Wind Energy: The End of the World's Largest Windmill

A winter storm decimates a Wyoming windmill with a 257 foot diameter blade, destroying the world's largest windmill on a wind farm focused on renewable wind energy.

| June/July 1996


The world's largest windmill located south of Medicine Bow, Wyoming.


A Medicine Bow renewable wind energy farmer endures alone. (See the windmill photos in the image gallery.)

Renewable Wind Energy

While the wind whips the dry grass around him, Bill Young, a wind farmer, walks across the sage flat just across the south of Medicine Bow, Wyoming, picking up the windmill pieces as he goes. He explains where each piece belonged before the blades flew apart in a January storm, spreading machinery over six acres of prairie. A flock of horned larks flushes from the wreckage, scattering like hand-flung oats, and a cottontail browses behind a metal hulk the size of a car engine.

"That's a teeter lock," Young says, explaining that it kept the blades from wiggling on the shaft. He studies a fist-sized plastic box with two torn wires: "And here's a $600 pressure transducer." Beyond that is a $1,200 electrohydraulic valve, a keg-sized blue cylinder, embedded a foot deep in the soil. They are pieces of the largest windmill in the world. Behind Young, the rusty tower stands like a giant's leg, 262 feet tall, topped with a turbine housing and its splintered stubs of blades.

In a battle of giants, windmill versus Wyoming's wind, the windmill lost. Young, at 66, intends to start over. His wind farm is Medicine Bow Power, and his solitary, broken windmill is a Swedish Hamilton Standard WTS-4. Its single propeller, 257 feet from tip to tip, pumped up to four megawatts—enough for 1,600 homes—into the Pacific Power and Light system. That was at optimum wind speeds, between 40 and 60 miles an hour, which provided 100,000 foot-pounds of energy and drove the blade tips at 178 miles an hour. A pitch-control system feathered the blades—turned them sideways to lessen the power of wind against blade—when the wind speed climbed over 40 miles an hour. At 60, with blades fully feathered, the system shut down.

The project was conceived in 1978, when America and the Carter administration were dedicated to clean, alternative energy. The Bureau of Reclamation, NASA, and the Department of Energy joined forces to study the feasibility of combining wind and hydroelectric power for efficient energy during peak demand periods when people are home using appliances and furnaces. Dams on the nearby Platte River produce hydropower, but a dam can meet peak demand only by releasing more water. Naturally, that extra water is lost and the reservoir, like a drained battery, is diminished. Conveniently, winds in the area peak between 10 AM and 10 PM, the highest-demand hours, and are higher during winter, so adding wind power would then allow reservoirs to store more potential energy. Also, energy available at peak demand periods brings wind farms a higher price. Young was sure the project would work: "Here they were going to spend over $10 million to find out if wind and hydropower could mix. Any engineer could have figured that out." He laughs, "I would have been glad to tell them for, say, five million."

The project would also test economy of scale: The larger the windmill, the more power it can produce—and the more inexpensively it can produce it—up to a point. "It's a square-cube law," says Young. "As the power produced by a windmill is squared, its size must be cubed." Rather than build massive single-unit systems, most of the country's wind farms use much smaller machines, ranging between 100 and 400 kilowatts. It would take 40 of the 100-kilowatt machines to supply Medicine Bow's four megawatts (only one other wind generator of nearly equal size exists, a four-megawatt turbine in Canada). Lastly, the project would test the harmony of windmills and wildlife: Would animals be attracted to the tower or repelled by it? How many passing hawks and eagles would be killed by the blades?

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