Clean Energy for a
Sustainable Future
Report on Wind Powering America technical
workshop and Green Mountain Wind Farm
Louis Zeller October 24, 2000
The Green Mountain Wind Farm is located in
southwestern Pennsylvania on the site of a former
strip mine. The farm has eight wind powered
electric turbines which generate a total of 10.4
megawatts, enough electric power for 2,500 homes.
On the day I visited Green Mountain,
the wind was moderate and all but one
turbine was operating. Arriving at the
farm, I spotted the 200 foot tall towers
from a distance. At the entrance our tour
bus stopped at the visitor center which
overlooks the rolling countryside, a barn
and silo, fields of corn and hay, and
eight wind machines. The serenity of the
farm was accented by the majestic white
rotors turning slowly in the breeze.
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As I approached the rotor, I expected
to hear a sound of a blade swishing
through the air, a humming turbine, or
some other noisy signature of the
industrial age. But when the tour group
reached the base of the structure, the
loudest sound by far was from people
around me speaking in normal
conversation. I made an audio/video
recording at the base of the tower which
supports the rotor turning 100 feet
overhead. No sound except the faint hum
from a nearby transformer.
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Green Mountain Energy Company purchases the
electricity for its customers and power is
distributed through the Somerset Rural Electric
Cooperative. The site is leased from the owner
who continues to live on the 500 acre farm. Over
90% of the farm continues to be used for
agriculture. Green Mountain Energy initiated the
project in 1998 and operation began May 1, 2000.
The company selected this site 2,300 feet above
sea level based on analysis of wind energy
potential in the Appalachian-Allegheny Mountains
with an eye toward minimal environmental impact
and benefit to the local economy. Green Mountain
Energy works in partnership with a British firm
National Wind Power which owns and operates the
generators. This arrangement shared credit risk
and enabled them to complete the project in less
than two years. The total development cost was
about $10 million. Experts estimate that average
annual wind energy potential in Pennsylvania is
38 billion kilowatt-hours.
The turbines need a minimum windspeed
of 8 mph to generate electricity, achieve
maximum output at 34 mph, and shut down
when the wind exceeds 56 mph. The rotors
turn at a steady rate, at either 12.7 or
19 rpm. The rotor speed is moderated by
computerized controls which vary the load
on the turbines so that stronger wind
generates more power, not more speed. A
computer also keeps each rotor pointed
into the wind.
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The environmental benefits of wind turbines
include zero air and water emissions and no solid
waste. Power generated annually at Green Mountain
Wind Farm displaces fossil fuel electricity which
would emit 35 tons of nitrogen oxides, 135 tons
of sulfur dioxide, and 17,000 tons of carbon
dioxide. This is equivalent to the pollution
generated by 40 million vehicle miles, or the
annual CO2 absorbed by 2 million trees.
Early wind turbine generators earned a reputation
for being noisy neighbors. But modern units seem
to have eliminated this problem. Normal
conversation 3 feet away produces 55 decibel.
Typical noise from a wind generator 500 feet away
is 45 decibel. The worst-case assessment for a
large 90 megawatt wind project with 60 turbines
predicts a 40 decibel sound level one-half mile
away, equivalent to a quiet room.
What is the impact on wildlife, particularly
birds? The companies completed an avian risk
assessment which indicated no potential risk to
bird populations from the operation of the wind
farm. They attribute this to improved blade
design and the controlled speed of the rotors.
Cost of wind generated electricity has dropped
from 40 cents/kilowatt-hour in 1979 to 4 to 6
cents/kilowatt-hour today. According to the
Department of Energy, prices will continue to
fall and by 2010 continued advances in technology
will further reduce cost to about 2 to 3
cents/kilowatt-hour. Wind Powering America’s
goal is to have 5% of American electricity
generated by wind by 2020.
BREDL video clip.
Panoramic view of wind turbines
at Green Mountain Wind Farm. Play
video clip.
(may take a few
minutes to download)
(
.mpg format - plays on Windows
Media Player ) |
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BREDL video clip.
Close-up of wind turbine at Green
Mountain Wind Farm. Play
video clip.
(may take a few
minutes to download)
(
.mpg format - plays on Windows
Media Player ) |
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US Department of Energy Wind Powering America
program
http://www.eren.doe.gov/windpoweringamerica
Green Mountain Energy
http://www.greenmountain.com
National Wind Power
http://www.natwindpower.com
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