of
Holland improved the basic design of the windmill. They gave it
propeller-type blades, still made with sails. Holland is famous
for its windmills.
used windmills to grind wheat and corn, to pump water, and to cut
wood at sawmills. As late as the 1920s, Americans used small windmills
to generate electricity in rural areas without electric service.
When power lines began to transport electricity to rural areas in
the 1930s, local windmills were used less and less, though they
can still be seen on some Western ranches.
The oil shortages
of the 1970s changed the energy picture for the country and the
world. It created an interest in alternative energy sources, paving
the way for the re-entry of the windmill to generate electricity.
In the early 1980s wind energy really took off in California, partly
because of state policies that encouraged renewable energy sources.
Support for wind development has since spread to other states, but
California still produces more than twice as much wind energy as
any other state.
HOW WIND MACHINES
Like old fashioned
windmills, today’s wind machines use blades to collect the wind’s
kinetic energy. Windmills work because they slow down the speed
of the wind. The wind flows over the airfoil shaped blades causing
lift, like the effect on airplane wings, causing them to turn. The
blades are connected to a drive shaft that turns an electric generator
to produce electricity.
With the new
wind machines, there is still the problem of what to do when the
wind isn’t blowing. At those times, other types of power plants
must be used to make electricity.
TYPES OF WIND
There are two
types of wind machines (turbines) used today based on the direction
of the rotating shaft (axis): horizontal–axis wind machines and
vertical-axis wind machines. The size of wind machines varies widely.
Small turbines used to power a single home or business may have
a capacity of less than 100 kilowatts. Some large commercial sized
turbines may have a capacity of 5 million watts, or 5 megawatts.
farm is a group of wind turbines used to generate electricity.
turbines are often grouped together into wind farms
that provide power to the electrical grid.
Most wind machines
being used today are the horizontal-axis type. Horizontal-axis wind
machines have blades like airplane propellers. A typical horizontal
wind machine stands as tall as a 20-story building and has three
blades that span 200 feet across. The largest wind machines in the
world have blades longer than a football field! Wind machines stand
tall and wide to capture more wind.
wind machines have blades that go from top to bottom and the most
common type (Darrieus wind turbine) looks like a giant two-bladed
egg beaters. The type of vertical wind machine typically stands
100 feet tall and 50 feet wide. Vertical-axis wind machines make
up only a very small percent of the wind machines used today.
The Wind Amplified
Rotor Platform (WARP) is a different kind of wind system that is
designed to be more efficient and use less land than wind machines
in use today. The WARP does not use large blades; instead, it looks
like a stack of wheel rims. Each module has a pair of small, high
capacity turbines mounted to both of its concave wind amplifier
module channel surfaces. The concave surfaces channel wind toward
the turbines, amplifying wind speeds by 50 percent or more. Eneco,
the company that designed WARP, plans to market the technology to
power offshore oil platforms and wireless telecommunications systems.
Wind power plants,
or wind farms as they are sometimes called, are
clusters of wind machines used to produce electricity. A wind farm
usually has dozens of wind machines scattered over a large area.
The world's largest wind farm, the Horse Hollow Wind Energy Center
in Texas, has 421 wind turbines that generate enough electricity
to power 220,000 homes per year.
plants, many wind plants are not owned by public utility companies.
Instead they are owned and operated by business people who sell
the electricity produced on the wind farm to electric utilities.
These private companies are known as Independent Power Producers.
wind power plant is not as simple as just building a windmill in
a windy place. Wind plant owners must carefully plan where to locate
their machines. One important thing to consider is how fast and
how much the wind blows.
As a rule, wind
speed increases with altitude and over open areas with no windbreaks.
Good sites for wind plants are the tops of smooth, rounded hills,
open plains or shorelines, and mountain gaps that produce wind funneling.
Wind speed varies
throughout the country. It also varies from season to season. In
Tehachapi, California, the wind blows more from April through October
than it does in the winter. This is because of the extreme heating
of the Mojave Desert during the summer months. The hot air over
the desert rises, and the cooler, denser air above the Pacific Ocean
rushes through the Tehachapi mountain pass to take its place. In
a state like Montana, on the other hand, the wind blows more during
the winter. Fortunately, these seasonal variations are a good match
for the electricity demands of the regions. In California, people
use more electricity during the summer for air conditioners. In
Montana, people use more electricity during the winter months for
In 2006, wind
machines in the United States generated a total of 26.6 billion
kWh per year of electricity, enough to serve more than 2.4 million
households. This is enough electricity to power a city larger than
Los Angeles, but it is only a small fraction of the nation's total
electricity production, about 0.4 percent. The amount of electricity
generated from wind has been growing fast in recent years. In 2006,
electricity generated from wind was 2 1/2 times more than wind generation
have decreased the cost of producing electricity from wind, and
growth in wind power has been encouraged by tax breaks for renewable
energy and green pricing programs. Many utilities around the country
offer green pricing options that allow customers the choice to pay
more for electricity that comes from renewable sources.
generate electricity in 28 different states in 2006. The states
with the most wind production are Texas, California, Iowa, Minnesota,
Most of the
wind power plants in the world are located in Europe and in the
United States where government programs have helped support wind
power development. The United States ranks second in the world in
wind power capacity, behind Germany and ahead of Spain and India.
Denmark ranks number six in the world in wind power capacity but
generates 20 percent of its electricity from wind.
WIND AND THE
In the 1970s,
oil shortages pushed the development of alternative energy sources.
In the 1990s, the push came from a renewed concern for the environment
in response to scientific studies indicating potential changes to
the global climate if the use of fossil fuels continues to increase.
Wind energy is an economical power resource in many areas of the
country. Wind is a clean fuel; wind farms produce no air or water
pollution because no fuel is burned. Growing concern about emissions
from fossil fuel generation, increased government support, and higher
costs for fossil fuels (especially natural gas and coal) have helped
wind power capacity in the United States grow substantially over
the last 10 years.
The most serious
environmental drawbacks to wind machines may be their negative effect
on wild bird populations and the visual impact on the landscape.
To some, the glistening blades of windmills on the horizon are an
eyesore; to others, they’re a beautiful alternative to conventional
Revised: July 2008
Sources: Energy Information Administration, Renewable Energy
Annual2006, April 2008.
Energy Information Administration, Green Pricing nad Net Metering,
The National Energy Education Development Project, Intermediate
Energy Infobook, 2005.
The American Wind Association, Wind Web Tutorial (http://www.awea.org/faq/index.html),
The Global Wind Energy Council (http://www.gwec.net/), April 2007.
FPL Energy, Plant Fact Sheets (http://www.fplenergy.com/portfolio/wind/plantfactsheet.shtml),
U.S. Department of Energy, Office of Energy Efficiency and Renewable
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IN WIND ENERGY
Energy Mission, Vision, and Goals
Wind Energy by 2030: Increasing Wind Energy's Contribution to U.S.
YOUR KNOWLEDGE OF THE MATERIAL
In A typical horizontal wind machine can stand ___ stories
enter your answer in the space provided:
2006 the amount of energy produced using wind was over _____ billion
3)In 2006 wind energy was generated in how many states?