State forecasts possible power supply woes

Southern California utilities have at least a 20% chance of being forced to curtail power supplies to some customers next summer to maintain the reliability of the power system, state regulators said.

The forecast covers the area south of Bakersfield and indicates that utilities may be required to reduce supplies to customers who agree to cuts in times of emergencies in exchange for lower rates.

The territory is served by Southern California Edison Co. and San Diego Gas & Electric Co. The Los Angeles Department of Water and Power, which serves the city, wasn’t included because the municipal utility does its own power planning. The projection was unveiled Monday at a meeting of the California Energy Commission and the California Public Utilities Commission in San Francisco.

The state declared power emergencies three times in July as a heat wave led to record demand for electricity. California’s utility regulators this year directed Southern California Edison to install by summer 2007 additional power plants that are designed to run at times of peak demand.

Excluding plans to add plants and new conservation programs, the probability of supplies being curtailed is about 37%, David Ashuckian, a manager with the California Energy Commission’s Electricity Analysis Office, said at Monday’s joint meeting.

Power curtailments may occur during Stage 2 emergencies, which are called when the reserve margin, a measure of surplus power, drops below 5%. Rolling blackouts may occur under Stage 3 emergencies, when the reserve margin falls below 1.5%.

There is a 1% to 6.7% probability of a Stage 3 emergency for Southern California next summer, depending on the availability of the planned power plants, Ashuckian said. There is a 40% to 47% probability of a Stage 1 emergency, which is a public call for conservation and occurs when the reserve margin falls below 7%.

The forecasts take into account the likelihood of extreme weather and outages at power plants and transmission lines.

There have been 11 Stage 2 emergencies in California in the last five years and two Stage 3 emergencies, Ashuckian said.

Southern California Edison is owned by Rosemead-based Edison International, and San Diego-based Sempra Energy also owns a utility serving the region, San Diego Gas & Electric Co. PG&E; Corp.’s utility, Pacific Gas & Electric Co., serves Northern California, which is considered to have adequate power supplies.