National Wind Watch: Wind Energy News » Turbines being thawed out naturally

Consumers Energy would not go into detail Monday about how it detected icing on its Lake Winds Energy Park tubrines Sunday, stating only that the company followed the ice mitigation plan it filed with the Mason County Planning Commission.

“As soon as icing conditions became apparent, they were shut down,” Consumers Energy Spokesman Dennis Marvin said. “They will stay shut down until we can determine that they can be safely operated.”

Bright white icy patches could be seen on blades Monday morning from hundreds of yards away on the 476-foot-high turbines. Bright sun came out in the afternoon and the utility was hopeful ice on the blades would thaw naturally.

The plan

According to the ice mitigation plan, Consumers detects ice buildup by mechanical means and by visual means.

The Vestas Ice Detection System consists of a vibrating tube that has a set frequency. When ice builds up on the tube, it changes the frequency at which the tube vibrates. The tube is then heated so an amount of ice can be determined by a sensor.

Turbine controls are also sensitive to ice buildup, according to the plan. Ice can cause an imbalance in the blades, which would prompt an operator to pause the wind turbines.

Weather reports and visual observation are also used, according to the plan.

How long?

One option in the mitigation plan calls for the blades on the turbines to be moved in short bursts to try to free ice.

“We’re not doing that,” Marvin said. “We’re waiting for the ice to melt.”

Marvin said Monday afternoon that it was apparent that some turbine blades were iced, but not all turbines had ice on them. Marvin said the utility opted to shut down the entire wind farm rather than shutting down individual turbines.

When the turbines will be ice free depends upon the weather. Bright sun on Monday afternoon probably helped the utility’s cause somewhat.

“We have our folks in the field inspecting them,” Marvin said.