HILO, BIG ISLAND (HawaiiNewsNow) - Hawaii Electric Light does not anticipate a need for rotating power interruptions for Sunday night during peak hours.
Saturday night's rotating outages that lasted for 20 to 30 minutes were necessary for about 26,000 customers due to a shortage of power generation when several generators experienced unanticipated problems.
"We want all of our customers to know we are truly sorry for disruption caused by last evening's power interruptions," said Rhea Lee-Moku, company spokesperson. "Crews worked hard to repair generation units to get them back on-line, 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 says Saturdays's events were unusual. At about 1:30 p.m., a combustion turbine unit at the Keahole plant shut down unexpectedly due to problems with its water system that is used to control exhaust emissions.
About two hours later, fuel system problems caused another combustion turbine unit at Keahole to shut down.
A steam turbine unit owned by an independent power producer, Hamakua Energy Partners, was already down for repairs since mid-morning Friday and repairs could not be made in time.
Hawai'i 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. Additionally, wind energy and hydroelectric resources were unavailable for the evening peak.
Crews are currently working to repair or troubleshoot generators that seem to have problems functioning.
Daily evening peak is from 5 p.m. to 9 p.m. with the highest demand from 6 p.m. to 8 p.m. when customers are home preparing dinner, doing laundry, taking showers, turning on lights, and doing other things that use electricity.
Added to the increased electricity use during this period, the sun is setting and rooftop solar panel systems stop generating power, leading customers to start using power from the grid.
Hawai'i Electric Light's normal contingency plans allow for meeting customer needs even if the largest generating unit on the system goes out of service unexpectedly.
In this case, two of the largest generators went out of service and there was insufficient time to start the Puna steam unit which takes at least 12 hours to start supplying power to the grid. The Puna unit was taken out of regular service in 2014 and now is used for this type of situation.