Residential Wind Power Facts | Turbines and Towers
It seems like every week or so a new wind turbine model is brought to
market. Even more so now with the 30% energy tax credit for renewable
energy systems that expires in 2016. Taken together with state mandated
tax credits, rebates, or grants you can get a shiny new wind or solar
powered system for as much as 50% off.
Before you choose a wind turbine and tower you have to decide how much of
your current power usage you want to replace. In order to do that you have
to know how many kWh (kilowatt hours) of electricity you consume annually.
So get out a years worth of electric bills, look at the meter reading section
for kWh usage and add 'em all up.
If you're the average American household you consume between 9,000 and
12,000 kWh per year. And if you're planning on replacing let's say 9,000
kWh a year with wind power you would need a 10k system costing upwards
of $40,000 plus installation. This might sound like a lot of money, but dollar
for dollar you'd get 4 to 5 times more energy than from a smaller 1.8K
system costing around 13,000 - $18,000.
Large Home Wind Turbine Manufacturers 1,000+ kWh/month
Bergey BWC Excel Endurance X Series Jacobs 31-20
The output of any size generator is determined by the diameter (3 props), or
length (2 props) of the rotor. The diameter, or length, determines the
"swept area" of the rotor; the larger the swept area, the more energy is
generated. The rotors on large generators are typically in the 20' range with
a swept area of 300 - 400+ square feet and generate 1,000+ kWh of power
a month at 12 mph winds.
You can estimate the monthly power production for any turbine on this page
by inputting your local wind speed and the prop diameter into this
Medium Home Wind Turbines 500 kWh/month @ 12/mph
Small Home Wind Turbines Less than 500 kWh/month @ 12 mph
Bergey XL.1 Battery only system: Whisper 200
Wind Turbines Towers
Each manufacturer listed above also sells tower kits on their websites to
complement their generators. Many towers can be used interchangeably with
other manufacturers turbines but may require an adapter kit.
Tower heights start at 33' and range upwards of 100'. As tower heights
increase, the wind becomes faster and less turbulent. A 20 foot increase in
tower height, from 60 to 80 feet for instance, can increase the output of
your wind turbine by more than 20%.
The general rule of thumb for placing wind turbines is that the bottom of the
blades should be at least 30 feet above any obstruction (trees buildings,
etc.) within 500 feet. The entire rotor needs to be well above obstructions,
so start your measurement from the tip of the lowest blade.
Three basic tower types are used for almost all home-scale wind generator
installations. Tilt-up towers make maintenance easy, with no climbing. Fixed,
guyed towers are very common, climbable towers. Freestanding towers that
resemble the Eiffel Tower, with no guy wires, are costly, but attractive, and
Tilt-up towers (See the video below) Tilt-up towers come in heights up to
around 130 feet (40m) for small-scale machines. The most common tilt-ups
are tubular steel, with sections of pipe coupled together, and guy wires
attached at each joint.
Tilt-up towers consist of the tower pole and a “gin pole” that is attached to it
at 90 degrees. When the tower is down, the gin pole sticks straight up in the
air. When the tower is up, the gin pole rests horizontally near the ground.
The gin pole is a big lever that allows you to easily lift the tower, which pivots
at its concrete base.
Fixed, guyed towers Another type of guyed tower, a fixed tower is lifted
up once, and does not tilt down. Guy wires hold it up, and any maintenance
on the tower or turbine is done by climbing the tower. These towers come in
various configurations, the most common being triangular lattice sections, 10
or 20 feet (3 or 6 m) long, that bolt together. You’ve probably seen this
type of tower used for commercial radio antennas and the like.
Freestanding towers If your budget isn’t tight, a freestanding tower might
be your first choice. No guy wires, and it only needs a modest clear space for
the tower base. The drawback, of course, is cost. Freestanding towers rely
on steel and concrete to hold them up instead of guy wires—lots of steel and
concrete. This means higher cost for these materials, as well as for
excavation, concrete forms, rebar, and labor.
Freestanding towers take two basic forms. Most common is the three-legged
Eiffel Tower style, with tubular legs connected by angle iron braces. The
other option is a monopole tower—a large, single tube, similar to what is
used for utility-scale wind turbines.
Will it help the environment if I install a wind turbine at my home?
Wind turbines produce no pollution and by using wind power you will be
offsetting pollution that would have been generated by your utility company.
Over its nominal 30 year life, a BWC EXCEL wind turbine will offset
approximately 1.2 tons of air pollutants and 200 tons of greenhouse gases.
Will the utility company allow me to hookup a wind generator?
Federal regulations (PURPA) require utilities to allow you to install a wind
generator, and pay you for any excess power you produce.
Will I have to change any of the wiring in my house?
No, a wind turbine is easily retrofitted to virtually any home without need of
changing any wiring or appliances. In some states a second utility meter will
be added so the utility can know how much electricity you have sold to them.
How are they as an investment?
That depends on your cost of electricity and average wind speed. The wind
system will usually recoup its investment through utility savings within 6-15
years and after that the electricity it produces will be virtually free.
Compared to purchasing utility power, a wind system can be a good
investment because your money goes to increasing the value of your home
rather than just paying for a service. Many people buy wind systems for their
retirement because they are concerned about utility rate increases.
In addition to the new 30% energy tax credit, many states in the USA offer
various types of tax incentives and even rebates for your wind system.
Follow the link to see what incentive programs your state offers for a small
A Ford van, out of camera
range, is all the power
needed to raise this 55'
guyed tower. The leverage
to raise the tower is
provided by the gin pole and
pulleys. The longer the gin
pole, the easier it is to
control the speed at which
the heavy tower and turbine
assembly can be raised and
The pole pivots on a hinged
base plate. The guy wires
are attached before the
tower is raised and then
tightened with turnbuckles.
Guyed tilt up tower with guide pole
|Freestanding lattice tower
|Freestanding monopole tower