Environmental Engineering Reference
In-Depth Information
were laid-up with iber orientations that gave them speciic torsional properties. Changes
in aerodynamic and centrifugal forces caused the spars to twist and untwist, enabling a
totally passive blade pitch control with varying wind and rotational speed.
40-kW Turbines
The larger 40-kW prototype wind turbines were developed by the
Kaman Aerospace
Corporation
and the
McDonnell Aircraft Company
. The Kaman design was a HAWT with
a 2-bladed, downwind rotor (Fig. 3-14), while the McDonnell design was a 3-bladed
giromill VAWT (Fig. 3-15). Both prototypes were delivered to Rocky Flats in 1980 and
tested in 1981.
17-m Alcoa VAWT
Alcoa Corporation
, under contract to Sandia National Laboratories, developed a pre-
commercial prototype of the
Sandia/DOE 17-m VAWT
(Fig. 3-20) and built four units. One
of these was installed at Rocky Flats for comparative testing, and to verify predictions of
performance and loads. Using the data obtained, two manufacturers developed the design
further for commercial use (Fig. 3-24).
Additional Small-Scale Wind Turbine Development Projects
A second series of competitions followed in 1980 with contract awards to
Tumac
Industries, Structural Composites Industries
(SCI), and
North Wind Power Company
for 4-
kW prototypes. The application for this size wind turbine were seen as a power source for
remote residences, either standing alone or inter-connected with a utility line. SCI designed
a HAWT with a 3-bladed, downwind rotor, while Tumac developed a small Darrieus
VAWT with a cantilevered tower and no supporting cables. The last of the competitions
for government support of small-scale wind turbine development was for a light agricultural
application, on farms and ranches. It resulted in awards to the Enertech and UTRC
companies, both of which selected HAWTs with downwind rotors.
The wide spectrum of design concepts listed in Table 3-1 is indicative of the early
uncertainty amongst wind turbine designers as to what constitutes an optimum coniguration
for a speciic application. While some blind alleys were followed for a time, a number of
these conigurations were eventually selected for commercial machines. The inclusion of
wind energy in the solar energy tax-credit legislation in the early 1980s encouraged
numerous other companies to enter the wind turbine development and manufacturing ield.
Future development of wind turbine systems in the U.S. was undertaken without direct
government support, while the federal program concentrated on supporting research to
expand the technology base for all sizes and applications of wind turbines.
Supporting Technology for Small-Scale Wind Systems
A series of analytical and experimental projects conducted under the Federal Wind
Energy Program provided data for both a technology base and decision-making related to
the further development of small-scale turbines. Paciic Northwest Laboratories tailored the
techniques of wind resource assessment for the use of manufacturers, planners, distributors,
and agricultural extension agents. This work led to the development of “stand-alone”
courses on the siting of turbines, using slides, audio tapes, and workbooks. Economic
and market analyses were made by organizations such as A. D. Little, JBF Scientiic, and
General Motors on subjects crucial to the developing wind turbine industry, such as
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