BAR HARBOR – For a small but rapidly growing number of people across the country, the answer to carbon-based power generation and high electricity rates is blowing in the wind.
As more people start installing wind turbines at their homes and businesses, communities are thinking about what if any rules they should adopt to minimize potential negative impacts. Should wind turbines be allowed on hilltops, where they can catch the most wind – and be seen for miles around? How tall should turbine towers be? How close to neighboring property? How many wind turbines per acre? Should there be limits on how much noise they can make?
“These are things we really need to address,” Bar Harbor Planning Director Anne Krieg said in an interview last week. “I’ve had inquiries from a couple of people who want to get together with their neighbors and share wind power. The fact that they are coming in means they are doing their homework, so we’ve got to get something going (in terms of a zoning ordinance).”
Last month, at the American Planning Association convention in Las Vegas, Ms. Krieg attended a session on regulating wind turbines.
“The session mostly focused on the individual windmill that you can put on your garage, which is something we need to focus on, too,” she said.
The American Wind Energy Association (AWEA) refers to individual electricity generating systems as “small wind,” as compared to wind “farms” with dozens of giant turbines on tall towers. Small wind systems have rotating blades as small as 23 inches in diameter, and they generate no more than 100 kilowatts of electricity.
This power is often used to supplement, not completely replace, electricity purchased from a utility such as Bangor Hydro-Electric Company.
As with cell phone towers, the height and visibility of wind turbine towers are among the main concerns that zoning ordinances usually address. With both technologies, the higher off the ground they are, the more effective they are. Cell phone antennas mounted on tall towers can cover larger areas than those that are closer to the ground. Wind turbines on tall towers or ridge lines catch more wind and generate more power.
So, visual impact will be a primary consideration in establishing rules for where turbine towers can be located in Bar Harbor and how tall they can be. A single small-wind system, perhaps mounted on a garage, isn’t likely to be an eyesore. A whole neighborhood of them could be a different story, especially if they are on tall towers.
“I think we’ll need to address the issue of a neighborhood generating its own power and how we want to deal with that,” Ms. Krieg said.
While making electricity, wind turbines also make a whirring or humming sound.
“I will be focusing a lot of my research on the noise issue,” Ms. Krieg said.
People who live near one or more large wind turbines sometimes complain about the loud, continuous noise. Small, individual turbines are much quieter.
According to a publication on renewable energy by the U.S. Department of Energy, “The ambient noise level of most modern residential wind turbines is around 52-55 decibels. This means that while the sound of the wind turbine can be picked out of surrounding noise if a conscious effort is made to hear it, a residential-sized wind turbine is no noisier than your average refrigerator.”
Danger to birds is a concern that people have, particularly in regard to large wind turbines and wind farms. But this has not been shown to be a significant problem.
“Statistically, a single house cat, a window pane or an automobile is a much greater threat to birds than a wind turbine of any size,” according to the AWEA.
Another issue, for some people, is the strobe-light effect created when the sun shines through the rotating blades of a wind turbine. That is known in the planning community as “shadow flicker.”
The AWEA has prepared what it calls a “model zoning ordinance” for regulating small wind energy systems. Its provisions include:
• An 80-foot limit on the height of wind turbine towers for lots smaller than one acre.
• No height restrictions on towers built on larger lots.
• A 10-foot setback from property lines.
• Noise levels no greater than 60 decibels, as measured at the nearest inhabited dwelling.
Over the next few months, Ms. Krieg said she plans to research wind turbine ordinances that other communities have adopted, discuss her findings with the Planning Board and draft an ordinance for the Planning Board and Town Council to consider. She would like to have an ordinance ready for citizens to vote on at town meeting next June. In the meantime, she said, she welcomes citizens’ comments and suggestions.
By Dick Broom
1 June 2008