Call it a perfect electric utility storm.
Call it a perfect electric utility storm.
The unexpected failure of three major generators, as well as a fourth generator being down for a planned overhaul, and a shortage of wind and water to drive renewable generators, all combined to necessitate rolling blackouts Saturday on Hawaii Island, according to Hawaii Electric Light Co.
Rolling blackouts, also known as load shedding, are a last resort for electric utilities responding to an inability to produce enough power to meet demand. Engineers intentionally shut down power to different parts of an area to prevent a blackout of the entire power system.
HELCO announced at about 5:30 p.m. Saturday that it was asking customers to conserve energy from 6-8 p.m. as a result of the utility not being able to produce enough electricity to meet demand during peak hours.
A total of 26,300 customers were affected by rolling blackouts lasting between 20 and 30 minutes, each between 6:17 and 8:05 p.m., according to a HELCO statement.
“Yesterday’s events were unusual,” the utility said in a Sunday afternoon news release.
At about 1:30 p.m. Saturday, a combustion turbine at the Keahole plant shut down unexpectedly because of problems with its water system used to control exhaust emissions, HELCO reported. About two hours later, fuel system problems caused another combustion turbine unit at Keahole to shut down.
Meanwhile, a steam turbine unit owned by independent power producer Hamakua Energy Partners already was shut down for repairs since mid-morning Friday, and repairs were not able to be completed in time.
“Hawaii Electric Light’s combustion turbine 1 was also on overhaul, and its Puna steam unit was on standby status and could not be started in time,” the statement reads. “Additionally, wind energy and hydroelectric resources were unavailable for the evening peak.”
HELCO said crews worked long hours to return a combustion turbine at the Kanoelehua facility in Hilo to service, three days before its planned return from a scheduled overhaul. Crews also were able to repair the problems on one of the Keahole turbines, returning it to service early Sunday afternoon. In addition, crews have been working to bring the Puna steam generator online to provide additional generation.
HELCO spokeswoman Rhea Lee-Moku apologized for the outages and for the late notice warning about the rolling blackouts.
“We want all of our customers to know we are truly sorry for disruption caused by (Saturday) evening’s power interruptions,” she said. “Crews worked hard to repair generation units to get them back online, but we just weren’t able to make it in time. We apologize for not providing earlier notice, but we’d hoped to be able to close the gap and tried to get the word out, including using social media, as soon as possible.”
HELCO spokeswoman Kristen Okinaka explained Monday afternoon that wind generation peaked Tuesday of last week and steadily declined from Wednesday before dropping to zero Saturday evening.
Meanwhile, “due to lack of rain, generation from hydroelectric units was near zero for most of last week,” she said. “Solar energy is unavailable during the evening peak hours.”
The Saturday power outages appeared to have impacted residences and businesses alike.
At the Sports Authority in Kailua-Kona, staff followed procedure and asked customers to leave merchandise at the front of the store and wait outside until power came back on, but most just left.
The exodus likely cost the store “a couple thousand” dollars, according to sales team leader James Welsh, who estimated there were at least 20 customers inside when the lights went out. The outage there lasted approximately a half hour before power was restored.
Teshima’s, a Japanese restaurant in Honalo, reported it lost power for about 45 minutes, starting at 7 p.m.
Reporter Graham Milldrum and former reporter Ryan Kazmirzack contributed to this report.
Email Colin M. Stewart at cstewart@hawaiitribune-herald.com.