Wind power comes from harnessing the kinetic energy of the wind and transforming it into electrical energy. Wind power has the potential to provide a significant portion of the nation’s energy supply. It is estimated that the potential of wind energy in the United States is ten times the amount of electricity consumption for the entire country.
In this article you will find information about small wind installations, which are defined as turbines that are 100 kilowatts or smaller. They are usually used to directly power a home, farm or small business. A wind system is site dependent and is only a viable investment if there is consistent wind of a certain speed.
Turbines mounted on high towers are the most efficient type of small wind installations because average wind speeds increase significantly with height. In general, the higher the tower, the more power the wind system can produce. The power available in the wind is proportional to the cube of its speed, which means that doubling the wind speed increases the available power by a factor of eight. For example, a turbine operating at a site with an average wind speed of 12-mph will generate about 29% more electricity than one at an 11-mph site.
Tower-mounted turbines may be a good option for you if:
• Your property has a good wind resource;
• Your home or business is located on at least one acre of land in a rural area;
• Your local zoning codes or covenants allow wind turbines;
• Your average electricity bills are $150 per month or more;
• Your property is in a remote location without easy access to utility lines;
• You are comfortable with long-term investments.
Mounting turbines on rooftops is generally not recommended because all turbines vibrate and transmit the vibration to the building on which they are mounted, which can lead to structural problems. Rooftop turbines are especially not recommended in urban areas because physical obstacles such as cell phone towers, skyscrapers and apartment buildings make it almost impossible for them to be consistently hit with adequate wind speeds. They are also very noisy.
How do wind turbines work?
Wind turbines convert the kinetic energy in wind into mechanical power and then into electricity. When wind blows past a turbine, the blades capture the energy and rotate, triggering an internal shaft to spin. The shaft is connected to a generator that produces the electricity. Turbine blades are aerodynamically designed to capture the maximum energy from the wind.
What are the components of a wind system?
A wind electric system is made up of a wind turbine mounted on a tower to provide better access to stronger winds. The average height for a small wind system tower is 80 feet. The turbine’s frame is the structure onto which a rotor, generator and tail are attached. The diameter of the rotor defines its “swept area” or the quantity of wind intercepted by the turbine. The tail keeps the turbine facing into the wind. The balance-of-system includes a controller, storage batteries, an inverter (power conditioning unit), wiring, electrical disconnect switch, grounding system and a foundation for the tower.
How do I determine if there is enough wind on my site?
Before considering installing a wind turbine, it is necessary to find out if the wind blows hard and consistently enough at your site to make a small wind turbine system economically feasible. Annual average wind speeds greater than four meters per second (m/s) (9 mph) are generally required for small wind electric turbines although less wind is required for water-pumping operations.
The most accurate way to determine wind speeds is to have a wind resource assessment done, however, this can be costly. As an alternative, wind speeds can be estimated from wind resource maps like the following: this wind resource map of the United States is from the United States Department of Energy and these resource maps are of New York State only: NYS Wind Resource Map #1 and NYS Wind Resource Map #2.
You can also get average wind speed information from a nearby airport. The wind at airports is generally measured at heights of about 20 – 33 feet above ground. Since average wind speeds increase with height, the wind speed for a typical turbine that is at 80 feet can be as much as 15%–25% greater than what is measured at airport anemometer heights. The National Climatic Data Center collects data from airports in the United States and makes wind data summaries available for purchase.
Note that local terrain differences and other factors may mean that the speed recorded at the airport is very different from your particular location.
For more information on wind resource assessment, go to NYSERDA’s Wind Resource Assessment Handbook.
How much electricity can one wind turbine generate?
The output of a wind turbine depends on the turbine’s size and the wind’s speed through the rotor. Power ratings for wind turbines generally range from 250 watts to 1.65 megawatts (MW), although today’s biggest onshore turbines, are over 3 MW and some offshore units at 6-7 MW are being tested. According to the U.S. Energy Information Administration, a typical home uses 920-kilowatt hours (kWh) each month or 11,040-kWh per year. A 10-kW wind turbine can generate about 16,000-kWh annually, which is more than enough for a typical household.
What permits and approvals are needed?
