Wind Turbines




Review Staff’s and the Planning Commission’s recommendation on wind turbines




Messrs. Tucker, Foley, Davis, Kamptner, Graham, Fritz, Clark






May 6, 2009


ACTION:     X          INFORMATION:   



  ACTION:              INFORMATION:   











Staff and the Planning Commission have been working on a possible Zoning Ordinance amendment that would permit wind turbines within the County. Examples of the types of wind turbines being considered will be included in the presentation at the Board meeting. Currently, wind turbines are neither permitted as a primary use nor as an accessory use in any of the County’s zoning districts.   The purpose of this worksession is for the Board to receive a brief presentation on the complexities of wind energy in Albemarle County, review the draft proposal outline as it currently stands (Attachment A), and provide an opportunity to comment and give direction. 




Goal 2:  Protect the County's Natural Resources

Goal 4:  Effectively Manage Growth and Development




Staff and the Planning Commission have not considered large commercial /industrial wind turbines, but have limited their considerations to small wind turbines.  Small wind turbines have been defined as those that are used to provide electricity for uses on the property rather than those used primarily for the sale of electricity (i.e., commercial “wind farms”).


Small Wind Turbine Issues

Based on its review of the literature, staff believes the following are important considerations for locating small wind turbines in Albemarle County:


1.   The visibility of monopoles and towers is one of the most common and usually the most controversial land use issue, and small wind turbines may be visible.  While most of the concern is with large commercial wind turbines, concerns have also been noted with small wind turbines, especially when they are proposed in areas of high aesthetic value, such as mountain tops and land in or near a conservation easement.  Another visual factor with small wind turbines has been shadow flicker, resulting from the sun behind the rotating blades.  This primarily is a concern with small wind turbines in close proximity to other uses.


2.   Small wind turbines create noise.  It appears that the technology has significantly reduced the noise levels with newer wind turbines, but noise concerns are still an issue when the turbines are in close proximity to other uses.   A whirring noise is often identified as an annoyance in places where wind turbines are placed near residences.


3.   Albemarle County has very limited areas where wind power will be cost effective, as most of the County is considered poor for wind energy production.   With this in mind, staff believes that if wind turbines are to be encouraged in the County, it will be necessary to keep County regulation of the use to a minimum and provide as much flexibility as possible.   Due to the marginal economic benefit that might be realized in low wind areas and the fact that turbine technology and design are evolving, staff believes a rigid ordinance could exclude some promising new technologies.  


4.   Turbine efficiency increases with height, and this is especially true when height is necessary to provide wind clearance from nearby obstructions. Given the challenging economics of wind turbines in this area, flexibility on the height of structures will be a critical consideration. The literature indicates that turbine blades should be a minimum of thirty feet above any obstruction within three hundred feet of the turbine.  For example, if nearby trees are seventy feet tall and the wind turbine blades are twenty six feet in diameter, the turbine shaft should be at least one hundred thirteen feet above the ground to be considered effective.  This height can be reduced based on the local conditions.  


5.   The consequences of a tower collapse, ice throws, and noise should be taken into account when considering the required clear zone and setback distances.  The literature suggests that most localities require a clear zone somewhere between one to three times the structure height.  For stand alone turbines, this would effectively limit wind turbines to sparsely developed areas. 


6.   The telecommunications industry may seek to co-locate personal wireless service facilities (cell phone antennas) on wind turbines.  Because most wireless facilities in the County are either attached to an existing structure (Tier I) or are limited to a height not exceeding 10 feet about the nearest tree (Tier II), the additional height required for a wind turbine could provide a tremendous incentive to co-locate these antennas on wind turbines.  There are still some technical issues with antenna co-location, such as vibration created by the turbine’s rotor blades, but those issues may be resolved in the future. Because a wind turbine would likely be considered an existing facility under the County’s wireless regulations, the current Zoning Ordinance could allow an antenna to be co-located as a “Tier 1 Facility”, which would be considered through an administrative process.     


Comprehensive Plan

Staff notes that the most desirable location for wind energy production will be the mountain ridges, and this appears to conflict with existing policies in the Comprehensive Plan.  In particular, elements of the Natural Resources and Cultural Assets section and the Land Use section of the Comprehensive Plan have policies regarding the siting of structures in order to protect the natural beauty of the mountains.  These policies discourage structures that alter the continuity of the ridgeline, that are located so that the structure is sky-lighted against the horizon, or that are taller than the natural tree canopy.


Current Proposal

The current proposal outline is provided as Attachment A.   This proposal attempts to balance the policy issues through a tiered approach, similar to the way the County regulates and permits wireless facilities.  Tier I would be reserved for those small wind turbines that are anticipated to have very low visual impact and be limited to the Rural Areas outside of the Entrance Corridors and designated mountain areas.  Tier II would require a modification of the regulations by the Planning Commission in order to locate a small wind turbine in either the Entrance Corridors or the mountain areas, but would not allow structures taller than otherwise allowed in the underlying zoning district (typically thirty-five feet).  Tier III would require a special use permit in order to build a small wind turbine taller than otherwise allowed in the zoning district.  This provides the Board the opportunity to make discretionary decisions on those wind turbines anticipated to have the most significant visual impact, particularly those in the Entrance Corridors or in the mountains.




No budget analysis has been prepared at this point.  




Staff requests that the Board provide direction to staff as to how to proceed with this proposal.   




A - Planning Commission April 21, 2009 report with attached proposal outline

B – Planning Commission April 21, 2009 Action Memo Work Session Summary

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