LIHU'E, Kaua'i — An islandwide blackout Sunday, followed by threats of rolling blackouts Monday, resulted from a chain of events at the Kaua'i Island Utility Co-op — and pointed up an issue that power managers say they'll need to address soon.

"We're running a little tight on generating capacity" and will need new sources of power within a couple of years, said utility President Randall Hee.

Sunday's failure occurred because of a sudden shortfall in generating capacity: one diesel generator was off-line for normal maintenance; a second broke last week with a camshaft failure; the company's 27.5-megawatt Kapaia generating plant shut itself down when a protective relay detected a line problem; and safety equipment responded to that sudden loss of power by automatically shutting down the utility's 10-megawatt steam plant. Suddenly, there was far more demand for power than there was available, and the island's power grid collapsed.

Coincidentally, a tree fell on a power line in Lihu'e less than a second before the Kapaia plant failed, and engineers spent a great deal of time trying to establish a link between the two events before realizing they were entirely unrelated, Hee said.

"It happened essentially simultaneously. The events were six-tenths of a second apart," Hee said.

Most of the island had power back fairly quickly, but parts of Lihu'e were down for two hours or more. At Lihu'e Costco, where cash registers were not operating, customers were asked to abandon their full shopping carts and leave the store as employees sought to restock perishables.

On Monday, as the island's evening peak electricity demand period approached and the Kapaia plant remained down, Hee issued an islandwide request for conservation.

"Should KIUC's requests for voluntary load shed be insufficient, we will need to commence with rolling outages," he warned. But engineers got the plant back on line before the island peak, and blackouts were avoided.

Hee said the utility is working on attracting wind generators to the island, and has reviewed solar power, but said they do not meet the need to be available in an emergency. If the wind isn't blowing or the sun not shining, "they don't add capacity for me," Hee said.

The company recently signed a contract for a generator that will burn locally grown wood scrap, but it is several years off and will not be available in time to meet a growing power demand.

"I'm looking for additional generation. I'd like quick-starting units we can recover from outages, and I'd like units that can burn naphtha, diesel and eventually biodiesel when it becomes available in bulk," he said.

That said, Hee says the island's power demand is rising at about 1.5 percent a year, which seems to be slower than the actual development rate on the island. He believes that customers' efforts to reduce consumption is making the difference.

"Industrial and even residential customers are installing conservation measures," he said.

Power customers have not had a rate increase in a decade, although automatic fuel cost adjustments have raised actual bills. Hee said the company is studying whether it can add generating capacity without raising rates — perhaps by using low-interest government loans available to cooperatives.

"We're trying to figure that out now," he said.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.