Wind turbine noise and associated impacts are some of the more important issues facing local authorities in permitting wind projects. Regulations in this category generally refer to a decibel measurement of the sound emissions from a turbine, and increasingly local authorities are asked to consider the concerns of the community in setting these regulations. Many Minnesota counties refer to the state noise standards, while some impose additional requirements and measurements on the appropriate levels of sound from wind turbines in their community.
Commercial wind turbines are installed on tall towers and proper lighting is required for the safety of any nearby aviation facilities. There are also concerns with the impacts different lighting mechanisms may have on local communities and wildlife. All wind projects must comply with any applicable Federal Aviation Administration (FAA) requirements regarding appropriate lighting, and many county permitting regulations refer to or incorporate those requirements.
Permitting regulations in this category refer to the maximum total height of a wind turbine allowed. Current wind turbine designs are the result of many years of research and development in establishing the ideal height of the tower and blade lengths in order to most efficiently capture the wind resource. Counties may chose to regulate in this category for a variety of reasons, including public safety or aesthetics.
These permitting regulations address the feeder lines and communications lines used to connect the wind turbines to the other project infrastructure, in order to minimize the visual impact from these components. Currently, the common industry practice currently is to bury these electric lines; however there may be certain geological conditions that make burying these lines impractical.
Decommissioning as a permitting regulation refers to the process for removing a wind energy conversion system once the project has reached its end. There are a variety of methods used to regulate this area of wind development, from requiring a bond or financial guarantee before a permit is issued to simply requiring a written plan for removing the turbine and associated components.
These permitting regulations refer to the minimum distance the tips of the blade must be above the ground or other nearby obstacles. This ensures both safety for structures and beings near operating turbines, as well as promoting the most efficient use of the wind resource.
Permitting requirements for safety equipment generally refer to the presence of braking systems in the event that the rotor spins too fast in high wind or to help prevent a catastrophic failure. Most modern turbines today include, in the technology design, both automatic and manual braking options to slow or stop the rotor altogether.
These permitting regulations are designed to reduce the visual impact of a wind turbine, as well as minimize the impact on wildlife, especially birds. The most common requirements are for a white or grey color, and non-reflective finishes to minimize glare.
This permitting regulation category refers to the standards that apply to the service roads or construction roads of a wind project. Construction equipment for large, commercial-scale wind turbines can exceed the allowable weight and size for some rural roads and therefore counties may impose certain requirements in this category.
Proposed wind energy projects in Minnesota with a total nameplate capacity of 5MW and greater are subject to state regulation while projects under that threshold are subject to local regulation. For more information about the state permitting requirements and process, visit MN Public Utilities Commission.
Additionally, counties may elect to assume the authority to regulate wind projects up to 25MW. In order to make this election, a county must submit a letter of their intention to the Minnesota Public Utilities Commission along with copies of any regulations adopted that are more stringent than the state guidelines.
|Category||State Minimum Setback|
|Wind Access Buffer (setback from land not under permittee's control)||3 rotor diameters on east-west axis and 5 rotor diameters on north-south axis|
|Internal turbine spacing||3 rotor diameters crosswind by 5 rotor diameters downwind|
|Noise||Distance sufficient to meet state standard of 50dBA at night|
|Homes||At least 500 ft and sufficient distance to meet noise standard|
|Public Roads||250 ft|
|Meteorological Towers||250 ft|
|Wetlands, Native Prairie, Sand and Gravel Operations||Variance required for approval|
Minnesota County Wind Ordinances
As of April 1, 2010, there are 87 counties in Minnesota, of which 61 had specific wind energy conversion system ordinances applicable to commercial scale wind projects. Our review of these 61 county ordinances currently regulating wind energy conversion systems in Minnesota focused on 15 specific categories:
|Common categories of local regulation of wind turbines||# of MN Counties|
|Identification of certain zoning districts that are allowed to have wind turbines||44|
|Whether a permit is required||61|
|Setbacks, including those from neighboring properties, public roads and right of ways, and conservation lands||59|
|Density of turbines or internal turbine spacing and distance||18|
|Height requirements that regulate the total maximum allowed height of a wind turbine in the county||21|
|Clearance between the ground and the blades||37|
|Standards for creating and maintaining access roads||4|
|Regulations on treatment of feeder and communication lines, generally requiring them to be buried||44|
|Requirement of brakes or other safety equipment in the turbine to prevent catastrophic failures||24|
|Standards for color, finish and overall appearance of the wind turbines||54|
|Signs for safety and identification of owner or other emergency contact||57|
|Identification of potential for signal and broadcast interference||41|
|Maximum noise thresholds||52|
|Regulations on lighting of the turbines||52|