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Wind Systems

Please note that the wind program is currently suspended until further notice.

Q. Wind energy systems- wind turbines: What they are and how do they work?

A. A wind energy system transforms the kinetic energy of the wind into mechanical or electrical energy. A wind turbine operates like a fan in reverse using wind to make electricity. The wind turns the blades, which spin a shaft, which is connected to a generator that makes electricity.

Q. What is the current capacity of wind energy systems in the US and worldwide?

A. As of March 31, 2012, 48,611 MW of wind power have been installed across the United States. View a larger image of the map.

The United States Department of Energy National Renewable Energy Laboratory (NREL) has made available an Installed Wind Capacity -  Animation Map

As reported by The Renewable Energy Policy Network for the 21st Century there are 238,000 MW of cumulative installed wind capacity as of the end of 2011 in approximately 70 countries.

Q. How is the output of wind turbines determined?

A. The energy output of a wind turbine depends on the turbine’s size and the wind’s speed at the turbine height. Wind speed is the crucial element in projecting wind energy system performance. A site’s wind speed is measured through a wind resource assessment prior to a wind system’s construction. Generally, annual average wind speeds greater than six meters per second (m/s) or 14 miles per hour (mph) are required for large-scale wind systems.

Q. How are wind areas classified?

A. Wind power is characterized by a simple system that assigns the wind potential to one of seven wind classes. The wind potential in Class 1 (1 -3 mph) and Class 2 (4 - 7 mph) areas are low and not suitable for utility-scale wind energy systems. Class 3 (8 - 12 mph) and Class 4 (13 - 18 mph) are fair to good, and Class 5 (19 - 24 mph) and higher are excellent. Most of New Jersey is a Class 1 or Class 2 wind area. There are some Class 3 wind areas along the New Jersey coast and in the northwestern mountain ridges. There are Class 4 sites along the barrier islands north of Atlantic City and at the southern tip of the state.

Q. What is the general capacity factor of a wind energy system?

A. A wind energy system is “fueled” by the wind, which blows steadily at times and not at all at other times. During the year there are times when the wind does not blow or at speeds below which the wind turbine will turn to produce energy. Even when the wind is blowing the wind energy system does not always produce energy at its full rated capacity. The capacity factor of wind energy systems ranges from 25 percent to 45 percent.

Q. Can wind energy systems meet all of New Jersey’s electric demand?

A. Wind is an intermittent resource and because of this intermittent nature some have looked at a limiting factor for wind of approximately 20% of the total system capacity. However, there is no firm or maximum limit. Development of future electric storage systems or advanced voltage regulation control technology with the wind energy system could significantly increase this factor. In addition, matched with other intermittent renewables like solar electric (photovoltaics), can also increase this factor.

Q. What does New Jersey'sClean Energy Program offer in terms of incentives for wind?

A. The Renewable Energy Incentive Program (REIP) offers financial incentives for the installation of small wind energy systems. However, the program is currently on hold and is not accepting any new applications at this time.

The questions and answers below address the methodology for calculating the incentive when the program is reinstated.

Q. What does Expected Performance Based Buydown (“EPBB”) mean?

EPBB is a methodology for calculating a rebate which is based on the expected kWh output of a specific wind turbine at a specific site.

Q. How does the EPBB work?

The EPBB estimates the kWh output for a specific wind turbine from an approved list at a given location based on the documented wind speed at that location. The associated power output of the turbine is determined using the turbines power curve at that wind speed. Incentive rates are designed to produce higher rebates for projects that maximize the power production at that wind speed. 

Q. What is a wind turbine manufacturer’s power curve?

The power curve of a wind turbine is a graph that indicates how large the electrical power output will be for the turbine at different wind speeds.  Power curves are found by field measurements, where an anemometer is placed on a mast reasonably close to the wind turbine (not on the turbine itself or too close to it, since the turbine rotor may create turbulence, and make wind speed measurement unreliable).   Power curves are based on measurements in areas with low turbulence intensity, and with the wind coming directly towards the front of the turbine. Local turbulence and complex terrain (e.g. turbines placed on a rugged slope) may mean that wind gusts hit the rotor from varying directions. It may therefore be difficult to reproduce the power curve exactly in any given location. 

