California Power Reserves Drop, Prompting Warning

A drop in California’s electricity reserves again triggered a “Stage Two” emergency in the state after a nuclear plant was shut Monday because of faulty testing equipment.

The drop in reserves to below 5% prompted the California Independent System Operator, the agency that manages the state’s electricity system, to declare the emergency for the fourth time in seven days. Unusually cold weather has increased heating demand, and other electricity generators have closed for maintenance.

Diablo Canyon 1, a nuclear plant in Avila Beach, owned by PG&E; Corp.’s Pacific Gas & Electric, shut down at 4 a.m. Monday. The reactor closed because of a false warning from testing, utility officials said.

The plant produces 1,073 megawatts of power. One megawatt is enough to light 1,000 homes. The plant had reopened Friday after being shut since Oct. 8 for refueling. It had reached about 50% of its generation capacity before the false alarm.

“It’s too early to tell when it’s going to get back to full power,” Diablo Canyon spokesman Jeff Lewis said. The plant is on “hot standby.”

The ISO declared a Stage One emergency when reserves dropped below 7% at 5:30 a.m. Stage One emergencies gave way to Stage Two alerts three times last week. During Stage Two emergencies, power is cut off to some large customers who pay lower rates in exchange for losing some or all of their power when reserves are low.

Generators usually close for maintenance in October and November after running at full capacity during July, August and September to power air conditioners.

About 11,200 megawatts of generating capacity are offline today, ISO spokesman Patrick Dorinson said.

In Northern California’s Napa Valley and Sonoma County, temperatures fell to around 32 degrees Sunday night, about 10 degrees lower than normal for this time of year, said Jim Carroll, a meteorologist with the National Weather Service.

The cold snap has hit the Pacific Northwest as well. The region often exports power to California during the year’s hottest months, and then imports power during the coldest.

“We’re actually looking at the possibility of importing, and we’re not sure it’s going to be there because they don’t have it,” said Ed Mosey, spokesman for the Bonneville Power Administration, which operates 80% of the high-voltage transmission lines in the Northwest United States.

The power that BPA markets is from hydroelectric plants, which have been hurt by one of the driest Novembers on record, Mosey said. BPA is based in Portland, Ore.

At the same time, California has been importing power from the region, which is unusual at this time of year.

The ISO expected peak demand of 32,900 megawatts at about 6 p.m. Monday. The Stage Two warning was to be in effect through 9 p.m. Monday, the ISO said.

Edison International shares fell 19 cents to $23.44 Monday. Edison International is based in Rosemead. San Francisco-based PG&E;’s shares closed unchanged at $28.63.

A Stage Three emergency is declared when California’s power reserves drop below 1.5%. In these conditions, utilities might institute rolling blackouts, which rotate power outages from one group of customers to another, so that no one group loses its power for long. Since the ISO assumed control of California’s power grid in March 1998, it has never declared a Stage Three emergency.