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Nebraska wind farm to go dark during storms to protect nearby weather radar

A commercial wind farm proposed for south-central Nebraska has agreed to shut down during severe weather, which will protect the integrity of radar scans by a nearby National Weather Service station.

NextEra Energy Resources, the nation’s largest wind developer, has agreed to voluntarily turn off the turbines at the proposed Cottonwood Wind Project when asked to do so by weather service meteorologists.

“We wanted to collaborate,” said Steven Stengel, spokesman for NextEra.

Groundbreaking for the up to $175 million wind farm is planned for May 2016, Stengel said. The wind farm would be built south of Hastings and within a few miles of the weather service’s Blue Hill radar station.

The weather service office announced the agreement this week.

“It was important to get this agreement,” said Ed Ciardi, a meteorologist at the NEXRAD Radar Operations Center in Norman, Oklahoma. The radar center, which is part of the weather service, has been tracking the impact of wind farms on weather radar.

Ciardi said the weather service has similar agreements with two wind farms in Kansas and one in New York, but none of those wind farms have raised as much concern as the one proposed for Nebraska.

For the most part, wind farms are a nuisance to forecasters, but Cottonwood would be the first time in Tornado Alley that a wind farm would be built so close to a radar station, Ciardi said.

Dozens of turbines, each standing nearly 20 stories tall, would be built 2½ miles to 7 miles from the Blue Hill radar station. Radar scans from that station are fed to the weather service office in Hastings, which provides forecasts and warnings for south-central Nebraska and north-central Kansas.

Because NextEra has agreed to turn off the turbines during violent weather, the turbine towers and blades won’t interfere with radar during those storms, meteorologists say.

Mike Moritz, meteorologist with the weather service office in Hastings, said the radar stations have been programmed to ignore things that are stationary, such as tall buildings and trees, and instead detect things that are moving, like rain and hail.

Thus, when the wind farm is turned off, its turbines will have no more effect than tall buildings in a city.

Under the terms of the agreement, the turbines could be shut off for 15 minutes to 60 minutes at a time during the peak storm period of March 21 to Sept. 21.

There could be some overlap between NextEra’s own need to shut down its wind farm and requests by the weather service. Wind farms typically shut down when the wind blows at 56 mph. This is to protect the turbines and motors.

Moritz said NextEra also has agreed to train its workers as storm spotters, and the company and weather service hope to share data.

Of the more than 900 wind farms in the nation, these four – the ones in Kansas, New York and now Nebraska – are the only ones to have signed agreements with the weather service to voluntarily shut down, Ciardi said. To the best of his knowledge, Ciardi said none of the existing agreements have been invoked.