Zoning Practice — August 2008

Ask the Author

Here are reader questions answered by Erica Heller, author of the July 2008 Zoning Practice article "Urban Wind Turbines."

Question from Rod Melanson, Natural Resource / Assistant Planner, Town of Topsham, Maine, and Kimberly C. Porter, AICP, Planner, Community Development Department, Village of Skokie, Illinois:

What have you seen as important aspects that must be placed into code to facilitate the implementation of this alternative energy source? Are there standard guidelines that all municipalities should include in a wind turbine ordinance?

Answer from author Erica Heller:

The key to facilitating small wind energy conservation systems (WECS) is to reduce potential negative land use impacts as much as possible without reducing the function of the WECS. Think about small WECS impacts in two categories: (1) nuisance impacts, such as noise and safety issues that could have a real detrimental impact on neighbors' ability to enjoy their own property or on their property value; and (2) and aesthetic impacts, which have not been shown to have any detrimental impact on neighbors' property values but are nonetheless unpopular.

Be sure to include reasonable standards that thoroughly address nuisance issues, as suggested in the article. Next, divide aesthetic impacts into appearance issues (color, signage, etc.) and visibility (location and height). Address appearance to control visual impact, and consider if there are certain character areas (historic districts or scenic byways) where WECS aesthetic impact is such a detriment that they should be excluded from that area. But hold the line for WECS on visibility. Simply put, good wind is in locations that are often visible: ridges, shorelines, bluffs, and well above other structures and trees. In most low and hidden places, wind is slow or turbulent, which severely reduces WECS effectiveness.

Height limits that restrict WECS from good wind access undermine the fundamental purpose of adopting an ordinance to allow them. It's like approving a coal-fired power plant where the coal supply can be delivered only by pack mule! See more on the issue of height in response to the question directly below.

Question from Wyeth Friday, AICP, Planning Division Manager, Planning & Community Services, City of Billings/Yellowstone County:

The City of Billings has drafted a wind turbine ordinance. One of the main issues we are wrestling with is allowance of turbines in high-density residential neighborhoods. We have proposed that the turbine must meet all structural setbacks, not be set closer than 110 percent of the height of the turbine from any property line, and the maximum height of a single use residential turbine is 80 feet.

We have been hearing that this will severely limit small wind turbine use for residential applications, but we are concerned about health, safety, and noise. What thoughts do you have on the regulation and allowance of small turbines in high-density, residential neighborhoods?

Answer from author Erica Heller:

Many communities struggle with setting appropriate height for WECS in residential areas. Height is often of utmost importance to gaining access to strong, steady, non-turbulent winds. The Department of Energy's Wind Powering America program offers a web presentation on the importance of tower height:
www.eere.energy.gov/windandhydro/windpoweringamerica/pdfs/
workshops/2008/sw_zoning_tower_height.pdf
.

A rule of thumb is that the turbine will need to be at least 25-35 feet above any obstruction within 300 feet, and ideally should be twice as high. Some general considerations:

  • How high are the structure height limits? If you allow a small WECS in an industrial area with a 65-foot height limit, the WECS should be 90-125 feet tall. Even if there are no 65-foot structures nearby today, the upwind property owner may decide to build up to the limit next year.
  • How high are the mature trees that are typically found in the area? Mature Lodgepole Pines (common throughout the Rocky Mountain West) are often 70-80 feet tall, so an 80-foot turbine won't clear these adequately. Also remember that today's saplings will grow tall over time!
  • Even where good winds are available much lower, such as along shorelines, there's usually no need to specify lower height limits for these areas, because towers/poles are very expensive. Taller ones are more so, in terms of both purchase price and installation. If excellent quality wind is consistently available at 40 feet, then there is no reason to expect that an owner will build higher if the WECS height limit allows it.

In higher-density neighborhoods, the required setback will often be the limiting factor on possible height. A required setback from property lines of 110 percent of turbine height stated in reverse is a height limit of 91 percent of the distance to the nearest property line.

