Evolution of Modern Wind Turbines Part A: 1940 to 1994 - Wind Turbine Technology: Fundamental Concepts of Wind Turbine Engineering - page 105

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Evolution of
Modern Wind Turbines
Part A: 1940 to 1994
Louis V. Divone
Director, Solar Energy Technologies
U.S. Department of Energy
Washington, DC
Introduction
The modern electricity-generating horizontal-axis wind turbine (now often labeled with
the acronym HAWT) is an obvious descendant of the historic European windmill and the
small, DC-generating wind turbines of the 1930s. The resemblance is somewhat deceptive,
however, since the HAWT and its less-familiar vertical-axis cousin, the VAWT, have
evolved as sophisticated products of current technology. Their high performance and
reliability are the result of steady improvement in methods of aerodynamic and structural
design, in new materials, and in mechanical and electrical engineering. The evolution of
wind turbine technology in the United States and elsewhere since World War II is described
in this chapter, along with some of the problems that have arisen and how these problems
have been faced.
The world's largest wind power plant prior to the 1970s was the Smith-Putnam wind
turbine (Fig. 1-22) erected in 1939 on Grandpa's Knob near Rutland, Vermont [Putnam
1948]. With a rotor diameter of 53.3 m and a power rating of 1.25 MW, this pioneering
HAWT was a major work of mechanical engineering. The Smith-Putnam project was a
milestone between the decline of fully-developed, stand-alone wind turbines generating DC
power only for local use and the new growth of wind power plants connected to utility lines
and producing AC power for distribution throughout the system.