Unalaskans left in dark for nearly 5 hours after mechanical failure causes power outage
A power outage caught Unalaskans by surprise Thursday evening when most of the island went dark.
According to the island’s acting public utilities director, Steve Tompkins, a failed transformer caused the outage, which occurred around 5:30 p.m. and lasted nearly five hours.
“Initial indications were that a unit had tripped offline,” Tompkins said. “And it caused an overload on the other unit, which took itself offline. And it resulted in a near universal outage.”
Standard Oil Hill was the only area on the island that didn’t lose power during the first outage, he said.
A crew rerouted power and brought what they thought to be the entire island back online. But as they were getting ready to head home, they discovered that some of the buildings near Ballyhoo still had no power, so the crew headed out to check on a transformer in the area.
Tompkins said that’s where things got tricky.
“That's a strange outage,” he said. “And that's one of the toughest kinds of outages — when it's out in the field. The line crew [goes] out, but there isn't like a glowing light that's showing you exactly where the problem is.”
The crew responded to a breaker near Ballyhoo, which Tompkins said caused an immediate and complete outage, including Standard Oil Hill.
The original interruption had been linked to a problem at the switchgear yard, near the powerhouse. Tompkins said it’s easier to fix issues at the powerhouse and switchgear yard, in part because the equipment is more centralized than transformers in the field, which are scattered throughout the island.
But with the help from a couple locals, public safety and the fire department, Tompkins said they finally found the failed transformer, routed electricity around it and had power restored around 11 p.m. Thursday.
Residents on Generals Hill were the last to come back online, as the crew had to finish a maintenance project in the area before they could turn power back on, according to Tompkins.
Island residents are no strangers to losing power. Some of the past outages have been attributed to finicky transformers and vipers — which help different pieces of the power grid talk to one another.
Tompkins said this outage was due to a mechanical failure. While the vipers didn’t have much to do with Thursday’s blackout, he said the city is working on installing new, more robust vipers that will be able to handle heavier power loads if and when the city transfers over to geothermal energy.
Last year, the city entered into a 30-year Power Purchase Agreement with Ounalashka Corporation and Chena Power to develop a geothermal power project located at Makushin Volcano — about 13 miles from Unalaska's current power grid.
OCCP has started road construction out to the volcano, and has said they expect to bring power to Unalaska near the end of 2024.
If the city does move to geothermal, Tompkins said there is a possibility of more customers, like UniSea or Westward, joining Unalaska’s grid. In that case, he said the current system needs some improvements.
“There could be, basically, more energy in all these electrical circuits,” Tompkins said. “And so we just need to upgrade ... a lot of things.”
The island experienced another outage Monday morning, when a unit overheated while being tested. It lasted about 20 minutes. Tompkins said that interruption was unrelated to Thursday’s.