Clean Energy Center explains how flicker study is conducted, Kingston town planner challenged 

KINGSTON – The first site-specific flicker study that includes the Independence wind turbine is underway.

The results to be presented in a report to the Board of Health and the community at large, possibly by June 10, will quantify the locations and number of hours where shadow flicker is likely to occur. But how is a flicker study like this one that started April 23 conducted?

Massachusetts Clean Energy Center spokesman Catherine Williams answers that question. The Clean Energy Center has coordinated the study, which includes all five wind turbines in Kingston – the Independence, Mary O’Donnell’s three turbines and the MBTA’s turbine.

The study uses modeling software that analyzes the known path of the sun, the location and height of the turbines, and topographic information to project where shadows may fall, in order to estimate the maximum potential flicker impact.

The model then takes into account historic year-round weather data (from National Oceanic and Atmospheric Administration, for example) to estimate actual shadow flicker impact for the entire year.

Once areas potentially subject to shadow flicker are determined, the contractor will conduct a field study to verify the locations that have a direct line of sight to the turbine. If the turbines aren’t visible because they’re blocked from view by a building or thick trees, property owners won’t have any shadow flicker impact at their location.

The Board of Health has been discussing creating shadow flicker regulations and may hire an engineer with knowledge of flicker effect to analyze the flicker study report.

The question, was there ever a shadow flicker study done before the Independence was installed, has been a point of contention at public meetings as recently as last week. Town Planner Tom Bott, for one, has come under fire by Leland Road residents Doreen and Sean Reilly, among others.

When the Reillys met with the Planning Board last week, they demanded to see the shadow flicker study that the Planning Board cited in its site plan approval for the Independence. They say Bott had been misleading about whether there was an official flicker study and finally acknowledged there wasn’t one.

Bott said this week that he has provided more than 100 pages of information, including a document titled “Community Wind: The Future of Wind Energy,” dated Oct. 21, 2008, from the Green Energy Committee, to the Reillys to respond to their questions.

Bott said he’s looking forward to the results of the official flicker study and acoustic monitoring study to guide action going forward.

“I will be happy when the flicker study and the sound study are complete so we will have some empirical evidence to go along with the anecdotes,” he said. “With studies in hand we will know what may need to be mitigated.”

At the last Planning Board meeting, Chairman Tom Bouchard said little information about flicker was known at the time, although it cited in its decision to approve the site plan information from the Green Energy Committee “based on the shadow flicker study.” He acknowledged that the information was more reading material and not a site specific study.

“In retrospect, in looking at that, that probably should not have said shadow flicker study and probably should have said shadow flicker information,” he said.