7 Environs 1 (1983)

handle is hein.journals/environs7 and id is 1 raw text is: environmental law society                   V7, N1 January 1983

HARNESSING THE
W.I.N'D
In most parts of the world winds seem as inevitable as day following
night. In fact, the diurnal cycle causes winds. Since sunlight falls unevenly
across the earth and because land heats faster than the oceans, some air masses
warm faster than others. As warm air rises, cooler air rushes in to replace it.
Wind is therefore simply another form of solar energy - a form which we can
harness to produce mechanical and electrical power.
Mankind has been utilizing windpower for over 2,000 years. The earliest
windmills were developed independently in China and the Middle East, and
were introduced to Europe during the twelfth-century crusades. The technol-
ogy then traveled to the New World where it was instrumental in opening up
the arid American West to grazing and agriculture. An estimated six million
windmills supplied irrigation and drinking water in the West by the end of the
nineteenth century. As America began to utilize more electricity in the early
part of this century, wind power showed promise as a generating source, but
the effects of cheap fossil fuels and hydropower rendered the then available
wind technologies uneconomical, and cut short the embryonic development of
wind-generated electricity.
The first Arab oil embargo prompted the United States to seriously recon-
sider windpower's potential as a commercially viable source of electricity. In
1973, the National Science Foundation sponsored a major project to explore the
practicality of wind as an energy resource. This project was first undertaken by
the National Aeronautics and Space Administration (NASA), but was subse-
quently assumed by the Department of Energy (DOE). It was DOE's objective
to convert windpower into electricity on a practical and economically feasible
scale. This project, together with the efforts of many private entrepreneurs, has
helped winapower technologies to mature during the last decade. It now
appears that windpower will be the first solar based energy system to make a
significant contribution to commercial electrical production.

I    From Wind t    riy
Current windturbine designs
are capable of capturing 401 of the
wind energy passing through the
area swept by their blades, com-
pared with a capture efficiency of
about 17% for the old farm wind-
mill. This advance is even more
significant than it seems since the
laws of physics limit the capture
efficiency of windturbines to a
theoretical maximum of 60/a.
A wind's speed is directly
related to the power contained in it.
The power in a wind is equal to the
cube of the windspeed, multiplied
by various constants. This means
that a small increase in windspeed
can result in a large increase in the
power available for capture. For
example, a 12 mph wind contains
over 70114 more power than a 10
mph wind (1OxlOxlO = 1000;
12x12x12 - 1728). For turbine
siting, both the average wind speed
of the site and the distribution of
typical windspeeds about this aver-
age are necessary data. As a gen-
eral rule, wind speeds of at least 12
mph are needed for electrical gen-
eration to be economical. For
mechanical water pumping, winds
of 8 mph are sufficient.

Wind   turbines follow  two
basic designs, vertical axis and hor-
izontal axis systems. In a vertical
axis system the blades look like an
egg beater and act like sails, rotat-
ing about a central pole. The
blades in a horizontal axis system
resemble an aircraft propeller but
perform the reverse function, the
airflow causing them to rotate.
Turbine generating capacities range
from   1 kilowatt (kW) to    40
megawatts   (MW;     IMW      =
1,000kW), with 100kW set as the
boundary between small and large
turbines. To give these numbers
some context, the electrical needs
of a typical American home could
be supplied by a 3 to 5kW turbine.
A IMW turbine could supply the
needs of approximately 400 such
homes.
Wind   turbines  do   show
economies of scale, but only to a
certain point. The primary con-
straint on turbine size is blade-tip
speed, since centrifugal forces can
tear blade materials apart. The
severe stresses on a blade (some
longer than the wings of a 747 jet)
combined    with   ever-changing
weather conditions can cause cracks
to develop, eventually causing a
blade to either break apart or tear

A Savonius Rotor

away   from   the   hub.   Blade
designers are testing materials such
as fiberglass and wood laminates to
eliminate this danger.
The size of the turbine must
also be chosen to best suit its par-
ticular application. Small turbines
are well suited for windy rural loca-
tions in need of power but far
removed from any transmission
lines.  The generation  of large
amounts of power, such as for a
utility, requires either several very
large turbines or a windfarm' com-
posed of many smaller units. One
problem with this approach is that
each   operating  turbine  creates
airflow turbulence which lessens
the capture efficiency of other
nearby turbines. On windfarms
turbines must be spaced at least 7
to 10 rotor diameters apart in order
to let the airflow restabilize, ena-
bling each turbine to perform at

maximum efficiency. This means
that large windfarms will require
expansive sites.
Windpower in California
Three large windfarms are
currently being developed in Cali-
fornia, and many entrepreneurs are
involved in smaller projects. U.S.
Windpower is building a windfarm
in the Altamont Pass area, about 50
miles east of San Francisco. This
farm will consist of 100 turbines
with a capacity of 50kW each, col-
lectively producing 15 million kWh
(kilowatt hours) a year. Later
phases of the project will add 500
more turbines. Pacific Gas and
Electric (PG&E) has signed a con-
tract to purchase all the electricity
produced by this windfarm.
Southern California Edison
(SCE) has signed two contracts to
purchase     electricity   from
windfarms. One is with Wind
Energy Conversion Systems for
5.5MW. This farm will consist of
55 turbines of 100kW each in the
San Gorgonio Pass area near Palm
Springs. This is considered the best
wind resource area in the state. The
other contract is with Zond Systems
for 1.8MW. They plan to use small
turbines with capacities of 25 to
50kW    each,  located  in  the
Tehachapi Mountains north of Los
Angeles. Within the next four
years Zond Systems hopes to
develop a windfarm with a capacity
of 25 to 30MW.
In    addition  to   these
windfarms, SCE is currently work-
ing on draft contracts or letters of
intent for 70MW of windpower.
The utility is at various stages of
negotiation  for  an  additional
200MW of capacity. ('California
Utilities Sign Up for Wind Energy,
Electrical World No. 196 (Feb.
1982), pp. 24-25.) The rate at
which this power will be developed
and go on line depends heavily on
the success of the initial installa-
tions, and on the terms of the final
contracts.
Further development of wind-
power and other alternative energy
sources in California is currently
stalled  because  of  uncertainty
about the terms of the final con-
tracts between the utilities and the
power producers. Section 210 of
the Federal Public Utilities Regula-
tory Policies Act of 1978, (PURPA
16 U.S.C. 824a-3), requires state
PUC's to conduct hearings with
utilities and potential small power
producers to set standard offer con-
tracts. The California PUC issued a
(See WIND, page 2)

*                       iEronmental Law Society                                                                     NONPROFIT ORG.
0          King Hall
University of California                                                                          U.S. POSTAGE
,   Davis, California 95616
PAID
Davis, Calif.
Permit No. 3

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