July 2 California's power grid operator urged customers in the northern part of the state to conserve energy for a second day on Tuesday as residents crank up air conditioners to escape a heat wave blanketing the region.
The California ISO, which operates the grid in most of California and Nevada, forecast peak demand topping 47,100 megawatts (MW) on Tuesday and 47,200 MW on Wednesday. It had forecast a peak of about 46,000 MW on Monday.
The state's all-time record was 50,270 MW, set in July 2006 before commercial and industrial usage of electricity was reduced during the economic crisis.
The ISO has several options to reduce power usage before it gets to the unlikely step of calling for rolling blackouts, but an unexpected shutdown of big power plants or transmission lines could force the grid operator to act, especially with wildfires raging in the west.
The ISO has not called for rolling blackouts since the Western energy crisis in 2000-2001, when market manipulation by energy traders like Enron caused a shortage of electricity.
Temperatures in Los Angeles, California's biggest city, will reach 90 degrees F (32.2 C) on Tuesday, about 8 degrees above normal for this time of year, and 87 on Wednesday, according to Accuweather.com.
The mercury in San Jose, the biggest city in northern California, will hit 96 degrees on Tuesday, 15 degrees over normal, before sliding to 87 on Wednesday, AccuWeather.com said.
On Monday, power prices in California markets for Tuesday delivery jumped to at least five-year highs in the $100s per megawatt hour. Power traders, however, said prices for Wednesday delivery fell to the $60s and $70s.
The California ISO issued an alert for northern California on Sunday that is still in effect due to heavy demand for power and the continuing outage of the state's biggest power unit, PG&E Corp's 1,122-MW Diablo Canyon 1 nuclear reactor.
Generating resources in California are below par after the permanent closure in June of the 2,150-MW San Onofre nuclear power plant and the unexpected closure last week of Diablo Canyon.
Diablo Canyon was trying to come back on line on Tuesday.
PG&E Corp is the biggest utility in California, serving about 5.1 million customers in the northern and central parts of the state.
The other big utilities are Southern California Edison, a unit of Edison International that retired the San Onofre reactors, and San Diego Gas and Electric, a unit of Sempra Energy.
Power traders said the heat wave was hitting northern California harder than the southern part of the state because of the Diablo Canyon reactor outage.
North American reliability coordinators in the spring warned California could face "operational challenges" from the shutdown of San Onofre, and that a prolonged heat wave could force utilities to use rolling blackouts in the San Diego and Los Angeles areas to keep the grid reliable. (Editing by Jeffrey Benkoe)