See the Panning Department's standards for the review of applications here. Most of the popular models of small HAWTs operate at about the same efficiency.
The energy production you should expect will be closely related to the swept area of the rotor blades, which is based on the diameter of the rotor. If you are offered a HAWT that promises to power your whole house with a turbine that is much smaller than conventional products, ask for more details. Because VAWTs are just starting to enter the marketplace, their efficiencies are much harder to predict. Always get several bids from different companies and ask for references from prior customers.
Help us improve your experience on this website. Please complete this 2-minute survey. All rights reserved. Skip to main content. San Francisco Department of the Environment. In addition to producing these special segments, Frank will provide additional information related to his stories through this North Carolina Science Now Reporter's Blog!
Related Resources:. Brain cancers are complex, aggressive and there are few treatment options. A potential new treatment of Covid patients is being developed in Clayton, North Carolina. It uses antibodies The most basic of environmental questions doesn't have an easy answer. December 23, "Plastic or paper? The turbine's frame is the structure onto which the rotor, generator, and tail are attached. The tail keeps the turbine facing into the wind.
Because wind speeds increase with height, the turbine is mounted on a tower. In general, the higher the tower, the more power the wind system can produce.
The tower also raises the turbine above the air turbulence that can exist close to the ground because of obstructions such as hills, buildings, and trees. A general rule of thumb is to install a wind turbine on a tower with the bottom of the rotor blades at least 30 feet 9 meters above any obstacle that is within feet 90 meters of the tower. There are two types of towers: self-supporting free-standing and guyed. Guyed towers, which are the least expensive, can consist of lattice sections, pipe, or tubing depending on the design ; supporting guy wires; and the foundation.
They are easier to install than self-supporting towers. However, because the guy radius must be one-half to three-quarters of the tower height, guyed towers require space to accommodate them. Although tilt-down towers are more expensive, they offer the consumer an easy way to perform maintenance on smaller lightweight turbines usually 5 kW or smaller. Tilt-down towers can also be lowered to the ground during hurricanes and other hazardous weather conditions.
Aluminum towers are prone to cracking and should be avoided. Most turbine manufacturers provide wind energy system packages that include a range of tower options. Costs in addition to the turbine and the tower are the balance of system, including parts and labor, which will depend on your application.
Most manufacturers can provide you with a system package that includes all the parts you need for your application. For example, the parts required for a water-pumping system will be different from the parts required for a residential, grid-connected application.
The balance of system equipment required will also depend on whether the system is grid-connected, stand-alone, or part of a hybrid system. For a residential grid-connected application, the balance of system parts may include a controller, storage batteries, a power conditioning unit inverter , wiring, foundation, and installation. Many wind turbine controllers, inverters, or other electrical devices may be stamped by a recognized testing agency, such as Underwriters Laboratories or Intertek.
Stand-alone systems systems not connected to the utility grid require batteries to store excess power generated for use when the wind is calm. They also need a charge controller to keep the batteries from overcharging. Automotive batteries are shallow-cycle batteries and should not be used in renewable energy systems because of their short life in deep-cycling operations.
Small wind turbines generate direct current DC electricity. In very small systems, DC appliances operate directly off the batteries. If you want to use standard appliances that use conventional household alternating current AC , you must install an inverter to convert DC electricity from the batteries to AC. Although the inverter slightly lowers the overall efficiency of the system, it allows the home to be wired for AC, a definite plus with lenders, electrical code officials, and future homebuyers.
For safety, batteries should be isolated from living areas and electronics because they contain corrosive and explosive substances. Lead-acid batteries also require protection from temperature extremes.
In grid-connected systems, the only additional equipment required is a power conditioning unit inverter that makes the turbine output electrically compatible with the utility grid. Batteries are usually not required. Installation costs vary greatly depending on local zoning, permitting, and utility interconnection costs. 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 avoided utility costs.
The length of the payback period—the time before the savings resulting from your system equal the cost of the system—depends on the system you choose, the wind resource on your site, electricity costs in your area, and how you use your wind system. Compare prices when shopping for a wind system as you would any major purchase by reviewing the product literature from several manufacturers.
To justify your investment in a small wind turbine, you will want assurances that your turbine model has been evaluated for safety, performance, and functionality. Research small wind turbine companies to be sure they offer certified turbines and that parts and service will be available when you need them. Ask for references from past customers with installations similar to the one you are considering.