Often it is necessary to get building permits, electrical permits, approvals and certifications prior to installing a wind system. Check that your installer has experience in getting the necessary permits. Make sure that they are all in place before ordering your equipment and beginning installation.
What type of maintenance is needed?
Wind turbines should last up to 20 years or longer if they get the annual maintenance that they need which includes: checking bolts and electrical connections to make sure they are tightened; checking for corrosion and that the guy wires have the proper tension; checking for and replacing any worn leading edge tape on the blades. Note that after 10 years blades or bearings may need to be replaced. Annual operation costs and insurance can range on average from 1- 3% of the initial installation cost.
Stand alone or grid connected systems?
Wind systems can be either stand-alone systems or connected to the utility grid.
In systems that are connected to the utility grid, all of the power that your wind turbine produces is fed back into the grid and the utility supplies all of your power. Through a system known as net metering the utility keeps track of how much electricity you generate and how much you use. If you use more than what you generate, the excess is generally credited to your next bill at the retail rate. The Database of State Incentives for Renewables and Efficiency (DSIRE) explains the rules on net metering in your area. When you connect to the utility grid you will need to enter into an interconnection agreement with your local utility.
In a stand-alone system you only have access to the energy that you produce. Since wind turbines only create electricity when the wind is blowing, you must install batteries to be able to use energy when the wind doesn’t blow. However, if the grid goes out, your power stays on as long as your batteries stay charged.
You can also install a battery system to provide backup in systems connected to the grid. When the grid system is functioning properly your home will use the power generated from your wind turbine or pull electricity from the grid. But when there is a grid blackout, the system can switch to “off-grid mode” which allows your home to be powered by your batteries, and your batteries to be recharged by your wind turbine.
In New York, state regulations require a homeowner to maintain liability coverage to protect the utility from liability for facilities they do not own and have no control over. The regulatory authorities have mandated that it be consistent with conventional residential or commercial insurance policies (e.g., $100,000 to $300,000).
What do wind systems cost?
Estimates for the purchase and installation of a system that is large enough to power a home range from $10,000 to $70,000 but average about $30,000. The cost variance depends on the system size, height of the tower and installation expenses. However, incentives offered by NYSERDA can cut the costs in half (see www.PowerNaturally.org).
Wind energy becomes more cost effective as the size of the turbine’s rotor increases. Small turbines are less expensive to install but are proportionally more expensive.
Small Wind Incentives in New York
There are a number of incentives and tax exemptions available that can significantly lower the cost of installing a small wind system. These include:
- Rebates up to 50% of the total installed cost of a wind energy system. Check the NYSERDA website for more information on this and other incentives.
- The New York Energy $mart Loan Program provides reduced-interest loans (4% reduction in available market rates) through participating lenders to finance renovation or construction projects that incorporate renewable energy systems (including small wind turbines) approved under NYSERDA’s incentive programs.
- In New York State a Solar and Wind Energy Systems Property Tax Exemption is available to encourage the installation of wind equipment systems and assure property owners that their real estate taxes will not increase as a result of the system installation.
To receive incentive funding from NYSERDA, the project must undergo a review under the State Environmental Quality Review Act (SEQRA). Speak to your installer about SEQRA requirements and forms.
How do I find a wind energy system service provider?
There are several ways to look for a wind installer:
- Check in your phone directory or the Internet for “Wind Energy System Service Providers” in your county or city.
- The NY State Energy Research & Develop Authority (NYSERDA’s) list of wind installers has the names of certified installers that are organized by region.
- Contact your local utility company to see which vendors they recommend.
It is recommended that you get bids from more than one company, if possible.
Additional Wind Resource Information
New York’s Wind Consumer Guide – information from this guide was used extensively in this article.
American Wind Energy Association – a national trade organization that promotes the use of wind energy. Their site includes details on large and small wind technology, policy initiatives, locations of installed wind projects, and links to other information including small wind case studies.
The U.S. Department of Energy-Small Wind Electric Systems site provides information on the latest small wind turbine research, homeowner information, wind energy basics, and links to wind publications and organizations.
Wind Turbine’s Buyer’s Guide by Mick Sagrillo and Ian Woffenden