Fire officials and representatives from the energy-producing First Wind project are gathering today at the company’s Kahuku wind farm to assess damage and investigate what caused a fire that appears to have destroyed a battery-energy storage facility.

Firefighters left the scene with the fire under control at about 7:30 p.m. Wednesday, leaving the situation in the hands of First Wind employees to monitor after it was determined that surrounding structures were not being threatened, said Capt. Terry Seelig, Honolulu Fire Department spokesman.

“From what I understand, there’s still some smoldering in the building that is producing heat and some gases,” he said this morning. “It’s not a danger to the rest of the property the way it was yesterday but it does have to completely burn out and cool down before any entry activity for assessment and investigation goes on.” 

It’s not certain when the building will be safe to enter, he said.

The 9,000-square-foot building is a key component to the system that allows the company to transmit as much as 15 megawatts of wind-generated power to the Hawaiian Electric Co.’s grid. It is unclear how long it will take for the plant to come back online. 

“Given the structural damage to the battery storage building and residual smoke, it will take some time for technical experts and fire inspectors to safely enter the facility to investigate the cause and extent of the damage,” said First Wind spokesman Kekoa Kaluhiwa.

Technical experts are flying in from the mainland, Kaluhiwa said.

Honolulu firefighters first responded to a call from First Wind about 4:45 a.m. Wednesday after a sensor in the complex picked up a buildup of heat, and video cameras showed flames growing in fuel cell banks.