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UD wind turbine struck by lightning; Unit shut down pending blade repair

Ohrel said it is not yet known exactly what repairs might be needed, when they would be completed or when the unit could be restarted. ...he did not know if the wind turbine is equipped with a system capable of suppressing damage caused by lightning strikes.

Lewes - Lightning has damaged the University of Delaware's wind turbine in Lewes, prompting officials to shut it down.

The 250-foot wind turbine adjacent to the college's Hugh R. Sharp Campus was struck June 22, said Ron Ohrel, director of Marine Public Education Office at the College of Earth, Ocean and Environment.

Ohrel said this is the first time the wind turbine has been hit by lightning. He said it looks as though one of the turbine's three blades is damaged.

"You can't see the damage from the ground without using a pair of binoculars," he said.

Ohrel said it is not yet known exactly what repairs might be needed, when they would be completed or when the unit could be restarted.

"We hope it's as soon as possible," he said.

Ohrel said he did not know if the wind turbine is equipped with a system capable of suppressing damage caused by lightning strikes.

According to information on International Association of Certified Home Inspectors website, lightning damages wind turbine control system components such as sensors and motors that steer the turbine into the wind.

The site states, according to the National Fire Protection Association updated handbook, "While physical blade damage is the most expensive and disruptive damage caused by lightning, by far the most common is damage to the control system."

A lightning strike to an unprotected blade raises its temperature as high as 54,000 degrees, resulting in an explosive expansion of air within a blade.

"This expansion can cause delamination, damage to the blade surface, melted glue, and cracking on the leading and trailing edges. Much of the damage may go undetected while significantly shortening the blade's service life," according to the site. One study found that wood-epoxy blades are more lightning-resistant than those made of glass-epoxy, the material used to produce the Lewes turbine's blades.

Ohrel said officials would not know how much repairs might cost until they have a detailed damage assessment.

Although the wind turbine is being used as a platform for several research projects, an investigation into the effects of lightning is not among them, Ohrel said.

Gamesa Technologies Corp. designed, engineered and manufactured the turbine. The company, based in Spain, has been the university's partner in developing the wind turbine and also co-owns and operates the unit.

The 2-megawatt wind turbine produces enough electricity to power the college's Lewes campus. Electricity produced in excess of campus requirements is sold at market rate to Lewes Board of Public Works, the city's utility provider. When the wind turbine is not producing electricity, the college buys power from the BPW.

Affordable technology that would make it possible to store electricity produced by the wind turbine is not yet available.

New generator in place

Ohrel said Gamesa and the university want to complete lightning-strike damage repairs in coordination with start-up of a new generator in the unit.

Late last month, Gamesa removed the wind turbine's original generator, put it in storage, and replaced it with a new one the company plans to manufacture in Wisconsin for use in the United States. Avinash Taware, Gamesa's electrical section manager, said the unit has undergone lab testing, and field tests in Lewes' wind turbine would take six months to a year.

Gamesa said domestic production of the generator would reduce shipping costs, shorten installation lead times, ensure parts inventory and boost the country's economy by creating new jobs.


Source: http://capegazette.villages...

AUG 3 2012
http://www.windaction.org/posts/34539-ud-wind-turbine-struck-by-lightning-unit-shut-down-pending-blade-repair
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