124 Electrical Power Systems Technology
ral geothermal steam production is limited to active volcanic areas, such
as the Geysers area of the United States. Since no fuel is burned, geother-
mal methods represent one way of saving our valuable and diminishing
quantities of fossil fuels. The major problem associated with geothermal
power production is the drilling of the deep holes into the ground.
WIND SYSTEMS
Nonpolluting, inexpensive power systems have been desired for
many years. Now, technology has advanced to the point where there may
be some inexpensive methods of producing electrical power that we have
not used significantly before.
In the early 1900s, in many farm areas, particularly in the Midwest,
electrical power had not been distributed to homes. It was conceived that
the wind could be used to provide a mechanical energy, not only for wa-
ter pumps, but also for generators with which to provide electrical power.
The major problem was that the wind did not blow all the time and, then,
when it did, it often blew so hard that it destroyed the windmill. Most of
these units used fixed-pitch propellers as fans. They also used low-voltage
DC electrical systems, and there was no way of storing power during peri-
ods of nonuse, or during times of low wind speeds. These early units used
a rotating-armature system (see Chapter 6) and, therefore, along with oth-
er maintenance problems, had to have the brushes replaced very often.
The wind-generating plants used today have a system of storage bat-
teries, rectifiers, and other components that provides a constant power
output even when the wind is not blowing. They also have a 2-blade or
3-blade propeller system that can be “feathered” during periods of high
winds so that the mill will not destroy itself. A simplified wind-power sys-
tem is shown in Figure 5-4. Most of the systems that are in use today are in-
dividual units capable of producing 120-volt alternating current (AC) with
constant power outputs in the low-kilowatt range. The generator output
may be interconnected through a system of series-connected batteries with
an automatic, solid-state voltage control that is designed to convert the DC
voltage to 120-volt AC. The cost of these individual, electrical power-gen-
erating systems is fairly low, and these systems provide a complete, self-
contained, nonpolluting, power source. Wind systems would be ideal for
remote homes that have a low-power requirement. They should prove to
be very dependable and have low maintenance costs. Larger power-gen-