Report on Wind Powering America technical
workshop and Green Mountain Wind Farm
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.
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.
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.
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.