WMOD00380

• Title: One Viewpoint Concerning Unit Sizes in the Development of Wind Turbines
• Date: 11/1/1981
• Weather Modification - Doc Type: Report

trepreneurs who honed the efficiency of financial and
management arrangements. There was rapid and effective
winnowing that tested fertile ideas and rejected chaff. After a
transition period lasting about 15 years, a broad base of
commercial producers had arisen, and the original prototypes
had differentiated into a variety of products adapted to
different markets and uses. Since then, each product brought
to maturity during that transition has gone on through
repeated cycles of differentiation and improvement of which
the end is not yet in sight.
The crucial role of size bore directly on the entrepreneurial
experiments and only indirectly on the machines themselves,
In a classic review of the topic, Morison [18] noted:

"In all areas of difficulty and doubt. . . the
development of a series of small experiments,
with the means available for observing the
evidence produced and analyzing the results,
would produce a set of alternative solutions
and the data necessary both for fuller un-
derstanding of the nature of the new situations
and for intelligent selection among alter-
natives, .... Each experiment should be
small enough in scale and sufficiently
detached from existing practice so that the
continuing state of things would not be
disrupted. In addition, in each area of interest
there should be not one, but a good many
different experiments of differing design so
that a suitable array of alternative solutions
could be offered,"

Most entrepreneurial experiments for automobiles and
airplanes required only modest risk and modest invest~ent.
Favorable features and differentiations were qUIckly
propagated, and the ill-adapted were quickly eliminated.
These experiments embraced inventions such as the self-
starter, production methods such as specialized ,machine
tools, management innovations such as assembly h,nes and
detailed division of labor, and a wide vanety of
specializations for different uses, Figure 7 suggests how
undertaking entrepreneurial experiments with large wind
machines might depend on monetary risk involved and time
required to determine the outcome. At some high level o~ risk,
no private-sector experimentation will take place. At a slightly
lower level, there will be a few experiments, but these are
likely to be irrelevant to the course of development, as was the
Smith-Putnam wind turbine of the 1940s. But as soon as the
risk is viewed as acceptable in comparison with the op-
portunity for profit, experiments are likely to proliferate
enormously, with a definite preference for those expected to
yield answers quickly, To the left of the sloping lines in Fig,?,
experiments with large wind machines have begun to anse
spontaneously. ,
When risk inhibits the private sector, the only expenments
are those financed by the Government. In the Federal Wind
Energy Program, a recognized objective is to attain as soon as
possible a level of windspread use that will result in handoff
of further development and commercialization to the private
sector, with respect to both the production of large wind
machines and their useful application. Figure 7 suggests that
technology transfer from Government experiments to the
private sector is very sensitively dependent on the priv~te-
sector risk entailed in the transfer. When the machmes
developed in the course of Government experiments are seen
as involving too much risk, the private sector is likely to
respond by undertaking its own experiments at a lower level
of risk when the opportunity arises. In fact, the years 1978 to
1980 have seen the start of several private-sector en-
trepreneurial experiments with large wind machines at the
level of a few million dollars' commitment and a few years'

Journal of Solar Energy Engineering

'1,,0.'1

~
~ 6
J
g
J
3

..
./

No development
atoll

,,..If!JIj~"

-----.l.
I

YEARS REOUIRED TO COMPLETE AN EXPERIMENT

Fig. 7 Schematic response of private-sector development activities in
windpower to commercialization risks and prospects

duration, involving machines in the 0.2-0.5-MW category.
Private-sector entrepreneurial experiments with machines in
the 2-MW category (with some atypical exceptions4) appear to
be still several years in the future. Although such experiments
may materialize, their number and variety are likely to be
limited to a small sector of the potential market.
The number of companies in the United States now actively
engaged in development of windpowered generators of I-MW
capacity and up is very small, and all but a few of those are
industrial giants. Obvious deterrents for smaller companies
are the very large investment of overhead effort required for
responding to the current requests for proposals from the
U ,S. Department of Energy in the range of 1.5-3 MW and the
risk of projects being canceled after proposals are submitted.
One important consequence is that the number of people
involved in innovative thinking and experimentation on the
subject of windpower is very limited, and access to the field
on the part of outside inventors with radical ideas is beset with
delays and difficulties. If the unit size of machines were
smaller and production targets were larger, the rate of in-
novation and development in the field of windpower might be
correspondingly greater.
A part of the experimental arena that embraces both the
private sector and the Government has to do with develop-
ment of alternative mechanical designs, alternative techniques
of siting, and alternative strategies for integration of wind-
power into the existing utility network. These, too, are af-
fected by machine size.
Alternative features of mechanical design are too numerous
to be adequately discussed in this presentation. Among the
more important ones are alternative materials and methods
for fabrication of rotor blades, alternative ways of designing
or managing the machine to avoid damage during episodes of
high wind, alternative approaches to power-train and
generator problems, and alternative ways of damping and
decoupling vibrational loads. So far, since policy has dictated
a very small number of machines escalating greatly in size
from one to the next, the number of such alternatives explored
in practice has been correspondingly small. Large size appears
definitely to have been a factor in limiting the number and
slowing the pace of such experiments.
Alternatives in the siting of wind machines also present
themselves. One conceivable limitation on the density of

~ne 3-Mw developmental machine is being built to order for a foreign
government. Another. with a rotor diameter about the same as the NASA
MOD-OA, but rated a 3 Mw in an 18-m/s wind. is undergoing testing for a
private utility,

NOVEMBER 1981, Vol. 1031311