Hawaiian Electric Co.'s urgent call last night to O'ahu residents to conserve power was a symptom of an "energy crunch" born of soaring customer demand and insufficient generators, company officials said.

HECO warned customers about 5 p.m. that it may have to cut power to as many as 50,000 homes for several hours to avoid shutting down power to an even greater number of the company's 292,000 O'ahu customers.

The outages were averted when customers heeded HECO's calls to conserve, but the near miss signals a larger problem for the power company.

"Even if we lost a small unit, we would be in trouble," said HECO spokesman Peter Rosegg.

With the booming local economy, demand for electricity has ballooned in recent years while HECO's generating capacity has stagnated.

The local utility said its power reserves have tumbled from about 30 percent more capacity than needed in the early 1990s to about 20 percent today, giving the company less of a cushion when events such as earthquakes, high winds or other damaging events occur.

Rosegg said the company is trying to address this "energy crunch" through the construction of a $130 million power plant at Campbell Industrial Park.

LARGER CAPACITY

The 110-megawatt plant, which requires regulatory approval, would add much-needed generating capacity and would ease the strain on HECO's aging generators, some of which have been operating since 1947.

HECO said it hopes to complete the plant by mid-2009.

"If that unit had been in place, we'd have a much better chance of riding through this problem," Rosegg said.

According to HECO, several factors played a role in Thursday's close call.

The high winds and rough surf of the past few days caused massive amounts of seagrass to seep into the cooling system of HECO's Kahe Power Plant along the Wai'anae Coast.

The company said the seagrass clogged the turbines' cooling system, forcing plant operators to run the generators at lower-than-normal capacity.

Workers spent most of the day cleaning the filters and clearing debris from the cooling system, and by lunch time had collected more than six dumpster loads of marine debris from the plant.

Three of the company's generators — including units at HECO's Downtown, Waiau and Kahe power plants — were off line for planned maintenance, and a fourth operated by HECO's independent power producer AES Hawaii went down when a boiler tripped. AES operates two 90-megawatt coal-fired turbines at Campbell Industrial Park.

MORE MAINTENANCE

According to Rosegg, HECO's older generators require more maintenance than new ones and take more time to service.

If service had been cut off, HECO said it had planned to cut power to part of Windward O'ahu, north central O'ahu around Waialua and East O'ahu from Kahala to Waimanalo.

The near-outage is just the latest shortfall faced by HECO. Last June, the company was forced to cut power to about 37,000 customers because of soaring demand.

The company also made urgent calls to consumers in January 2005 when usage was getting too high.

Earlier this week, power was cut to 25,000 to 45,000 mostly Windward O'ahu customers because of winds of up to 69 mph. The high winds knocked branches into power lines, causing them to short out.

Reach Rick Daysog at rdaysog@honoluluadvertiser.com.