Ask the system owners about performance, reliability, and maintenance and repair requirements, and whether the system is meeting their expectations. Also, find out how long the warranty lasts and what it includes.
You must decide whether you will perform the installation and maintenance work on your small wind turbine or whether you will hire an experienced small wind installer. This decision will affect your system's cost. Many people elect to install their own turbines. Before attempting to install your wind turbine, ask yourself the following questions:. If you answered no to any of the above questions, you should probably hire a system integrator or installer.
Contact the manufacturer for help or call your state energy office and local utility for a list of local system installers. A credible installer may be able to provide many services such as permitting, obtaining interconnection approval, etc. Find out if the installer is a licensed electrician. Ask for references and check them. You may also want to check with the Better Business Bureau.
Turbine and tower manufacturers should provide their own operations and maintenance plan; however, turbine owners should be aware that all rotating equipment will require some maintenance. Many turbines require periodic lubrication, oil changes, and replacement of wear surfaces such as brake pads.
The machines should be checked for corrosion and the guy wires for proper tension. In addition, you should check for and replace any worn leading edge tape on the blades, if appropriate. After 10 years, the blades or bearings may need to be replaced, but with proper installation and maintenance, the machine should last 20 years or longer.
Every turbine should include an owner's manual or operations manual to provide the consumer with scheduled and unscheduled maintenance information as well as other unique product information.
Scheduled maintenance guidelines should be followed. If you do not have the expertise to maintain the machine, ask whether your installer provides a service and maintenance program. Notice that the wind speed V has an exponent of 3 applied to it.
This means that even a small increase in wind speed results in a large increase in power. That is why a taller tower will increase the productivity of any wind turbine by giving it access to higher wind speeds.
The rotor-swept area A is important because the rotor captures the wind energy. So the larger the rotor, the more energy it can capture. A density correction should be made for higher elevations as shown in the Air Density Change with Elevation graph. A correction for temperature is typically not needed for predicting the long-term performance of a wind turbine. Although the calculation of wind power illustrates important features about wind turbines, the best measure of wind turbine performance is annual energy output.
The difference between power and energy is that power kilowatts [kW] is the rate at which electricity is consumed while energy kilowatt-hours [kWh] is the quantity consumed. They will use a calculation based on the particular wind turbine power curve, the average annual wind speed at your site, the height of the tower that you plan to use, micro-siting characteristics of your site and, if available, the frequency distribution of the wind an estimate of the number of hours that the wind will blow at each speed during an average year.
They should also adjust this calculation for the elevation of your site. To get a preliminary estimate of the performance of a particular wind turbine, use the formula below. The Wind Energy Payback Period Workbook is a Microsoft Excel spreadsheet tool that can help you analyze the economics of a small wind electric system and decide whether wind energy will work for you. It asks you to provide information about how you will finance the system, the characteristics of your site, and the properties of the system you're considering.
It then provides you with a simple payback estimation assumes no increase in electricity rates in years. If the number of years required to regain your capital investment is greater than or almost equal to the life of the system, then wind energy will not be practical for you. Is the wind resource at your site good enough to justify your investment in a small wind turbine system? That is a key question and not always easily answered.
The wind resource can vary significantly over an area of just a few miles because of local terrain influences on the wind flow. Yet, there are steps you can take to answer the above question. The highest average wind speeds in the United States are generally found along seacoasts, on ridgelines, and on the Great Plains; [25] however, many areas have wind resources strong enough to make a small wind turbine project economically feasible.
Although there may be many methodologies for understanding the wind resource at a specific location, gathering on-site, measured wind data is typically preferred. A Pika Energy small wind turbine in Gorham, Maine. Prior to conducting an on-site measurement campaign, some small wind project developers use state wind maps to conservatively estimate the wind resource at turbine hub height. While these maps can provide a general indication of good or poor wind resources, they do not provide a resolution high enough to identify local site features.
State wind maps cannot include information on complex terrain, ground cover, wind speed distribution, direction distribution, turbulence intensity, and other local effects. Purchased maps or services can often provide higher resolution and more flexibility with zooming, orientation, and additional features. Pay attention to a map's height above ground as it relates to the potential project's tower height.
Adjusting the wind speed for the height difference between the map and the turbine height adds a potential source of error depending on the wind shear exponent that is selected, and the greater the height difference the greater the potential error.
Therefore, for small wind generator applications, to m wind maps are far more useful than , , , or m wind maps. It is also important to understand the resolution of the wind map or model-generated data set.
