Residential Wind Power Facts
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Notice that a 20% increase in wind speed from 10 to 12 mph yields a 66% increase in
energy production.
Wind speeds are typically highest during winter months and taper off throughout the
summer. To illustrate this, you can view a monthly kWh production chart kept by the
owner of a Skystream 3.7.
What are the requirements for a viable wind system?
1. Zoning laws that enable the installation of wind powered systems. The first place to
start is your town's building department. Here's a link to a short but instructive zoning
overview for small wind turbines. (PDF)
2. Sufficient land and open space. The land requirement will depend on zoning laws
but the suggested minimum is one acre. As far as open space goes, the tower and
generator should be sited in an area free of obstructions for 500 feet around the
tower.
3. Wind - the minimum requirement is 10 mph average annual wind speed. As the
monthly energy chart above shows, a seemingly insignificant increase in wind speed
pays big dividends. The most cost effective method to increase wind speed is to
increase tower height.
Find your local wind speed in 3 easy steps
1. The first step in determining if your local wind resources warrant an investment in
wind power is to take a quick look at the U.S. 50 meter wind resource map. If you live
in an area where the map color is white you should forget about wind power and
consider solar power instead. If not, continue to step 2.
2. Next, on the same page, scroll down to the State wind resources map and click on
your state. You'll see a color coded map; left click on the map to enlarge. Look at the
color coded Wind Power Classifications and determine if you live in a class 3 or better
area. Although some wind turbine retailers will tell you class 2 wind power is sufficient,
I think your chances of success will be marginal with anything less than class 3 winds.
The one drawback to the maps you just viewed is the wind speed measurements
were taken at 50 meters, or 164 feet, and don't accurately reflect the wind speeds at
the top of shorter towers used for home wind generation.
3. A more accurate, though still imperfect solution to this problem can be found at the
Wind Energy Resource Atlas. This resource lists the wind speeds at elevations closer
to standard tower heights. To start, click on your state and look through the list of
towns. If your city or town isn't listed, substitute a town with similar geographic
characteristics, i.e., proximity to the same body of water or mountainous location.
Below is a snapshot of what you'll see, and I've underlined the two columns with
pertinent information. The column underlined in blue gives the height, in meters, at
which the measurements were taken. The column with red underlining shows annual
wind speed, in meters/second. ( Height: 1 meter = 3.26 ft., Wind speed: use this
calculator to convert m/s to mph)
First look at the red column to see whether or not your location has a wind speed
greater than 4.5 m/s (10 mph). If it does, look at the corresponding height to get an
idea of the tower height your system will need to achieve that wind speed.
energy production.
Wind speeds are typically highest during winter months and taper off throughout the
summer. To illustrate this, you can view a monthly kWh production chart kept by the
owner of a Skystream 3.7.
What are the requirements for a viable wind system?
1. Zoning laws that enable the installation of wind powered systems. The first place to
start is your town's building department. Here's a link to a short but instructive zoning
overview for small wind turbines. (PDF)
2. Sufficient land and open space. The land requirement will depend on zoning laws
but the suggested minimum is one acre. As far as open space goes, the tower and
generator should be sited in an area free of obstructions for 500 feet around the
tower.
3. Wind - the minimum requirement is 10 mph average annual wind speed. As the
monthly energy chart above shows, a seemingly insignificant increase in wind speed
pays big dividends. The most cost effective method to increase wind speed is to
increase tower height.
Find your local wind speed in 3 easy steps
1. The first step in determining if your local wind resources warrant an investment in
wind power is to take a quick look at the U.S. 50 meter wind resource map. If you live
in an area where the map color is white you should forget about wind power and
consider solar power instead. If not, continue to step 2.
2. Next, on the same page, scroll down to the State wind resources map and click on
your state. You'll see a color coded map; left click on the map to enlarge. Look at the
color coded Wind Power Classifications and determine if you live in a class 3 or better
area. Although some wind turbine retailers will tell you class 2 wind power is sufficient,
I think your chances of success will be marginal with anything less than class 3 winds.
The one drawback to the maps you just viewed is the wind speed measurements
were taken at 50 meters, or 164 feet, and don't accurately reflect the wind speeds at
the top of shorter towers used for home wind generation.
3. A more accurate, though still imperfect solution to this problem can be found at the
Wind Energy Resource Atlas. This resource lists the wind speeds at elevations closer
to standard tower heights. To start, click on your state and look through the list of
towns. If your city or town isn't listed, substitute a town with similar geographic
characteristics, i.e., proximity to the same body of water or mountainous location.
Below is a snapshot of what you'll see, and I've underlined the two columns with
pertinent information. The column underlined in blue gives the height, in meters, at
which the measurements were taken. The column with red underlining shows annual
wind speed, in meters/second. ( Height: 1 meter = 3.26 ft., Wind speed: use this
calculator to convert m/s to mph)
First look at the red column to see whether or not your location has a wind speed
greater than 4.5 m/s (10 mph). If it does, look at the corresponding height to get an
idea of the tower height your system will need to achieve that wind speed.
