CEDAR RAPIDS – Renewable-energy specialist Mike Fisher cites a YouTube video of a Wisconsin man incensed by his neighbor – a giant wind turbine.
The outrage comes from the off-on, second-by-second shadow created on the angry man’s house as the wind-turbine blades rotate nearby in the sun.
It’s called ‘shadow flicker,’ and it is now an issue in Cedar Rapids.
Fisher, vice president and leader of the environmental business unit at engineering firm Howard R. Green Co., and his client, Kirkwood Community College, are working to persuade the city to tweak its 6-month-old ordinance that regulates wind tur bines. As written now, the ordinance says the flickering shadow caused by the blades of a big turbine can’t fall within 100 feet of a residential property.
That standard would kill Kirkwood’s plans to erect a $5.5 million, 417-foottall, 2.5-megawatt turbine on its campus. The turbine would be used to train a renewableenergy work force of turbine technicians and engineers, while it also cuts the campus’ annual electric bill by $300,000 a year – a fourth of the college’s costs at today’s electric rates.
Fisher has asked the city to adopt a standard for big wind turbines that would allow shadow flicker on homes but limit it to 30 hours a year. Such a standard, Fisher notes, was adopted in August by the Wisconsin Public Service Commission and is the standard elsewhere.
It’s not the standard everywhere, though. Cities in the Des Moines metro area, for instance, all but exclude big wind turbines inside city limits. They even have a flicker standard for small wind turbines, which Cedar Rapids’ ordinance does not have.
Computer software, when programmed with weather data, the changing trajectory of the sun over the course of a year and other information, can calculate the duration of shadow flicker around a wind turbine, with the flicker typically affecting individual properties at the standard level a few to several minutes a day when the sun is out, Fisher said.
The Wisconsin standard, which takes effect March 1, would allow jurisdictions to seek mitigation measures the planting of trees, for instance – if the shadow flicker reaches 20 hours per year on a particular residence or community building. Cedar Rapids’ ordinance also includes a mitigation mechanism.
Brad Larson, a planner in the city’s Community Development Department, said his office reviewed other state and local wind-energy ordinances, as well as materials published by the American Planning Association and the wind industry. In January, the Cedar Rapids City Planning Commission approved Larson’s recommendation to modify the city’s shadow flicker standard for large wind turbines. The ordinance change, which will be the subject of a City Council public hearing Tuesday, will require the applicant to notify those living in properties affected by the shadow flicker.
For the Kirkwood project, a computer analysis shows that no residentialproperty around the proposed wind-turbine site – in an open space just north of campus ball diamonds and northeast of the main campus entrance – would endure more than 30 hours of shadow flicker a year.
According to the modeling, spots along Kirkwood Boulevard SW generally will experience less than 10 hours of shadow flicker in a year, though one spot near an apartment building at Kirkwood Boulevard and 66th Avenue SW will experience shadow flicker of 19.3 hours a year.
Fisher calls it ‘a pioneering adventure’ to try to bring a giant wind turbine to campus, like the kind found in rural wind farms.
‘We’re trying to do the right thing,’ said Tom Kaldenberg, executive director of facilities management at Kirkwood. ‘We’re trying to educate the work force for tomorrow, and this is going to be a huge piece for that.’ Fisher and Kaldenberg believe the Kirkwood location may be one of just a few spots inside city limits that will meet the ordinance’s standards.
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