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.
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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.
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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.
