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The Honolulu Advertiser
Posted on: Tuesday, November 3, 2009

Power use reflects muggy days


Advertiser Staff

The recent string of kona-wind days has convinced many Honolulu residents to crank up their air conditioners and draw more power from the electric grid.

On Oct. 7, Hawaiian Electric Co. experienced the highest demand of the year on Oahu.

Residents were running everything from air conditioners to home computers, water heaters, televisions, hair dryers and even stoves — providing you were brave enough to cook at home.

HECO spokesman Darren Pai said the daytime demand for electricity peaked at 1,246 megawatts while the evening demand reached a high of 1,260 megawatts.

Normal summertime peak demand is around 1,200 megawatts, Pai said.

"We're kinda opposite of the Mainland where daytime peak typically is greater than the evening peak," he said. "That's because we have no real heavy industry to speak of here," which puts a high demand on electrical power during the daytime work hours.

Instead, many Oahu residents work in air-conditioned comfort during the day and then return home at night to homes that have been locked and collecting heat all day.

National Weather Service records show that Oct. 7 was not a particularly hot day, with the mercury topping out at 86 degrees.

But the humidity averaged 72 percent and a steady on-shore wind was blowing out of the southeast and southwest.

Translation: All of the variables combined to make it feel unbearably hot and miserably sticky.

Despite the highest demand level of the year, HECO never came close to having the demand for electricity outstrip the company's ability to produce it.

"There's a reason why October is 'Energy Awareness Month,' and it's really taken off here," Pai said.

In addition, a new power plant is up and operating at Barbers Point specifically to meet peak demand.

EFFICIENT SYSTEM

And HECO's "Energy Scout" program that uses radio signals to turn off residential and commercial water heaters during periods of peak demand has been extended to large central air conditioning systems as well.

"Most of the time, the customer never even notices," Pai said. "The water is already heated in their tanks," and the power, if it is switched off, is switched back on before the last of the heated water is used, Pai said.

The Energy Scout program was put into operation several times over the past summer and fall months, not to stave off an impending rolling blackout, but to keep from having to fire up additional generating units to boost the amount of available electricity, Pai said.

"We're trying to run the system as efficiently as possible," he said.

And then there's the economy.

With less money to spend even on basic commodities, consumers have wised up and are quicker to turn off unneeded lights, take shorter showers and use fans instead of room air conditioners, Pai said.

He has his own theory on why energy use can ramp-up on Oahu during muggy, kona-wind weather.

"A lot of it has to do with what the weather was like leading up to those kinds of days," Pai said.

"If the trades are blowing and it's not really that humid, you feel cool."

But then the wind switches around and warm, moist air blows in off the ocean and general misery sets in.

It's then that the appetite for energy soars.