Three Homer Electric generators failed at once, and hydro covered the gap

Three of Homer Electric Association's generating units went down at the same time in August, unplanned, and the cooperative kept the lights on across the Kenai Peninsula by buying extra power from Bradley Lake.

The Nikiski Combined Cycle plant, HEA's largest gas generator, went down on lube oil heat exchanger contamination and control system failures. Bernice Combustion Turbine #3 had high vibration. Bernice #4 had an exciter control failure. The weather was ordinary, but demand stayed high because the refinery was drawing more power than usual.

System load was "maintained without interruption through the strategic purchase of additional Bradley Lake generation," the cooperative's September report says. Repairs are done at Nikiski and Bernice #4 and both are running again. The report does not say where Bernice #3 stands.

It cost something. HEA's margins are running about $600,000 below budget for the year, against a $6 million unfavorable variance in the cost of electric service, which the cooperative attributes mostly to purchased power and to billings from its own generation subsidiary that will not be squared until year end.

The backup HEA leaned on has a limit of its own. Bradley Lake, 27 air miles northeast of Homer, is the largest hydro plant in Alaska at 120 megawatts and supplies roughly a tenth of the Railbelt's power. But the transmission lines running out of it were never built to carry all of that. "You're not getting the full capacity necessarily when you need it," Alaska Energy Authority CEO Curtis Thayer told a legislative hearing on Cook Inlet gas supply in August. HEA holds an 11 percent share of the plant's output.

The energy authority and the five Railbelt utilities announced more than $200 million in transmission upgrades this year meant to relieve that, including work on the lines between Bradley Junction, Soldotna and Quartz Creek.

HEA staff are meanwhile occupied with the Nikiski repower and a compressor addition at the Soldotna turbine. Members can ask about all of it at the cooperative's community meetings, running through November in Port Graham, Nikiski, Funny River, Anchor Point, Sterling and Homer.