Ask the Author: March 2003

Here are reader questions answered by Mark A. Wyckoff, co-author with Erin Kilpatrick of the February Zoning News article, "Planning and Zoning for Wind Power Facilities."

Question from Debbie Hillman of Evanston, Illinois:
Our citizens group (Evanston's Energy Future) is considering replacing a small wind turbine at the local Ecology Center (with a larger, more modern system). The city (Evanston, Illinois) has requested that we investigate the possibility of combining the turbine (on a 120-foot tower) with cell phone antennas; they are getting many requests for additional cell phone towers. A well-known cell company is very interested in doing this project.

Do you know of any existing such combinations, do you have any opinion about them, or any other information that might be useful? Thank you.

Answer from author Mark Wyckoff:
What a novel idea: co-location of cellular communication equipment on a wind turbine tower! Aesthetically it makes a lot of sense.

Here is what I was able to turn up after calling a cell phone industry siting expert in metro Detroit, who in turn called a cell communication engineer, a manufacturer of both cell towers and wind turbine towers, and cellular marketing experts in Las Vegas, Toronto, and Dallas:

1. There is certainly discussion of this possibility going on in the industry, but none of the people consulted was aware of anywhere it has yet happened.

2. There are several basic issues that need to be addressed: strength of the wind turbine tower for the extra weight (not likely a problem); engineers would have to examine the EMF created by the wind turbine generator and whether it would interfere with the RF of the cellular antennas (could definitely be a problem for many types of typical cellular equipment); turbulence impact on the cellular equipment (probably not a problem); aesthetics (a platform and the cellular antennas mounted on the wind turbine tower could greatly modify the aesthetic of the wind turbine tower).

3. In your case, the rotating shaft of the turbine may push the available location for the cellular antenna below 90 feet (on a 120-foot tower), which may not make it high enough for cellular equipment in a particular situation.

Apparent bottom line, it is an idea worth exploring, if for no other reason than the additional revenue that leasing tower space to the cellular industry might generate. However, the long-term viability of this option is likely to be much greater in rural areas than in urban areas, due to the likely rapid implementation of distributed antenna systems for cellular service in urban areas which has the potential to eliminate the need for most urban cell towers in just a few years.

Hope this helps.

Question from Charles Wunder, AICP, Director of Planning and Zoning, Champaign County, Illinois:
We allow wind electrical generating towers by Special Use Permits. The ordinance requires that a financial guarantee be provided to cover the county's cost of removing the tower in the event that the facility is abandoned. Do you have any information on the expected costs of decommissioning a large tower (225')? Do you know if any of the ordinances listed in Zoning News require a financial guarantee for decommissioning?

Answer from author Mark Wyckoff:
Many of the ordinances I have examined require a financial guarantee/performance guarantee in the general provisions related to special land uses, but not separately in the wind energy section (as that would be redundant). I am not aware of any concrete information on what the decommissioning costs would be.

The State of Minnesota wind energy permits have a provision that places the burden on the wind energy company to figure out what these costs are and then to provide adequate assurances that they have the financial means to ensure the decommissioning plan will be properly carried out. See, for example, www.mnplan.state.mn.us/eqb/pdf/2002/FileRegister/enXco/Draftsitepermit.pdf

Question from Larry Sullivan, Planning Director, Charlevoix County, Michigan:
Have there been any documented instances of ice forming on, and subsequently being thrown from the revolving wind turbine blades?

If this is an issue or concern, is there a means of predicting the distances that ice may be thrown?

Are methods available to reduce the risk of ice throw by way of the design, manufacturing and/or use of surface coatings on the blades?

Not everyone in Northern Michigan is thrilled with the prospect of commercially sized wind turbine generators being located within their viewshed? The major issues being raised are ice throw, noise, light flicker from the sun shining through the revolving blades. This is a difficult issue to deal with in light of the need for clean generation of power while maintaining the visual beauty of this area of Michigan.

Answer from author Mark Wyckoff:
You asked several questions about icing, about noise and about aesthetic issues. I will tackle them in that order.