If the resolution is lower than the terrain features, adjustments will be needed to account for local terrain effects. Local airport or weather stations can offer local wind data, but these data may be less reliable than actual site data. If airport data typically recorded at 30 ft or 10 m above ground or weather station data typically recorded at 5 to 20 ft above ground are used, inquire not only about the site's current equipment and location but also if it is historically consistent with the data collection equipment and siting.
Equipment at these sites is not primarily intended for wind resource assessment, so it may not be positioned at an appropriate height or in a location free of obstructions. Unfortunately, airport and weather stations are usually far from the site of interest, with considerably different orography, tree cover, and monitoring height, making these data of questionable usefulness.
Given the expertise required to effectively establish and correlate wind resource data, the data provided by airport and weather stations may only provide a rough screening assessment. The National Climatic Data Center collects data from airports in the United States and makes wind data summaries available for purchase.
Another useful indirect measurement of the wind resource is the observation of an area's vegetation. Trees, especially conifers or evergreens, can be permanently deformed by strong winds.
This deformity, known as "flagging," has been used to estimate the average wind speed for an area. Flagging, the effect of strong winds on area vegetation, can help determine area wind speeds. Small wind site assessors can help you determine whether you have a good wind resource on your site. State or utility incentive programs may be able to refer you to site assessors with training in assessing the wind resource at specific sites.
Computer programs that estimate the wind resource at a particular site given specific obstacles are also available. Site assessors and computer programs can help to refine the estimates provided on wind resource maps. On-site data measurement adds a new layer of confidence to the techniques discussed above, but with substantial additional costs, effort, and time, especially when the preferred methodology is to match turbine hub height and collect data for a minimum of 1 year.
Obtaining several years of data is better, or 1 year that can be referenced to a longer-term data set if there is good correlation with the on-site data. A number of small, affordable wind data collection systems are available for on-site measurement and are best run for at least 1 year. These systems include anemometers, wind vanes, and temperature sensors that are mounted as close to hub height as possible.
Calculating the wind shear exponent requires collecting data at two different heights. Having wind shear data is essential for conducting an accurate analysis of the cost versus benefits of taller towers. In addition, analysis must be performed to determine wind speed averages and extremes, wind distribution, Weibull parameters, the wind direction rose, turbulence intensity, vertical wind shear exponent, and associated uncertainties.
Finally, if there is a small wind turbine system in your area, you may be able to obtain information on the annual output of the system and also wind speed data if available. The farther you place your wind turbine from obstacles such as buildings or trees, the less turbulence you will encounter. A proper site assessment is a detailed process that includes wind resource assessment and the evaluation of site characteristics. Employees in the News.
Emergency Management. Survey Manual. Many turbine components are domestically sourced and manufactured in the United States Wind Technologies Market Report. However, many internal parts such as pitch and yaw systems, bearings, bolts, and controllers are typically imported. Learn more: Wind Energy. Access to affordable and reliable energy remains a critical need for people and the economy.
This scientific investigations report describes an effort by the U. Geological Survey USGS that used research, monitoring data, and modeling to develop a methodology to assess both the current and future population-level consequences of wind energy development on species of birds and bats that are present in the United States during any part USGS scientists provide scientific information and options that land and resource managers and private industries can use to make decisions regarding the development of energy resources while protecting the health of ecosystems.
Studies focus on delivering information to avoid, minimize, or mitigate the impacts of energy infrastructure on fish and Solar photovoltaic PV and wind turbine technologies are projected to make up an increasing proportion of electricity generation capacity in the United States in the coming decades. By , they will account for 36 percent or gigawatts of capacity compared with about 11 percent or gigawatts in fig. There are This dataset provides industrial-scale onshore wind turbine locations in the United States, corresponding facility information, and turbine technical specifications.
The database has wind turbine records that have been collected, digitized, locationally verified, and internally quality controlled. Turbines from the Federal Aviation Administration The generation of electricity in the United States from wind-powered turbines is increasing. An understanding of the sources and abundance of raw materials required by the wind turbine industry and the many uses for these materials is necessary to assess the effect of this industry's growth on future demand for selected raw materials relative to In contrast, others have expressed concern that newer, larger turbines may actually increase bird and bat deaths.
There are more than 57, wind turbines across the United States, and a new tool allows you to get up close and personal with each one! Today, the U. This photo shows one of the three ft blades of a turbine before installation.
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