Printer-friendly version

15 August 2003

Power From the Wind

by Forrest M. Mims, III
Geronimo Creek Observatory
Seguin, Texas

 

Giant wind generators like these in West Texas provide a few percent of the electricity in San Antonio. Photograph by Forrest M. Mims III. Click image to enlarge.

If you drive to Los Angeles from Texas on Interstate Highway 10, you'll pass through two regions sprinkled with huge wind generators. These are known as wind farms.

The first wind farm is near Iraan on the way to Fort Stockton. More than a hundred wind generators line the mesas on the north side of the highway. The second wind farm is a giant array of more than 5,000 wind turbines in the Altamont Pass near Indio, California. Wind power produces none of the air pollution that accompanies the burning of coal, which is the key reason San Antonio began buying wind power for some customers in 2000.

San Antonio's huge power plants at Calaveras Lake burn some 135 railroad cars of coal every day. Each car holds more than 100 tons. The new power plant they propose to build will mean burning 200 cars or more of coal every day. Wind power will reduce the need for some of this coal. The Desert Sky project in West Texas that provides power to San Antonio has 107 turbines capable of generating 1.5 million watts each.

These are the largest turbines manufactured in the United States. Those used in the Desert Sky project can power around 30,000 homes. The wind generators at Desert Sky are huge. Each turbine weighs more than 160 tons, about the same as 75 Ford Explorers.

The turbines are mounted atop towers 213 feet tall. The total diameter of the three giant blades attached to each turbine is 260 feet. The propellers rotate less than 30 revolutions each minute. But because they are so big, their tips move around 150 miles per hour. California needs electricity even more that Texas. But they don't need the air pollution that accompanies most power generation methods. The air pollution problem in Los Angeles becomes apparent to travelers a hundred miles or more before arriving at the outskirts of the cluster of cities that surround the city.

Thick, gray smog obscures the mountains and the view through the spaces between them. In many places, there is haze between you and whatever you are looking at more than a few hundred yards away. On bad days the haze even blocks the view of the vast arrays of wind generators.

Environmentalists have mixed feelings about wind power. While many support wind power, some claim that wind generators kill large numbers of migrating birds.

While wind generators do kill some birds, the wind energy industry claims the number is minuscule compared to the tens of millions of birds killed by vehicles on highways, tall buildings, power lines and antennas. A recent report by Mick Sagrillo for the American Wind Energy Association discusses the bird kill controversy in detail. Sagrillo claims that only around 90 birds are killed each year in collisions with the thousands of wind generators at Altamont Pass in California.

This number is dwarfed by the number of birds killed by electrical transmission facilities, which in the United States alone amounts to at least 130 million birds each year.

The birds are killed by collisions with power line poles, towers and wires or by electrocution when their wings touch a wire adjacent to the wire on which the bird is perched. There are no precise figures on the number of birds killed by collisions with tall buildings and glass windows in houses. According to Sagrillo's report, the estimates range from 100 million to a billion annually. Radio, television and cell phone towers kill at least 40 million birds each year. Cars and trucks kill another 60 million. In short, wind generators kill only a tiny fraction of the birds killed by human structures and activities. Yet some folk vigorously oppose them anyway.

Apparently the novelty of watching giant pinwheels spin in the breeze wears off rather quickly when you live nearby. Yet based on their success and the growing need for clean electrical power, wind farms are here to stay. Oil and gas are non-renewable fuels, but wind is a natural feature of the environment.

Recently I stopped to photograph a row of big wind generators spinning merrily in the West Texas wind. Just off the road was a sign of the times, an old oil pump standing lifeless and useless in the hot Texas sun.

Forrest M. Mims III is vice-chairman of the Environmental Science Section of the Texas Academy of Science and an amateur scientist. He studies the ozone layer, sunlight, haze, water vapor, tree rings and airborne bacteria.

This feature was originally published in Forrest Mims's weekly science column in the Seguin Gazette-Enterprise, Seguin, Texas. The column is written for a general audience.