Generating Electricity
from the Wind and other Natural
Resources
Have you ever thought about where the electricity you use everyday comes from?
When you turn on your hair dryer or your computer, you use electricity to power
those appliances. From what natural resource is it made? Well, if you look
at electricity usage nationwide, it is more than likely the source was coal,
or perhaps nuclear power. It also could have come from natural gas or even
a renewable resource.
According to U.S. Department
of Energy data, in 2003 about
51 percent of electricity was
produced using coal and about
20 percent came from nuclear
power. Nationally, natural
gas generated about 16 percent of electricity, and renewables produced about 9 percent. Petroleum contributed
3 percent. For more
information about the past,
present and predicted future
energy needs and sources for
the United States, go to the U.S.
DOE's Energy Information Administration's
Energy Outlook web
site. You can also visit AEP's
Learning from Light web
site to figure out which natural
resources are used in your
state for electricity generation.
How does wind power fit into
the energy puzzle? Wind is
considered renewable energy
-- a natural resource that
is constantly replenished and
never runs out. Most renewable
energy comes either directly
or indirectly from the sun.
In contrast, nonrenewable fuels
-- such as coal, natural gas,
uranium (fuel for nuclear power),
or petroleum -- can run out
because there are finite amounts.
In 2003, a small portion
of renewablable generation
came from wind. Just about
4,850 megawatts (MW, or million
watts) or 5 percent, comes
from wind power. However, that
number is expected to grow
as more utilities and individuals
use wind to generate electricity
and better wind turbine technology
makes wind power even more
competitive.
The Pacific Northwest Laboratory
has studied and mapped the
available wind resources nationwide
in the Wind
Energy Resource Atlas of
the United States . If you
browse the atlas, you'll notice
that most states have at least
some wind resources that are
rated at 2 and many have land
areas rated 3 or higher, indicating
better wind generation potential.
To use wind resources effectively,
the right size wind turbine
is required to economically
harness the available energy.
When it comes to generating
electricity from wind, you
need wind turbines. Wind turbines
are the modern equivalent of
the windmills used during the
past century and a half to
power farms and their rural
homes. All wind turbines have
a few basic components. Most
are horizontal-axis (some are
vertical-axis) propeller type
systems consisting of a rotor
and propeller. The propeller is the blade(s) that actually rotate in the wind and capture the kinetic energy of wind. The propeller converts the wind’s kinetic energy into rotary motion that turns the rotor, or electrical generator, which uses magnets and wire windings to create electricity. Each
turbine is placed on a tower
to ensure that it is high enough
to avoid the turbulent wind
usually found close to the
ground and to avoid wind shadows
from trees, buildings and hills.
The turbine needs to be high
enough to catch the faster
winds.
The largest machine has propellers
that span more than the length
of a football field and stands
20 stories high, producing
enough electricity to power
1,400 homes in the United States.
Groups of these large turbines
are usually located in higher
wind class areas such as California,
Texas or on mountain tops.
On the other hand, a small
turbine for home or small business
use would have rotors between
eight and 25 feet in diameter
and stand about 80 feet high.
The small turbine would supply
enough power to meet some or
all of the needs of a home
or small business, depending
upon when the wind was blowing
and when the electricity was
needed for heating, cooling,
lighting or other energy needs.
Since 1992, the U.S. Department
of Energy has worked with the
wind turbine industry to develop
low-cost wind power technologies.
Central and South West Corp.,
an electric utility company
in Texas that has since merged
with AEP, worked with DOE to
install 12 commercial 500-kilowatt
(kW) wind turbines in Fort
Davis, Texas. Building the
wind farm provided CSW with
extensive experience in siting,
installing and monitoring wind
power. Check out the project
by linking to Renewable
Energy Projects or http://www.eere.energy.gov/windandhydro/
AEP also built the Trent
Mesa wind generation project,
a 150-megawatt development
completed in 2001 that generates enough power
to serve about 30,000 homes.
TXU purchases the electricity from Trent Mesa for its customers.
AEP also owns the Desert Sky Wind Wind Project, a 160-megawatt wind farm in Texas completed in 2001. Electricity from Desert Sky is sold to City Public Service of San Antonio.
One important consideration
in the design and installation
of any wind turbine is lightning,
which strikes tall objects
including turbines on towers.
To avoid damage and down time
needed for repairs, turbine
manufacturers are incorporating
features to protect internal
electrical components and specifying
careful grounding methods for
towers.
Click Image to Enlarge |
Wind turbines are designed
to generate specific amounts
of electricity using as much
of the energy in wind as possible.
The turbine's electrical output
rating (1000 kW, 10 kW, etc.)
is the maximum amount of power
it produces at a high wind
speed. It produces less electricity
at lower wind speeds. Power
curves like this one show the
wind speed the turbine needs
to begin generating power (8
miles per hour in this case)
and the wind speed when maximum
amount of electricity is generated
(about 36 mph). In this case, if a homeowner
needs 8 kW to heat his or her
home -- which is the average
peak amount for AEP customers
-- the wind must blow at more than 28 mph to produce the
power he or she needs. If not,
additional sources of electricity
would be needed.
Large turbines can be used
to generate lots of electricity
and some utility companies
are planning to add them to
their system. AEP's Texas wind farms use large turbines that can generate up to 1.5 MW (1,500 kW) of power.
Small turbines, about 10
kW, are gaining in popularity
as owners of homes and small
businesses consider how to
meet their electricity needs.
AEP purchased small turbines
for our research project from Bergey
Windpower Co.