  • The smallest possible lot on which an 80-foot tower could meet a 110 percent setback requirement if it is placed in the exact center of a perfectly square lot, is 30,976 s.f. — or a bit more than 2/3 acre. In the center of a square half-acre lot, the setback rule limits turbine height to about 68 feet. Of course, most lots are not perfectly square and the exact center of the lot may not be available for WECS installation, so the practical reality is that an 80-foot turbine is rarely sited on a lot less than one acre.
  • Stating an 80-foot maximum height in a higher-density zoning district (less than 1 acre lot size) may confuse property owners, as they may not immediately understand that setbacks and lot dimensions further limit height.
  • Consider using the setback requirement as the only codified limit to turbine height. It effectively accomplishes the desired purposes of (a) scaling the turbine height to the lot area and (b) keeping taller towers further from the neighbors' land and views.
  • If your community just isn't comfortable without a stated maximum height, consider using 125 feet (in addition to the setback rule). Most manufacturers' standard towers/poles for small WECS are 125 feet or smaller, so from a practical standard, few if any residential installations would be likely to exceed this height.
  • Remember that increased height has an upside: It puts the turbine unit further away, reducing noise impacts at ground level.

Question from Fred Snow, Community Planner, Kennebec Valley Council of Governments, Fairfield, Maine:

Most ordinance definitions of small wind energy systems (SWES) have a maximum capacity of 100kW. A few ordinances have 10 kW as the threshold and a Massachusetts state model has threshold of 60 kW. Maine's Report of the Governor's Task Force on Wind Power Development) proposes 3 sizes: (1) Small: Up to 20 to 25 kW, which would include residences or small business; (2) Medium: 25 to 250 kW, which would include groups of homes, schools, or larger electricity users; (3) Large: 660 kW to 2 MW.

My questions are:

  1. Which is more useful to apply to a unified ordinance, three sizes or the more typical two classes with threshold of 100 kW?
  2. If three size classes were applied to a unified ordinance, what performance standards should differ and how should they differ according to each class?

Answer from author Erica Heller:

In answer to your first question, I believe the two-tiered approach is most common. The wind industry defines "small" wind energy conservation systems (WECS) as anything less than 100 kW, and many regulations follow suit. However, this definition includes a wide range of power output and size. Thus, some state and local ordinances define a third "very small" type to be allowed in more densely developed or sensitive areas, which in my experience is most often a residential-scale turbine definition with a maximum output of 10 kW.

Let's put these definitions in context: A 10 kW-rated WECS working at just 50 percent capacity only 40 percent of the year would produce about double the national average household energy use. Most homeowners install smaller, more cost effective turbines. A well-sited 2 kW capacity turbine can readily offset typical household electricity use. A commercial or agricultural user may use enough energy to install a turbine of 10 to 20 kW capacity.

In most cases, a third-tier definition is not necessary because turbine cost and state net metering laws result in the desired outcome of scaling turbine output to match the use being served. Turbines are expensive. It is simply not cost effective for a property owner to invest in a turbine with more energy capacity than will be used on site. Also, utilities generally won't buy back energy above what is used on site each year, and so provide no financial reason to generate extra energy. Thus, those that invest in the larger "small" turbines are typically heavy energy users such as factories, large campuses, or similar uses, not homes or small businesses.

Despite this general rule, a community may have a locally specific reason to specifically restrict even heavy energy users to "very small" turbines in certain locations. Another common reason for defining a third tier of turbines is that because it is concrete and easy to understand, it may give citizens and elected officials a greater level of comfort than the economic rationale. My own bias is not to add regulatory text if the anticipated outcome is the same without adding it, but if including a third-tier definition is needed to gain support for a WECS ordinance, go ahead and add it!

In answer to your second question, large WECS require additional performance standards beyond those for small WECS, which is why they are outside the scope of this article. Consult large wind resources such as those on the American Wind Energy Association and Wind Powering America websites and state model ordinances that address large wind such from Pennsylvania and Massachusetts and as a starting point for information on large wind.

Performance standards should remain relatively constant between "small" and "very small" WECS. For, potential nuisance impacts such as noise or safety, and basic appearance considerations such as lighting and signage should be limited at the turbine owner's property lines. Also see the questions above for related discussion.