First, wind turbine blades are made to be aerodynamic with smooth surfaces that are not conducive to icing in order to make them conducive for wind generation. However, ice still does form and the larger the blade, the more ice that can form. However, a quick search of the websites listed at the end of our article, revealed the following direct quotes on ice:

What about icing?
Unlike tree branches, wind turbine blades are designed to withstand a heavy load of ice. And when ice builds up on the blades, they simply don't "fly" any more — they lose their aerodynamic properties. In fact, an ice-covered rotor will turn so slowly (at only several revolutions per minute) that there is no danger of ice being "thrown" off. Typically, the ice melts and falls — straight down — to the base of the tower.
www.awea.org/smallwind/toolbox/INSTALL/fs_safety.asp

and

One concern that arises in the colder regions of the country involves ice flying from the blades during the winter, potentially harming nearby residents. While ice buildup on blades is an occasional problem for wind turbines, flying ice is not. When ice builds up on the blades, they turn very slowly (at only several revolutions per minute) until the ice is shed. This is because the airfoil has been compromised by the ice, and the blades are unable to pick up any speed.

When icing occurs, it is best to shut the system down until the ice melts and falls from the tower, generator, and blades. The ice will fall straight down to the base of the tower. Because these are small systems with relatively small surfaces, not a lot of ice is actually involved, and the ice is never in large chunks or sheets. Realistically, this situation is no more dangerous than being near a tree covered with ice. In fact, because the weight of ice often causes branches to break, ice-laden trees are actually more dangerous than iced wind turbine blades. Unlike trees, towers are specifically designed to withstand heavy ice loads.
www.awea.org/faq/sagrillo/ms_zoning4.html

Obviously, larger turbines will have a greater potential for ice throw. However, at the maximum speed of a wind turbine (even when not laden with ice — when it will be much slower) the usual setbacks should be more than sufficient to address the issue. It appears to be a complete non-issue on the small wind turbines. If you have a greater concern here, I would contact manufacturers for more information. They are easy to reach from many of the websites listed at the end of the article. Those websites are constantly adding new information and are reputable.

You also raised noise. A good piece on the noise issue is one of the AWEA fact sheets on noise available at www.awea.org/pubs/factsheets.html. This issue is more significant the larger the wind turbine and the greater the number sited together. It is basically a non-issue with the small turbines.

Your last set of observations deal largely with aesthetic concerns. While beauty is in the eye of the beholder, many studies have shown that natural landscapes tend to more pleasing to people than built ones. Also, when the landscape is altered, the change is more noticeable and may be perceived negatively. That is why I think communities need to be very proactive when it comes to siting large wind turbine facilities. The wind power benefits are sooooo great, that communities are easily characterized as hypocrites if they only oppose wind power facilities. And, if they merely sit back and criticize proposals by the industry, or fight each one that arises, I believe in the aggregate, they (and us) will ultimately lose. The pendulum is clearly moving in the industry's favor with the growing need to diversify our energy resources in ways that are non-polluting.

So what to do? Communities should band together on a multi-jurisdiction, metropolitan, or regional basis and work with the industry to find appropriate areas that meet the wind needs for large facilities and minimize the negative aesthetic and noise impacts. This needs to be led by citizens that believe strongly about both protecting scenic vistas and the benefits of wind energy. If communities don't get proactive very soon, I suspect either the industry will continue to site where it wants to (often where it is easiest), or some states will pass laws exempting them from local zoning. Perhaps a few states will require a siting process similar to the above planning process — something all planners are well suited to facilitate.

What it comes down to is education and growing accustomed to the landscape change. When TV antennas were first added to homes there was a huge outcry against them on aesthetic grounds. The same happened with the first large satellite dishes. Then came the cell towers with an even more visceral response. While it is easily argued that many of communication structures were poorly sited from an aesthetic standpoint, and some wind turbines have been as well, very few communities were proactive in determining where they should be sited to preserve aesthetics and meet a communication need. I strongly believe there are appropriate locations that meet both sets of needs. This is a classic planning problem that can be solved using classic planning processes. If it isn't done, communities will (for the most part) get what the industry proposes.

Part of the solution also needs to be wide allowance of the small wind turbines as uses by right in local zoning. This will help familiarize people with them and they have a fraction of the objectionable characteristics. Unfortunately, if many states, like Michigan, do not make it easy for small wind powered generators to feed into the electricity grid, this will greatly slow the implementation of small generators.

Hope this helps.

Question from Betty Clack, AICP, Nez Perce County Planning, Idaho:
Do you know of any actual zoning ordinances that have been developed regarding wind power facilities?

Answer from author Mark Wyckoff:
The following communities have adopted wind energy ordinances:

Emmet County, Michigan
Eveline Township, Charlevoix County, Michigan
Elmwood Township, Leelanau County, Michigan
Sioux Falls, South Dakota
Monterey County, California
Buffalo, Minnesota
Scott County, Minnesota
Borough of Lititz, Pennsylvania
Lincoln, Nebraska
Boulder, Colorado
Maple Grove, Minnesota
Marin County, California
New Pattonsburg, Missouri