Hawaiian Electric Co. asked O'ahu residents to conserve energy earlier this week to avoid rolling blackouts.

Get used to it.

The same thing happened in November and, until capacity is increased and use decreased, emergency conservation requests are likely to happen again, HECO officials said.

"We've had a couple and it is likely we'll have more," said Peter Rosegg, a HECO communications consultant. "When it gets hotter, and we're using more air conditioning, it'll get worse."

Emergency conservation is a short-term fix. Long-term conservation is essential, but power company officials and environmentalists agree that O'ahu must also increase its ability to make electricity.

HECO says the answer is a combination of alternative and fossil fuel energy sources, including a wind farm proposed for a Windward location and a $130 million fossil fuel plant scheduled to be built at Campbell Industrial Park by 2009.

Environmentalists approve of the wind farm but not the fossil fuel plant, which they say is unnecessary if renewable energy sources are encouraged and fully used. Everyone, however, agrees that something must be done now.

"We don't have the luxury of time anymore," said Jeff Mikulina, director of Sierra Club's Hawai'i chapter and a member of an advisory group that helped the electric company explore energy alternatives.

O'ahu is approaching crisis time because of a shrinking reserve margin — the amount of give between electricity used and electricity produced, HECO says.

A minimal reserve margin must be maintained to keep the electrical grid from shutting itself down, Rosegg said.

The first step taken in an emergency is to ask customers to cut back. If that doesn't work, technicians will impose "rolling outages," or blackouts.

"We black out an area for an hour or two and then move on to the next area if we need to, until we get through it," Rosegg said.

As of late last night, O'ahu had avoided the need for rolling blackouts in the most recent generating problem.

The call for emergency conservation went out Tuesday after a HECO generator was taken off-line for emergency repairs. Two other generators already were down for scheduled maintenance and a turbine at an independent power plant that sells energy to HECO also was down, cutting energy production from that source.

Last night, thanks to conservation, HECO technicians completed repairs and ramped up the largest of the downed generators.

Although maintenance is staggered to avoid such conditions, Rosegg said, increased demand for power strains the system and more maintenance — including emergency maintenance — is becoming necessary.

Annual energy demand has increased by an average of 2 percent each year on O'ahu for several years and usage during peak periods — between 5 and 9 p.m. weekdays — has increased even more dramatically, power company officials said. But HECO's capacity to produce power hasn't changed since 1992.

Because islands are too isolated to borrow from energy-producing neighbors, HECO officials like to keep O'ahu's reserve margin at about 30 percent to prevent forced outages if equipment fails.

The system hasn't operated with that big a margin at peak times since shortly after the turn of the century, Rosegg said.

HECO's plans call for a variety of energy-production methods, including increased use of smaller generators in high-use areas to cover peak usage, Rosegg said.

Using Hawai'i's sources of renewable energy is important, Rosegg said, but a recent attempt to put a wind farm on a ridge overlooking the 'Ewa shore was shot down by community residents, and the defeat made HECO officials wary.

Residents who turned out for public meetings were overwhelmingly against the farm, and were supported by the mayor and by the environmental group Life of the Land.

"If we go into the communities and say, 'We'd like to put a wind farm here,' and they all say, 'Not in our backyard,' then we might not be able to meet our goals," Rosegg said.

Henry Curtis of Life of the Land said a wind farm in another location would make more sense and would be supported by his group and other environmental groups.

"This was the wrong place, both in terms of energy needs and in terms of cultural significance," he said.

Kahuku, site of an early wind-generation experiment a couple of decades ago, has been proposed as an alternative site.

Even if the community embraces it, Rosegg said, the farm won't produce enough energy to meet O'ahu's needs.

HECO is moving forward on a proposal to build a $130 million power plant at Campbell Industrial Park, which it hopes to have running by 2009. The plant would run on naphtha, a fuel made from crude oil that is available from local refineries.

Naphtha is cleaner than fuels now in use, Rosegg said, but is still a fossil fuel.

"We're going to fight that tooth and nail," Curtis said.

"Climbing oil prices and the problems with climate change make it ill-advised to sink more money into fossil fuels," Mikulina said.

Solar power, on the other hand, is a natural for Hawai'i, the environmentalists said.

"We think the rooftops of government buildings, schools and other places look like great places for solar generators," Curtis said.

Other technologies, such as wave generators that harness the power of the ocean, are also possibilities, he said.

Mikulina said power companies elsewhere deal with peak power by charging more during peak hours and less during off-hours.

He said he hopes the recent near-crises will help bring legislators' attention to the need for alternative fuel sources and the legislation that encourages their development.

Reach Karen Blakeman at kblakeman@honoluluadvertiser.com.