Question from Dave Dietrich, AICP, Planning Director, Geauga County, Ohio, and Stephanie E. Ashe, Historic Preservation Planner, Economic and Urban Development, City of Decatur, Illinois:

I'm wondering if you could suggest a few zoning ordinances from other municipalities for examination. Thanks.

Answer from author Erica Heller:

I suggest caution when looking at other local WECS ordinances. Many include inappropriate requirements for small WECS that are based on standards for wind farms, while many others limit height much too strictly. Page 4 of the Zoning Practice article contains a list of urban and suburban communities whose small WECS provisions are consistent with many of the recommendations in the article. The WECS regulations can be accessed online from the listed websites. To round out the list, here are a few additional suggestions:

  • The Town of Nevada, Indiana, allows small WECS by right in the industrial districts and by special use permit in all other districts, subject to performance standards. WECS are exempt from the general height restricts of the zone districts, but height is limited through a use standard. www.ci.nevada.ia.us
  • The Camden County, North Carolina, wind ordinance setbacks are based on the height of the WECS. Smaller setbacks are allowed with a wind easement from an adjacent property owner. Permits for large WECS require an acoustical study, but not for small WECS. www.camdencountync.gov/
  • The planning department in Anchorage, Alaska, is in the midst of writing a WECS ordinance. The draft document does not appear to be available online as of this writing, but is a very strong example.

To find ordinances from communities in your state: (1) Google "wind ordinance" and the name of your state. In most states, this will bring up news articles and meeting records from communities addressing WECS; or (2) contact the state agency of energy or environment that deals with alternative energy and ask if they know of communities that have enacted a WECS ordinance. You may be able to get the local ordinance online or may need to contact the locality for a copy — the latter gives you a chance to ask about their first-hand experience.

Question from Walter Wehenkel, Ottawa County, Ohio:

Are there permits or authorizations required from agencies like the U.S. Fish & Wildlife in areas where wind turbines are proposed to be located in the areas of flight paths for migratory birds and eagles?

Answer from author Erica Heller:

No, agencies such as the U.S. Fish & Wildlife Department do not require permits for small wind conservation energy systems (WECS) (except on publicly owned land, in which case the controlling agency would have to approve the installation). Documented avian impacts of the Altamont wind farm in California, which is located in a major raptor migration corridor, raised concerns about how turbines interact with birds. Subsequent studies found that on average, a small WECS kills fewer birds annually than housecats or sliding glass doors. Even the Audubon Society has weighed in and supports well-sited wind turbines of all sizes. In general then, small WECS should not be excluded from areas with birds any more than should cats or glass doors.

If critically endangered bird species frequent your areas, very small population losses may be of concern. If so, you may want to consult with wildlife agencies and consider extra protection based on the attributes or habitat of the sensitive population. For example, if the endangered species are birds of prey, you may want to discourage a single property from hosting both a WECS and another land use that attracts or supports high numbers of rodents (e.g., grain crops or a landfill), as rodents are an attractive food source for these birds.

Question from Matthew T. Neeb, Senior Planner, Monroe County Planning Commission, Stroudsburg, Pennsylvania:

Monroe County is currently in the process in developing a small wind energy conversion system model ordinance at the request of several municipalities. The state of Pennsylvania has two model ordinances regarding wind energy conversion systems (WECS), but these ordinances seem to address only large wind farms. We have reviewed wind maps that indicate that Monroe County has a variety of different average wind speeds, some of which appear to be adequate for small WECS.

  1. Could you please direct me to a few model ordinances regarding small WECS?
  2. Should provisions for small WECS be stand alone or should they be incorporated in both the zoning, and subdivision and land development ordinances?
  3. If you have any additional information regarding small WECS, it would be greatly appreciated. As you may know, including provisions for wind energy isn't easy.

Answer from author Erica Heller:

Large-scale wind maps are a great resource if you are deciding whether to make the effort to adopt a WECS ordinance. They are available from the National Renewable Energy Laboratory and the U.S. Department of Energy, including on the Wind Powering America website (www.eere.energy.gov/windandhydro/windpoweringamerica/wind_maps.asp). Some states have more detailed maps as well. As a rule, Class 2 or above is adequate for small WECS, while Class 3 is minimum (and Class 4 or 5 more typical) for wind farms. However, so many factors can create micro-conditions that alter wind on a site-by-site basis that the maps tell very little about whether the wind resource on a specific parcel will power a small WECS. It's best to draft a WECS ordinance to apply broadly, and leave it to the individual property owner to assess whether her site-specific wind resource is adequate.

