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Scituate turbine study shows shadow flicker more than predicted

Posted by Jessica Bartlett  January 12, 2014 12:01 AM

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Scituate officials said they are exploring options to reduce shadow flicker caused by the industrial wind turbine, after discovering several homes were experiencing the strobe-like effect more frequently than predicted.

According to an analysis presented to selectmen last Tuesday, three Scituate homes are experiencing over the state-recommended 30 hours of shadow flicker a year – with one home as high as 69 hours. Five other homes are estimated to experience between 10 and 25 hours of shadow flicker a year.

Shadow flicker occurs when the blades of the turbine travel in front of the sun.

“Flicker only occurs late afternoon for a few weeks in late fall and early winter and late winter/early spring,” said Al Bangert, former director of the Department of Public Works who still oversees the turbine.

The sun has to be at a certain angle in the sky for flicker to impact residents, Bangert said. Even then, it occurs only on sunny and windy days.

Though the analysis doesn’t take trees or other buildings into account – which could obstruct the shadow being created - the numbers are higher than predicted in some areas.

The home with the biggest impact, at 151 Driftway, was predicted to have 51 hour of flicker annually, Bangert said. Current studies suggest the home could get as much as 69 hours a year.

Bangert characterized the differences as “slight,” and said they are due to different testing criteria, including the size of the affected area and the number of hours the turbine would operate.

In a worst-case scenario, the turbine would create flicker an hour and 44 minutes a day for 151 Driftway, the study said.

Mark McKeever, who owns the property at 151 Driftway, said he wasn’t surprised to hear the study had increased the amount of estimated shadow flicker on his home, and said that even 69 hours might be low.

Though Bangert said predicted shadow flicker was 51 hours, McKeever said he was told shadow flicker wouldn’t be more than 30 hours a year.

“It said 30 in the original proposal, that we were going to have approximately 30 [hours]. That’s what the state mandated. But going from 30 to even more than 60, when I should have zero, is unfortunate,” McKeever said.

Bangert said the town was looking in to technology that could obstruct the flicker, including the creation of a billboard-like wall to block the shadows.

Little will be done in the interim, however. According to Bangert, a berm nearby had already been planted with trees to try to obstruct some of the problem. The homeowners at 151 Driftway were also given $20,000 from Scituate Wind in mitigation to deal with some of the flicker.

“We’re looking at what we can do nominally to help out,” Bangert said.

McKeever said the mitigation money had nothing to do with shadow flicker.

“They are trying to spin it to make it look like it was,” he said.

The McKeevers filed a lawsuit against the town in January 2013 to try to shut the turbine down, complaining of problems associated with noise and shadow flicker coming from the machine.

In February, the family decided to withdraw their lawsuit until the town had completed a turbine study with the Board of Health.

The study is ongoing. McKeever would not say whether the family would continue the lawsuit.

Yet the complaints initially prompted the town to undertake the most recent study, Bangert said. With funding from the Massachusetts Clean Energy Center, engineers from EAPC were hired to review the turbine.

While changes won’t come short-term, Bangert said the town did feel it was important to investigate complaints.

“We’re willing to participate,” he said. “We want to help the industry and the residents and help science learn more about this stuff.”

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