Q. Why are we adopting the EPBB methodology?

The EPBB methodology is designed to provide greater incentives to systems that have a higher expected kWh output.  This new approach calibrates the rebates more closely to the goals defined in the Renewable Portfolio Standard, and Energy Master Plan, which are based on energy output (kWh).  This method is superior to the previous approach of basing rebates on system size (capacity) or installed cost methodology, neither of which incorporates the key drivers of wind system performance which are wind speed and turbine performance. 

Q. What are the EPBB incentive levels?

The table below shows the incentive levels that were available when the program was last open. These incentive levels are subject to change upon reinstatement of the program.

Annual estimated production Incentive level

  • 1-16,000 kWh    $3.20/Annual kWh
  • 16,000 - 750,000 kWh  $.50/Annual kWh

Annual estimated production is based on the location average annual wind speed and turbine power characteristics curves. 

Residential Wind EPBB rebate incentives are capped at 16,000 kWh, which is equivalent to a maximum rebate of $51,200.

Q. What factors are considered when determining the annual energy output?

The EPBB requires an estimation of the annual energy output of the proposed wind system.  Estimating energy production for a small wind energy system can be achieved according to the following formula:

Annual Energy Output (kWh/year) = 0.01328 (D^2) (V^3)

Where D^2= the blade diameter in feet squared, and V^3 =the wind velocity cubed in mph -- this is the year round average wind speed. 0.01328 = a conversion factor of blade diameter and mph to kWh per year.

This method of calculation does not compensate for site specific variables such as wind shear, turbulence, weibull, air density at site altitude and turbine specific output. This calculation is designed to give a generic evaluation of turbine output. Turbine specific outputs of accepted turbines in NJ are based on independent third party evaluation of each turbine listed.

Q. Where can I get my location’s average annual wind speed?

Wind maps are available at no charge at FirstLook. Use the 50m hub height since this is a common height for wind speed calculators.

Please note that wind speed used in the rebate calculation will be capped at 13.7 mph.

Q. Is the wind calculator sufficient for determining the project's feasibility?

The average wind speed from the free wind map above is acceptable for rebate calculations.  However, there are other, more accurate ways to determine your location’s wind speed. The first way is to hire a certified site assessor to evaluate the site topography and specific site characteristics to provide a more accurate evaluation. The second way is to hire an engineering firm to do a detailed site assessment, including a local wind speed analysis based on an anemometer reading.  If either of these methods is used, you should provide the study to the program staff that will use this revised wind speed information instead of the online wind maps when calculating the rebate.

Q. What wind turbine equipment is accepted by the program?

When the program is reinstated, we will post a list of acceptable wind turbines.

Q. What do I do if I have a turbine that is not on the list?

If you are requesting to use a turbine that is not listed above you will need to provide the following:

  • For wind turbines less than or equal to 1 MW the system must be evaluated and certified by an independent third party that can verify the turbine power curve. The manufacturer’s power curve shall be based on at least one year of actual energy production data at a customer site. Once this evaluation has been completed the documentation must be submitted to the NJCEP for evaluation prior to being included in the wind rebate program. Once the new turbine has been accepted the above list of approved turbines will be updated reflecting this change.
  • If the turbine you are interested in is not listed in the above table it is not eligible to receive a rebate and the process previously described must be followed to have the wind turbine listed.
  • Wind turbines greater than 1 MW are not accepted in the program.

If you are interested in a turbine that you think should be on the list, please direct the manufacturer to contact the program staff for specific requirements.

Q. How does the program staff calculate the rebate from the application information?

This information will be provided upon reinstatement of the program.

Q. What is the purpose of the anemometer installed on the turbine as part of the installation?

The anemometer will be used to collect and provide site specific wind data in conjunction with the system production data to ensure electric production is as expected for the wind turbine.


Q. What are the requirements of the anemometer installed on the turbine?

The anemometer will be installed one rotor length below the swept area and will face the direction of the predominant wind direction at the location based on the wind rose. The output of the anemometer will need to have a data logger system that can be accessed to show instantaneous and average wind speed and direction. The access of the data can be either via a land line or web based system that can provide dedicated reporting information on the system.

Where can I get more information on how to select a wind turbine?

Visit NJCEP's trade ally database for a list of wind installers.

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