Several state model ordinances address small wind separately from large wind. The draft Wisconsin and the Michigan model codes are examples that include standards specifically for small WECSs. American Wind Energy Association is drafting a small wind guidebook and model ordinance forthcoming in September 2008.

Either a stand-alone ordinance or standards integrated into the development code can be effective. My own preference, as a planning and zoning consultant, is the latter. I think it is more readily apparent and clearer to the average code user when she can quickly see that small WECS are listed with other allowed accessory uses, as an example. Similarly, when WECS are in the code, they can be listed in the exceptions to general height limitations, clarifying the meaning of any conflicting provisions.

I suggest you review the resources on page 6 of the article. The websites noted in Daniel Green's question below and the U.S. Department of Energy's Wind Powering America website (www.eere.energy.gov/windandhydro/windpoweringamerica/ ) are also excellent.

Questions from Daniel Green, Land Use Project Manager, Latham & Watkins, LLP, Los Angeles, California, and Ernie Monaco:

What is the approximate range of costs to install wind turbines on a "typical" single-family dwelling, apartment building, or office building? What is the typical savings per year in utility bills?

Are there small WECS available in the states that are quiet and nonobtrusive that you can recommend for a house? What companies are now offering these?

Answer from author Erica Heller:

As a land-use planner, my expertise is on the regulatory aspects of WECS, not installation. However, I hope the following resources and information will be helpful to those interested in installation.

In answer to the first question, it is very difficult to state "typical" cost and savings of WECS because there are so many variables. On the installation side, a big cost component is local permitting fees, which range from very reasonable (several hundred dollars) to quite expensive (several thousand dollars). Utility savings depend on the rates you pay and on whether your utility pays wholesale or retail rates for the energy the turbine generates, which varies from state to state. A strong net-metering law increases the potential savings. Potential savings and pay-back times for the investment also depend on energy production, which depends on the site-specific wind resource and factors such as local height limits that may keep the turbine from reaching optimal wind.

The American Wind Energy Association (www.awea.org) provides the following information on cost and pay-back times in their small wind FAQs:

How much does a small wind system cost?
Small wind energy systems cost from $3,000 to $5,000 for every kilowatt of generating capacity, or about $40,000 for a 10-kW system (installed). This is much cheaper than solar systems, but the payback period can still be lengthy – as little as six but up to 30 years. That's why it's important to take advantage of rebates or tax credits available for small wind system installations. Well-sited small wind turbines can usually pay for themselves within 15 years, about half their serviceable lifetime, if the right incentives are applied.

As part of its small wind tool kit, American Wind Energy Association has an online database of state-by-state information on small wind energy regulations and incentives. (See link below.)

In answer to the second question, many U.S. companies now offer small, quiet models of turbines that are appropriate for residential use, including rooftop models. Recent studies in the U.K. show that the performance of rooftop models is generally poor due to wind turbulence. However, in some places, such as along shorelines, good wind may be available at rooftop height. What will work best for your need depends greatly on factors that are site-specific that will drive the selection of specific model or manufacturer. Start with some of the readily available on-line resources. Next, a local distributor or installer that carries several models and can help you understand the pros and cons of each model for your need.

There is a great deal of useful information online. Three such resources include:

  • American Wind Energy Association (www.awea.org/smallwind/) offers a small wind tool kit that includes how-to information, success stories, a list of "commercially proven" (their term) equipment providers, frequently asked questions, and more. Also part of the toolkit is an online database of state-by-state information on small wind energy regulations and incentives.
  • The National Renewable Energy Laboratory offers a well-regarded "Small Wind Buyer's Guide." www.nrel.gov/docs/fy07osti/42005.pdf
  • International Renewable Energy Council (www.irecusa.org/index.php?id=73) also offers buyer's guide to small turbines, including state-specific information.