Blackouts in neighborhoods across O'ahu this week are likely a taste of what's to come as the weather gets hotter and Hawaiian Electric Co. says it struggles with insufficient generators to supply an increasingly demanding population.

Peak usage months, said HECO spokesman and engineer Jose Dizon, aren't until September and October, and O'ahu has barely crept into the moderate-use months of early summer. Outages will increase as thermometer mercury moves higher.

"We expect to see more of these unplanned outages and emergency repairs," Dizon said.

The situation would ease should a $130 million power plant be built in Campbell Industrial Park, he said. If the company gets the necessary approval, it expects the plant to go on line in 2009. Until then, existing HECO generators, some of which are nearly 60 years old, will feel the strain.

"Our units are running harder and longer," Dizon said. "Electricity use follows economic growth, and there are more people building more new houses with air conditioners, stoves and lights. And it is not just more people using electricity, it is how they are using it; more people are adding air conditioners to existing houses, too."

HECO customers increased from 286,677 in 2003 to 291,580 in 2005, he said. In 2005, electrical use increased 4.1 percent among residential users.

With business customers folded in, "the increase was 3.3 percent overall," he said. "So a lot of the increase is in residential use."

Nearly 37,000 customers were left without power Thursday when demand came dangerously close to exceeding supply. Four generators had been shut down for routine maintenance, and on Wednesday night a generator at Kalaeloa Partners, a company at Campbell Industrial Park that sells electricity to the electric company, was taken down for repairs. On Thursday afternoon, a second generator at Kalaeloa unexpectedly went down, and the jolt was felt throughout the system.

In response to increased demand, two generators in Waiau shut themselves down, and HECO dispatchers protected the rest of the system by shutting off power for thousands of customers in Hawai'i Kai, Waimanalo, Kahala, Manoa, Kalihi, Iwilei, Mapunapuna, Pearl City, Waipahu, Kunia, 'Ewa Beach and Makakilo.

The power was restored by 6:09 p.m., after HECO asked its customers to go into emergency conservation mode, and brought the Waiau generators back on line.

REPAIR OVER REPLACE

Two of the generators that were down for routine maintenance were brought back up yesterday, Dizon said, adding that Kalaeloa is expected to have both of its units on line this weekend.

Dizon said some of HECO's generators are nearly 60 years old. They are built well and it would cost more to replace them than repair them, but regular maintenance is essential to keep them functioning.

Plans for the new power plant in Campbell Industrial Park were put in place in 2002, Dizon said, noting that at that time HECO had not anticipated use to increase to current demand levels until the plant is on line in 2009.

The plant is designed to run on naptha, a cleaner-burning fossil fuel made from crude oil. HECO president and CEO Mike May has said he hopes to find a way to use an ethanol blend to fuel the plant.

'ECONOMIC FOLLY'

Jeff Mikulina, director of the Sierra Club's Hawai'i Chapter, said he doubts whether the ethanol plan is a commitment, and questions the wisdom of tapping fossil fuels.

"A fossil fuel plant is economic folly when oil is over $70 a barrel," said Mikulina, whose group opposes the new power plant.

Mikulina said environmental groups hope to see O'ahu step up conservation by using smaller, renewable energy sources sprinkled throughout the grid.

Dizon said HECO is moving in that direction, along with exploring options in wave and fuel cell energy. OTEC (ocean thermal energy conversion), which uses the cool water at the lower level of the ocean to drive a specific type of generator, could become an economically viable alternative if oil prices remain above $70 a barrel, he said.

Also, federal and state tax credits are making the installation of solar water heaters by residents more economically attractive, he said, noting that HECO is aggressively promoting that option.

HPOWER, in Campbell Industrial Park, burns trash to create energy, and HECO is looking at ways to make more energy from solid waste or landfill gases, he said.

NO WIND FARM

A plan to put a wind farm on a ridge overlooking the 'Ewa shore was ditched after community groups, supported by the mayor, complained that the farm would be visually unattractive. Dizon said HECO is in talks with the Army to put wind generators on military land in Kahuku.

Despite some strides, Mikulina said the move toward renewable energy is inching along much too slowly.

"We're using the same percentage of renewable energy as we were 10 years ago," he said. "We need bold commitments, like Kennedy's promise to put a man on the moon by the end of the decade.

"Right now, we're just running in place."

Reach Karen Blakeman at kblakeman@honoluluadvertiser.com.