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Wind Power
Wind Energy System Basics
Unlike yesteryear's
windmill, today's wind turbines use technological innovations that have substantially
reduced the cost of electricity generated from wind power. In the 1920s and '30s,
farm families throughout the Midwest used wind to generate enough electricity
to power their lights and electric motors. The use of wind power declined with
the government subsidized construction of utility lines and fossil fuel power
plants. However, the energy crisis in the 1970s and a growing concern for the
environment have generated an interest in alternative, environmentally friendly
energy resources. Today, homeowners in rural and remote locations across the nation
are again examining wind power to provide electricity for their domestic needs.
Benefits
of Wind Power
 A
wind energy system can provide a cushion against electric power price increases.
Wind energy systems help reduce U.S. dependence on fossil fuels; and they are
nonpolluting. If you live in a remote location, a small wind energy system could
help you avoid the high costs of having utility power lines extended to your site.
Although wind energy systems involve a significant initial investment, they can
be competitive with conventional energy sources when you account for a lifetime
of reduced or altogether avoided utility costs. The length of the payback period – the time before the savings resulting from your system
equal the cost of the system itself – depends on the system
you choose, the wind resource on your site, electricity costs in your area, and
how you use your wind system.
Is
Wind Power Practical for You?
Small wind energy
systems can be used in connection with an electricity transmission and distribution
system (called grid-connected systems), or in stand-alone applications that are
not connected to the utility grid. A grid-connected wind turbine can reduce consumption
of utility-supplied electricity for lighting, appliances, and electric heat. If
the turbine cannot deliver the amount of energy you need, the utility makes up
the difference. When the wind system produces more electricity than the household
requires, the excess can be be returned to the grid. With the interconnections
available today, switching takes place automatically. Stand-alone wind energy
systems can be appropriate for homes, farms, or even entire communities (a co-housing
project, for example) that are far from the nearest utility lines. Either type
of system can be practical if the following conditions exist.
Conditions for Stand-Alone Systems
- You live in an
area with average annual wind speeds of at least 9 miles per hour (4.0 meters
per second).
- A grid connection is not available or can only be made through an
expensive extension.
- The cost of running a power line to a remote site to connect
with the utility grid can be prohibitive, ranging from $15,000 to more than $50,000
per mile, depending on terrain.
- You have an interest in gaining energy independence
from the utility.
- You would like to reduce the environmental impact of electricity
production.
- You acknowledge the intermittent nature of wind power and have a strategy
for using intermittent resources to meet your power needs.
Conditions for Grid-Connected
Systems
- You live in an
area with average annual wind speeds of at least 10 miles per hour (4.5 meters
per second).
- Utility-supplied
electricity is expensive in your area (about 10 to 15 cents per kilowatt hour).
- The utility's
requirements for connecting your system to its grid are not prohibitively expensive.
- Local building
codes or covenants allow you to legally erect a wind turbine on your property.
- You are comfortable
with long-term investments.
- Net metering is
available
Is
Your Site Right?
The U.S. Department
of Energy (DOE) has compiled wind resource maps that are available from the
American Wind Energy Association and
Wind Powering America. DOE maps are good sources for regional information
and can show whether wind speeds in your area are generally strong enough to justify
investing in a wind system.
Wind-turbine manufacturers can use computer models to predict machine performance
at a specific location. They can also help size a system based on your electricity
needs and the specific local wind patterns. However, you will need site-specific
data to determine the wind resource of your exact location. If you do not have
on-site data and want to obtain a clearer, more predictable picture of your wind
resource, you may wish to measure wind speeds at your site for a year. You can
do this with a recording anemometer, which generally costs $500 to $1,500. The
most accurate readings are taken at "hub height" (i.e., the elevation
at the top of the tower where you will install the wind turbine). This requires
placing the anemometer high enough to avoid turbulence created by trees, buildings,
and other obstructions. The standard wind sensor height used to obtain data for
the Department of Energy maps is 33 feet (10 meters).
Maps available in the table at right give general information on the average wind
resources available across the country and in Montana. Of course, the actual wind
resource on your site will vary depending on such factors as typography and structure
interference.
You can have varied wind resources within the same property. If you live in complex
terrain, take care in selecting the installation site. If you site your wind turbine
on the top or on the windy side of a hill, for example, you will have more access
to prevailing winds than in a gully or on the leeward (sheltered) side of a hill
on the same property. Consider existing obstacles and plan for future obstructions,
including trees and buildings, which could block the wind. Also realize that the
power available in the wind increases proportionally to its speed (velocity) cubed
(V3). This means that the amount of power you get from your generator goes up
exponentially as the wind speed increases. For example, if your site has an annual
average wind speed of about 12.6 miles per hour (5.6 meters per second), it has
twice the energy available as a site with a 10 mile per hour (4.5 meter per second)
average.
Additional Considerations
In addition to the factors listed previously, you should also:
- research potential
legal and environmental obstacles;
- obtain cost and
performance information from manufacturers;
- perform a complete
economic analysis that accounts for a multitude of factors;
- understand the
basics of a small wind system, and
- review possibilities
for combining your system with other energy sources, backups, and energy efficiency
improvements.
You should establish
an energy budget to help define the size of turbine you will need. Since energy
efficiency is usually less expensive than energy production, making your house
more energy efficient first will likely result In being able to spend less money
since you may need a smaller wind turbine to meet your needs.
Before you invest any time and money, research potential legal and environmental
obstacles to installing a wind system. Some jurisdictions restrict the height
of the structures permitted in residentially zoned areas, although it's often
possible to obtain a variance. Your neighbors might object to a wind machine that
blocks their view, or they might be concerned about noise. Consider obstacles
that might block the wind in the future (large planned developments or saplings,
for example). If you plan to connect the wind generator to your local utility
company's grid, find out its requirements for interconnections and buying electricity
from small independent power producers.
Pricing
a System
When you are confident
that you can install a wind machine legally and without alienating your neighbors,
you can begin pricing systems and components.
Approach buying a wind system as you would any major purchase. Obtain and review
the product literature from several manufacturers. Lists of manufacturers are
available from the AWEA. However,
not all small turbine manufacturers are members of AWEA. Once you have narrowed
the field, research a few companies to be sure they are recognized wind energy
businesses and that parts and service will be available when you need them. Also,
find out how long the warranty lasts and what it includes. Check this website
under Products and Services for Montana
companies that sell and service wind energy systems.
Ask for references of customers with installations similar to the one you are
considering. Ask system owners about performance, reliability, and maintenance
and repair requirements, and whether the system is meeting their expectations.
A residential wind energy system can be a good long-term investment. However,
because circumstances such as electricity rates and interest rates vary, you need
to decide whether purchasing a wind system is a smart financial move. Be sure
you or your financial adviser conduct a thorough analysis before you buy a wind
energy system.
Montana offers a wind energy system personal tax credit for commercial, industrial,
and residential users. The state allows a 35- percent tax credit for an individual,
partnership or corporation that makes an investment of $5,000 or more in a wind
electricity generating system or facilities to manufacture wind energy equipment.
Eligible property includes wind energy system equipment, transmission lines, and
equipment used in the manufacture of wind energy devices. Contact the Montana
Department of Environmental Quality for more information: (406) 444-6697.
Excerpted in part from Small
Wind Energy Systems for the Homeowner, published by the National Renewable
Energy Laboratory in 1997.
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