GVEA fires up backup generators after earthquake knocks Intertie offline in Mat-Su

Earthquake damage has disabled the Alaska Intertie, the 170-mile transmission line that runs from Willow to Healy. (Credit Alaska Energy Authority)

The massive earthquake that hammered Anchorage on Friday also damaged the 170-mile transmission line known as the Intertie, which along with Northern Intertie brings power from southeast Alaska into the Interior. Because of that, Golden Valley Electric Association has been running its backup generators to compensate for the 30 megawatts that GVEA is now unable to get over the Intertie.

When Friday morning’s earthquake hit, Golden Valley customers were using a total of 165 megawatts of electricity, and about a fifth of that was coming over the Intertie. But soon after the magnitude-7 quake rumbled through the Anchorage area, the Intertie went dead.

“All of a sudden, we no longer had access to that 30 megawatts of power that we were purchasing from the Anchorage area,” says Golden Valley Power Systems Manager Pete Sarauer.

He says the utility’s Healy Generating Station, including both Healy 1 and 2, was pumping out about 80 megawatts Friday morning, and one of its North Pole power plants was producing another 35. And it was getting about 24 megawatts from Aurora Energy’s downtown power plant. So he says when the Intertie went down, Golden Valley started to fill the gap with its big battery called BESS, the Battery Energy Storage System.

“It immediately puts out whatever power it needs, up to 40 megawatts,” Sarauer said in a Monday interview.

But BESS can only provide 27 megawatts for about 15 minutes, so Sarauer says GVEA also temporarily fired-up a 30-megawatt power plant in Fairbanks until it could bring a 60-megawatt turbine generator in North Pole online.

“Then were able to back the load down on BESS, and get it turned off and recharged, so that if we had another event, it would be ready,” he said.

The backup system worked, and Golden Valley kept the lights on. Sarauer says it’s likely that few if any of its customers were even aware that the co-op was scrambling to avoid a blackout.

“Unless you were really watching meters, you probably wouldn’t have even noticed it.”

Sarauer says Golden Valley officials spent part of Friday morning checking with the operators of the Petro Star Refinery in Valdez to ensure GVEA could secure enough fuel for the 60-megawatt turbine. They were concerned because the Trans-Alaska Pipeline had been shut down when the quake hit, so the Petro Star Refinery in North Pole would be unable to produce the fuel, called naphtha.

Sarauer says Golden Valley only had about 16 hours’ worth of the fuel on hand and at that time it wasn’t known when the pipeline would be restarted.

“So we were making sure the road was intact, that they had fuel in storage available that we could have trucked up to Fairbanks to provide the fuel for our generator, if we needed it,” he said.

As it turned out, Golden Valley didn’t need it, because the pipeline was restarted later FridaySaruaer says there wasn’t a concern over the supply of other fuels it uses to generate electricity. He says there’s plenty of diesel available in Fairbanks. And he says the supply of coal for the seven power plants around the Interior that burn that fuel was never threatened, because the quake didn’t damage the Alaska Railroad tracks between the coal mine in Healy and Fairbanks.

“So if the Intertie didn’t come back and if the pipeline hadn’t come back, we would have been pretty good for several days.”

Sarauer says the Intertie was back in service around 5 p.m. Friday, and functioned until it was shut down again just after 3 p.m. Sunday. He says the cause is thought to be problems with a substation at Point MacKenzie that was damaged by the earthquake. A Matanuska Electric Association spokesperson says the substation is located in MEA’s service area, but is owned by Chugach Electric Association.

“The Point MacKenzie substation had some damage to it, and they’re looking at a couple of weeks to do some repair,” Sarauer said.

It took Golden Valley about 20 minutes to restore power Sunday to nearly 5-thousand (5,000) customers in North Pole and Delta Junction. Sarauer says freezing rain and earthquake-damaged roads kept utility crews from repairing the substation Monday and inspecting the Intertie for other damage. And he says until the Intertie back in operation, Golden Valley will continue to generate its own electricity.