HELCO: Power outages possible

A 60-megawatt power plant will remain out of service through Friday, leaving the Big Island’s power grid vulnerable to outages, Hawaii Electric Light Co. cautioned Monday.

The Hamakua Energy Partners plant, the second largest power producer on the island, shut down following two unexpected trips last week tied to faulty fuel valves, said HELCO spokeswoman Rhea Lee-Moku. It will return to service Friday at the earliest, she said.

The utility said it’s running all available units to make up for the loss, but with little room for error, it warns that customers might be asked to conserve power if other problems arise.

“If something were to happen to a unit, and we suddenly find ourselves with insufficient generation, it could occur,” Lee-Moku said of potential power interruptions.

The sudden loss of the HEP plant, powered by a petroleum product known as naphtha, resulted in brief loss of power to 13,400 customers Wednesday and 9,800 customers Thursday, she said.

HELCO’s Puna steam and Keahole power plants also tripped offline Friday, leaving about 10,000 customers without power for seven to 20 minutes while backup generators were started.

“We were able to get them online back pretty quick,” Lee-Moku said. The cause was unknown.

To offset the loss of HEP, located in Honokaa, HELCO says it is working to return its 20.5-megawatt Hill 6 steam plant from its annual overhaul by this evening. A Puna steam unit on standby was returned to active service.

HELCO announced in late December it signed an agreement to buy HEP from ArchLight Capital Partners for $84.5 million.

Lee-Moku said that deal awaits approval from the state Public Utilities Commission.

The power supply issue follows nearly two months after rolling blackouts affected 23,600 customers the evening of Feb. 20. The utility attributed the issue to the loss of three power generators while a fourth was down for a planned overhaul.

Email Tom Callis at tcallis@hawaiitribune-herald.com.