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Wind turbines go back online; Fasteners on undamaged towers have been replaced

Seven of the Auwahi Wind turbines in Kanaio were back online Thursday after being shut down Oct. 2 when the turbine on the eighth unit separated from the tower and fell to the ground, according to wind farm operators.

The wind farm stopped providing power to the Maui Electric Co. grid for safety reasons and to conduct an investigation, said an official with San Diego-based Sempra U.S. Gas & Power, the owner of the wind farm, after the incident. The blades, hub and nacelle separated from the tower and fell to the ground.

There were no injuries, and the damage was limited to the one turbine.

The initial investigation revealed that the turbine had problems with fasteners connecting the nacelle to the tower, said Buz Schott, director of external affairs for Sempra on Friday. Fasteners on the seven remaining towers were replaced.

The seven turbines were gradually returned to service and were all operating Thursday, said Schott. Shayna Decker, MECO spokeswoman, said Friday that Auwahi has been providing power again to MECO since Oct. 14.

Decker said there were no disruptions in MECO operations due to the problems at Auwahi.

“We continue to conduct a root-cause investigation of the incident at Auwahi Wind,” Schott said.

The eighth turbine remains out of service, Schott said.

“We do not know when we will replace the turbine on tower No. 4 at this time,” he said. “Our focus has been on resolving the problem and getting the remaining seven back in service.”

Through August before the accident, Auwahi produced 56,369 megawatt hours with MECO accepting 55,525 MWh, according to MECO filings with the state Public Utilities Commission. Last year, Auwahi produced a total of 91,155 MWh of wind-generated power.

According to the final environmental impact statement for the project, filed in August 2011, each tower weighs 283 tons, based on transport weight. The nacelle, which houses all of the generating components of a wind turbine, is 82.5 tons, alone.

Each tower is 262 feet high with blades running 166 feet, according to the EIS. The turbine manufacturer is Siemens, which has been consulted on the accident, said Sempra.

The wind farm, with a footprint of about 68 acres on Ulupalakua Ranch land, has an estimated 20-year lifespan. The power purchase agreement with MECO, approved by the PUC in June 2011, was for 20 years.

The 21-MW wind farm went online in December 2012.