Wind Energy – Basic Information

How Wind is Made

Where does the wind come from? In general terms, wind is created by the solar cycle through the uneven warming and cooling of the earth’s surface. As the sun warms the land, air above the land is also warmed. This air rises and cooler air rushes in to replace it, producing a gentle breeze – or a howling tempest.

Large-scale winds are caused by the fact that the earth’s surface is heated to a greater degree at the equator than at the poles. The rotation of the earth also affects these planetary winds. On a smaller scale, winds flow through mountain valleys and spill over high peaks across unobstructed prairies.

Using Wind to Produce Energy is Not a New Idea

Wind propelled the sailing ships that led to the discovery of the New World. But even before, wind was used to pump water, grind grain, power mills and produce paper. In fact, wind was one of the primary sources of energy before the Industrial Revolution.

Immigrants brought wind machines to America, where they were used extensively to pump water for human use, irrigate crops and pump water for steam locomotives. Since the mid-1800s, many small windmills have been erected in the United States.

Names like Jacobs and Wincharger were common during the 1930s and 1940s as small wind machines provided energy for millions of rural Americans. These small generators were usually connected to a series of batteries, which stored the energy. Most of these units were ultimately replaced by the powerlines of the rural electric associations.

But while wind generators of less than 1 horsepower were lighting bulbs and heating irons throughout rural America, engineers were looking at much larger units. This work culminated in the U.S. during the early 1940s with the construction of a 1.25 MW unit near Rutland, Vermont. The machine produced power for the local utility until 1945, when a combination of equipment failure and the availability of cheaper electric power led to the unit’s demise.

Following the Vermont experience, work on larger-scale wind generators continued on a limited basis, both here and abroad.

In 1975, a 100 kW unit went up near Sandusky, Ohio. The federally-sponsored test unit used two blades located on a horizontal axis, faced downwind, and sat atop a 100-foot tower. Machines of increased output and refined design subsequently were built at Clayton, New Mexico; Boone, North Carolina; and other locations.

These large-scale test generators were the forerunners of the units designed for the Medicine Bow area.

Medicine Bow–Windy Site for Wind Generators

“Strewn there by the wind…” was the way Owen Wister described the town of Medicine Bow during the late 1800s. a hundred years later, the town demonstrated its tenacity and is the home of about 400 people–many connected with the coal and uranium mining in Wyoming.

Spawned as a fuel stop for the Union Pacific Railroad, Medicine Bow is located within a C-basin formed by the Laramie, Medicine Bow and Shirley Mountain ranges. It is this very basin that helps propel the howling westerly winds that have created so much interest among energy researchers.

U.S. Bureau of Reclamation scientists spent a great deal of effort verifying Medicine Bow’s windy reputation. Technicians analyzed many years of climatological data collected from southern Wyoming. Eventually, a 600-square-mile area surrounding Medicine Bow was designated for further study.

Using aerial photographs and data gathered by the University of Wyoming, five sites were identified as potential locations for wind generators. Instruments installed at the sites gathered wind data beginning in 1977.

A 200-foot tower (later raised to 360 feet) equipped to measure wind at three elevations was erected during 1978 at one of the sites, located five miles southwest of Medicine Bow.

That same year, Bureau officials selected two sites on which large-scale wind machines could be constructed. The site southwest of Medicine Bow was chosen for the first test units. This site eventually became Platte River Power Authority’s Medicine Bow Wind Project in 1998. The second site, with the colorful name “Greasewood Flats,” located 17 miles northeast of the town, was designated at the probable site for a larger wind field.

Data showed that average wind speed, back then, exceeded 20 miles per hour (at 200 feet above the ground)- more than enough for efficient wind generators. In addition, records show that the Medicine Bow wind blows more between 10 a.m. and 10 p.m. than during other hours of the day. This is significant since this is the time of day when demand and use of electricity is greatest.

A Complex Environment

The high plains of the Medicine Bow area support a variety of wildlife. Antelope graze freely and several types of birds, like Killdeer, inhabit the area. Hundreds of varieties of plant life add to the complex grassland world.

Although wind energy is generally considered less disruptive than many other energy sources, Bureau engineers were concerned from the very beginning about any possible impact a large-scale wind energy project might have on this environment.

Beginning in 1977, studies focused on two major areas. First, ecologists needed to determine any possible impact from erection and operation of the data-collecting towers and the two test generators.

Next, they analyzed the possible impact of a 100 MW wind field consisting of as many as 40 units.

Bureau scientists worked closely with specialists from the Wyoming Game and Fish Department and the U.S. Fish and Wildlife Service in planning and conducting the environmental studies. Proposed construction sites were surveyed and information collected concerning antelope movement and distribution, birds of prey, waterfowl and other wildlife.

The bottom line? Construction of the wind project would have no adverse effect on the environment of the Medicine Bow area.

Platte River continued this program of concern for the environment when it purchased the wind site assets in 1998. Additional environmental impact studies have been completed and show the same results of no adverse effects on the site.

For more information contact wind@prpa.org.