Alternative-Heating-Info.com
The American Wind Energy Association (AWEA) reports that the U.S. market for small
wind turbines – those with capacities of 100 kilowatts (kW) and less – grew 78% in
2008. The largest sector of this market is residential wind turbines in the 1-10 kilowatt
(Kw) range and are the focus of this article.
The mechanics of a wind turbine are pretty basic. In most small wind turbines the
rotor (propeller blades and hub) are connected directly to the generator. The
generator produces wild 3 phase alternating current (AC). The wild AC is rectified to
direct current (DC) and either stored in a battery bank or sent through an inverter
and modified into appliance friendly AC power.
Grid tied systems
When the power from the inverter is routed directly into your home's main circuit panel
you have a grid tied system. A grid tied wind system provides electricity to your home
only when there's sufficient wind. On calm windless days your home will rely on the
"grid." Most residential turbines will not produce usable amounts of electricity until the
wind speed exceeds 7 mph.
Battery systems
Another option is to route the power directly into a battery bank for current and future
needs. The incorporation of this type of system into your lifestyle is referred to as
"living off the grid." But to ensure that 100% of your power demand is met you must
carefully size the system taking into account wind resources, turbine size, and tower
height.
Hybrid systems
The third option is a combination grid tied system with a battery backup. A battery
backup is good to have when the grid is down or on windless days, but it will add
about a third again as much to the total cost of the system. For this reason, the
majority of wind systems sold are grid tied only.
Some manufacturers make only battery-charging machines, and may offer a variety of
turbine voltages. Others produce machines intended to connect to grid-synchronous
inverters without batteries. One machine by Skystream integrates the inverter with
the turbine.
Wind turbine power ratings
All home wind power generators are assigned a Kw (kilowatt) rating by their
manufacturers. Unfortunately, the peak power "rated at" Kw number assigned to
various wind turbine models is meaningless since there is no accepted, industry wide
standard for measuring a turbine's output. The rating inconsistencies are mainly due
to differing "example" wind speeds used by individual manufacturers to calculate peak
power.
A more accurate approach to estimating the energy output of a turbine at various
wind speeds is to use the chart provided on the manufacturer's website.
wind turbines – those with capacities of 100 kilowatts (kW) and less – grew 78% in
2008. The largest sector of this market is residential wind turbines in the 1-10 kilowatt
(Kw) range and are the focus of this article.
The mechanics of a wind turbine are pretty basic. In most small wind turbines the
rotor (propeller blades and hub) are connected directly to the generator. The
generator produces wild 3 phase alternating current (AC). The wild AC is rectified to
direct current (DC) and either stored in a battery bank or sent through an inverter
and modified into appliance friendly AC power.
Grid tied systems
When the power from the inverter is routed directly into your home's main circuit panel
you have a grid tied system. A grid tied wind system provides electricity to your home
only when there's sufficient wind. On calm windless days your home will rely on the
"grid." Most residential turbines will not produce usable amounts of electricity until the
wind speed exceeds 7 mph.
Battery systems
Another option is to route the power directly into a battery bank for current and future
needs. The incorporation of this type of system into your lifestyle is referred to as
"living off the grid." But to ensure that 100% of your power demand is met you must
carefully size the system taking into account wind resources, turbine size, and tower
height.
Hybrid systems
The third option is a combination grid tied system with a battery backup. A battery
backup is good to have when the grid is down or on windless days, but it will add
about a third again as much to the total cost of the system. For this reason, the
majority of wind systems sold are grid tied only.
Some manufacturers make only battery-charging machines, and may offer a variety of
turbine voltages. Others produce machines intended to connect to grid-synchronous
inverters without batteries. One machine by Skystream integrates the inverter with
the turbine.
Wind turbine power ratings
All home wind power generators are assigned a Kw (kilowatt) rating by their
manufacturers. Unfortunately, the peak power "rated at" Kw number assigned to
various wind turbine models is meaningless since there is no accepted, industry wide
standard for measuring a turbine's output. The rating inconsistencies are mainly due
to differing "example" wind speeds used by individual manufacturers to calculate peak
power.
A more accurate approach to estimating the energy output of a turbine at various
wind speeds is to use the chart provided on the manufacturer's website.
The chart on the left illustrates estimated
monthly output in kWh (kilowatt hours)
based on average annual wind speed for
the Whisper 500 by Southwest Windpower.
At average wind speeds of 10 mph you
could expect 300 kwh of energy production.
At average wind speeds of 12 mph the
energy output is around 500 kWh.
monthly output in kWh (kilowatt hours)
based on average annual wind speed for
the Whisper 500 by Southwest Windpower.
At average wind speeds of 10 mph you
could expect 300 kwh of energy production.
At average wind speeds of 12 mph the
energy output is around 500 kWh.
Even though you've narrowed down your location to a class 3 wind site, it's still
possible not to have sufficient wind resources at every location. Next, let's take a look
at turbines and towers.
possible not to have sufficient wind resources at every location. Next, let's take a look
at turbines and towers.
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