wind power
Power
from
the
Wind
by MIck SAgRILLo
SetH MASiA
keep the system well tuned
and it will generate electric-
ity for decades.
Mick Sagrillo, a small-wind
consultant, owns Sagrillo
Power & light and is wind
energy specialist for Focus
on energy, Wisconsin’s
renewable energy program.
Contact him at msagrillo@
wizunwired.net.
Americans have relied on wind power to pro- duce electricity for generations, and today’s mall wind turbines are a reliable way to cut utility bills. Federal tax credits along with state and local incentive programs make wind
energy more economically attractive than ever.
At the core of the small-wind industry lies a mature,
tried-and-tested technology. This growing industry also
attracts a lot of startup businesses, many of them based on
half-baked ideas or wishful thinking. It’s important to know
which products will perform as promised on your property.
Here is a list of issues to consider when shopping for a small
wind system:
You need wind. Most areas with average wind speeds
of eight to 14 miles per hour ( 3. 6 to 6. 3 meters per second) can produce usable power for a home, farm, school
or small business. Wind
turbines are mounted on
tall towers because that’s
where the wind is, up
above nearby trees and
buildings. The ground
and everything attached
to it creates friction,
slowing the moving air
masses we perceive as
wind. These obstacles
also create turbulence. A
turbine needs a smooth
flow of wind to produce
steady power.
The bottom line
is, there is little power
available at rooftops, at
or below the tree line
or in urban and suburban areas. Usable winds are pretty
much restricted to open rural areas, above the buildings
and treetops.
So, you need a tower. The rule of thumb for the wind
site assessor is that the entire rotor of the wind turbine must
be at least 30 feet ( 9 meters) above any surrounding obstacles for 500 feet (150 meters). This is a minimum. Keep
in mind that, over the life of the wind system, the trees in
your area will grow, but your tower will never be any taller
than the day it was planted. When determining the tower
height for your site, plan on tree growth 20 to 30 years into
the future, the life expectancy of a wind system.
Size matters. A number of vendors now offer small wind
systems featuring “breakthrough technologies,” but these
companies offer little data proving why their product is better than mature products in the marketplace. Most of these
products also sport very small rotors so that they can safely be
mounted on a roof. Running a home, farm or business takes a
more significant amount of power. Just as with a solar system,
the power of a wind system depends on the size of its collector — in this case, the rotor. Double the size of the collector
and you double the power you can extract from the wind. If
you want to generate enough electricity from the wind to
power an exit sign, buy a wind turbine with a small rotor. To
power the average North American house, you need a rotor
18 to 30 feet ( 5. 5 to 9 meters) in diameter. You’ll need an
even larger rotor for a farm, school or small business.
Be prepared to spend money. The average North American home consumes about 1,000 kilowatt-hours (k Wh) of
electricity per month. A wind turbine and tower to offset
that entire load will cost $55,000 to $80,000 installed. The
range has more to do with extraneous expenses than the
cost of the turbine itself. These include the tower height
based on your local obstacles; the local cost of concrete and
rebar, wire run and electrical components; excavation and
crane costs; shipping and labor. Any grants or tax credits
will reduce this amount, but be wary of dealers who quote
prices for installed systems lower than this. Either something was not taken into consideration, or the equipment
is of below-average quality.
Do it yourself? Probably not. Towers are tall, and
climbing them for installation, service and repair is not for
the meek or weak of knees. It takes training to climb, as well
as to maintain, a sophisticated wind system. A tilt-up tower
is fraught with its own problems and is not a project for the
weekend mechanic.
Choose your installer well. Keep in mind that you will
live with your wind system for 20 to 30 years, maybe even
longer. It will need inspections and maintenance during
that time, and the best qualified person to service the system is the installer who commissioned it. You will depend
on your installer for decades. Ask other wind system owners
who provides the most reliable service after installation.
Don’t pinch pennies here.
Expect decades of commitment. Wind systems are
dynamic machines operating in the harshest environment
imaginable for untold hours. A wind turbine operating for
only one-fourth of a year logs as many hours as a car does
in its 200,000-mile lifetime. This means your system will
require annual inspections and prompt attention to any
requisite repairs. It is well understood in the small-wind
industry that the life of a wind system is directly proportional to the owner’s involvement. Keep the system well
tuned and it will generate electricity for decades. Preventative maintenance is critical; a mechanical malfunction of a
spinning turbine is not pretty.
A small wind system needs adequate wind, a sizable
tower, a collector of significant size and regular maintenance by a knowledgeable installer. Anyone willing to commit to a project on this scale will be rewarded with many
years of renewably generated electricity. GS
